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Marchaudio P422 Stereo Power Amplifier Review

SDC

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But would need same gain....

No. If you adjust gain in the DSP domain it works perfectly with different gain in amp domain.

3vol - 복사본.jpg


Here is the example of my system.

Each 8351b and JBL 128H woofer is crossed at 100hz, JBL uses seperate amp MM8077 and Genelec 8351b has -30dB switch on.

But with JRiver DSP individual volume control it works fine in all volumes.
 

Chrispy

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No. If you adjust gain in the DSP domain it works perfectly with different gain in amp domain.

View attachment 220326

Here is the example of my system.

Each 8351b and JBL 128H woofer is crossed at 100hz, JBL uses seperate amp MM8077 and Genelec 8351b has -30dB switch on.

But with JRiver DSP individual volume control it works fine in all volumes.
In passive bi-amping how would that be accomplished with typical gear folk are doing it with, tho?
 

SDC

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In passive bi-amping how would that be accomplished with typical gear folk are doing it with, tho?

Yes, so I said he would have meant active crossover.

For passive bi-amping, one should not do such thing from beginning IMO.
 

Chrispy

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Yes, so I said he would have meant active crossover.

For passive bi-amping, one should not do such thing from beginning IMO.
Agreed. But that's the way I took the question that took that stream....could be my reading of it but knowing typical audiophilia.....
 
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MCH

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No. If you adjust gain in the DSP domain it works perfectly with different gain in amp domain.

View attachment 220326

Here is the example of my system.

Each 8351b and JBL 128H woofer is crossed at 100hz, JBL uses seperate amp MM8077 and Genelec 8351b has -30dB switch on.

But with JRiver DSP individual volume control it works fine in all volumes.
Hi SDH,
I struggle to see the benefit of doing different gains with the same amplifier and i am very curious.
At the end of the day you are limiting the overall gain to the gain of the tweeter. Why not then setting everything to low gain if what you want is to minimise hiss?
I can understand it when you have different amps, but with the same..... What is the benefit in this case?
Thanks.
 

SDC

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Hi SDH,
I struggle to see the benefit of doing different gains with the same amplifier and i am very curious.
At the end of the day you are limiting the overall gain to the gain of the tweeter. Why not then setting everything to low gain if what you want is to minimise hiss?
I can understand it when you have different amps, but with the same..... What is the benefit in this case?
Thanks.

Well if I were to build a custom speaker and drive 2 way with one stereo amp,

changing gain of two channel will have advantage. Especially horn setups as they require exceptionally low noise level and high watts are not needed.

This is not the case as it changes the gain of the whole amplifier, though.


edit: In my case I used volume knob in PA5 to reduce noise coming from the audio interface.

But typically, better amp performance is achieved in lower gain setting too.
 
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thin bLue

thin bLue

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Hi SDH,
I struggle to see the benefit of doing different gains with the same amplifier and i am very curious.
At the end of the day you are limiting the overall gain to the gain of the tweeter. Why not then setting everything to low gain if what you want is to minimise hiss?
I can understand it when you have different amps, but with the same..... What is the benefit in this case?
Thanks.
Hints : EQ works reducing way, not increasing. Bass extension.
 
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MCH

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Hints : EQ works reducing way, not increasing. Bass extension.
Ah ok, so that means that you would apply positive EQ at the lower frequencies to improve bass extension, overall negative dsp gain at the woofer to be able to do the former and higher amp gain at the woofer to compensate the negative dsp gain. Ok, i get it. Interesting, thanks!
 
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Chrispy

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Ah ok, so that means that you would apply positive EQ at the lower frequencies to improve bass estension, overall negative dsp gain at the woofer to be able to do the former and higher amp gain at the woofer to compensate the negative dsp gain. Ok, i get it. Interesting, thanks!
Generally just better to use eq to cut rather than boost....boosting costs extra amp for one and often doesn't do a lot for a deep null (if even necessary).
 

Holmz

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With passive bi-amping why you would use amps with different gain?
Instead of running 10-15dB of PAD in a passive XO, just give it 10-15 less gain in the amp.

All too much power (gain) would do is increase the chance of hissing.
 

Holmz

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For active crossover I think he meant.

But IMO seperate amp with low gain and low watt for tweeter is better for $$$$ purpose.

Assuming we want the harmonics the same, then we want the same amplifier (brand/type) to be powering the woofer and tweeter.
 

Chrispy

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Instead of running 10-15dB of PAD in a passive XO, just give it 10-15 less gain in the amp.

All too much power (gain) would do is increase the chance of hissing.
You consider that the usual approach of passive bi-ampers? Makes it seem even less appealing than the nonsense it usually is....
 

Holmz

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You consider that the usual approach of passive bi-ampers? Makes it seem even less appealing than the nonsense it usually is....
I want to use a DSP and a two channel amp behind each speaker… and no internal XO.
 

Chrispy

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I want to use a DSP and a two channel amp behind each speaker… and no internal XO.G
That is generally identified as active bi-amping vs. that the silliness that is passive bi-amping has entered the audiophilia range....generally with a speaker with simple bi-wiring/bi-amping terminals that's more a stupid marketing thing.....
 

Holmz

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That is generally identified as active bi-amping vs. that the silliness that is passive bi-amping has entered the audiophilia range....generally with a speaker with simple bi-wiring/bi-amping terminals that's more a stupid marketing thing.....

And hence the need for 2 or 3 channels.

Where/how did I give the impression that it was a passive-XO with bi-wire ?
 

Holmz

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Ah ok, so that means that you would apply positive EQ at the lower frequencies to improve bass extension, overall negative dsp gain at the woofer to be able to do the former and higher amp gain at the woofer to compensate the negative dsp gain. Ok, i get it. Interesting, thanks!

Or with two channels of similar gains, then more negative on the tweeter and some negative in the woofer band… and then crank the volume knob up to get back what was cut.
 
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thin bLue

thin bLue

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Fatal mistake has founded.
Do not use SIANAD numbers of this review.


You can check the Voltage at oscilloscope window, 9 V
It's not an 5 W for 4 Ohm
, we pushed way more...

We used different projects with level sweeps and others(but still possibilities of same mistake has occurred...). But 5 W SINAD shows 100% wrong W, It's not 5, 10 W


I can't understand myself, how could I done this.

Still data can be used as checker for L/R uniformity. but yes otherwise we lost reliability of our data so we have to re-measure them all.

I promise, next measurements are fully checked before posting. sorry for make massive inconvenience.
 
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