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Old 24th October 2009, 05:17 AM   #1
sexya is offline sexya  India
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Default Tda7265 + tda7439

hii i have built a board using the TDA7265 amp chip which 25+25 in 4ohm, and TDA7439 which for volume , bass, mid , treb and gain and 4 source selection,
i want to know is 25 watts good enoug for a small room or should i use two 7265 in bridged mode,
or should i shift to TDA7294,,
i'll be posting my pcb layout soon i would like some tips on the design
thanks any comments welcomed
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Old 24th October 2009, 05:46 AM   #2
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Hi Sexia , I've take a look at the various plots of power , distortion , frq. response towards power supply etc .
The conclusion for me is that you don't have to expect much from that chip -as others- since 25 W are reached with a 4 Ohm load but with 10 % THD.
Moreover , if you choose to "play" with higher power chip such TDA 7294 then you 'll find that the preamplifier/tone control Ic would introduce distortions also,which would be "masked" when played at low volumes with low power amps. So my suggestion is to make it simple , just a rotary switch for the inputs and no tone controls , since they might be nice but are often used to help a poor speaker's frequency response .I forgot the volume control deliberately
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Old 24th October 2009, 06:13 AM   #3
sexya is offline sexya  India
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Default pcb

here is the pcb layout in pdf, its the top view of copper layer
Attached Files
File Type: pdf AMP.pdf (36.2 KB, 575 views)
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Old 24th October 2009, 07:21 AM   #4
sexya is offline sexya  India
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Quote:
Originally Posted by picowallspeaker View Post
Hi Sexia , I've take a look at the various plots of power , distortion , frq. response towards power supply etc .
The conclusion for me is that you don't have to expect much from that chip -as others- since 25 W are reached with a 4 Ohm load but with 10 % THD.
Moreover , if you choose to "play" with higher power chip such TDA 7294 then you 'll find that the preamplifier/tone control Ic would introduce distortions also,which would be "masked" when played at low volumes with low power amps. So my suggestion is to make it simple , just a rotary switch for the inputs and no tone controls , since they might be nice but are often used to help a poor speaker's frequency response .I forgot the volume control deliberately
hii thanks for the supper quick reply, well i do need a volume and tone control, and i came acrros this TDA7439 chip in some Sony Stereo,
since i need a volume control can i use a pga2311 ( i have some samples)
i sort of like the sound of the 7265 m not in a position to purchase some nice speakers since htey are mighty expenssive in india, so i have to relay on good car speakers from sony or pioneer, may be blaunk punk,
anyways we do get some jvc 6" drivers but cant say it original, and then getting good wood is expensive,
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Old 24th October 2009, 07:52 AM   #5
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Blown-punk might be good speakers !
For cabinet making , you don't need to spend much : you need only to invest on screws , cables and binding posts ; the rest , the cabinet or just somewhere to attach a speaker , can be built with your fantasy .
Volume control : did anybody tell you that a variable resistor , ie a potentiometer , has been working good in millions of apparatuses from the birth of electronic ?
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Old 24th October 2009, 07:59 AM   #6
sangram is offline sangram  India
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Mx5021 from AL uses the same chip, plus a 7295 for the woofer.

Where are you in India? Look at Tarun's project for inspiration, he's built some very good stuff using Indian drivers. Consistency is a pretty big issue with Indian-made drivers, but it is possible to work around some of the issues. Some stuff is available in the Mumbai market. It is possible to get everything you need to replicate the emerald Physics CS2.3 and CS3, for example, and without too much fuss or wallet strain as Eminence drivers are widely available...

Car speakers are pretty much a no-no for home use. I agree with the suggestion of a pot over a digital volume control. It's simpler, and(to me) sounds a bit better.

Wood is ~Rs 1000 ($20) for a 4x8 sheet of Grade II MDF, around a third of what a pair of car speakers cost. Getting a carpenter to build it is the biggest issue you'll ever face.
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Old 24th October 2009, 08:29 AM   #7
sexya is offline sexya  India
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Default hii

Quote:
Originally Posted by sangram View Post
Mx5021 from AL uses the same chip, plus a 7295 for the woofer.

Where are you in India? Look at Tarun's project for inspiration, he's built some very good stuff using Indian drivers. Consistency is a pretty big issue with Indian-made drivers, but it is possible to work around some of the issues. Some stuff is available in the Mumbai market. It is possible to get everything you need to replicate the emerald Physics CS2.3 and CS3, for example, and without too much fuss or wallet strain as Eminence drivers are widely available...

Car speakers are pretty much a no-no for home use. I agree with the suggestion of a pot over a digital volume control. It's simpler, and(to me) sounds a bit better.

