KVR Audio

jp008 · Post by **jp008** » Wed Jan 20, 2021 2:23 pm

So.. I've been recording music privately at my own studio for decades and something odd (to me at least) happened a few years ago that I'm curious about, which I should probably be able to explain by now, but I'm actually still not extremely inclined in some of the more deep technical aspects of hardware.

That said, one day I tried this on a whim and it made my head do a 360 degree turn when I heard what came out of the amp:

Guitar -> small tube DI box -> Microphone Impedance matching transformer plug -> High gain input on amp

I should also note that the tube DI box was not 'starved plate' and used a transformer. The amp was also a 120 watt tube head.

Anyways, what I heard was an almost lifeless sounding tube amp - virtually turning into a raging, almost triple rectifier amp type sound. I just stared at the amp in disbelief for like 5 minutes scratching my head.

Technical explanation?

Winstontaneous · Post by **Winstontaneous** » Thu Jan 21, 2021 8:42 pm

Hard to say without knowing the input/output impedances and a little more info/specs about the gear. If it sounds good, it is good!

matt09 · Post by **matt09** » Thu Jan 21, 2021 8:45 pm

It may relate to the changes in impedance over a wide frequency range.

jp008 · Post by **jp008** » Fri Jan 22, 2021 2:06 pm

Winstontaneous wrote: ↑Thu Jan 21, 2021 8:42 pm Hard to say without knowing the input/output impedances and a little more info/specs about the gear. If it sounds good, it is good!

The DI was a Bellari ADB3 (the version without an input knob, three buttons per channel) and the adapter plug was a vintage Shure A95UF Line Matching Transformer. It was plugged into the high gain input on a Peavey VTM-120.

Winstontaneous · Post by **Winstontaneous** » Sun Jan 24, 2021 2:41 am

Looking at the spec sheet for that Shure tranny, if you're going from low-Z input to high-Z output you're getting 20+ dB gain. There is internal wiring that can be changed depending on input impedance...whatever settings it's on seem to be working great for you! Also the more you slam a transformer with lots of level the more saturation you'll get.

Tj Shredder · Post by **Tj Shredder** » Tue Feb 09, 2021 10:55 am

jp008 wrote: ↑Wed Jan 20, 2021 2:23 pm Guitar -> small tube DI box -> Microphone Impedance matching transformer plug -> High gain input on amp.

A DI box simply isn't made for this scenario and you definitely don't need it there.
https://www.soundonsound.com/techniques ... -impedance

Explain this: Impedance matching transformer from DI into amp