Well the second cabinet/case is on its way. I have no excuses now! So, I will start this weekend prototyping the various sections on the circuit on my PDB and then I may build the audio section on a separate breadboard to test it. It looks like I may be having the face plates milled via CNC. That will certainly give much more professional results than me using a Dremel, File and drill.
The Bi-Color LED thing will depend on one thing…How well the LEDs I have match up for brightness between Red/Green using a single current resistor. I am one of those people who, when using multiple LEDs in a circuit I tend to try and match them for brightness, since sometimes I get one that is a little brighter or dimmer. In the middle of an array of LEDs that can stick out visibly. If my 74HC595 test this weekend works out I will do it. Of course the down side is the necessity to double the audio switching circuit, so in the end that may dissuade me from doing it.
In any event I will get the logic stuff done and work on the other stuff over time. I would like to get the menus and other options in so I can properly allocate memory both on the BS2p40 and the DS1302 RAM. I think I will start the program templates today just to have them ready. Hey, when you wake up, I'd like to hear any ideas that you have...Maybe there is something else I could do that I am not thinking of which would be more important than older ideas. As it is I was asked why I am bothering with a Tape Monitor circuit. My thoughts are that I will at least have separate record output jacks.
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this would be my first post in this thread and even the board itself, I have gone though the thread and have found it very interesting. Particularly application of MPC50x for signal switching, I along my friend did develop preamps using PIC micro devices PG231x, vfd, and few buffers.
But one thing was unique about the project that it had QS5.1 chip in it, which is processor by QSound and produces 5.1 out from any stereo source.
Any ways enough about·our project, I would be interested in seeing schematics of the project and may be I could help in some ways including parts (which I have·got tons lying around).
So I would appreciate if Dave or·Chris could take the initiative in welcoming someone new to the thread.
If anyone is interested is an extremely linear 12AX7 tube preamp in a stereo set up, try to find a dual Textronic Tube Oscilloscope plug in pre-amp. Years ago, I had several for one very large boat anchor scope.
So as a lark to impress an audiophile friend, I stripped one module out and and found that the dual pre-amps with all the linear compensation from 0 to 20mHz [noparse][[/noparse]a little high for audio] were on one circuit board. I just had to build a power supply for the tubes HV and heaters that was rock solid. Everything else is on one 6" by 6" board.
A very clean hack.
By the way, the circuit board included silver wire for condutors. Take a look around E-Bay for old scope plug-in preamps. HP stuff will probably do the same.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Welcome to the forums…As you have no doubt noticed a few of us are really into home-brew audio amplifiers, however we all suffer the same “lack of time” for much of it. I recently purchased two Aluminum Audio Enclosures from a store on eBay and am just waiting to get them milled out. I am also getting PCBs made for each cabinet at which point I will get them assembled. As I go I will be documenting the build as I always do on Projects. Any input or information you want to share is welcome. Anything we can offer we will. Take care.
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Junkie, welcome indeed. I've had my hobbies on hold as of late, since work and an impending wedding have taken over most of my waking hours, but I'm glad someone else jumped into what had become Chris' and my chat thread
Kramer-
I've actually done the same thing. Any 500 series plugin would be a good start. I used a single channel version for a bass preamp. I loved it...until I dropped it down a flight of stairs and it was damaged beyond repair.
-dave
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Its nice to find like minded "decent people" here which are becoming kinda scacrce at many of the boards.
Anyways same problem with me that my job keep me tied up (that happens when one becomes regional head of sales of a large invetment bank), but i keep trying to make something new.
Amp, pre-amp, DAC, CDP, whatever
For the PCB stuff I think I have enough amp designs lying around to last for years, as for PCB fabrication I am lucky to have all three option toner transfer, Photo Resist boards, and availability of a cheap fabrication unit in my city.
Even parts and LCD modules I could get from my vendors at good prices, no need to buy bulk quantities.
Here's a view of some of my collections
So I ll try to help as much as I could, but I would appreciate schematics of the mentioned pre-amp employing MPC50x chips, coz I am working on a new pre these days and would love to have the idea of MPC50x usage and its noise performance versus normal relays.
Junkie said...
Here's a view of some of my collections
That's a lot of equalization!
Junkie said...
So I ll try to help as much as I could, but I would appreciate schematics of the mentioned pre-amp employing MPC50x chips, coz I am working on a new pre these days and would love to have the idea of MPC50x usage and its noise performance versus normal relays.
