Thunderbird amp - vintage amp newbie

[GFooChombey]

Hey everyone. I just joined this forum after discovering Guilds of Grot and asking him questions about a Guild Model Two that was giving me problems.

Since then, I gave up on the Model Two and won a Thunderbird on eBay. I've wanted this amp since I realized Guild made amps, but this is my first vintage tube amp and I have a lot of questions:

While doing research, I discovered the Polarity switch aka "the death switch" can electrocute me if not set correctly. How do I know where to set it? I honestly haven't tried it out yet because I'm scared of this.

What on earth is hum balance?

I don't think the speakers are stock, but I could be wrong. Are these speakers good quality?

It looks like I have 4 channels total. 1 and 2 on the left side, and 1 and 2 in the middle. Assuming the switches are normal, bright, and brighter, why do I have so many channels?

 

[fronobulax]

Welcome. We need default to come along.

In the absence of better information I believe your fear is justified and you should fix the problem as soon as you can.

I define a channel as a signal path through a preamp. So a two channel amp has independent paths and you can set tone, volume and such independently. So just looking at the front panel, this looks like a two channel amp. However, it looks as if each channel has two inputs. This is fairly common. If you plug in two guitars into the same channel whatever you do to one on the amp will happen for both. When active electronics became common, there were many amps with two inputs per channel and one had a resistor or some other means of attenuating the signal from active electronics because they were otherwise "too hot" for the preamp. I have also seen amps that just have two inputs per channel with no difference. Those were marketed at garage bands that could only afford one amp, but everyone wanted to plug in.

Check your private messages.

 

[AcornHouse]

Just to add a couple of more ¢, if not actual sense.
The two inputs on the left had reverb, the two on the right do not.

 

[mavuser]

Awesome that u got a Thinderbird and quite the upgrade from a model 2!

I don't have any real technical info to add, but based on my experience with the Maverick 2x10,if I owned that Thunderbird my first thought is I would run one straight direct path from the guitar to the reverb channel and run pedals thru the other non-reverb channel. Great score

 

[The Guilds of Grot]

Nice to see you made it to the forum!

 

[Default]

Hi, was working on my next big post subject.
Hum balance is exactly what it is. Turn the amp up and turn it back and forth until you find the least amount of background hiss and then forget it's there.
The CTS speakers are original. They are ok speakers and unless you are a speaker aficionado, I wouldn't worry about swapping them out.
Polarity switch. Do you still have a 2 prong cord? If you do, you need to get a three prong cord and that cap will get removed at the same time. If you have a three prong cord, it's probably been removed.
Channels.
You have two and two input jacks for each. On my Maverick, the top jack is more sensitive than the bottom one. Check it and see if that's the case.

And howdy! ;-D

 

[Bill Ashton]

GFoo, the CTS speaker is undoubtedly original (I had a Thunder 1 Reverb back in the late 60's, and that is what it had), however the large speaker is a Jensen, possibly a C12R...good stuff if it is working...look for a little six digit number (on Jensen probably all together xxxxxx not xxx xxx like on the CTS) which tells you the manufacturer (CTS=197) and date of manufacture (on the CTS "702" = 2nd week of some year ending in "7"...so, '67).

On paper the Jensen speaker would be a much better and more expensive speaker than the original CTS branded ones.

As Steve described, one input is more sensitive than the other on each channel...guitars with single coil p'ups usually go into the "louder" input, humbuckers (by design) into the softer one...they are padded so as to prevent distortion. Of course, that's just what we want, right? =) So, just plug in where it sounds best to your ear.

 

[GFooChombey]

I'm scheduling an appointment with a local amp guy soon. I can't wait to get this thing up and running so I can tell you more about it. Thanks for all the comments though. I'm glad that the speakers good (so long as they're working).

 

[GFooChombey]

Long overdue update:

An amp tech replaced the power cord, added new filter/bypass caps, new bias range resistor, 1 ohm cathode resistors on tubes, repaired reverb and various other things that were damaged.

And now? This amp sounds beautiful. I've put quite a lot of money into it including purchase price, but I have no regrets.

 

[Default]

Audio clips are always appreciated!

 

[GFooChombey]

Hopefully I can have those soon. My duet is starting to get the wheels rolling again and I want to use it with my Polara.