Questions about mesa boogie dual rectifier

[fossilshark]

Note: sorry for all the questions on this amp.

I have 2 questions.
The first is for anyone who owns/has played a mesa boogie dual rectifier:
What amp setting is the most "metal" or has the best sounding distortion in your opinion? (Like orange mod or red vintage channel?)

The second is for the more experienced tube freak:
How would i make a preamp for a guitar amp (like the mesa boogie, or a marshall or any high gain amplifier) and make the output stage from the tone stack useable with the input of another guitar amp? In other words: instead of preamp to power amp it would be preamp to another guitar amp for use as a pedal. Would i have to modify the signal level? Because i have a feeling something like that would be too much signal to use as a pedal.

[kagliostro]

Is good practice (when you build a stand alone preamp) to have as output tube a CF (Cathode Follower)

this way the impedance of the output is low and you have a better drive of pedals and amps

the same also if you use long cables

Franco

[sluckey]

Would i have to modify the signal level?

yes

[kagliostro]

Would i have to modify the signal level?

yes

Of course you can also do without a CF using a partition divider



Franco

[fossilshark]

So the last tube in the preamp would be a cathode follower? Do you have a schematic for something like that?

[kagliostro]

It is not mandatory, but it solves some problems (those of which I said)

http://www.valvewizard.co.uk/accf.html

http://www.valvewizard.co.uk/dccf.html

Franco

[fossilshark]

Thanks, that helped alot. My main concern was, dont 12ax7s put out like 12v or something way higher than a normal guitar? That would cause a problem especially if i wanted to use it with a solid state amp correct?

[VMS]

If this was used as a stand alone preamp I would also include the first part of the fx-loop V4B.


Also because preamp uses only 5 triodes I would use V1b as V2a, V2a as V2b and so forth.

[kagliostro]

Here something you can use as an example



consider the preamp till the FXLoop send

Franco

[fossilshark]

That makes sense, because you wouldnt want a massive signal going to your effects. Should have thought of that lol. Thanks

[PRR]

To drive "any" load, a buffer (cathode follower) is often wise.

But here we want to make a tooth-pick out of a log. Well, a kabob stick out of a branch. What we start with is far bigger than what we need.

For the specific case of going from any amplifying system into a "Guitar In" jack, buffering not necessary. You have 1K or more of signal. Usually less than 100K source impedance. The guitar jack needs like 0.1V signal and is usually up around 1Meg impedance. A voltage divider ("partition divider") to give 10:1 loss between these impedances might be 1Meg and 100K. The source sees >1Meg. The guitar in jack sees <100K. This is usually a fine starting point. 470K:47K or 220K:22K may also be good.

[2deaf]

Maybe a low-Z tone stack.

[VMS]

Maybe a low-Z tone stack.

Is there one cap missing on your tone stack?

[2deaf]

No.  The straight piece of wire in place of a large (for audio) capacitor works in a low-Z tone stack.

[VMS]

But isn't there now dc-voltage on the bass control (and other pots)?

[2deaf]

Good point.  Better put a cap. in there.

[PRR]

> Better put a cap. in there.

Agree.