Well, my pre schematics are going to stay under wraps for a little longer, since the project as a whole is still being considered as a submission by a few project magazines, but I'm happy to help in any other way. Basically, the 507 I used was set up exactly as intended, as a 2x8 differential analog mux. I fed it a balanced signal, and it sent it where I asked. The interface is incredibly simple, with what amounts to a 3 to 8 line decoder with an enable as the control interface on the chip. THD and noise were below mesaurable limits on my test fixture when I did the evaluation (0.004%). It desperately wants to be buffered at both it's input and output with high quality op-amps. The input buffer should present as low an output impedance as possible, and the output buffer should present a very high input impedance. I used an OP27 and a FET input op-amp I can't remember for mine, respectively. Other than that, everything you need to know is in the datasheet.
Anything else?
-dave
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I should be able to start getting some boards made soon. I will start on the schematics for the specifics either this weekend or next weekend (since I have a few other unfinished projects) and then work on the PCB. There should be about 5 boards unless I condense some of it. Main power supply, Controller Power Supply, Main Amplifier, Pre-Amp/Switcher, Control Board. That will take me a little time to get done though. I will probably work on the power supply and control boards first until I have the audio stuff tuned, then I will get those boards made.
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Ooh...progress! I can't wait to see! I'm really looking forward to your pre/switch box.
My only progress to report is that I'm designing more PCBs for my homemade flight sim cockpit. It'll be a loooong time before I get them made (there's a project backlog of epic proportions right now) but it's fun to plan.
-dave
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He he thats me, initially I intended to use these chips in my 5.1 pre and every other version of pre but then again you guys understand that planning is one part and materliaizing the plan is another so these chips will lie around for eternity....
Chris:
what software you use for schematics and layouts (reason is I have some PSU designs, should you need them I could email them to you, P.S I use Protel DXP SP2)
Heres how I connect different boards, hope you guys like it. Sorry for picture quality coz I took them with my iMate.
Dave thanks for your inputs, but for now I think I should stck to my Relays based signal switching coz adding more buffers would make the pre too complicated, however, may be I decide to build a signal switching project around SSM2404 or MPC50x chips and smaller PIC like 16F84A.
Dave thanks for your inputs, but for now I think I should stck to my Relays based signal switching coz adding more buffers would make the pre too complicated, however, may be I decide to build a signal switching project around SSM2404 or MPC50x chips and smaller PIC like 16F84A.
Understandable. I ended up doing little SMT boards for each '507, with the buffers all integrated, so all I had to do was plug them into a pair of headers I soldered onto my main board, kinda like giant DIPs. It was pretty easy, but I designed it that way from the ground up. Swapping them in for relays would be a bit of a pain.
FWIW, I use Eagle at home, and Altium Designer at the office (it's the genesis of DxP, currently we're at some 6.6.x version). I prefer Altium, but can't afford a seat for my house.
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This is not a sig. This is a duck. Quack.
For PCB layout I had Protel available at one time, however in the interest of being able to share with those who could not afford larger packages I actually started using ExpressPCB for the quick and simply stuff and Eagle recently to try and get things more polished and include schematics. Before with ExpressPCB I would hand-draw the schematics.
Dave, as I said above, there are a couple of other projects which will come first. Fortunately they are pretty much done but I need to get schematics and parts lists together along with source code for publication. Once those are done I can start on the Amp boards. The cabinets won’t be milled completely until I know exactly what I will be using. As a side-note I will attempt to use the VFD on the controller. We’ll see how well it works out.
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Lucky for me I have got almost every software for layout Protel DXP 2004 SP2, EAGLE, PROTEUS VSM,all registered just dont ask how, I did use express PCB but you know it limits. I like DXP 2004 better than Altium Designer coz later is extremely resource hungry.
As promissed here are schematics and layouts of PSU for preamp (dxp files), along bridge and monoblock of OPA549 (pdf format)·hope they would be of help to others.
Thanks, but how does on view the schematic??? I do not have the program to read em...
The reason I ask, is that a pre-amp/power-amp is one of the projects I will be starting this spring...
I like the idea of a class D, or the T-amp, and plan on a pre-amp/ switcher to complete the project,
which will be hooked up to a Mini/Nano ITX multimedia system... I haven't decided how many channels yet.
Junkie said...
Lucky for me I have got almost every software for layout Protel DXP 2004 SP2, EAGLE, PROTEUS VSM,all registered just dont ask how, I did use express PCB but you know it limits. I like DXP 2004 better than Altium Designer coz later is extremely resource hungry.
Probably true....my workstation here at the office is a dual proc 3.2GHz monster with 2GB of RAM, and some things take a little while, but I find it so much more reliable than 2004 was...I can't tell you how much work I lost to crashes and corruption in the older versions of DxP. It might have just been me, but the flurry of updates they pushed out before 6.x appeared....
The files worked fine for me....
