Guild Thunderbass Head

Here's some specs I've found out about this amp

Model Quantum X Quantum Bass Deluxe Quantum Bass Standard
Available 1967 1969 1969
Power Output 200W (100W RMS)
Tubes 3-12AX7/7025, 1-7247, 2-8417
Speakers 2 15" J.B. Lansing D 130F 2 15" J.B. Lansing D 140F 2 15" heavy duty
Channels 2 channels (4 inputs)
Controls Volume, bass, treble controls and 3-position tone switch for each channel. Master volume and standby.
Dimensions head: 10??" high, 21??" wide, 11??"deep
cabinet: 45" high, 30" wide, 11 7/8"deep
1969 Price $895 $925 $675

Well, you know, this IS a 40 year old amp, but it does what it does well. This only thing that sucks is that it's a single channel clean amp only, you need pedals for distortion, but any crappy distortion pedal sounds great with this puppy.

In the eleven years I've owned this amp, its always been great. For the people saying it can't keep up as a bass amp, I don't know about yours, but I've had this thing hooked up to a 15" PA cab with a big old 18" carvin bass cab under it and could blow away the drummer any time, it always rattled my chest, I don't think I've ever had it above half on the master.
I never even thought about using this as a guitar amp until I read some other posts about it, and let me say that I am now a true believer. I'm now running a Schecter blackjack ATX into a old 15" cab and it sounds amazing (though I am planning on getting a better 2x12 cab to run it through). Now in my older more wiser days I'm going to retube and clean this puppy up, even though it still sounds great even with half burnt out tubes.
For anyone who wants to know, the output of this amp is 8ohm (seems like no one knows what the output really is) Here's a link to the schematic for this amp (took quite a while to find this!)

http://www.prowessamplifiers.com/schematics/misc/Guild_Quantum_bass-Guild_Quantum_bass_8417_w_6gf7_regulator.html

This will give you all you need for biasing this amp....even if you can't read schematics, this is the easiest amp to retube and bias. On the back panel all the way to the left is a two prong outlet looking thing...that is the bias check, take your multimeter and put the red lead in each hole and the other to ground (anywhere on the case) and adjust the pots near each power tube, bias each tube to .3VDC, easy.

When I first got this amp 11 years ago, it was from a guy using it in a punk band, it still had the original bracket thats supposed to be screwed on to the cab, so he just used it set upsidedown, and the power and standby switches were both broken so he just plugged it and unplugged it when he used it. Even with this brutal punishment, it always performed flawlessly. When I got it I replaced the power switch and took the handle off, so at least it sat facing up, but I only recently got around to replacing the standby switch but even with all that abuse it's never given me the least bit of trouble, I think the power tubes might be the original tubes even, they look burt as hell, but still keep working flawlessly. This puppy is tuff.

Finding anything on this amp is tough, here's a link to all I could find.
http://www.vintageguitars.org.uk/guildQuantumAmplifier.php

I've kicked this amp around for so long, I now see how stupid I've been and I'll clean it up and hopefully keep it around for a long time. This amp rocks!

1968 Thungerbass head
Traded a few guitars for this one and it needed $200 in repairs after that to replace 4 tubes and cleaning. I wish it had more EQ than just low and high. Has a bright, medium and dark setting. As a bass amp it is OK, but not load enough to hear when my buddy turns up his Peavey 5150 and there's a drummer banging as well. It's real use is as a guitar amp. Totally amazing sound comes from this amp. Very unique.

Bass it rates a 10
Guitar is an 11

Only have played about 10 times but after spending $200, I hope it will hold up abit.

There is no real supprt as Fender bought them out a many years ago. The story I get is there was a fire at Guild that destroyed alot of their equipment info.

Late '60s all tube guitar or bass head. Black tolex. Very handsome faceplate design. Two pairs of inputs, one listed "bass" one listed "guitar." Each channel has bass and treble knobs, channel volume, and a 3-position fixed band filter switch. Front side standby switch and light, power switch and light. Not very heavy and there is a handle up top. The only flaw in the design for me is that the faceplate rattles sometimes since it only is attached to core of the amp and not the wooden casing.

The amp is exceptionally bright in its tone. Also, since this amp was made when it was, it is a generally clean sound. Of course the sound will breakup to a rather brutish overdrive fuzz when the amp is cranked.

The amp was burned out when I got it for free. A resistor had blown up and started a small fire some years before. Since it was repaired and refurbed its been very trusty.

None, you know...

This amp is a rarity, sounds great, and looks stylish and dated. I love it.

this post is more of a cry of help than a review. i will hapily post a review of this amp as soon as i can plug the head into a speaker cabinet. i can not find anywhere what the correct impedance for this amp is. i would greatly appreciate any help. a simple 4ohm, 8ohm, 16ohm answer is fine. but i would love to know where you got the answer
as well. my email address is three_pear@yahoo.com.

i will comment that in general the amp looks like it has a bare bones all you need for great tone recipe (tubes and volume!)

i plugged it in for a few seconds into a 1x15 cabinet i had around. sounded good but i did not want to push my luck and blow the head the first day i got it. i do not know the correct impedance. i believe these were orinally matched with a 2x12 cabinet but i do not know what ohm they were :(

cannot find out the most basic info on this amp. trying to find any kind of phone number or email contact on the Fender site is quite a frustrating experience.

Ive been playing for about 19 years and i pretty much suck as bad today as i did the first few years of playing. but i love to play. some of my gear...

guitars - stratocaster, les paul, paul reed smith, harmony h-75 (dad bought this new back in the day, 1960 or 1961 i think, sounds awesome), a 12 string, a coupple of 6 strings, a classical

amps - this thunderbass head that im dying to use, 2 redknob twins (the twin), blackface tremolux, silverface vibrolux reverb, ampeg v-2, peavey classic 50, univox 1235 bass amp, sano160R, garnet tube PA head (sounds awesome, 4 inputs each with own gain), marshall bichorus valvestate

hammonds - A-100 with a leslie 147, M-100, L-100. hammonds may be the funnest thing you will ever own. any model (as long as its the tonewheel generator type)

odds and ends synths, effects, pianos, etc. its easy to collect this stuff when you have a good friend in the storage business. Can you say warehouse?

seems like late 60's... awesome overall tone with very simple controls- treble, bass, volume and 3-position treble cut switch each for 2 channels and 1 master vol. I use it for guitar. Mine was found at a dump and I put $100 into it- new caps and tubes, re-biased for EL34's and replaced the chewed-up, burnt tolex with brown suede. Stainless steel faceplate with huge knobs. There is nothing I have seen to compare with the coolness of it's look. Incredible simple to get a tone- most every tone position is usable. I use it live- very dependable, loud, beefy and perfect.

a little spitty if the pickups are too hot. check out the sounds on my mp3 page at www.aqualove.biz. This thing sounds SOOO thick at high volume but it's really too loud for most gigs- unless the amp could be used in a bar unmiked. Very unique tone- sets itself apart from common sounds like Fender, Boogie, Marshall. Round and full and lower frequency of top end than avg. Bell-like when used clean- you can really hear the strings vibrating.

since I fixed it up, great. The previous owner mistreated it horribly. Looked like it had been left out in a barn with some bats or something. Occasionally makes funny sizzle sounds but I just pat the top and they quit.

non-existent. I have a great amp tech in Athens, GA tho. write me if you need his #

Totally happy.
Guitars:
a bunch of custom art guitars I made
an early 60's (?) Silvertone hollow-body electric