[sdiy] DIY Mixer - please help!

[cheater cheater]

Antti,
thanks for your reply.
I have found that a lot of vintage consoles use very high voltage outputs.
For example the Manley 16x2 has a maximum of +33dBu output.. by using
a calculator here:
http://www.sengpielaudio.com/calculator-db-volt.htm
this gives us 98 volts p-p.
I believe this is to achieve high headroom. Unconfirmed information
tells me that most op amp designs will distort more the closer you get
to the maximum output voltage.
Do you think that a 741 will handle this sort of use?
I believe the Harrison used completely discrete op amps for similar reasons.


And this brings us to the question of power supply.
When buying houses: location, location, location
When building analogue audio: power supply, power supply, power supply
But that's not a big problem since we (synth-diy) have some good PSU
designs and this is a bit off topic anyways. I just thought it's worth
mentioning.

Regarding transformers: there's a lot of opinion and little
information surrounding these, since most of them are based on secret
designs anyways. They can be very interesting. But I think
transformers are not necessary in the first run.

Thanks
Damian

On Thu, Sep 3, 2009 at 12:04 PM, Antti Huovilainen<ajhuovil at cc.hut.fi> wrote:
> On Wed, 2 Sep 2009, Paul Dhillon Weber wrote:
>
>> Often designers used output transformers to achieve greater level and
>> headroom without having to add additional, phase inducing and noisy amp
>> stages.
>
> Transformers actually have far worse phase problems than amplifier stages.
> So much so that interstage transformers can't usually be used inside
> feedback loop which is part of the reason they fell out of favor in tube
> circuits when lower THD amount required using feedback.
>
>> Think about your favourite THICK recordings from the 70s.  That's the
>> sound of transformers.
>
> As much or even more likely to be due to distorting transistor circuitry.
> Vintage designs using discrete components aren't exactly what you'd call low
> distortion these days. 0.1% THD was considered good back then and in
> simulation many circuits produce even more distortion. As for opamp designs,
> one word should be enough: 741.
>
> I once tried to measure distortion in a cheapo behringer DI isolation
> transformer. We had problems getting enough signal to produce any measurable
> distortion in FFT view.
>
> Antti
>
> "No boom today. Boom tomorrow. There's always a boom tomorrow"
>  -- Lt. Cmdr. Ivanova
>