-dave
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You need protel DXP 2004 and later to views those files.......
workstation here at the office is a dual proc 3.2GHz monster with 2GB of RAM
·holy smokes, yummy I would love to put my hands on this machine.
BTW I am changing my home PC to dual core Intel with 4 GB RAM and dual 120GB SATA HDDs hopefully after that I ll give Altium Designer a try.
Dave I am looking forward to have glimpses on schematics of your project, which I think would be one hottie.
Since I was on leave yesterday due to backache therefore I found time to fiddle with MPC50x·for a·signal switching and I guess the code is alright·coz it worked fine in the simulator.
More details later.
BTW yesterday I recieved these awesome VFD's 40x2 (1) and 20x2 (3) and man they are good.
Yup, it's a pretty awesome workstation, but the boards I do still tax it. I just spent 3 minutes waiting for a ground pour to regenerate on my latest effort, watching the CPU meters peg the whole time. No matter how fast the hardware gets, the software guys will always find a way to make it slower
The schematics really aren't that impressive....just a 507, some inputs fed with THAT1606s (RCA inputs) and some with XLRs hung off of them and double buffered with OPA2604s. Duplicate that for the other stereo channel, and add 2 more buffered 507s (2604s again) for single ended surround channels (LS, RS, C, S), control it with a BS2, add a 2x20 VFD and a 32 position rotary encoder and a few buttons, and you're done. The hard work was on the low noise board layout, the tweaks to the DC servos I added at the main outs (not necessary, but I wanted them there anyway), and the software. The actual block design is cookbook in nature.
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What make are the VFD’s you mentioned? The ones Dave and I were talking about are Noritake. I have both a 2X16 and a 4X20, both with graphics capability. One will be the lucky display.
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Dave: its a nice configuration and i think it will be a good piece of hardware. Hope you have used an encoder with a push button that way its easier to access menus.
Chris the VFDs are CU40026SCPB-T20A and NA202MD13AA , first one is an obsolete one with serial and parallel interface, and second one is i guess LCD compatible havent used them so far but i think if they have parallel or serial interface i could hook them up with the Pre. Pulled the first one off ebay for 10.5$ and others hunted by a friend in Newyork. Though I have a few 20x4 lcds but I want to use VFD in my pre.
As for mcu though I have used BS2, but based upon speed I opted for a PIC mcu at 20MHZ.
It seems that you guys have already made final designs of PCBs and for me I am waiting for double sided pre-sensitized boards to arrive (which would be coming any time today), once the prototype works fine I may opt to order a few ones from the production house.
My config is a 6x2 input selector (relay based), a PCM270x USB DAC, a QS5.1 processor with output buffers, PGA2310 with output buffers and relays at output to prevent from poweroff thump, a switched rotary encoder by ALPS, 6 buttons for pre, and 2 for USB DAC. a VFD and for buttons i still want buttons having LEDs inside them, PIC id dual powered so that volume could be saved and a power button to bring PIC chip to life.
for power I have a 5 channel OPA549 and bridged 549 for the sub.
Actually, the VFDs I originally used were from Futaba. The one occupying my desk right now though is a Noritake 4x20 intelligent. Very nice indeed.
Junkie-
I actually haven't made any boards for my preamp since the v1.0 I did for my senior design project in college (6 years ago). Everything since then was done entirely electronically.
Nope, no pushbutton on my encoder yet...maybe in the next rev, if I ever build it. My need for real live surround decoding has made me rethink the application of my pre over the last year. It'll probably end up slimmed down a bunch for the den or bedroom now...maybe. Things are always open for negotiation until I start soldering.
I'm a big fan of the services offered by Advanced Circuits. Check out http://33each.com for a nearly unbeatable deal for double sided boards with top and bottom silk, soldermask, plated through holes and vias, and 7 mil line/space limits...oh yeah, 3 boards (panelize/depanelize them yourself up to the size limit to save $$) for $99.
The OPA549 looks a lot like the LM3886s Chris and I are so familiar with. Nice choice
Have you checked out the SX series chips at all? I know we're in the sandbox, but as a long time devotee to Parallax, I like to push their stuff when I can I use the BS series, SX, and Atmels...my experiences with PICs have been less than wonderful, mostly due to their memory systems. How are you dealing with the RAM?
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Futaba is nice but the one I could get from RS Pakistan (thats where I live) costs about $430 for a 20x4 , 5 mm characters VFD so I guess ebay would be a better choice, and some small component shop in Newyork, LCD of 20x4 costs about 8$ here, but then again VFD is VFD.
Ahan and I thought that you have finalized your PCBs .
Well for :
real live surround decoding has made me rethink the application of my pre over the last year said...
