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Hi,
as far as I know, The pots in guitars are paralleled with pickups. And guitar pickups have impedance from 5 to 20 Kohms (or about that). So this pot is in the good ballpark.

Laurent.

> A guitar has a much more higher impedance than the 20k

Are you saying Jensen picked the wrong impedance?

The -pickup- impedance is 5K at low frequency rising to 50K-200K at the upper resonance.

All modern guitars have volume pots, and the output impedance is generally 60K-100K.

The guitar-amp input IS high impedance, 470K-1Meg.

BUT you usually drive a high impedance with a low impedance.

And usually the lower the better.

However "some" impedance before a high-gain input may help roll-off supersonic hash.

I'd stick with Jensen's plan. IMHO: it isn't wrong. Deane and the company he put together know rather a lot about impedances and interfaces.

The guitar impedances aren't really of any importance - as the re-amp is used for replay from a recording system into a guitar amplifier, the output of which is recorded again  - so the Jensen PDF will work well. There is no reason why almost any transformer shouldn't be suitable - as you are simply trying to inject more 'flavour' into the guitar sound when recording (or re-amping) from the guitar amplifier.

As you have the transformers already - it will be easy to 'try it and see'.......

AudioJohn said:

The guitar impedances aren't really of any importance - as the re-amp is used for replay from a recording system into a guitar amplifier, the output of which is recorded again  - so the Jensen PDF will work well. There is no reason why almost any transformer shouldn't be suitable - as you are simply trying to inject more 'flavour' into the guitar sound when recording (or re-amping) from the guitar amplifier.

As you have the transformers already - it will be easy to 'try it and see'.......

Click to expand...

The impedance pot as shown in the pdf is pretty worthless.  Feed your instrument amplifier from a low Z pot across the transformer secondary and be happy.
The pdf was copyrighted no earlier than 1995.  Deane died in 1989.
A Stancor 1:1 is not ideal.  A better solution would be a 4:1 or greater step-down.

is this transformer look good ?
http://uk.farnell.com/neutrik/nte4/transformer-audio-1-4/dp/724609?Ntt=724609

There's always Nydaves plan in case you haven't seen it.



The Neutrik transformer should work great. It saturates quite early but that shouldn't matter if you're going to a guitar amp anyway. 
Most people love the sound of overloaded iron.

I either pad down a preamp output or pad down a line output to go to the guitar amp.  Don't know why I would need a special box for this.. 

Svart said:

I either pad down a preamp output or pad down a line output to go to the guitar amp.  Don't know why I would need a special box for this.. 

Click to expand...

No doubt you mind your grounding and interfacing schemes, in which case, there really is no need. These boxes are intended as Swiss-Army knives or Gerber multi-tools, incorporating the padding, de-balancing, and possible ground lifting all in one. Sure you can always pull the fader down in your DAW, pre-send, but I hate reaching for the mouse while fiddling knobs on stomp boxes on the floor. It's convenient to fiddle the send level on my reamp box right next to the stompers or atop the amp.

The output impedance pot will make an audible difference when feeding certain amplifiers and effects, the Fuzz Face or Woolly Mammoth for instance are highly sensitive to the impedance seen at their inputs. I used 50k as shown in the NewYorkDave schemo. In most cases it won't do anything, but when your effect just isn't sounding like you know it should, you'll be glad it's there.

The 1:1 transformer is fine, you'll just be working the level pot at the low end of it's travel if you recorded with decent level to tape/disk.