Just for kicks - Is there an easy way to reduce the gain of an existing amp?

With my limited knowledge and understanding of the Integrated amp in discussion, it appears this one is not a good candidate for such a conversion.
Even if I would go ahead and add the main inputs with all the circuit adjustments, it would be a contraption and not perform as expected.
 
With my limited knowledge and understanding of the Integrated amp in discussion, it appears this one is not a good candidate for such a conversion.
Even if I would go ahead and add the main inputs with all the circuit adjustments, it would be a contraption and not perform as expected.
I wouldn't draw such a conclusion just yet. We're discussing a method to retain full performance by adding two resistors and shunting one existing resistor per channel. Pretty easy, as these things go.
 
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I'd probably knock together external attentuators that simply go between the source and the amp. No mods required, and its completely reversible. You can build or buy. I made a couple for testing purposes from some large size RCA plugs off some fancypants looking cables I found at the flea market and some genuine yellow Chinesium plated RCA jacks. I think it uses a 220k and a 22k as the divider to keep the load impedance relatively high.

If there's preamp jumpers, what's the problem??!! Just do it!

And if not, how about in-line attenuators for all the high level inputs (I hunch the phono inputs are already fine)?
That's what I did for my signature system. I recall using 6dB on the tuner and 12?15? on the CD players. Maybe they were even more, but they brought all inputs to parity with phono and made it pleasant to switch around sources without big changes in volume.
It also made it possible (but not real likely) to play stuff at full volume without frying something!

PS: I made up some very short ICs keeping everything quite neat. I also made matching/shortened PCs.
I've wondered why the purists don't debate length! Maybe it's too Freudian. So, it an IC is "great", what changes and in what direction if you change it's length by 80%?? Hmmm.....a head scratcher.
I guess I should be a subjectivist and tell you the results are CLEAR AND COMPELLING! Making my wires GREAT!
This
 
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If there's preamp jumpers, what's the problem??!! Just do it!
The unit has always-on preamp outputs, but there are no power amp inputs and no breaks in the signal path between the stages.
 
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So a voltage gain of 4.33 in the power amp drives the 8Ω speakers at the rated 150 Watts. There is more gain in the power amp's differential amp than in the preamp. Did I figure that right @BinaryMike? I'm not an EE.
That doesn't sound right. The OP is saying that power amp gain is far in excess of typical, so I'm guessing that it's 35dB~40dB or 56X~100X. Actual gain will be roughly equal to the ratio of the feedback divider resistors attached to the right side diff pair base, which I cannot read.
 
That doesn't sound right. The OP is saying that power amp gain is far in excess of typical, so I'm guessing that it's 35dB~40dB or 56X~100X. Actual gain will be roughly equal to the ratio of the feedback divider resistors attached to the right side diff pair base, which I cannot read.
The feedback resistor on the right side diff amp base is 33kΩ bypassed by a 5.6pf cap. The other resistor from the base goes to ground through a 100µf cap and is 1kΩ. The divider is roughly 33:1.
 
I worked backwards from a max output of 150 watts @ 8 Ω with a power amp input of 1.2v, but I did the math wrong, the voltage gain of the power amp is about 34.6, not 4.33. :oops: I learn something every day on AK :biggrin:. Thanks!
 
So it seems that existing power amp sensitivity is about 1Vrms for full output. This conflicts with the OP's claim that it has excessive gain. Maybe not so much?
 
No measurement.
I had the sweep/function generator, BK 4001A set up for a 1kHz tone. At min gain I could connect the generator to the RCA's and hear a normal listening level tone.
I then plugged in a Yamaha pre amp, volume at min and got a heck of buzz and audio at a considerable volume.
 
Something has to be miswired or defective. I would check especially for bad ground connections. With respect, if your soldering skills are less than proficient, then It might be time to back out of this one.
 
I did do something but I reversed the whole thing and now listening with a sigh of relief.
The one channel was working well but the other was misbehaving. Relatively simple mod but I couldn't find where it was getting voltage without more time in it.
I admit, I fix this audio like no ones business but when it comes to mocking up a circuit, I struggle. Hacking in components I'll do on my own stuff but on a nice unit like this, a completely different story.
 
I did do something but I reversed the whole thing and now listening with a sigh of relief.
The one channel was working well but the other was misbehaving. Relatively simple mod but I couldn't find where it was getting voltage without more time in it.
I admit, I fix this audio like no ones business but when it comes to mocking up a circuit, I struggle. Hacking in components I'll do on my own stuff but on a nice unit like this, a completely different story.
Would you share what your modification was?
 
I'm not going to continue the mod.
What I did to confuse the circuit was not grounding the temporary input jacks. Well at least one of them was accidentally grounded for a moment and appeared to work.
Thanks for your input. I did pick-up a lesson it the discussion so all was not lost.
 
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