Guild Thunderbass - Treble and Bass Control Questions

[guitarhuckster1]

My first real bass amp back in 1975 was a Guild Thunderbass. Cool amp!

 

[unlined4string]

In the earlier days of BS&T Jim Fielder used a Thunderbass head with two Guild cabinets which probably 1x12's or 1x15's. He got a great sound live (with PA of course). Later he switched to a Fender Dual Showman with JBL's.

 

[anderbass]

I saw the manual claimed flat response with the tone knobs centered but did we ever really determine if this model is a passive cut/boost tone knob design or not?

All my Mesa and Fender tube amp tone knobs (Passive cut/boost design) cause my amps to go completely silent when set to 0. You never responded to my previous post so I'm still kinda curious if you ever gave this easy test a try with yours?

 

[PikeoftheLake]

I saw the manual claimed flat response with the tone knobs centered but did we ever really determine if this model is a passive cut/boost tone knob design or not?

All my Mesa and Fender tube amp tone knobs (Passive cut/boost design) cause my amps to go completely silent when set to 0. You never responded to my previous post so I'm still kinda curious if you ever gave this easy test a try with yours?

Hey, yeah I gave it a try and although the volume gets lower, it does not completely cut out.

 

[PikeoftheLake]

In the earlier days of BS&T Jim Fielder used a Thunderbass head with two Guild cabinets which probably 1x12's or 1x15's. He got a great sound live (with PA of course). Later he switched to a Fender Dual Showman with JBL's.

Great band! Love that spinning wheel song. It seems with this Guild amp, and other things Guild for that matter, much got sucked into the void of rock and roll history. It's great to see people chime in and hear about all the history of this thing in the 60's and 70's.

Take good pictures of the insides?

I'll do my best if I get a second. It's tough to take the guts out of the case as it involves a rather precarious sliding and twisting.

 

[KramerBassFan]

Its not that big of a deal, then. Just satisfies my personal curiosity.

 

[BassmanPaul]

Thanks! I think it looks really good next to the piano in our main room.

My B15 sits next to my Baby Grand in our basement.

 

[anderbass]

Hey, yeah I gave it a try and although the volume gets lower, it does not completely cut out.

Cool thanks, I was just curious if your tone stack worked like some of my vintage tube amps and wanted to learn more about this subject.

So now I have a question for our Amp experts:

Without seeing a Schematic, do we have the info needed to answer the OP's original question whether this amp has some form of an active tone control system here, or could it still be passive?

 

[BassmanPaul]

I have the schematic. In fact I was very surprised by the fact that the output tubes have individual bias pots. A variable bias in an old amp is unusual, a pair is very rare.

If the OP wants a copy I'll need a PM with a real email address and I'll pass it on.

 

[BassmanPaul]

Its tone stack is passive but can boost or cut much like that used by Ampeg. Flat is at about 50% rotation.

 

[KramerBassFan]

Paul - would you say these amps were relatively well designed?

 

[ldscott70]

Hi,

I bought a Guild Thunderbass a couple months ago off Alec from our forum and I'm loving it. I was just messing around with it this morning and wondered if anyone knew about the treble and bass controls on this beast. Are they true cut offs like on the Traynor amps where 10/10 is even or do they boost and cut left and right of 12:00?

Thanks!

Hey I just pick up on of these also. Yours seems to be in much better shape than mine. Did you replace the covering on it?

 

[PikeoftheLake]

No I haven't done a thing to the amp. I'm still loving it especially for late night piano/bass duos!