Reference: Guild Thunderbird (later model)

Early 70s Guild Thunderbird amp. This amp in the pics below is listed on eBay Here see also LTG Amp pics According to the brochure and the auction text; twin 6L6, 50 watts, 1X6GW8 reverb, 4X7025 or 12AX7 + 7247 driver, 2X12" Jensen speakers; foot-switched tremolo and reverb. Sold without speakers.




In this model, reverb in a 'can' as opposed to a 'pan' in the earlier model. See also water damage at far right of cavity; delaminating plywood. This amp is a 'split plan'; preamp tubes, power supply filter cap, controls, and reverb transformer and 6GW8 reverb tube shown on the upper chassis; 'power' section shown below.



'Power' chassis; power and output transformers, output tubes, primary filtering and 7247 driver tube. Hangs inside right (facing amp) below speaker. Covered in a layer of corrosion; can be cleaned up, not mission critical but evidence of storage in damp conditions. The three caps are 2 high uf/vdc in series and 1 3-or 4-section can cap.



Underside of power chassis; typical Guild polyester 'green' caps, diode rectifier, easy enough access for the DIY inclined; no pc board here. Pics don't indicate whether pc boards in control chassis or not. The 'Astron' brown paper cap is bias filtering.

I know just enough electronics (having built a Heathkit computer and terminal in the '70's and kept them running for 10 years) to understand and appreciate these kinds of posts and threads. Thanks for your hard work Cap'n.

Thanks 'Frono; we're piling on threads so fast; alot of this stuff has been covered but retrieving it gets tougher by the week. I 'Bookmark' this kind of stuff; I've spent several hours chasing old threads in the 'stacks' ... gets old :evil: :wink: cj

cj, what do you think about asking Don to stick an amp tech/schematic thread?

Default said:

cj, what do you think about asking Don to stick an amp tech/schematic thread?

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Well, we have a Forum for Guild amps and another for non-Guild gear but as far as I know, it's finding an e-home for the schematics that's a little awkward. He has everything I have .... I think including the recent-to-me Thunderbird. I'm not exactly sure how the BB hosting works anyway; software and database live on a server somewhere; allows lots of real-time, simultaneous connections and so on. The schematics in jpeg / pdf / whatever have to 'live' somewhere too but up- and down-loading may generate security and access issues and may also drive host fees. Maybe by the time we get enough 'library books', we'll have figured out a way to keep the threads from getting washed away .... :wink:

Way to go Matsickma!! $175 and change, hope it got to the house ok Mike. Best wishes, cj

capnjuan said:

Early 70s Guild Thunderbird amp. This amp in the pics below is listed on eBay Here According to the brochure and the auction text; twin 6L6, 50 watts, 1X6GW8 reverb, 4X7025 or 12AX7 + 7247 driver, 2X12" Jensen speakers; foot-switched tremolo and reverb. Sold without speakers.

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Not here yet! Hope to get it next week. Shipping is over a relativly short distance so I am optimistic it will arrive OK. This Thunderbird amp is equivalent to a 2-12 Superstar (2-6L6's). I may hot rod this amp a bit with the power amp section of a 6550 Quantum. I need to decide what speakers to load into this amp. I am thinking about EV-EVM's. They might be a good match if I use the Quantum 6550 power section.

M

p.s., I passed up on one of these a few years back because I was concerned about the distance and shipping cost. I never saw another on. I figured it is now or never.

hope I didn't out you prematurely; hoping for the best; great looking amp and, when rodded, might just be the King of the LTG Guild amp-hill!! cj

The Guild late model Thunderbird amp arrived today. It handled the trip ok. Good packing.

The amp was very dirty. I cleaned most of this up. Tolex needs some repair. The power amp section was not mounted in the amp. However it was packed well inside the cab. I checked it out and other than rust on the transformers and some small particles of junk inside the point-to-point wiring it looks ok. I need to bring home a variac from work before I turn this on.

The big issue with the amp is that the control and bias cable from the preamp is completely missing! I don't get it? I failed to observe this in the auction. I am going to need a octal plug connector and will need to make up a harness. Not overly difficult to do. However I didn't pull the preamp out of the cab yet so I don't know the condition of the preamp.

I'll update sometime tomorrow.

