Bassman 5b6

[da Geezer]

Don't you need a cap to make the grid leak work?

RP

I used a different schematic which has been posted many times. https://tubeamparchive.com/download/file.php?id=25858

On the single input version, Doesn't that 2.7k Rk on the input need to be changed to 5.4k (or thereabouts) to maintain "stock" performance?

G

[M Fowler]

On the single input version, Doesn't that 2.7k Rk on the input need to be changed to 5.4k (or thereabouts) to maintain "stock" performance?

Going to a higher value then 2k7 would set tube gain too high I'm thinking.

[da Geezer]

https://tubeamparchive.com/download/file.php?id=25858

On the original, the Rk is shared.
For a single triode, the value of the cathode resistor would need to be approx double to maintain the same bias....correct? Just like when Fender used shared cathodes on the 12AX7's of some amps, 820R was used when shared, 1.5k when split.

G

[Colossal]

Told my lovely wife we are getting small Class A land yacht and going motoring

Hahaha, so it generates the most power when it's idling and 2nd order harmonics at highway speeds, eh?

[M Fowler]

Told my lovely wife we are getting small Class A land yacht and going motoring

Hahaha, so it generates the most power when it's idling and 2nd order harmonics at highway speeds, eh?

Very funny stuff

[Matt D]

Mark, I'm wiring up the different ohm taps from the OT to three different jacks as you did. I notice that you have the negative feedback hooked up to the the middle output jack (presumably 8 ohm only). Does this need to be connected to the jacks of the other OT taps?

[M Fowler]

Mark, I'm wiring up the different ohm taps from the OT to three different jacks as you did. I notice that you have the negative feedback hooked up to the the middle output jack (presumably 8 ohm only). Does this need to be connected to the jacks of the other OT taps?

No.

I have 2/4/8 ohm impedance so I connected the NFB to the 4 ohm jack.

[rp]

Mark, I'm wiring up the different ohm taps from the OT to three different jacks as you did. I notice that you have the negative feedback hooked up to the the middle output jack (presumably 8 ohm only). Does this need to be connected to the jacks of the other OT taps?

No.

I have 2/4/8 ohm impedance so I connected the NFB to the 4 ohm jack.

Anyone know for sure what the original had? It was 1 x 15" @ 8 ohm, yes? Shouldn't the NFB be off the 8 ohm?

[M Fowler]

I think your correct about the 15" and 8 ohm load.

Some amps have the NFB on the middle impedance load of the OT secondary so that is where I put mine. I'm running 2/4/8 ohms. I could change it but sounds nice right where it is.

[Matt D]

Thanks Mark. Pictures of my build will be up soonish.

[M Fowler]

Thanks Mark. Pictures of my build will be up soonish.

I'm looking forward to seeing the builds.

[Matt D]

Here is a link to some pictures of my build over on the steel guitar forum:

http://bb.steelguitarforum.com/viewtopic.php?t=239390

[M Fowler]

Matt,

Your off to a good start. So did you rotate the transformers 180 degree apart or going to try it the way it is?

I've seen a photo of a commericailly built amp that had the PT and OT so close together I couldn't believe my eyes but it had no noise issues.

Mark

[telentubes]

Matt D, What are the dimensions of your chassis? I have a Dirty Dawg Custom 2.5 X 8 X 16 that I'm going to use. Looks about the same as the one you used. I've got Tito's book, somewhere in a box in storage, I need to dig out.

[Matt D]

My chassis is 16x8x3. I bought it to fit a cabinet made and rejected by Loctal, a forumite who is a more meticulous builder than me. I totally blew it on the transformer orientation. The Zolota layout uses a laydown PT and I used his OT orientation without thinking about it. Live and learn. I'm going to take this opportunity to try the headphone trick for OT orientation.