PCB makers in Bangalore, India

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Hi Members,

I require some advice on the following:

I intend to construct a chip amp based on the STK412-170, as shown in the attached pdf.

I would like to know if there are any firms that can make the PCB, as well as the availability of the components mentioned to construct the amp.

awaiting your responses,

Thanks,

Nitin.
 

Attachments

  • stk412-170.pdf
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There are some questions u have to ask yourself...

Why 180 Watts/Ch when 50Watts/ch in a minute is unpleasantly loud when listening in a large living room.

Why STK...
There are so many reasons not to use them except less component count.
A discrete amp will sound much better.
Suppose, somehow u source an STK and then blow it now or later, then u will have to buy one somehow. ICs are never made for long time due to new/better products.
This is never the case with transistors.

enough for now

Gajanan Phadte
 
Hi gmphadte,

Thanks very much for the response.

The main reason for choosing STK is for the less number of external components required.

I do understand that discrete component amplifiers sound even better, but unfortunately, I do not have the time and patience to assemble one.

As for the wattage, I thought of constructing the best possible amplifier, so that I can listen to music at low or moderate volumes with good bass and music quality.

Please let me know if there are any organizations that can make the PCB for me.

Please let me know of good alternatives as well, as you sound more experienced. I'm located at Bangalore as well.

Cheers,

Nitin.
 
Please let me know if there are any organizations that can make the PCB for me.

Mahesh B.J.
Orion computers
366, 38th cross, opp 21st main,
4th T block, jayanagar,
Bangalore 560 041
India

bj.mahesh@gmail.com
orioncomputers@airtelbroadband.in

Phone- 080-26655442
Mobile- 9886092836

Besides making pcb from your file, they will also design an artwork if u want.
Also their charges are reasonable. (Cheap in International standards)

Please let me know of good alternatives as well, as you sound more experienced. I'm located at Bangalore as well.

I am in Goa.
The two nice well documented amps are Symasym and DX amp. Read about them on the forum and decide which one u prefer.
If u ask me, both are good.

Kesee wrote
If you are planning to build very hi quality chip amp follow the lead on diyAudio Forums > Top >Amplifiers >Chip Amps >LME49810 - a new cousin for LM4702
Check this out I have change little bit of the original design by gmikol [ ]diyAudio Member

This will be a better choice but not in our part of the world.

Enjoy.

Gajanan Phadte

Edit +/-54V is required for the STK. That makes it 108 Volts. This voltage is considered dangerous and is not for the inexperienced.
 
I'd suggest doing a gainclone/chipamp instead of one based on STK hybrid modules. The TDA7294 is widely available and gives excellent results up to 50W+, and it can be bridged to give about 100W. There's also a Class-G version that can give over 100W. The LM3886 is slightly more expensive, but also gives great results. There are also very good op-amp + power drivers avilable today, like the LM4702/LME49810, which can be used to drive multiple external output power devices to give fairly high output powers (up to 250W is easily within reach).

My personal suggestion is the TDA7294, which is inexpensive (lots of devices can be stockpiled) and for which bare PCBs are readily available.
 
if you're unable to make the PCB or unable do find the PCB Maker just to it in veroboard. I've made some high end amps in veroboard and this works very fine. can u tell the cost of the STK412-170 that u purchased coz I wanna make the circuit same :whazzat:
 
Thanks everone for all the valuable suggestions.

I have not purchased the STK412-170, I'm not sure of its availability in India, though its available online, for about US$30.

I just wanted to be sure of the PCBs and the full availability of all the components before I venture into this project:)

Linuxguru has made a wonderful suggestion of the TDA7294 chipamp. I too have been considering this chip for quite sometime.

A quick question: Would there be any difference in the quality/performance of amps made of monolithic chips, STK modules and discrete components?

Am also attaching the circuit of TDA7294 that mentions a "high efficiency circuit". I could not attach the entire pdf as its too big.

Please suggest if this circuit is good enough.

What is the opinion of assembling a chip amp on a generic PCB?
I believe there may be some instability due to oscillations etc.

Has anyone also come across a circuit that boosts bass & treble as found in some televisions with "super woofer" etc?
 

Attachments

  • tda7294 - hi efficiency.jpg
    tda7294 - hi efficiency.jpg
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The TDA7294 high-efficiency circuit is actually a Class-G output stage with dual rail pairs, a low pair at +/- 20V and a high pair at +/- 40V. It is worth reading and understanding Class-G operation before attempting this circuit. Douglas Self's book has a chapter and example discrete bipolar circuit for Class-G operation, but the principles are the same here.

The basic TDA7294 circuit (non-bridged) is simple and reliable - there are numerous tweaks to it in various gainclone threads on this forum. I would strongly recommend it as an excellent first DIY amplifier project.

The TDA7294 is available at Modern Electronics (off S.P. Road) for Rs.85, and the basic circuit PCB is available at Om Electronics for Rs.20. You'll need two each for dual-channel (stereo) operation.

The entire assembled module is also available for Rs.180, but I'd advise buying the bare PCB, IC, passives, etc. and assembling it - this allows the use of premium capacitors, components, etc.

A well-designed discrete solid-state amp like the Symasym, Leach, Aleph, GEM, AKSA, JLH, SoZ, DoZ or derivatives can easily outperform anything else, but the quality of components, careful matching, assembly, testing and tweaking are mandatory.

Chipamps/hybrid modules can give reasonable results without expending as much effort, but for best results, a similar process of iterative tweaking is recommended.

For Bass/Treble adjustment, I'd suggest using a stock passive Baxendall tone control. These are available as stock populated PCBs with all components, dual-ganged pots, etc. already installed at Pooja Electronics (off S.P. Road).
 
In electrolytic capacitors: Elna, Panasonic, Nippon Chemicon, Rubycon, Nichicon, Sanyo. Specific series have specific properties - some are good in the signal path, some only for supply filtering and bypass. They're not always available in the desired values. The premium types like Cerafine, Black Gates, Silmic IIs, etc are pretty much unobtainium, and are likely to be counterfeits. I've found Panasonic FC (which is the best inexpensive electrolytic for just about any audio application) and FJ from time to time. Elna ROS can be hard to find, except some occasional surplus items. Elna RJH and RJ4 show up from time to time, and they're OK for supply filtering/bypass.

In polypropylene: Wima - hard to find.

In film/mylar: Vishay, Philips are OK.

In most other types: brand doesn't really matter. Silver Mica is preferred for some small values related to compensation/stability. Ceramics are to avoided in the signal path.

Toroidal transformers: Salzer, Miracle (both are made to order)

E-I transformers: brand probably doesn't matter as long as it meets specs.

Metal film resistors: Dale, Vishay is OK - any 1% tolerance type should be OK. Carbon-film should be avoided unless that value is unavailable in metal film.

Transistors: Toshiba, Panasonic, Hitachi, NEC, ON Semi, Philips, SG. Transistors and ICs are very heavily counterfeited, especially power, driver and high-voltage types. Never buy in quantity unless you're sure that you've got a genuine item.

RCA connectors: Neutrik gold-plated (only the male connectors are available at S.P.Road for making the external line-level cables).
 
They are there in Bangalore, but you may have to pay through your nose or buy in quantity. RS Components will sell retail quantities, but marked up hugely. Arrow and Future Electronics are wholesale distributors, and will only sell in volume. You probably can't economically build DIY prototypes with parts sourced this way.

For DIY, you best bets are the traditional electronics bazaars like Ritchie Street, Lamington Road, S.P. Road, etc., where you can buy single-unit quantities of parts with only a small markup to wholesale.
 
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