Separation of amp/pre-amp?

[Momato]

Hi all, first post here, hope someone who knows electronics more than I can help. I have a Teac Reference A-H500i integrated amp that I would like to use as a per-amp instead. The service manual indicates to me that the per-part is quite separate from the power-amp, so it should be "easy"?

However, I do not h
Know exactly what to tap into. Could anyone have a look at the service manual and give some advice? I guess it would be best to uncouple the power-amp all together.

Manual is at link, under preview picture is a download (appears after some seconds)

Best regards, Morten

Link removed due to concerns over copyright and pirated material.

 

[maylar]

It's hard to tell from the schematic, but does the amp have tape outputs?

 

[Momato]

Yes, but they are not volume controlled?

Here is a pic of the internals, think pre-to-power is the blue wires ending in a White connector on each power-amp board.

 

[TonyTecson]

you can normally get preamp output at the top of the main volume control.....

 

[madtecchy]

I dont think it is the blue wire !! It is more likley to be the grey cables with the black sleeving on the ends . The grey wires pass just next to the blue ones

 

[dry joint]

Some power amps would want the signal after it comes out of the volume control - passive pre, these amps could have a problem if the signal is amplified first. You need to cosnider what you're going to first.

 

[Ian Finch]

I can't speak for forum management, but no organisation needs to have it's reputation sullied by openly supporting illegal activity by its members.
That's the issue. Unfortunately, it's also a cultural issue, most strongly supported in the US, less so in Europe and almost ignored in Asian countries.

There are adequate provisions for accessing material via links to other sites, as in the case of the constant references made to ESP site material and free schematic download services - these are often superior schematic archives because the site and contributors are set up for the purpose. If the interest is really there, a download may prove more useful in any case.

 

[Nico Ras]

I dont think it is the blue wire !! It is more likley to be the grey cables with the black sleeving on the ends . The grey wires pass just next to the blue ones

I think Madtecchy is right. It would most probably be a screened cable like the one he says.

 

[Mooly]

Posts on moderation and copyright removed.

Guys... copyright is a fine line sometimes but there are valid concerns over some sites.

 

[tvrgeek]

There are many very good, some very very good preamps on the auction sites for darn near nothing. Only a few of us want a non-remote stereo preamp. I picked up a Nac CA-5 for almost nothing. One of the best preamps ever built. Easier than hacking up an existing integrated amp.

Tape out is usually before the volume control.

On schematics, I fully respect a companies intellectual property. I do wish a few more would have an enlightened view that if it is a technology based product, like our amps, than after 10 or so years post production it is no longer any real use to protect the company or their service affiliates, so it is good PR to release said schematics for the enthusiast market. Patents may still apply and should be respected. Besides, the real secret to many of the top products is actually the physical execution, not just the schematic.

 

[Jay]

I would like to use as a per-amp instead.

On the amp board there is a socket of 9 cables. Pin#8 is signal input, pin#9 is ground. You can re-route this to Tape2-Out RCA (to use it as PRE-OUT), but first disconnect a few components from the RCA.

The tone control is useless (bad quality) as it uses the lousy 4558 op-amp. So you may want to bypass this (CD DIRECT) and use only the volume control. The preamp is okay.

The amp is not too bad (JFET LTP input). It is a waste not to use or modify it, as the power supply and the transformer looks okay.


VOLUME ---> [PREAMP] OR [OPAMP TONE CONTROL] ---> AMPLIFIER