Have a look at QS5.1 datasheet I think instead of fiddling with a STA310 and trying to figure out how to get it working QS would be a much better choice I could post the datasheet, but then again dont want to violate any copyrights
Advanced Circuits seem a good choice but a photoresist double side board costs me 30$ for 12x12 inch board, and production house with same specification for a 12x12 inch board would cost around 144$, which in fact is 1$ per square inch.
For BS2 SX, though I have used BS, but based on a cost benefit analysis I have opted for PICs due to the following reasons:
BS are not available here,·I have to purchase them from international vendors, then pay atleast 30$ shipment cost and then import duties and taxes worst of all waste hours in customs justifying·why I need it.
Since PICs are available here from 3$ to 12$ range I think its more viable.
for Atmel Chips though they are availabe here too but·due to shortage of time I could'nt afford to spend time in learning their assembly or·debugging Bascom AVR code.
Managing PICs RAM is kinda tricky but I think·PIC Basic Pro does a lot for people like me who are always short of time.
I understand that this is Parallax forum but unfortunately due to mentioned reason I couldnt opt for BS in most of my applications, though the later offers many advantages as well.
If I had your email I would email you and chris menu logic I use with button based encoder.
mine is rehanabid at the rate of gmail dot com.
As you mentioned about 3886 I have a few amps made out of these chips and appreciate their quality but many a time I end up with Fake chips made in china which have such low quality and fry up fast, therefore, OPA and TDA729x are my choices.
Here is·PCB layout for·monoblock of LM3886. Hope you could provide feedback on it.
Junkie said...
Have a look at QS5.1 datasheet I think instead of fiddling with a STA310 and trying to figure out how to get it working QS would be a much better choice I could post the datasheet, but then again dont want to violate any copyrights
I actually found the QS5.1 a while back, and gave it some thought, but after experiencing real live 7.2 decoding in a friend's living room, I'm pretty much hooked. Hopefully there's an Anthem AVM-40 in my future.
The 3886 monoblock looks pretty good. Nice fat traces.
As far as counterfeit chips, have you tried National's sample service? It's not fast, but the chips ship direct from National Semiconductor for the cost of postage. It might be a way to get reliable samples. Believe it or not, I've even run across fakes here in the US from tier 1 distributors (Newark and Digikey, both of whom were very quick to find and fix the problem). It's a problem everywhere.
The best way to get things to me is via PM here....my inbox is crazy full, and my spam filter is a little hyperactive as a result.
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This is not a sig. This is a duck. Quack.
I have a Rotel and a creative AVR, but who would call me a DIYer if i dont make one for myself
Thanks for commenting on 3886, do you think anything could be improved.
Unfortunately for me none of the chip manufacturer supports a sample program to my country, except maxim-dallas. So only option is commercial purchase and if I need larger quantities like 50 or more I could get them from authentic dealers, so no regrets just avoid whatever fake material I could. At times this fake things might come in handy, particularly when it comes to LCDs and components etc.
Believe it or not, I've even run across fakes here in the US from tier 1 distributors (Newark and Digikey, both of whom were very quick to find and fix the problem).
and i thought it was a problem only in this part of the world.
Well I ll try to PM you and chris menu logic used for the program, hope it would be of use to you.
Something that has been bugging me over the weekend was usage of MPC50x, though technically speaking I have made the software to work and make desired switching (at least in the simulation model).
However, I am a bit confused whether to use MPC as a single ended input switching solution or B.L, if later is selected how to balance the inputs without using something like DRV134, as you know that CD, DVD, Tuner, iPod, etc may not have balanced outputs.....
Something that has been bugging me over the weekend was usage of MPC50x, though technically speaking I have made the software to work and make desired switching (at least in the simulation model).
However, I am a bit confused whether to use MPC as a single ended input switching solution or B.L, if later is selected how to balance the inputs without using something like DRV134, as you know that CD, DVD, Tuner, iPod, etc may not have balanced outputs.....
I used the chip as the datasheet intended...either all balanced, or all single ended. If I needed to mix the two, I balanced unbalanced inputs with a ThatCorp balanced driver, as you said.
Your other option, and one that is used in a lot of very high end 'balanced' equipment, is to unbalance the inputs that come in balanced, using high quality balanced line receivers (ThatCorp again...can you tell I like them? ), and leave the unbalanced inputs unbalanced. No one will look down on you for that. If companies like Tag Maclaren and EAD and Krell can do it, you can too. It's also a lot easier to design boards and pay for parts when you don't artificially double your piece count.
There is a third option....use two units, one for balanced inputs and one for normal, unbalanced ones, and only do the bal/unbal conversion once, right at a summing buss before your main output amplifier.
-dave
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This is not a sig. This is a duck. Quack.
