Basic Simple 50 watt Bass Head

[big_teee]

Terry, if you haven't already committed to a preamp design I'd like to point out the "white" Fender Bassman of the early 60's. Essentially it sends your bass signal thru one gain stage then a cathode follower, then into EQ. Cuts out a needless gain stage & yields a clearer more authorotative bass tone. I suspect SVT's designers may have had a peek at this, then added their fancy midrange control to create their preamp. You could do that, or substitute a pot for Fender's midrange-setting resistor for simplicity. We PM'd about this awhile back.

Thanks Leo,
Can you point me at the correct Schematic.
Not sure about what a white bassman is?
T

[Leo_Gnardo]

Thanks Leo,
Can you point me at the correct Schematic.
Not sure about what a white bassman is?
T

I tried bringing schemos over from Hoffman's site but no dice. Go there and have a peek at Bassman_6G6 and 6G6A and 6G6B over there, they're on PDF. You'll see right away something unusual about the bass channel. In fact the treble control isn't even part of the stack - it's implemented as a tone control further on in the circuit. To me that means you can tailor your treble response by selecting c and r values in the main tone stack treble department. Rarely seen anywhere else, but for me, this is a "go to" tone machine for bass. Whether you want to have a presence control also, is up to you. Here's a link to the 6G6:

http://el34world.com/charts/Schemati..._6g6_schem.pdf

[Mick Bailey]

Don't overlook the Traynor bass amps if you're thinking of EL34s.

[big_teee]

I tried bringing schemos over from Hoffman's site but no dice. Go there and have a peek at Bassman_6G6 and 6G6A and 6G6B over there, they're on PDF. You'll see right away something unusual about the bass channel. In fact the treble control isn't even part of the stack - it's implemented as a tone control further on in the circuit. To me that means you can tailor your treble response by selecting c and r values in the main tone stack treble department. Rarely seen anywhere else, but for me, this is a "go to" tone machine for bass. Whether you want to have a presence control also, is up to you. Here's a link to the 6G6:

http://el34world.com/charts/Schemati..._6g6_schem.pdf

yes I have looked at those a lot.
here is another place off the mojo page, with lots of schematics.
Fender | Ampwares
I just didn't know what a white bassman was, Let's call it Blonde! lol
So in your first post, was you just saying to use the one preamp and the PI tube or use all 3 tubes in the 6G6 circuit?
with the B25 I was going to use the preamp of the B25 and use the long tail PI an amp section of the 1986 marshall.
Also I would use the bias of the marshall circuit, i'm familiar with.
It looks like the tone stack with the .25uf caps, it would have an awful low thumping bass.
I guess if I didn't like that tone, could go to a .1uf or higher.

[Jazz P Bass]

The 'white' bassman is commonly refered to as the 'blondey' amps.
6G6 is the circuit.

[big_teee]

Don't overlook the Traynor bass amps if you're thinking of EL34s.

Which one, please get me close?
Something on the simple side.
T

[Leo_Gnardo]

Which one, please get me close?
Something on the simple side.

The Traynor BassMasters YBA1 series I've seen are copies of Fender's 5F6A preamp & drive section with little variation. That's a winner too.

The now blonde 6G6 series Bassman pre "reaches way down there" similar to SVT, also gives weight to the G string in a way few bass amps do. Clarity of the top end is somewhat dependent on the caps you use to pass treble thru the EQ's. Also very much dependent on speakers*. For regular tonestacks I use silver-mica 250 pF. For the unique location of treble control in the blonde, I use Mallory 150's.

To test amps I keep a Mesa Diesel cab with electrovoice 15", with cloth grill replacing the original steel one which rang like a bell. Plus an Ampeg V4 cab loaded with Altec 417's. A lucky find that reveals what amps are really doing. It's survived everything I've thrown at it with bass amps too.

To keep you confused, I have to say the B25's I've fixed sounded mighty good too - so if you go that route you'll be OK there too.

[gui_tarzan]

Don't overlook the Traynor bass amps if you're thinking of EL34s.

I have a YBA-1A head. It's amazing how many variations of these are out there. Mine came with 6CA7s on the schematic and in the chassis originally, that's what I ordered to put back in it.

[big_teee]

I have a YBA-1A head. It's amazing how many variations of these are out there. Mine came with 6CA7s on the schematic and in the chassis originally, that's what I ordered to put back in it.

Do you use it for guitar or bass?

[g1]

Various versions of the Traynor yba-1 schematics here: http://www.lynx.bc.ca/~jc/YBA1Schems.pdf

[big_teee]

I may try that last version, on the Trayner layout from gone.
It looks a lot like a 1986 Marshall with a different wrinkle on the tone stack.
So the low and High range expander is a bit of an EQ?
That could all be built on a 1986 Type Turret board with a few changes.
Also I'm going to only use Chan 1 with the two marshall clift jacks.
If worse came to worse with the extra unused gain stage, and the 2 jacks I could always make a Cascade 2204 out of it!
T

[Leo_Gnardo]

So the low and High range expander is a bit of an EQ?

Lo range expander = midrange, and hi range expander = presence. Those clever Canadians renamed the controls maybe to evade detection by Fender's legal team. Or appear to have "something special."

[big_teee]

Lo range expander = midrange, and hi range expander = presence. Those clever Canadians renamed the controls maybe to evade detection by Fender's legal team. Or appear to have "something special."

You are absolutely Correct!
Those Slick Canuck B_$t__d$.

[gui_tarzan]

I'm going to try both through it once I get it re-capped and tubed. I've got a Sunn cabinet and a couple of 15" speakers to go in it to try and I'll try it through my EV & Jensen 12" speakers to see where it sounds better. This is another amp I bought 20+ years ago and never got around to fixing. It's in excellent shape so it should be an easy tune-up.

[Mick Bailey]

I have a Traynor YBA-1A MK II, it makes more than 50w (claimed 90w) but it could be tamed down to 50w. Or build the earlier MK 1. Local bassist Chris Cliff dropped by with his favourite SS Eden WT800 rig and we A/B-d both amps through a couple of Eden cabs using his Wilkes 5-string 'Precision' Surprisingly, the Traynor has a profound depth and richness that the Eden doesn't have, but soon runs out of clean headroom.

Pretty large OT in the Traynor compared to most amps, though.