Point 2 Point (no PCB) for TDA7293, TDA7294, TDA7295, TDA7296. - Page 6

danielwritesbac · 7th February 2013, 01:39 AM

Power off thumps from the speakers?
Check the standby circuit.

simply14prem · 7th February 2013, 12:03 PM

Well preamp gave me an impact,But It has suck some treble,,I think I need compensation cap in Ne5534.I kept it empty.
IM using Fb shunt R=1K, Feedback R=22K,Low gain for Tda7294.

simply14prem · 7th February 2013, 12:38 PM

I tried 8pf in Comp. cap,,but I don't like the sound.Removed again.Treble is not strong enough.Something went wrong.

danielwritesbac · 8th February 2013, 07:58 AM

You could try raising the gain of preamp and then adding a resistor for global negative feedback from the output of the power amp to the inverting input of the preamp. See also composite, nested designs. Check for DC offset before connecting speaker. A composite design with a Class A preamp will force the power amp to sound like Class A, in proportion to the added global negative feedback.

simply14prem · 8th February 2013, 08:21 AM

Now I know the taste of music is a never ending adventure.
I have remove the classA bias,it's just the NE5534.Now I think Its a bit sweeter in treble.

danielwritesbac · 8th February 2013, 04:42 PM

Question: Did you have the 4.7u output cap of the preamp in series with the 1u input cap of the TDA729X?
Question: Did you put a potentiometer or other disturbance between preamp and power amp?

simply14prem · 9th February 2013, 12:43 AM

Quote:

Originally Posted by danielwritesbac

Question: Did you have the 4.7u output cap of the preamp in series with the 1u input cap of the TDA729X?
Question: Did you put a potentiometer or other disturbance between preamp and power amp?

I have no 4.7uf after preamp.I have two 2.2+--+2.2 uf as input cap in TDA7294.I have 10K pot for Tda7294.

simply14prem · 9th February 2013, 12:56 AM

Quote:

Originally Posted by danielwritesbac

You could try raising the gain of preamp and then adding a resistor for global negative feedback from the output of the power amp to the inverting input of the preamp. See also composite, nested designs. Check for DC offset before connecting speaker. A composite design with a Class A preamp will force the power amp to sound like Class A, in proportion to the added global negative feedback.

Sorry that is way advanced from me.I can't understand it.

danielwritesbac · 9th February 2013, 01:04 AM

Loss before cap can act like tone control.

simply14prem · 11th February 2013, 02:24 AM

This is not from my preamp that made a muddy treble.I think this is the tda7294 itself.Becoz when i removed preamp ,,same sound.

7th February 2013, 01:39 AM	#51
danielwritesbac diyAudio Member Join Date: Nov 2007	Power off thumps from the speakers? Check the standby circuit. __________________ ♦ Tools & Guides ♦ ClipNipper headroom boost ♦ Parallel LM1875 pt2pt ♦ Easy parallel TDA7293 board ♦ TDA7294 pt2pt ♦ My post has opinion.

8th February 2013, 07:58 AM	#54
danielwritesbac diyAudio Member Join Date: Nov 2007	You could try raising the gain of preamp and then adding a resistor for global negative feedback from the output of the power amp to the inverting input of the preamp. See also composite, nested designs. Check for DC offset before connecting speaker. A composite design with a Class A preamp will force the power amp to sound like Class A, in proportion to the added global negative feedback. __________________ ♦ Tools & Guides ♦ ClipNipper headroom boost ♦ Parallel LM1875 pt2pt ♦ Easy parallel TDA7293 board ♦ TDA7294 pt2pt ♦ My post has opinion.

8th February 2013, 04:42 PM	#56
danielwritesbac diyAudio Member Join Date: Nov 2007	Question: Did you have the 4.7u output cap of the preamp in series with the 1u input cap of the TDA729X? Question: Did you put a potentiometer or other disturbance between preamp and power amp? __________________ ♦ Tools & Guides ♦ ClipNipper headroom boost ♦ Parallel LM1875 pt2pt ♦ Easy parallel TDA7293 board ♦ TDA7294 pt2pt ♦ My post has opinion.

9th February 2013, 01:04 AM	#59
danielwritesbac diyAudio Member Join Date: Nov 2007	Loss before cap can act like tone control. __________________ ♦ Tools & Guides ♦ ClipNipper headroom boost ♦ Parallel LM1875 pt2pt ♦ Easy parallel TDA7293 board ♦ TDA7294 pt2pt ♦ My post has opinion.

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7th February 2013, 12:03 PM	#52
simply14prem diyAudio Member Join Date: Jan 2011	Well preamp gave me an impact,But It has suck some treble,,I think I need compensation cap in Ne5534.I kept it empty. IM using Fb shunt R=1K, Feedback R=22K,Low gain for Tda7294.

7th February 2013, 12:38 PM	#53
simply14prem diyAudio Member Join Date: Jan 2011	I tried 8pf in Comp. cap,,but I don't like the sound.Removed again.Treble is not strong enough.Something went wrong.

8th February 2013, 08:21 AM	#55
simply14prem diyAudio Member Join Date: Jan 2011	Now I know the taste of music is a never ending adventure. I have remove the classA bias,it's just the NE5534.Now I think Its a bit sweeter in treble.

11th February 2013, 02:24 AM	#60
simply14prem diyAudio Member Join Date: Jan 2011	This is not from my preamp that made a muddy treble.I think this is the tda7294 itself.Becoz when i removed preamp ,,same sound.

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