The Noritake you originally got me interested in I believe is the one I have. As soon as I start on it I will start posting pictures and you will see it in action. Currently I am trying to optimize the layout of the display for certain things so I don’t ruin everything with a trashy display. Ditto on the LM3886…I have used these since just prior to them being available, including several variants and through the changes of their specifications. But this OPA549 looks worth checking out too.
Junkie,
You mentioned a friend in NY…That is where I am from myself (upstate). I agree that the VFD would look great (and be useful) on the Pre-Amp. There will only be one visible thing on the front of my Power Amp and that is the output meters. And this is if I come up with a configuration I like (layout, type of LED). I will be using the LM3914 with a circuit I posted to this thread some time ago. I am using a Rotary Encoder with a pushbutton. It is a Grayhill unit which is actually optical inside rather than mechanical. I believe it is only 16ppr since I am using a BASIC Stamp in my design.
BTW, I could not get the PDF to open…
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Dave thanks for your inputs I ll try to implement them, but due to limited grey matter inside my skull I think it will take another month or so for me to completely implement it. I only want to use unbalance option so one MPC would be enough. ·
Chris·you would like to check the follwoing link: http://www.primelec.com/Shop/Control/fp/SFV/31734
and search for VFD
BTW if you could buy a couple extra I might want to get a few more and later we could agree on some trade...
My experience with LED bar graph is that they do tend to produce noise and proper isolation of signals is necessary, Here are some of the specifications I have shortlisted so far:
MPC50x for signal switching followed by 5532 buffers, Tone control build around AD5206 or AD5204 and OPA134, followed by buffer, PGA/CS, and output buffers around OPA627, menu, menu+/-, vol +/- buttons, IR, Encoder and VFD..
Sounds too many things afraid that code is gonna go beyond 14K limit but lets see.
Chris I am uploading LM3886 layouts along OPA549 stereo version hope you get the download link right this time.
Comments
The Bi-Color LED thing will depend on one thing…How well the LEDs I have match up for brightness between Red/Green using a single current resistor. I am one of those people who, when using multiple LEDs in a circuit I tend to try and match them for brightness, since sometimes I get one that is a little brighter or dimmer. In the middle of an array of LEDs that can stick out visibly. If my 74HC595 test this weekend works out I will do it. Of course the down side is the necessity to double the audio switching circuit, so in the end that may dissuade me from doing it.
In any event I will get the logic stuff done and work on the other stuff over time. I would like to get the menus and other options in so I can properly allocate memory both on the BS2p40 and the DS1302 RAM. I think I will start the program templates today just to have them ready. Hey, when you wake up, I'd like to hear any ideas that you have...Maybe there is something else I could do that I am not thinking of which would be more important than older ideas. As it is I was asked why I am bothering with a Tape Monitor circuit. My thoughts are that I will at least have separate record output jacks.
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Chris Savage
Parallax Tech Support
this would be my first post in this thread and even the board itself, I have gone though the thread and have found it very interesting. Particularly application of MPC50x for signal switching, I along my friend did develop preamps using PIC micro devices PG231x, vfd, and few buffers.
But one thing was unique about the project that it had QS5.1 chip in it, which is processor by QSound and produces 5.1 out from any stereo source.
Any ways enough about·our project, I would be interested in seeing schematics of the project and may be I could help in some ways including parts (which I have·got tons lying around).
So I would appreciate if Dave or·Chris could take the initiative in welcoming someone new to the thread.
Cheers.
Post Edited (Junkie) : 2/21/2007 9:45:15 AM GMT
So as a lark to impress an audiophile friend, I stripped one module out and and found that the dual pre-amps with all the linear compensation from 0 to 20mHz [noparse][[/noparse]a little high for audio] were on one circuit board. I just had to build a power supply for the tubes HV and heaters that was rock solid. Everything else is on one 6" by 6" board.
A very clean hack.
By the way, the circuit board included silver wire for condutors. Take a look around E-Bay for old scope plug-in preamps. HP stuff will probably do the same.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
Welcome to the forums…As you have no doubt noticed a few of us are really into home-brew audio amplifiers, however we all suffer the same “lack of time” for much of it. I recently purchased two Aluminum Audio Enclosures from a store on eBay and am just waiting to get them milled out. I am also getting PCBs made for each cabinet at which point I will get them assembled. As I go I will be documenting the build as I always do on Projects. Any input or information you want to share is welcome. Anything we can offer we will. Take care.
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Chris Savage
Parallax Tech Support
Kramer-
I've actually done the same thing. Any 500 series plugin would be a good start. I used a single channel version for a bass preamp. I loved it...until I dropped it down a flight of stairs and it was damaged beyond repair.
-dave
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This is not a sig. This is a duck. Quack.
