Slo Recto Twin?

[psychepool]

http://s57.radikal.ru/i157/1101/7d/728f780b18ee.jpg
http://guitar-gear.ru/forum/index.php?a ... h_id=40276
Is there anyone that familiar with this circuit? I want to ask you questions.

It is a 3 channel (2.5 channel?) Preamp circuit which puts Fender Twin reverb / Solano / Mesa Rectifier in one.
It is based on Mesa Boogie Rectifier as lead channel.
The second stage of the lead channel is switched to a 470K / 470pF filter to implement the Solano-JCM type crunch channel.
There is also a Blackface type clean channel that shares the first stage of lead/crunch channel.

The channel switching configuration is largely divided into clean / drive.
It is possible to switch the crunch / lead mode in the drive channel.


Personally, I would like to make a full amp connected with PI~power amp.
I want to know the related contents, but I am having difficulty because there is only a page in Russian.


Is there no popping noises even if make it only the contents of this circuit? It's my main question.
I have made an amplifier that switches the channel through the relay is only Dumble.
It doesn't has any special popping noise, but I don't know how about other relay-switched amp circuits are like.
I will mention it again, but I will make it a full amplifier, not a preamplifier. Are there any popping noises when made with full amplifiers?
If there is no popping noise without mute circuit, it seems to be more comfortable to make. Because I am not an electrical major, but just a hobbyist. I want to avoid complicated circuits.

And what is the power amplifier circuit that fits to this preamp?
Commonly used JCM800 power amplifier? Or a similar Soldano slo power amp? Or is the Mesa Boogie Rectifier's power amp with the most complete form in the preamp?
I would like to use all three channels evenly.


In addition, I would like to ask opinions of people who made it.
To be honest, the sound samples from the search are not enough to judge the sound, so there is no certainty about the feel of this amp.
I just want to hear some more opinions for judgment. Because the reason that I am trying to make it is just because I like concept of the circuit.


I look forward to your advice.

[roberto]

Better to attach the file here.

First point: the B+ is not correct, it has to be around 500VDC, not 350.

Second: I'd use a split load on the first stage for the clean channel, or even better add a valve and integrate the circuit that way:
- separate clean with one single 12ax7;
- dedicate half a 12ax7 for the crunch channel without high dampening and cathode bypass.

Then... but we are going far, those will be the two major improvements, IMHO.

[sluckey]

350V should be plenty since this is a preamp only circuit.

[roberto]

Not really.
Let's consider 6 mA as total absorption from the whole preamp (source follower included).
That's 60V drop on the 10k, so on the source follower you have 290V.
Then from that let's consider 2,5 mA for each of the two parts: that's 40V drop after each 15k.

So your preamp works at 250V, and your source follower at 290V.
You should have 100-120V more.

[psychepool]

Thanks for the advice.

In fact, I have not thought about B + yet.
I was intended to find a suitable configuration with reference to other similar configuration amplifiers.
Thanks for reminding you of things I have not thought of yet.

And why is it recommended to separate the first tube of the clean channel?
Personally, I liked this circuit because it uses three tubes economically.
I saw many brands of amplifiers share the first stage like this, and I do not want to increase the number of tubes as much as possible, so if it dosen't have any special advantages, I will make them like this.

As it is written in the text, the most interesting part of personally is the popping noise when switching the channel.
I do not have much experience in making amplifiers that channel-switch to relays, so I can't predict the result.
I wonder what the opinions of experienced people are. Especially when switching crunch / lead, tone stack is unreliable to me.

[roberto]

I'd add a "M" resistor between C13 and R14 to ensure the grounding to the cap.
Same thing after C4.

[martin manning]

So your preamp works at 250V, and your source follower at 290V. You should have 100-120V more.

As shown, there will be a little over 100V on V1.1 anode, 150V on V1.2 anode. No reason that won't work, and evidently this was the intent of the original circuit, no?

[roberto]

Hi Martin,

I was not talking about working or not, I was talking about having a slo-like sound.
Even 20V can be noticed on those circuits, and here we are talking about 44% more voltage on the circuit.
That's a huge difference.

So yes, it will work in any case, but no, it will not sound close to the Slo sound with such low voltages.

[psychepool]

I'd add a "M" resistor between C13 and R14 to ensure the grounding to the cap.
Same thing after C4.

Is the purpose of removing the popping noise?
Is there any change of sound by put this resistors?
And Does this cause popping noise if I do not put this resistor?