New amp projet: Z-Carbia. UPDATE: CLIPS!

[Carbia]

Hi guys!
I'm here to introduce you my new build, the Z-Carbia

It's something between a DR Z Route66 and a Z28 with some mods/adds by me.
Essentially, it's an EF86 based preamp, with a 12ax7 phase inverter pushing a pair of 6v6's un ultralinear mode on the power stage. All fed by a GZ34 tube rectifier. No NFB and Lar/Mar MV.

I have plugged now a pair of EL34's just to test while I wait to get a nice pair of 6V6's

I used Hammond transformers 372DX on mains power and 1650FA as OT, carbon film resistors, Mallory caps and Alpha pots.
The board is a generic turret board from Tube-town (as all the other stuff) with some turrets added.

Here is the amp chassis:


the back:


Only a few knobs...


And with his cabinet (made at Tube town too)






And now... the PORN:








Hope you like it!

[JimiJames]

Nice.
No Mid's. O.K.
So, no SS recto... How's the bottom end with that GZ34. Looking forward to a clip.

[Carbia]

Thank you JimiJames

No, no mid's pot, but I have to say that I don't miss it. It works fine with different guitars as a kind of plug and play machine.

The GZ34... is a little bit SS sound. Does not compress or soften so much really. In fact, it's overspec for feeding that circuit that needs less current than a JTM45 for instance.

I have to get a nice pair of 6V6 an then I'll try to record some clips

[Carbia]

hey guys!
I've recorded some demo clips of the amp.

Sorry, but I don't have great recording resources. It was recorded with a Shure SM58 and a M-Audio Fast Track.

Full distorted amp (with the master volume turned down to 4)
https://soundcloud.com/josecarbia/z-a-tope" onclick="window.open(this.href);return false;

Half gain.
https://soundcloud.com/josecarbia/z-medio" onclick="window.open(this.href);return false;

The guitar is a '78 Gibson Les Paul Deluxe with the original mini's

[Carbia]

any opinion?

[RagnarMarGunn]

Sounds really good

[Carbia]

Thanks!

People use to say me that sounds in the style of Townsend in "live at Leeds" although I wasn't looking for that song when I built it

[Carbia]

New audio clip with better quality

https://soundcloud.com/josecarbia/carbia" onclick="window.open(this.href);return false;

[Carbia]

What do you think guys?

[Haze13]

Sounds Raw! Dirty! As it should be!

[Haze13]

UltraLinear... Is it a Class A Push-Pull power amp?
How much of the PPIMV do you use?
I set mine on the JCM800 on 2-3 o'clock, so it's attenuate not that much. Still the amp is a tinny bit fizzy, but it's much better than it was.

[Carbia]

It's a regular AB push-pull, but with the screen grids feed by a tap on the OT's secondary.
Basically, like this, but fixed bias, not cathode bias as the picture shows:



The Master volume was around 4 over 10 during the recording, but it works much better in this amp than in PLexis or 800's due to this amp doesn't have negative feedback, so doesn't sound fizzy at low master settings.

Thank your for comment

[Haze13]

Thanks for the info!
I see a wire soldered on the backs of the pots. I had to remove mine to get rid of a radio interference... It creates several ground loops (At least in my build), so I was wondering, do you have some strange noises like RF on the louder settings?

[Carbia]

No, mine is totally quiet.

All the grounds from the board goes to the ground buss bar on the pots. And then to a ground point in one of the PT screws, among the ground from electrolitics of the power supply.

The only ground that don't go to that point is the cathode os the power tubes, that it's on their own socket screw.

[Am_I_Evil]

Nice , is this similar to trainwreck amps?