Plexi 6V6 Hoffman style

[DummyLoad]

nice. very, very nice!  :-)


--pete

[EL34]

Curious about the working voltages in the amp
I guess you will be updating your PDF files with that?

[tubenit]

Wish I could do a demo but I'm just not set up for that.

As an side FYI to everyone,  I met Sluckey some years ago & we got to jam. It was a lot of fun for me.  He is an excellent guitarist and is a better player than I am, IMO.  He knew all kinds of stuff and was kind enough to share some of it with me.

And he is just a great person also.  It was a really a treat to meet him.

With respect, Tubenit

[sluckey]

Doug, node A is 400V with a GZ34 and running the bias at 25mA. It was 370V with a 5Y3. I like the GZ better. I'll post all voltages in the updated pdf. Stay tuned.

Jeff, you're too kind buddy.

[sluckey]

I've updated the pdf file to include actual voltage readings on the schematic. I've also shown a couple minor changes. I'll post the entire web page in a couple days.

     http://home.comcast.net/~seluckey/amps/6v6plexi/6v6plexi.pdf

[kagliostro]

WOW Steve !!!

beautiful work 

You beat yourself

Thanks for sharing

Franco

[drew]

Doug, node A is 400V with a GZ34 and running the bias at 25mA. It was 370V with a 5Y3. I like the GZ better.

If you were going to do it again, would you just go with solid state rectification?

[EL34]

I would include a tube socket for a tube rectifier for those that want that but I would plug in a solid state rectifier in that socket for me personally.

[sluckey]

If you were going to do it again, would you just go with solid state rectification?

No. I wouldn't change a thing about the way I built this.

However, I initially laid out the board for SS rectifier diodes. Doing so adds 1/2" to the board length, but it allows the tubes to be spread out more on the chassis if you drop the rectifier socket. I thought a lot about dropping the recto socket but I'm glad I kept it.

[EL34]

Hey Steve,
On your PDF schematic, you show two 100k plates load resistors on the phase inverter

It looks like you used a 82k and a 100K on your layout image


Also, the heaters don't show any ground reference
Did you use a pair of 100 ohms or did your tranny have a CT?


nevermind, I see now that you grounded one side of your heaters

[sluckey]

On your PDF schematic, you show two 100k plates load resistors on the phase inverter

Hmm. Look again. The top triode (V3-A) has a 82K plate load. Maybe you're looking at the 100K grid resistors for the 6V6s?

Also, the heaters don't show any ground reference
Did you use a pair of 100 ohms or did your tranny have a CT?

My PT has a real CT. It's shown on the "Mains Wiring" page. You can also see the green wire connected to a ground lug near the cap cans in the close-up gut shot pic. My schematic is wrong. I'll fix that. That's what I get for using so much copy/paste between schematics.

Are you drawing up a Hoffman style board layout? If so, I'd love to get a copy of the Visio file.

[EL34]

I must have been looking at something else while I was doing 3 things at the same time 


working on a layout right now
just started today so it may be a while

[JBP]

The tranny I'm using does not have a CT for the heaters. Do I need to create one with 100 ohm resistors ? Jeff

[EL34]

yes

[EL34]

Here's is my first draft of the Hoffman Plexi 6V6

I still have to rename all the parts on the schematic and do some other stuff
Copy and pasting things from other files always has snags

http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6.pdf

Let me know if you see any obvious errors
I have not spent much time double checking things yet
Eyes are tired and I am stopping work on this project today

The filter cap values are not all correct on the PDF file yet
[40uf x 20uf x 20uf x 20uf] cap can + 16uf is what I designed

[EL34]

Here is version 2 with a shorter board

Plexi 6V6 version 2
http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf

Screen grids are on the sockets
100k plate load is on a socket

Thanks to steve for the suggestions

The board size is down under 7 inches now

[sluckey]

Recheck the wiring on V2. Red wire goes to pin 6. Resistor goes between pin 6 and pin 1. Jumper from pin 1 to pin 7.

[EL34]

yeah, thanks
I can only do this for so many hours before I get tired of staring at the screen


I uploaded a fresh copy of the PDF with the fix
Thanks for double checking


I was headed out the door to get away from the computer for a while :)

[EL34]

On the next batch of Stout chassis i think it would be a good idea to add another pre amp tube hole in addition to the other changes we came up with a while back

[tubenit]

On the next batch of Stout chassis i think it would be a good idea to add another pre amp tube hole in addition to the other changes we came up with a while back

I think that's a good idea also. Definitely help increase options in using that amp chassis.

With respect, Tubenit

[MakerDP]

Here is version 2 with a shorter board

Plexi 6V6 version 2
http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf

Screen grids are on the sockets
100k plate load is on a socket

Thanks to steve for the suggestions

The board size is down under 7 inches now

Hey I really like this. Easily convertible to a JTM45 w/KT66 with a couple component changes also!

[EL34]

Thanks
The official Stout Chassis thread is here if you guys want to add your comments
Thanks


http://el34world.com/Forum/index.php?topic=17502.150

[hardhead]

Here is version 2 with a shorter board

Plexi 6V6 version 2
http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf

Screen grids are on the sockets
100k plate load is on a socket

Thanks to steve for the suggestions

The board size is down under 7 inches now


That is one "slick whistle"....when do you have time to sleep, Doug

[EL34]

Thanks

[mresistor]

Sluckey, that's a nice lookin' amp and the documentation is top-drawer. I bet it sounds great.  Thanks for sharing.

[EL34]

Here's version #3 of the Plexi 6V6


This version has the Blend control, pre amp volume and a master volume


http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V3.pdf

[EL34]

Version 2 is the dual volume pot version
http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V2.pdf


Version 3 is the Blend and Pre Volume version
http://el34world.com/Hoffman/files/Hoffman_Plexi_6V6-V3.pdf


I want to see how the V3 blend sounds first
I just may go back to the V2 dual volumes if I don't like V3

[pickinpop]

so a new chassis with an extra preap tube hole is possibly in the future?

[EL34]

yes, and some other hole changes on the next batch
Gonna dial in this chassis so it can be used for many types of builds

Have to use up this batch of chassis first

[EL34]

Got quite a bit done today on the Plexi 6V6

Here's my build pic album on Facebook

Hopefully all the pics should be visible to you guys
https://www.facebook.com/media/set/?set=a.446459778835904.1073741838.264340103714540&type=3

[smackoj]

Just a sort of wild ### question. does the 'Plexi 6v6' really sound like a lower power version of the early Plexi face Marshall, or are you mostly using the name based on the wiring design, component values etc?  I like the looks of that compact design for the Plexi or Stout chassis. nice work.

thanks

[EL34]

It's the Plexi circuit with 6V6's
That's why it's called a Plexi 6V6


I can't tell you what it sounds like yet, I am still wiring up the amp

[macula56]

I built one of these last year sort of based on Sluckey's layout but with KT66s in a 15 1/2" x 7 1/2" x 2 1/4" chassis. And since I don't really like cap cans I added a Deluxe Reverb dog house for my caps. I thought about tube rectification but I went with diodes for the rectifier. It fits inside of a Blackheart 15 Watt head cabinet. Rockin' Marshall tones and great cleans as well. Sort of a stealth amp as people see how small it is then hear the balls that come from it. A great circuit for sure and Sluckey's drawings are awesome.