Anyways same problem with me that my job keep me tied up (that happens when one becomes regional head of sales of a large invetment bank), but i keep trying to make something new.
Amp, pre-amp, DAC, CDP, whatever
For the PCB stuff I think I have enough amp designs lying around to last for years, as for PCB fabrication I am lucky to have all three option toner transfer, Photo Resist boards, and availability of a cheap fabrication unit in my city.
Even parts and LCD modules I could get from my vendors at good prices, no need to buy bulk quantities.
Here's a view of some of my collections
So I ll try to help as much as I could, but I would appreciate schematics of the mentioned pre-amp employing MPC50x chips, coz I am working on a new pre these days and would love to have the idea of MPC50x usage and its noise performance versus normal relays.
Cheers.
Post Edited (Junkie) : 2/22/2007 10:07:59 AM GMT
That's a lot of equalization!
Well, my pre schematics are going to stay under wraps for a little longer, since the project as a whole is still being considered as a submission by a few project magazines, but I'm happy to help in any other way. Basically, the 507 I used was set up exactly as intended, as a 2x8 differential analog mux. I fed it a balanced signal, and it sent it where I asked. The interface is incredibly simple, with what amounts to a 3 to 8 line decoder with an enable as the control interface on the chip. THD and noise were below mesaurable limits on my test fixture when I did the evaluation (0.004%). It desperately wants to be buffered at both it's input and output with high quality op-amps. The input buffer should present as low an output impedance as possible, and the output buffer should present a very high input impedance. I used an OP27 and a FET input op-amp I can't remember for mine, respectively. Other than that, everything you need to know is in the datasheet.
Anything else?
-dave
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I should be able to start getting some boards made soon. I will start on the schematics for the specifics either this weekend or next weekend (since I have a few other unfinished projects) and then work on the PCB. There should be about 5 boards unless I condense some of it. Main power supply, Controller Power Supply, Main Amplifier, Pre-Amp/Switcher, Control Board. That will take me a little time to get done though. I will probably work on the power supply and control boards first until I have the audio stuff tuned, then I will get those boards made.
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Chris Savage
Parallax Tech Support
My only progress to report is that I'm designing more PCBs for my homemade flight sim cockpit. It'll be a loooong time before I get them made (there's a project backlog of epic proportions right now) but it's fun to plan.
-dave
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Chris:
what software you use for schematics and layouts (reason is I have some PSU designs, should you need them I could email them to you, P.S I use Protel DXP SP2)
Heres how I connect different boards, hope you guys like it. Sorry for picture quality coz I took them with my iMate.
Dave thanks for your inputs, but for now I think I should stck to my Relays based signal switching coz adding more buffers would make the pre too complicated, however, may be I decide to build a signal switching project around SSM2404 or MPC50x chips and smaller PIC like 16F84A.
Understandable. I ended up doing little SMT boards for each '507, with the buffers all integrated, so all I had to do was plug them into a pair of headers I soldered onto my main board, kinda like giant DIPs. It was pretty easy, but I designed it that way from the ground up. Swapping them in for relays would be a bit of a pain.
FWIW, I use Eagle at home, and Altium Designer at the office (it's the genesis of DxP, currently we're at some 6.6.x version). I prefer Altium, but can't afford a seat for my house.
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Dave, as I said above, there are a couple of other projects which will come first. Fortunately they are pretty much done but I need to get schematics and parts lists together along with source code for publication. Once those are done I can start on the Amp boards. The cabinets won’t be milled completely until I know exactly what I will be using. As a side-note I will attempt to use the VFD on the controller. We’ll see how well it works out.
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Chris Savage
Parallax Tech Support
As promissed here are schematics and layouts of PSU for preamp (dxp files), along bridge and monoblock of OPA549 (pdf format)·hope they would be of help to others.
However heres the 549 file zipped.
The reason I ask, is that a pre-amp/power-amp is one of the projects I will be starting this spring...
I like the idea of a class D, or the T-amp, and plan on a pre-amp/ switcher to complete the project,
which will be hooked up to a Mini/Nano ITX multimedia system... I haven't decided how many channels yet.
Bob
Probably true....my workstation here at the office is a dual proc 3.2GHz monster with 2GB of RAM, and some things take a little while, but I find it so much more reliable than 2004 was...I can't tell you how much work I lost to crashes and corruption in the older versions of DxP. It might have just been me, but the flurry of updates they pushed out before 6.x appeared....
The files worked fine for me....
-dave
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BTW I am changing my home PC to dual core Intel with 4 GB RAM and dual 120GB SATA HDDs hopefully after that I ll give Altium Designer a try.
Dave I am looking forward to have glimpses on schematics of your project, which I think would be one hottie.
