Manzamp!

[Dingleberry]

That's an astonishing job you have done ic-racer!

I had empty chassis and transformers for 2xEL34 project so I couldn't help myself...
Power supply wiring is nearly completed.

-T

Is this going to be another Manzamp? How are you going to do the main board? Eyelet board? Do you know how to etch copper boards? Do you want a pattern?

Not an exact clone but very "Manzampish" with just some minor tweaks so I can use those parts I have on hand. Chassis and transformers have waited about two years for suitable build. Now I have some spare time and finally I have decided what to build;)

I'll be using diode bridge because my PT didn't have neither 5V winding nor center tap. B+ should be very close to 430V.
And probably I wire the first triode parallel and keep just one volume so I don't have to drill any new holes to front panel. I like to keep the original aesthetics with old donor amps if possible.
And I don't have the cathode bypass inductor, but that I can figure out somehow.

I've etched boards before, but I think I wire this point to point. There ain't many components inside. Probably use only terminal strips because I have some on hand. Usually I design the layout on the fly when I play with terminal strips and with this kind of salvaged donor amps.

I'll keep you in touch when I gain some progress with that build.
-T

[LeftyStrat]

Thanks for showing us your schematic. The clips sound good too.

I was a little confused by the choke 1-22Hy in the first stage. What does that achieve and did you include it in your amp?

Using an inductor in series with a cap in the cathode changes the response from high pass to band pass, so it would give a mid boost.

However, those values seem a bit high. Here is a similar circuit in an Orange amp with variable boost:

[img1653]http://www.orangefieldguide.com/OFG_SCH ... output.jpg[/img]

[ic-racer]

Thanks for your reply. What does it do in the amp?

Bass boost.

[ic-racer]

Thanks for showing us your schematic. The clips sound good too.

I was a little confused by the choke 1-22Hy in the first stage. What does that achieve and did you include it in your amp?

Using an inductor in series with a cap in the cathode changes the response from high pass to band pass, so it would give a mid boost.

However, those values seem a bit high. Here is a similar circuit in an Orange amp with variable boost:

[img1653]http://www.orangefieldguide.com/OFG_SCH ... output.jpg[/img]

Thanks for posting that. So, there are a number of ways one might incorporate the choke. The active tone circuit I posted used a 22Hy (not mHy!) choke. The circuit I came up with is 3Hy (not 3mHy!) so there are some big differences. A lot of room for experimentation on this.

[LeftyStrat]

At 3Hy and 25uf, the resonant frequency should be at 18hz.

How sure are you about the value of the cap?

[ic-racer]

Here is another example of a choke on the cathode of a preamp tube that I used in my research. This one is the distortion circuit from the Fender Super Twin Reverb.

[IMG706]http://img.photobucket.com/albums/v670/ ... ortion.jpg[/img]

[ic-racer]

At 3Hy and 25uf, the resonant frequency should be at 18hz.

How sure are you about the value of the cap?

Just a guess based on the size and presumed voltage of the cap in the picture and cap value in the Thordarson circuit.

The other point that I want to share is that the circuit research on this amp involved more of a 'cut and paste' from other known working circuits (Skyliner tone, Precision Power, etc) rather than any new circuit engineering on my part.

[Mark]

Thanks for that, what was the equation again, I can't believe I have forgotten it.

[ic-racer]

Here is another preamp circuit with a choke that I studied:
[IMG731]http://img.photobucket.com/albums/v670/ ... EH-195.jpg[/img]

[LeftyStrat]

That's an interesting design. Here's the Ampeg V9 preamp with three different inductors to switch the range. The V4 used a tapped 800mH inductor with taps at 300mH and 100mH. Note that this schematic incorrectly labels them micro henries.

[img:800:600]http://www.drtube.com/schematics/ampeg/v9pre-jp.gif[/img]

[ic-racer]

So far the Manzamp is sounding good with every guitar I have tried. Here it is with my new-to-me ES 335 (1997).
Still have 19 guitars to try....
http://www.youtube.com/watch?v=0D81FMc6Dc4

[LeftyStrat]

So far the Manzamp is sounding good with every guitar I have tried. Here it is with my new-to-me ES 335 (1997).
Still have 19 guitars to try....
http://www.youtube.com/watch?v=0D81FMc6Dc4

I really love the bass response on the amp. Very throaty, even with the strat. No hint of woofyness.

[Mark]

Agreed it is a very pleasing sounding amp, I would like to have heard it without the additional effects though.

[ic-racer]

As I come up on 24 hours with this completed amp it seems as if I am incredibly lucky to have it sound so good. In reality, I think that 90% of the good sound of this amp is from the 'known' elements. That is, the Skyliner tone, Precision Power, phase inverter and known 5f6a elements.
I think the 'unknowns' probably contribute only 10% of the overall tone.

[ic-racer]

Agreed it is a very pleasing sounding amp, I would like to have heard it without the additional effects though.

My computer is in a very 'dry' sounding area but here it is without the Verbrator.
http://www.youtube.com/watch?v=MQfv41Da0IY