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Old 7th November 2012, 12:17 PM   #101
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Quote:
Originally Posted by bobodioulasso View Post
Nobody mentionned LME498XX chips + discrete outputs. A choice i prefer when some power is required compared to paralleling plain chipamps.
Yes, I mentioned driver chip. Seems like it could also be used for an extra nice MyRef, and much easier to implement than parallel chip amps. I wonder why people have worked so hard on the MyRef series and still haven't upgraded the project to a high quality driver chip with high end outputs?
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Last edited by danielwritesbac; 7th November 2012 at 12:28 PM.
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Old 7th November 2012, 12:24 PM   #102
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Originally Posted by danielwritesbac View Post
Thanks! That is really great! Got an example? Maybe a schematic?
Here you go: Project 115 - GainClone

Though it's actually over the pre amp. My memory is poor.
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Old 7th November 2012, 01:10 PM   #103
AndrewT is offline AndrewT  Scotland
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Originally Posted by Robert Kesh View Post
Here you go: Project 115 - GainClone............
C5 is once again far too small in comparison to C1.
Classic and repeated all over the web.
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Old 7th November 2012, 01:31 PM   #104
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Originally Posted by AndrewT View Post
C5 is once again far too small in comparison to C1.
Classic and repeated all over the web.
Sure, and plenty else. If you're jumping in, then the discussion here is about the DIP switching, but placed in the NFB of the power chip, to tune gain resistors. The rest you can take or leave.
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Old 7th November 2012, 02:36 PM   #105
AndrewT is offline AndrewT  Scotland
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Quote:
danielwritesbac View Post
Thanks! That is really great! Got an example? Maybe a schematic?
Quote:
Originally Posted by Robert Kesh View Post
Here you go: Project 115 - GainClone

Though it's actually over the pre amp. My memory is poor.
Quote:
Originally Posted by AndrewT View Post
C5 is once again far too small in comparison to C1.
Classic and repeated all over the web.
Quote:
Originally Posted by Robert Kesh View Post
Sure, and plenty else. If you're jumping in, then the discussion here is about the DIP switching, but placed in the NFB of the power chip, to tune gain resistors. The rest you can take or leave.
the discussion is somewhat off topic but does try to address the issue ot trying to get the best performance from the chipamp.
That schematic that you linked falls at the first hurdle.
Quote:
220u (or more) for NFB cap
from Daniel's preceding post.
using the typical NFB resistor values he has suggested.
22uF does not get near.
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Old 7th November 2012, 02:41 PM   #106
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No one is disputing it. Just as no one is disputing the sky is blue.

It was posted as it has an interesting way of getting over another hurdle. Choosing NFB resistors.

Last edited by Robert Kesh; 7th November 2012 at 02:44 PM.
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Old 7th November 2012, 03:01 PM   #107
bcmbob is offline bcmbob  United States
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Can someone point or link to the data sheet for an example of the "Driver Chip" that's been mentioned? If it can be incorporated into the MyRef series, more concrete design information would be helpful.
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Old 7th November 2012, 03:03 PM   #108
AndrewT is offline AndrewT  Scotland
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lme498xx Threads
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Old 7th November 2012, 03:12 PM   #109
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by danielwritesbac View Post
Well, do it.

TDA7294 non-inverting amp:
Pair 220u amplifier board power caps and a single 2u polyester rail to rail.
47u (or 68u) for bootstrap
10k for input load resistor
10k for mute (no cap)
22k with 10u timer for standby
60k (120k||120k) for feedback resistor
2.7k for feedback-shunt resistor
220u (or more) for NFB cap
1u (or less!) for input
Output zobel is 10n with ~8R
Add RF filtering to input cap
Use a stiff power supply (20,000u per rail, 3a per chip)
Use less voltage than max (under-volt)
I have done a lot, may be more than anybody else. I cannot see anything there that I haven't tried. But may be on the high feedback resistance I have missed the 60k/2k7 combination.

I'll do this one tomorrow (being ill right now). Thanks.

BTW, when I said I couldn't make a TDA7294 to sound good enough, I haven't found a schematic that I think will blow away any other schematics from the LM overture series. There have been many blind tests since the popularity of Gainclone, and TDA7294 never won against the overture series (3876/3875/3886). If that will make the statement less subjective.

Last edited by Jay; 7th November 2012 at 03:17 PM.
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Old 7th November 2012, 03:31 PM   #110
bcmbob is offline bcmbob  United States
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Thanks Andrew. I found it here. Now just have to investigate and decipher.
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