Since I was on leave yesterday due to backache therefore I found time to fiddle with MPC50x·for a·signal switching and I guess the code is alright·coz it worked fine in the simulator.
More details later.
BTW yesterday I recieved these awesome VFD's 40x2 (1) and 20x2 (3) and man they are good.
Post Edited (Junkie) : 2/28/2007 10:54:49 AM GMT
Yup, it's a pretty awesome workstation, but the boards I do still tax it. I just spent 3 minutes waiting for a ground pour to regenerate on my latest effort, watching the CPU meters peg the whole time. No matter how fast the hardware gets, the software guys will always find a way to make it slower
The schematics really aren't that impressive....just a 507, some inputs fed with THAT1606s (RCA inputs) and some with XLRs hung off of them and double buffered with OPA2604s. Duplicate that for the other stereo channel, and add 2 more buffered 507s (2604s again) for single ended surround channels (LS, RS, C, S), control it with a BS2, add a 2x20 VFD and a 32 position rotary encoder and a few buttons, and you're done. The hard work was on the low noise board layout, the tweaks to the DC servos I added at the main outs (not necessary, but I wanted them there anyway), and the software. The actual block design is cookbook in nature.
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What make are the VFD’s you mentioned? The ones Dave and I were talking about are Noritake. I have both a 2X16 and a 4X20, both with graphics capability. One will be the lucky display.
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Chris Savage
Parallax Tech Support
Chris the VFDs are CU40026SCPB-T20A and NA202MD13AA , first one is an obsolete one with serial and parallel interface, and second one is i guess LCD compatible havent used them so far but i think if they have parallel or serial interface i could hook them up with the Pre. Pulled the first one off ebay for 10.5$ and others hunted by a friend in Newyork. Though I have a few 20x4 lcds but I want to use VFD in my pre.
As for mcu though I have used BS2, but based upon speed I opted for a PIC mcu at 20MHZ.
It seems that you guys have already made final designs of PCBs and for me I am waiting for double sided pre-sensitized boards to arrive (which would be coming any time today), once the prototype works fine I may opt to order a few ones from the production house.
My config is a 6x2 input selector (relay based), a PCM270x USB DAC, a QS5.1 processor with output buffers, PGA2310 with output buffers and relays at output to prevent from poweroff thump, a switched rotary encoder by ALPS, 6 buttons for pre, and 2 for USB DAC. a VFD and for buttons i still want buttons having LEDs inside them, PIC id dual powered so that volume could be saved and a power button to bring PIC chip to life.
for power I have a 5 channel OPA549 and bridged 549 for the sub.
well thats about my design.
Actually, the VFDs I originally used were from Futaba. The one occupying my desk right now though is a Noritake 4x20 intelligent. Very nice indeed.
Junkie-
I actually haven't made any boards for my preamp since the v1.0 I did for my senior design project in college (6 years ago). Everything since then was done entirely electronically.
Nope, no pushbutton on my encoder yet...maybe in the next rev, if I ever build it. My need for real live surround decoding has made me rethink the application of my pre over the last year. It'll probably end up slimmed down a bunch for the den or bedroom now...maybe. Things are always open for negotiation until I start soldering.
I'm a big fan of the services offered by Advanced Circuits. Check out http://33each.com for a nearly unbeatable deal for double sided boards with top and bottom silk, soldermask, plated through holes and vias, and 7 mil line/space limits...oh yeah, 3 boards (panelize/depanelize them yourself up to the size limit to save $$) for $99.
The OPA549 looks a lot like the LM3886s Chris and I are so familiar with. Nice choice
Have you checked out the SX series chips at all? I know we're in the sandbox, but as a long time devotee to Parallax, I like to push their stuff when I can
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Ahan and I thought that you have finalized your PCBs .
Well for : Have a look at QS5.1 datasheet I think instead of fiddling with a STA310 and trying to figure out how to get it working QS would be a much better choice I could post the datasheet, but then again dont want to violate any copyrights
Advanced Circuits seem a good choice but a photoresist double side board costs me 30$ for 12x12 inch board, and production house with same specification for a 12x12 inch board would cost around 144$, which in fact is 1$ per square inch.
For BS2 SX, though I have used BS, but based on a cost benefit analysis I have opted for PICs due to the following reasons:
BS are not available here,·I have to purchase them from international vendors, then pay atleast 30$ shipment cost and then import duties and taxes worst of all waste hours in customs justifying·why I need it.
Since PICs are available here from 3$ to 12$ range I think its more viable.
for Atmel Chips though they are availabe here too but·due to shortage of time I could'nt afford to spend time in learning their assembly or·debugging Bascom AVR code.
Managing PICs RAM is kinda tricky but I think·PIC Basic Pro does a lot for people like me who are always short of time.
