# power amp connection?



## Deleted member 24505 (Jun 6, 2014)

Here is a pic of the circuit diagram of the main amp board of a kenwood A58 amplifier. What i need is someone to point out were to connect to so i have a direct input to the power amp section, bypassing the pre amp. I have a nice rotel pre amp rsp 960ax, and i want to try and use the kenwood as a power amp.

Here is my pre amp, and the denon ud-m31 i am using for power at the moment


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## Shambles1980 (Jun 7, 2014)

cant you just go through the phono input.


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## Deleted member 24505 (Jun 7, 2014)

Shambles1980 said:


> cant you just go through the phono input.



It's a integrated amp, i already have a high quality pre amp, so i was gonna by-pass the pre amp in the kenwood and connect direct to the power amp section. I know it is possible, just need to find the right place.

If it helps, here is the diagram for the seperate pre amp board that connects to CN6 at the top left of the diagram i poste in the op, i am sure this is were i need to connect to. From what i can figure out, the inputs go through their input section, then through the dolby section, then to here and then to the power amp section. I think i need to connect to 4-L 5+6-G 7-R from CN6 but need to be sure.


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## Ferrum Master (Jun 7, 2014)

My suggestion? Just measure... I bet it needs to be recapped already...

Use a passive load, use trim pot, and adjust levels acceptable for measurement... (at preferable power level, measure voltage and multiply it twice divide by load resistance it will give approx level at sine) use some basic RMAA. For domestic use its is alright and gives precise results just as expensive audio analyzing equipment, the recording DAC has enough resolution these days. Just loop measure your integrated crap audio to ensure it works alright, then loop it via amp section... your distortion numbers will be shown... try without preamp and other combinations whatever...

My hand build amps manage to outperform their factory brothers judging from their spec sheet... and don't lie... I even test smart phones using RMAA, custom android ROMS usually break audio stuff and I am poking the dev in the ass about that...

If you blow something, sue yourself 

phono section is a hi-gain part, don't use it for 0,7V signal.

Just feed the IC3 input... and down below... I cannot see if it uses a balanced design


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## Shambles1980 (Jun 7, 2014)

what i mean is if you connect to your tape in or aux in they already assume that what you are connecting has a preamp..
the turn table connector would sometimes have a separate preamp though.

so im not sure why you aren't just connecting it directly like that.
i made the semantic error of referring to all inputs as phono which is something i should smack my self in the head for.

but are you just trying to by pass the receivers volume controls or something?


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## Ferrum Master (Jun 7, 2014)

I guess he wants to get rid of the "possibly" problem making preamp part...

The main hurdles may be... just look how negative feedback is implemented and protection parts... the stupid thing, they usually have a specialized processor that actually located in preamp/channel selector part that he wants to cut off... it may shut down... I don't know really, we only can guess.


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## Deleted member 24505 (Jun 7, 2014)

Here is the full main board diagram-





basically, i cant afford a power amp to go with my rotel rsp-960AX so figured i would try and use the power amp section of the kenwwod, it is 60wx2, rather than using the denon.

thanks guys.



Shambles1980 said:


> what i mean is if you connect to your tape in or aux in they already assume that what you are connecting has a preamp..
> the turn table connector would sometimes have a separate preamp though.
> 
> so im not sure why you aren't just connecting it directly like that.
> ...



Yes i am trying to bypass the amps pre amp totally.


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## Ferrum Master (Jun 7, 2014)

It has a dedicated fully separate amp section... look OMN1@CN4?... the resolution is shitty... but see yourself, completely independent from preamp section... IC4 opamp. There must be a dedicated AUX input for it that exactly does what you want.


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## Deleted member 24505 (Jun 7, 2014)

Ferrum Master said:


> It has a dedicated fully separate amp section... look OMN1@CN4?... the resolution is shitty... but see yourself, completely independent from preamp section... IC4 opamp. There must be a dedicated AUX input for it that exactly does what you want.



The OMNI are extra speaker pre outputs, It does not have a direct input to the power section. Here is a pic of the back of the amp.

It has aux in but that is going through the pre amp, which is what i am trying to by pass.


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## goldenpaper (Jun 28, 2014)

It looks like the input to the power amp is at Q5 / Q6 base.


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