View Full Version : Building a preamp out into an integrated amp


darkerror05
01-10-2011, 06:58 PM
I have a few integrated amps that have preamp sections that I like but I already have a power amp I prefer. Unfortunately these integrated amps do not have preamp outputs. I would like to use one of these amps as a preamp for my power amp. I was wondering if anyone has any experience "building" a preamp out into a integrated receiver. I have tried using the "phones" output in the past and used a 1/4" to rca cable to work as a preamp. To me this felt janky and I honestly didn't know if there would be an impedance or voltage mismatch that might damage something. So does anyone know if I could just wire up rca jacks into the back of the receiver and solder them onto the phones output?

Maybe this is all just a stupid idea... :scratch2:

mashaffer
01-10-2011, 07:33 PM
I have used phone outputs as preamp and it works but most phone outputs are just a resistor from the speaker outs so you are still getting the whole amp. To do a real preamp out you will need to tap into the circuit before the power amp which requires a schematic or good detective skills.

mike

darkerror05
01-10-2011, 07:45 PM
Well currently the integrated amp I have is a Realistic STA-116 ready for the job. I have yet to find much information about this model let alone a schematic. :tears:

VictoriaGuy
01-10-2011, 07:56 PM
You can use the TapeOut from the integrated to feed your power amp but you MUST put a volume control between the TapeOut and the PA. The TapeOut bypasses the preamp volume control in the amps I've seen.

mulester7
01-10-2011, 08:20 PM
You can use the TapeOut from the integrated to feed your power amp but you MUST put a volume control between the TapeOut and the PA......or, the amp must have gains.....

darkerror05
01-10-2011, 08:50 PM
Will the tape out still use the equalizer? The last integrated amp I tried bypassed the entire preamp section except the source selector. Volume I am not as worried about because 1)I am feeding this through a computer where I control the volume and 2)the power amp has gain adjustment.

VictoriaGuy
01-10-2011, 08:55 PM
.....or, the amp must have gains.....

Exactly...somehow there must be an attenuator in the chain.

mulester7
01-10-2011, 08:58 PM
somehow there must be an attenuator in the chain......yes, it could even be L-pads after the power amp.....

mulester7
01-10-2011, 09:26 PM
Will the tape out still use the equalizer? The last integrated amp I tried bypassed the entire preamp section except the source selector. Volume I am not as worried about because 1)I am feeding this through a computer where I control the volume and 2)the power amp has gain adjustment......check if there's a tape monitor on the back of the eq, the 901 eq's had them....the signals at that point will have been worked by the eq and ready to send to amp sections....this is a game of follow the signals.....

mulester7
01-10-2011, 09:40 PM
Will the tape out still use the equalizer?.....I better back up a little, what equalizer are you talking about?.....

darkerror05
01-10-2011, 09:49 PM
Well part of the reason I want the preamp between my source and the power amp is so I can use the bass/treble controls. I live in a dorm which is acoustically dead so a little eq helps.

mulester7
01-10-2011, 10:26 PM
Well part of the reason I want the preamp between my source and the power amp is so I can use the bass/treble controls. I live in a dorm which is acoustically dead so a little eq helps......aah, gotcha'....well, if you don't have pre-outs, and you don't have a tape monitor, you'll have to have a stereo repair shop wire you some pre-outs....probably woundn't cost as much as you think....just go talk to them and see.....

Portkula
01-11-2011, 06:12 AM
Well part of the reason I want the preamp between my source and the power amp is so I can use the bass/treble controls. I live in a dorm which is acoustically dead so a little eq helps.
...if you don't have pre-outs, and you don't have a tape monitor, you'll have to have a stereo repair shop wire you some pre-outs...
Yes. If some of your integrateds has “TAPE MONITOR” button, “REC OUT” selector or “SOURCE-TAPE” selector, you can connect the “LINE IN” terminals of an equalizer to the “TAPE REC” of the integrated’s terminals coming from the “monitored” “TAPE” on the “INPUT SELECTOR”, and “LINE OUT” terminals of the equalizer to the “TAPE PLAY” terminals going to the same “monitored” “TAPE” on the “INPUT SELECTOR”. And send the L and R signals from the equalizer’s “REC (TAPE OUT)” terminals to the input terminals of your stereo power amp equipped with volume knob, or to a separate volume attenuator between the equalizer’s “REC (TAPE OUT)” terminals and your power amp not equipped with volume knob.

darkerror05
01-11-2011, 08:54 AM
Portkula, thanks for the reply but I think you entirely missed the point of my post. I already know how to hook of a equalizer, but that is not my goal. I'd rather just use the bass/treble knobs of the integrated receiver to control the sound that is outputting to my power amp. I could just use a equalizer on my PA but when I tried that it didn't suit my needs.

mashaffer
01-11-2011, 08:15 PM
Why not open her up and take a few pics. Maybe you will get lucky and find that the power amp section is on a separate circuit board or something.

mike

darkerror05
01-11-2011, 11:27 PM
Maybe I will throw up some pics tomorrow. I don't have any classes.

clydeselsor
01-11-2011, 11:42 PM
If you use the tape outs with some sort of attenuation, you still will not have use of the tone controls...

darkerror05
01-12-2011, 08:17 AM
Yeah I realize that. Thus why I need to "build" my own output.