I understand that this is Parallax forum but unfortunately due to mentioned reason I couldnt opt for BS in most of my applications, though the later offers many advantages as well.
If I had your email I would email you and chris menu logic I use with button based encoder.
mine is rehanabid at the rate of gmail dot com.
As you mentioned about 3886 I have a few amps made out of these chips and appreciate their quality but many a time I end up with Fake chips made in china which have such low quality and fry up fast, therefore, OPA and TDA729x are my choices.
Here is·PCB layout for·monoblock of LM3886. Hope you could provide feedback on it.
Post Edited (Junkie) : 3/2/2007 8:43:10 AM GMT
I actually found the QS5.1 a while back, and gave it some thought, but after experiencing real live 7.2 decoding in a friend's living room, I'm pretty much hooked. Hopefully there's an Anthem AVM-40 in my future.
The 3886 monoblock looks pretty good. Nice fat traces.
As far as counterfeit chips, have you tried National's sample service? It's not fast, but the chips ship direct from National Semiconductor for the cost of postage. It might be a way to get reliable samples. Believe it or not, I've even run across fakes here in the US from tier 1 distributors (Newark and Digikey, both of whom were very quick to find and fix the problem). It's a problem everywhere.
The best way to get things to me is via PM here....my inbox is crazy full, and my spam filter is a little hyperactive as a result.
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I have a Rotel and a creative AVR, but who would call me a DIYer if i dont make one for myself
Thanks for commenting on 3886, do you think anything could be improved.
Unfortunately for me none of the chip manufacturer supports a sample program to my country, except maxim-dallas. So only option is commercial purchase and if I need larger quantities like 50 or more I could get them from authentic dealers, so no regrets just avoid whatever fake material I could. At times this fake things might come in handy, particularly when it comes to LCDs and components etc.
and i thought it was a problem only in this part of the world.
Well I ll try to PM you and chris menu logic used for the program, hope it would be of use to you.
Signing off to enjoy weekend.
Something that has been bugging me over the weekend was usage of MPC50x, though technically speaking I have made the software to work and make desired switching (at least in the simulation model).
However, I am a bit confused whether to use MPC as a single ended input switching solution or B.L, if later is selected how to balance the inputs without using something like DRV134, as you know that CD, DVD, Tuner, iPod, etc may not have balanced outputs.....
Post Edited (Junkie) : 3/5/2007 7:53:24 AM GMT
I used the chip as the datasheet intended...either all balanced, or all single ended. If I needed to mix the two, I balanced unbalanced inputs with a ThatCorp balanced driver, as you said.
Your other option, and one that is used in a lot of very high end 'balanced' equipment, is to unbalance the inputs that come in balanced, using high quality balanced line receivers (ThatCorp again...can you tell I like them?
There is a third option....use two units, one for balanced inputs and one for normal, unbalanced ones, and only do the bal/unbal conversion once, right at a summing buss before your main output amplifier.
-dave
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The Noritake you originally got me interested in I believe is the one I have. As soon as I start on it I will start posting pictures and you will see it in action. Currently I am trying to optimize the layout of the display for certain things so I don’t ruin everything with a trashy display.
Junkie,
You mentioned a friend in NY…That is where I am from myself (upstate). I agree that the VFD would look great (and be useful) on the Pre-Amp. There will only be one visible thing on the front of my Power Amp and that is the output meters. And this is if I come up with a configuration I like (layout, type of LED). I will be using the LM3914 with a circuit I posted to this thread some time ago. I am using a Rotary Encoder with a pushbutton. It is a Grayhill unit which is actually optical inside rather than mechanical. I believe it is only 16ppr since I am using a BASIC Stamp in my design.
BTW, I could not get the PDF to open…
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Chris Savage
Parallax Tech Support
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12259
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12258
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Chris Savage
Parallax Tech Support
Chris·you would like to check the follwoing link:
http://www.primelec.com/Shop/Control/fp/SFV/31734
and search for VFD
BTW if you could buy a couple extra I might want to get a few more and later we could agree on some trade...
My experience with LED bar graph is that they do tend to produce noise and proper isolation of signals is necessary, Here are some of the specifications I have shortlisted so far:
MPC50x for signal switching followed by 5532 buffers, Tone control build around AD5206 or AD5204 and OPA134, followed by buffer, PGA/CS, and output buffers around OPA627, menu, menu+/-, vol +/- buttons, IR, Encoder and VFD..
Sounds too many things afraid that code is gonna go beyond 14K limit but lets see.
Chris I am uploading LM3886 layouts along OPA549 stereo version hope you get the download link right this time.
Post Edited (Junkie) : 3/6/2007 8:21:33 AM GMT