Preamp difference : if it's not the frequency, not the slew rate, and not the harmonics, what is it ?

[RoadrunnerOZ]

I built a V76 with transformers from Ollie and NOS EF 804's, exact same circuit,

A friend bright over a real one and boy was I disappointed , they did not sound the same at all. His was better. What was the difference? I have no idea.

You could try swapping his tubes for yours see if that changes anything

 

[gyraf]

Those "replica" transformers were most hot air, perhaps?

 

[RoadrunnerOZ]

Sounds like it would be the transformers……

 

[PermO]

If the chemical composition of the circuit is not exactly the same, it will not sound the same.
It could measure the same though.

But still not sound the same.

 

[rock soderstrom]

I built a V76 with transformers from Ollie and NOS EF 804's, exact same circuit,

A friend bright over a real one and boy was I disappointed , they did not sound the same at all. His was better. What was the difference? I have no idea.

I think the inductors make the difference.

When I was young and did my basic EE training, we had two old men in our company (more than 3000 employees) who were experts in this field and they did nothing but wind mains & signal transformers and chokes. They had a hell of respect for the "Wickelgüter" in the V76 and related units even though they had the best machines and materials for the job.

Other experts, such as Gerhard Haas, also considered these inductors to be not fully reproducible at a justifiable economic cost.

It's not that simple, even if some would like it to be...

 

[DaveP]

I once followed a tip about the loading of an SM57 for drums. Instead of the normal 10x bridge impedance it suggested a 600 ohm load and boy did that make a difference. Maybe the impedance matching element is the main variable?
best
DaveP

 

[ruffrecords]

I once followed a tip about the loading of an SM57 for drums. Instead of the normal 10x bridge impedance it suggested a 600 ohm load and boy did that make a difference. Maybe the impedance matching element is the main variable?
best
DaveP

In what way was it different?

Cheers

Ian

 

[DaveP]

In what way was it different?

I would have to use the word "fatter" and it made the drums sound more like you might want them to sound, sorry its not much help!
The mic had to work much harder into 600ohms, so maybe that cut some frequencies?
best
DaveP

 

[RoadrunnerOZ]

Interesting read here:
https://repforums.prosoundweb.com/index.php?topic=5442.0

 

[maosante]

Isn't it all about impedance? The load impedance would change the tone, each one has a different curve which contributes to the "color". Of course the components and all the circuitry affects the signal. But in general terms I think this is the approach of UAD interfaces/plugins, they have a variable impedance so when choose a different plugin preamp it does change the tone, just by changing the impedance. They also should give other properties of each preamp in the digital realm.



What transformers do is an impedance match, that would explain part of the color.

 

[s wave]

I do not know much of internal impedance but but Aspen Pittman's video below sure can make one a believer of how switching impedance (when using a transformer in the circuit) can seem to almost put the sound catching source right down a vocalist's throat - and I imagine can do a similar thing with mic'ing drums with a 57. He called impedance switching with a transformer an 'isolation characteristic' (@ the 12:57 mark)

 

[ruffrecords]

I do not know much of internal impedance but but Aspen Pittman's video below sure can make one a believer of how switching impedance (when using a transformer in the circuit) can seem to almost put the sound catching source right down a vocalist's throat - and I imagine can do a similar thing with mic'ing drums with a 57. He called impedance switching with a transformer an 'isolation characteristic' (@ the 12:57 mark)

So much technical BS. Unbelievable.

Cheers

Ian

 

[Paul W]

Isn't it all about impedance? The impedance curve would change the tone, each one has a different curve which contributes to the "color". Of course the components and all the circuitry affects the signal. But in general terms I think this is the approach of UAD plugins, they have a variable impedance so when choose a different plugin preamp it does change the tone, just by changing the impedance. They also should give other properties of each preamp in the digital realm.

How does a plugin change impedance? Or do they just shape the frequency response in ways that resemble what different impedances would do?

 

[sahib]

How does a plugin change impedance? Or do they just shape the frequency response in ways that resembles what different impedances would do?

Exactly.

 

[maosante]

Here's an excerpt of their website.

"The secret to Unison is its hardware-software integration between Apollo’s mic preamps and its onboard UAD-2 QUAD Core DSP Acceleration. Simply place a Unison preamp plug-in on your mic input in Apollo Console software, and it physically reconfigures the Apollo interface's impedance — so you can tap into the classic sounds of the world’s most recorded mic preamps."