Homemade AMP Parts List Problem

[Paprika]

Hello Everyone, I have a bit of a problem here.
You see, I am tring to build a Amplifier for my room so I can get better sound out of my things such as my Xbox & Cable Box, Anyway I need a parts list I made up verified to work with the sample schematic provided by STMicroelectronics for the AMP chip i am using, which is the TDA7265 25W STEREO AMP. The sample schematic for a sterio amp setup can be found in the Datasheet which can be found here:
http://us.st.com/stonline/books/pdf/docs/1478.pdf

Now the problem which brings this up is the fact I don't have much experiance with picking out capacitiators, resistors & such things, so I am asking you for your help. Below is the parts list which I have assembled, please tell me what you think, thank you. I have put it in 'code' format to retain the original structure.

Part Name      | Part Number     | Price & Qty| Part # in Schematic & Notes
---------------------------------------------------------------------
Black RCA Jack | Jameco #185842  | $0.12 x 10 | Audio Input
25W Stereo AMP | Arrow #TDA7265  | $4.75 x 1  | Overall Amp Chip
10k Carbon Res | Newark #84N2583 | $0.18 x 3  | R1
15k Film Res   | Newark #84N1584 | $0.07 x 5  | R2, R4
18k Film Res   | Newark #84N1592 | $0.03 x 6  | R3, R5, R8
560 Coat. Res  | Newark #02F2609 | $1.06 x 4  | R6, R9
4.7 Carb. Res. | Newark #84N2432 | $0.06 x 4  | R7, R10
1uf 25v Cap.   | Newark #36C7091 | $0.54 x 6  | C1, C2, C3
1000uf 25v Cap.| Newark #36C7097 | $1.34 x 4  | C4, C6
0.1uf 50v Cap. | Newakr #39C1394 | $0.30 x 8  | C5, C7, C8, C9

Newark = newark.com
Jameco = Jameco.com
Arrow = arrow.com

Thanks in Advance!

[Jeff R]

I see no one has come in to help!

Sorry, but what you are asking will take someone a lot of time to figure out for you. I think you are on the right track with what you have, though DigiKey or Mouser might be a better place than Newark. You might visit Prof. Marshall Leach's web site (do a search) and look up his Leach Amp plans. He has schematics and parts lists, and by studying those you may get some ideas on how to do it. If you have a couple of questions, feel free to come back and ask.

[sam9]

Without troubling to work out exact numbers, here is what I would do:

R7 and R10 should be 2Watt or greater resitors as they will see quite bit of current (1W is probably ok, or even 1/2W but it won't hurt to overdo it). All other resistors can be standard 1/4W. Use 1% metal film if you like, but I doubt you will hear much difference.

C5 and C7 can be ceramic disk. Infact this is the the application (power supply decoupling) where they excell. C1 and C2 are in the signal path - this is a good place for film type capacitors rather than electrolytic amthough they are larger than the footprint shown in the pdf. C4 and C6 are electrolytic and that is appropriate. C3 is not in the signal path and nearly any damn 1uF capacitor will serve there. C8 and C9 would also be metal film.

Since the supply volage will be about 25V, you want the capacitors all rated the next stepo up from that, 35V. This protects them from surges, blips etc when the power switches on and off. The ceralic and metal film caps will be way higher than that anyway so no problen. It's the electrolytics you need to watch.

Cost:
A: check you local phone book to see if there is an surplus electronics supply store near by. The quality is usualy good and while the prices are not neccessarily lower per unit, you won't have to buy 10 resistors to get just one. This is often the case with catalog and on-line sources.
B: If you buy from a catalog or on-line source, try to get everthing from one place. Each one will charge you shipping and handling which on small orders will be more than the components.
C: As another poster says, try Digikey if you buy online. No shipping (or is it handling?) for orders over $25.

On the RCA jacks, check to see whether they are insulated or not. For some wierd reason an awful lot don't come with insulated gromets. If you are going to use these on a metal enclosure, you NEED insulators. Ditto binding posts for connecting the outputs.

You don't mention power supplies. Are you planning to build one? For a first effort and the powewr requirements, take a look at your Jameco catalog. There is a page or two just before or afterthe "wall-wart" transformers that has external table top power supplies. That might simplify things for you.

[Paprika]

Ok, I thank you guys allot!

[Paprika]

Hey, Listen. I am using the Eagle pcb design software, form Cadsoft, i wanted to know if there is a way to force a project to only work on 1 Layer(bottom), so that I can keep the design simple and won't have to construct vias.

Thanks,

[OliverD]

If you route manually, well, you can route everything on the bottom layer - easy.

Autorouting is NOT recommended for audio, and the Eagle autorouter is one of the worst I've come across. But it can also be done: Select the autorouter setup dialog box, go to the "general" tab and select all layers except bottom layer to "N/A" (not available).

[screwdriver]

Did you finally build the amp? did it work?

I'm also building an amp based on TDA7265 and I'm only getting trouble, up to the point I've decided to change the chip.

Does anyone know why there are so few people using this chip?, it looks to me very interesting in its specs.

[sexya]

hey man its a sweet chip..
it was my first amp that i built which was above 2watts and guess what my pcb worked from the first minute and i have been using it for last 4 years and its still going on...
now i have added a digital pre amp to it TDA7439 well hving issues iwht its firmware but hte amp is beautiful
and tda7439 is used by sony in one of its stereos also...
but in sony's case they have used TDA7269 which is mono 25watt chips but mosfet based outputs like the TDA7294 but same family..
hey check your mail and let me knwo what you need
aditya

[nands7]

Guys, i just got my audio preamp built using TDA7439,IICed by a microchip dspic30f2010 with a panasonic rotary encoder connected at i/p.This preamp works fine ,able to change the volume and tones.

My problem is ,i hear a ticking sound whenever i rotate the encoder ,i beleive its something to do with the I2C ground (AGND and DGND)signal breking into analog side.
I even isolated the power to both micro and audio dsp ,but no effect!

DOES all the I2C based audio dsp's give the same effect?
Anybody has similar noise problems?

Please help!

[aditya]

Originally Posted by nands7

Guys, i just got my audio preamp built using TDA7439,IICed by a microchip dspic30f2010 with a panasonic rotary encoder connected at i/p.This preamp works fine ,able to change the volume and tones.

My problem is ,i hear a ticking sound whenever i rotate the encoder ,i beleive its something to do with the I2C ground (AGND and DGND)signal breking into analog side.
I even isolated the power to both micro and audio dsp ,but no effect!

DOES all the I2C based audio dsp's give the same effect?
Anybody has similar noise problems?

Please help!

i have used the same audio tone control circuit with 89C51 processor but havent faced any problems .. i dont think its power related

i think its probably some delay in sending data to the processor or communication related issue, and hope u have kept your I2C lines pulled up

if u want to try i could share my firmware. for 7439