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PostPosted: 03 Jul 2013, 11:59 
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Joined: 18 Jun 2013, 11:39
Posts: 6
i got the old transformer rewound.

I have a problem here. i etched a batch of tda 2050's pcb. just finished with the first prototype.

the high frequency and vocal response in few speakers is VERY bad i mean its not that bad bad..its there sharp and easy..it just seems a bit wobbly..still the vocal response is not satisfactory bad...I tried putting my engineering skills to use( i know i'm dumb) i removed the input capacitor as the preamp already has the output capacitors. is this happening because of that? should i try adding 1uf MKT capacitor to input and check again?


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PostPosted: 03 Jul 2013, 16:13 
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Joined: 04 Jan 2013, 16:59
Posts: 6
Location: Alabama, USA
Well, remember, series capacitors combine like parallel resistors, which means that your effective capacitance with both capacitors in the circuit will be much lower. This can seriously eat into your bass response, depending on your input impedance. If the previous stage already has a DC-blocking capacitor of the appropriate value, then by all means leave out the input capacitor.

If you are unsure, then play it safe and disconnect your speakers from the TDA2050's outputs before applying power. Use a voltmeter to determine if there is any DC offset on your outputs. If it's more than 10-20 mV, then something's wrong.

Good luck!

~ T


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PostPosted: 03 Jul 2013, 16:20 
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Joined: 04 Jan 2013, 16:59
Posts: 6
Location: Alabama, USA
I wanted to mention something to everyone regarding the power supply. I built mine per Tom's instructions and it worked great, with the exception that I would hear a very loud pop every time something in my house with a motor on it stopped/started (e.g. pumps, A/C blower, etc). This told me that transients from the mains were finding their way through the power supply and into the amplifiers.

At the suggestion of a friend of mine, who also happens to be an extremely experienced analog engineer, I placed a 0.1 uF ceramic cap (50V, I think) across the each rectifier input. This completely eliminated my popping problem.

Regards,

~ T


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PostPosted: 10 Aug 2013, 01:49 
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Joined: 18 Jun 2013, 11:39
Posts: 6
Hey guys,

I have a transformer 18-0-18 @8Amp i am planning to make 6 channels, since it corresponds to ~290VA, is it safe to hookup 6 boards and if possible 8 boards? i know its kinda overkill(i have lots of spare 2050 and phenolic boards) but will it be possibly safe?

as far as i understand the concepts, tda 2050 needs 60VA for 35w RMS(Continuous sine wave), but since we are dealing with music here, can i get away with that transformer? it might be that guys running to my dorm room be turning up the volume to the max for fun, but i hope things dont go that bad that it leads to damage to transformer.

Can someone please suggest?


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PostPosted: 29 Oct 2013, 06:06 
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Joined: 25 Feb 2013, 22:29
Posts: 6
Location: Malaysia
hi.

Is it possible to use the power supply from this amp for TDA7292?

Thanks


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PostPosted: 29 Oct 2013, 18:54 
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Joined: 28 May 2008, 21:53
Posts: 4579
Location: Winnipeg, CANADA
Hi blacklizard,

Yes you can. +/-26V is the limit on the TDA7292

Cheers

_________________
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PostPosted: 04 Nov 2013, 07:52 
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Joined: 25 Feb 2013, 22:29
Posts: 6
Location: Malaysia
Hi Gio.

Thanks. How would the TDA7272 sound if compared to TDA2050 or LM chips?


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PostPosted: 06 Nov 2013, 21:31 
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Location: Winnipeg, CANADA
I've not heard the TDA7272. IME most of the chipamps sound good considering the low cost, provided that you use good caps and rectifiers and a short signal path.

Cheers

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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PostPosted: 06 Nov 2013, 21:38 
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Joined: 25 Feb 2013, 22:29
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Location: Malaysia
Gio wrote:
I've not hear the TDA7272. IME most of the chipamps sound good considering the low cost, provided that you use good caps and rectifiers and a short signal path.

Cheers


Thanks Go. I will try few pcb design and decide which one sounds good.
Cheers


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PostPosted: 06 Nov 2013, 21:48 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Try keep the signal path and feedback loops as short as possible.

Cheers

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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