Wood is ~Rs 1000 ($20) for a 4x8 sheet of Grade II MDF, around a third of what a pair of car speakers cost. Getting a carpenter to build it is the biggest issue you'll ever face.
hii
sangram, well i will look in shop around my place, i m from bombay well there's some famous guy called chaudary in lamington road who says he will give me 6 ohms jvc low mid drivers for 700/- each, and hte cabinet for it will cost me 600/ a box 200 for bolton balanced tweeter a piece

i dont have currently 2800/- to spend on speakes who's genunity is unknown, he also has peerless but then he wont give details and he's like bring your amp listen to it and then you buy the speaker,,
which i havent been able to as i have dismentled my TDA7265 amp as i want to put a optical dac using DIR9001 and pcm1794 , and also PCM2704 ( usb Dac) i want these two coz i would be connecting the amp with the laptop and i want to avoid the ground issue that normally occcur witl laptops since my laptop has spdif and usb i could use either opto dac or usb dac,
do you feel that i should dump TDA7439 ( digital controll tone , source selection) and keep just one volume pot and direct amp, with a input switch
i want to finish this amp now i m toooo bugged up
i have the follow chips as samples
1) tda7265
2) Tda 7294
3) DIR9001
4) pcm 1794
5) pcm 2704
6) TDA 2050


what i need is good sound,,,
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Old 24th October 2009, 08:38 AM   #8
sangram is offline sangram  India
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Quote:
do you feel that i should dump TDA7439
Yes.

Go to Dev Sound systems. It is on the first floor of the building opposite the Lamington Road cop station, next to Vegakit. They have the Peerless 20NISH drivers, steel frames and coated paper cone (locally referred to as the 'Peerless 8 incher', about 1000 each). A pair of soft dome tweeters (~1000 the pair) will work very well with these with just a single 4.7uF cap on the tweeter as long as you don't push too much power into it and keep your overall expectations low, you will have beaming issues as well as poor off-axis performance - unless you can design a proper XO (and then you'll need a better tweeter to be able to cross over at ~1.5KHz). I have the driver parameters somewhere, they work well in a 0.7-0.9 cu ft box, rolling off smoothly below 80Hz sealed, with extension to 40Hz ina ported enclosure. They are not bass boomers, so if that's what you're looking for Chaudhary is the better bet.

The JVC drivers from Chaudhary are useless. They have Qtc of over 0.9 (the 8 incher has a Qts of 1.5). He has some equally useless 'Sony' speakers. He gets the Peerless from Dev. You can whip up as good a system with these drivers, though it does get slightly more expensive it's worth the effort.

Good Luck.
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Old 24th October 2009, 08:41 AM   #9
sexya is offline sexya  India
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Quote:
Originally Posted by sangram View Post
Yes.

Go to Dev Sound systems. It is on the first floor of the building opposite the Lamington Road cop station, next to Vegakit. They have the Peerless 20NISH drivers, steel frames and coated paper cone (locally referred to as the 'Peerless 8 incher', about 1000 each). A pair of soft dome tweeters (~1000 the pair) will work very well with these with just a single 4.7uF cap on the tweeter as long as you don't push too much power into it and keep your overall expectations low, you will have beaming issues as well as poor off-axis performance - unless you can design a proper XO (and then you'll need a better tweeter to be able to cross over at ~1.5KHz). I have the driver parameters somewhere, they work well in a 0.7-0.9 cu ft box, rolling off smoothly below 80Hz sealed, with extension to 40Hz ina ported enclosure. They are not bass boomers, so if that's what you're looking for Chaudhary is the better bet.

The JVC drivers from Chaudhary are useless. They have Qtc of over 0.9 (the 8 incher has a Qts of 1.5). He has some equally useless 'Sony' speakers. He gets the Peerless from Dev. You can whip up as good a system with these drivers, though it does get slightly more expensive it's worth the effort.

Good Luck.
hii could you email me your contact details on adityamody@gmail.com
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Old 24th October 2009, 02:49 PM   #10
sexya is offline sexya  India
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Default ref my amp

Quote:
Originally Posted by sangram View Post
Yes.

Go to Dev Sound systems. It is on the first floor of the building opposite the Lamington Road cop station, next to Vegakit. They have the Peerless 20NISH drivers, steel frames and coated paper cone (locally referred to as the 'Peerless 8 incher', about 1000 each). A pair of soft dome tweeters (~1000 the pair) will work very well with these with just a single 4.7uF cap on the tweeter as long as you don't push too much power into it and keep your overall expectations low, you will have beaming issues as well as poor off-axis performance - unless you can design a proper XO (and then you'll need a better tweeter to be able to cross over at ~1.5KHz). I have the driver parameters somewhere, they work well in a 0.7-0.9 cu ft box, rolling off smoothly below 80Hz sealed, with extension to 40Hz ina ported enclosure. They are not bass boomers, so if that's what you're looking for Chaudhary is the better bet.

The JVC drivers from Chaudhary are useless. They have Qtc of over 0.9 (the 8 incher has a Qts of 1.5). He has some equally useless 'Sony' speakers. He gets the Peerless from Dev. You can whip up as good a system with these drivers, though it does get slightly more expensive it's worth the effort.

Good Luck.
hey,
i guess i will build one useing TDA7294 with 20 0 20 @ 5 amps trafo, and a rotatry switch and a good dual pot, for volume control,
and i dont know waht to do with the efforts me and a friend put in to make the routine for TDA7439, for the speakers i m thinking i will take the amp with me at chaudhry or dev and see if they can help me or
manage to ask uncle to pick up
Polk Audio Monitor 30 Bookshelf Speaker System (Priced per pair) in Bookshelf Speakers at JR.com
when he comes to india ,,year end or in jan 10
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