Tweed Overdrive Special

[azatplayer]

I wonder how important the operating point is for the power section on this amp, wondering if 450V would work ok? I just got some other donor iron to use up, and nothing in the 420V range.

[gingertube]

Guys,
For those having trouble finding the 5879 there is another tube you might try. The 6BR7, seems that there are reasonable NOS levels around the place as it hasn't yet become "fashionable". 12BR7 also seem to be available.

I haven't tried one myself yet but have started collecting a few to use in lieu of EF86 or 5879. In its day it was advertised as a lower noise alternative to the EF86.

Cheers,
Ian

[M Fowler]

What is your settings to get that honky tone. I get some but not to the degree I would like it.

Mark

[10thTx]

I don't really remember what settings I used, but probably pretty close to this:

Vol 6
Tone 7
Fat 5-7
OD trim 3-4
Drive 5
Level 6-7
Tone 7
PPMIV (level) 8

Probably had a 5751 in V1 and 12AY7 in V2 with 5881 Tungsol thru either an Emminence Cannabis Rex or a Red, White and Blues.

I just feel that I could free up some space loosing that recto tube and also go with fixed bias. I really like a lot of my cathode 6L6 builds but..... I always have to do things differently it seems

Did you do cathode biased or fixed bias? I think that will make a significant difference.

With respect, 10thtx

[M Fowler]

I did use fixed bias and after listening to the posted clips I am getting the same tone after all I was just thinking the TOS had a little more honk is all.

Still tunning the amp. My OD trimmer is on the back side easy to get to.

[M Fowler]

Still fiddling around this weekend when I can, having fun.

Mark

[M Fowler]

Well I reworked the tone circuit to .0047 from volume pot to tone pot and .01 to ground.

I might either change clean tone pot to rotary switch or just use a treble cut control on PA rather then the simple treble cut tone control. Change the OD tone circuit back to the schematic posted.

[10thTx]

My Tweed Overdrive Special has undergone some mods since I first built it.

Here is a sound clip that shows the transition from clean, to somewhat clean, to slight overdrive, to more overdrive. Excuse the mediocre playing.

http://www.soundclick.com/player/single ... i&newref=1

The OD trim was at "5", drive at "3.5" and level at "3". So there was considerable OD left to be had.

I think this version has somewhat better contrast between the clean and the OD, perhaps. However, the basic "TOS" tone is still the same, IMO.

With respect, 10thtx

AND here is a slow blues version ........... same setting, amp, guitar and cab.

http://www.soundclick.com/player/single ... i&newref=1

http://www.soundclick.com/player/single ... i&newref=1

[M Fowler]

Changed the tone controls to 47pf with .0047 to ground.

Now onto more tube testing 5751, 12AU7, 12AY7 and 12AT7 in V1 and V2 positions.

Look at lowering the EL34 grids to 5k1 or 1k5.

Mark

[surfsup]

MF, what size chassis is that you're using? Thanks.

[M Fowler]

Ken Watt's 17.5x8x2.5 chassis with inside mounting tabs. Fits in my drawer kit cabinet from WoodCraft


Mark

[surfsup]

I don't see anything in your gutshots requiring the need for the 2.5", so assuming I can cram this into a 16.8.2"

I'll start the layout and planning. I'm debating this one or a modded version of a different amp before I finish that 4 gain express/Marshall. I'm still debating what output tube and ot to use.

[M Fowler]

Plenty of room in a 16x8x2 chassis for this type of build.

Mark

[memphis032]

How about 12"x7"x3"...? How close can trannies be mounted to each other?

Also, what OT are you using? It's the only thing on the schematics that isn't labelled!

[M Fowler]

I used Magnetic Components (MC) Bassman iron and I think 10thTX used Hoffman Bassman trannies?

I think 12"x7"x3" would be a too tight to fit all this in.

Mark