M

matsickma said:

The big issue with the amp is that the control and bias cable from the preamp is completely missing! I don't get it? I failed to observe this in the auction. M

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Sometimes I get so hung up looking at what is there, I don't notice what isn't: "This might be a problem for a lesser man". Tom Cruise, A Few Good Men Good luck! cj

Hey capn,

Check out this part (PLG-8-P1) and let me know if this is a standard octal plug to fit a 6L6/EL34 tube socket? This is the type of part I'll need to build the new harness. http://www.radiodaze.com

Also, I checked out the preamp wiring and it looks like someone simply cut all the wires. I didn't see any damage and it looks like the their is enough wire left to splice into.

The amp came with some pretty good quality control knobs. I don't think they are origional Guild. A new feature I found on this amp is that the Reverb control has a snap position which implies an on/off function. I'll find out when I get it working.The reverb pan (Gibbs Type F) looks to be ok.

This amp is going to be more work than I planned but it looks to be relativly simple repairs.

Also, the amp appears to have been stored in an area of high moisture. Your observation of delaminating plywood near the reverb pan looks to be the result of a large void in the plywood and high moisture/humidity. I don't think the amp was immersed in water.

M

matsickma said:

Hey capn,

Check out this part (PLG-8-P1) and let me know if this is a standard octal plug to fit a 6L6/EL34 tube socket? This is the type of part I'll need to build the new harness. http://www.radiodaze.com

Looks good, keyway and all!

Also, I checked out the preamp wiring and it looks like someone simply cut all the wires. I didn't see any damage and it looks like the their is enough wire left to splice into. There are laws on the books against this type of crap ... where are the police when needed? :evil: :evil:

This amp is going to be more work than I planned but it looks to be relativly simple repairs. As is often the case; the good news is that you're on it; and another Guild amp rescued from the dumpster!! 8)
M

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best regards, cj

That's the exact model I had. Some bozo before me had cut up the cab to put a 6x9 car speaker in the side of it - monitor?

Anyway, I got tired of having it around and not using it, so I stripped out the chassis, hardware, screws, nuts, bolts, washers, everything but the box, baffle, and speakers and sold it off to somebody who wanted them. Maybe it was CapnJuan...come to think of it, probably was.

Speakers were really nice Jensen C12N's with beige crinkle paint and bell covers. A friend has them now. I'm thinking of buying them back. They sounded really nice.

I sure could use the special leather covered handles! They were greart in their day but don't hold up over the decades.

Kap'n said:

so I stripped out the chassis, hardware, screws, nuts, bolts, washers, everything but the box, baffle, and speakers and sold it off to somebody who wanted them. Maybe it was CapnJuan...come to think of it, probably was.

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Hey Kap'n ... not me ... but you knew that 8) cj

capnjuan said:

Hey Kap'n ... not me ... but you knew that 8) cj

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Actually, I didn't. It was a few years ago, and wasn't aware of the infamous capnjuan yet. :lol:

Now, that you know, apparently there's somebody else out there that valued those parts to restore other amps. You're not alone in the universe.

Kap'n said:

capnjuan said:

Hey Kap'n ... not me ... but you knew that 8) cj

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Actually, I didn't. It was a few years ago, and wasn't aware of the infamous capnjuan yet. :lol: Now, that you know, apparently there's somebody else out there that valued those parts to restore other amps. You're not alone in the universe.

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Feeling better already K although it coulda been me; I've bought my share of buckets of bolts - sometimes on purpose .... sometimes not :twisted: Regards! cj

The latest on the Guild Thunderbird amp, is not the best of news. I dismantled the amp. Did a complete removal of the front and back panels. Performed a major cleaning and sprayed the wood with Frebrees to minimize the mildow smell. There was some cabinet damage that needed to be re-glued. That is now in good shape.

I still need to build the wiring harness for the umbilical connection to the power amp. I checked out the power amp section and it isn't working. Tried a tube swap but that wasnt the issue.

So it will take a while to get this baby to full operation. Given all the project I have outstanding it will be some time before it is back to "origional". My plan is to finish any cabinet repairs and build the harness over the holiday period . If the preamp is OK I'll drop in the 6550 power amp section from a Quantum. If this sounds as good as I suspect it might that may be the "working" configuration of this amp for a considerable period of time-maybe forever.

M

matsickma said:

If the preamp is OK I'll drop in the 6550 power amp section from a Quantum.

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Mr. No-Electrical-Training asks: Isn't the reverb powered by a separate power amp section?

Hi Mike; sorry about the amp, good luck in getting it running.