Installing an Isolation Transformer in a Vintage Guitar Amp
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- čas přidán 8. 09. 2024
- In this video we'll discuss how to install a power isolation transformer in a vintage series filament (aka widowmaker) guitar amp. We will also discuss the differences between a power isolation transformer and an isolation transformer for the preamp tube filament. For good measure, we'll change all the power caps and install a 3-prong power cord.
This was really helpful. I am researching this modification for a 1962 Valco Airline 62-9031 (same as a Supro Bantam). My dad got it from a buddy in the late 70's, but it's a live chassis and I got blasted through my guitar when I was younger. Pretty cool circuits, but best to make them safer.
Bravo - I love this stuff! Thank you for all the great information. Today I acquired an all original (except for 3 prong cord), Wilson(Magna)(Windsor)707-3 amp, sounds very sweet, crunchy. Planning for the Triad N68X PT & cap service. I wouldn’t have this if I didn’t learn about them from Guitologist!
MIGHTY special guitar! Thanks for posting this video! I recently acquired an amp from a Bell & Howell 285 that is gonna have to have a isolation transformer of some kind.
One approach might be to galvanically isolate the input rather than the power supply.You could use a floating input jack and an audio small signal transformer.
The Western Electric 19C was an audio sig gen that was AC/DC but the outer cab, the knobs and the output terminals were all isolated. Worked fairly well. The orientals tear them apart for the transformers for making some kind of WE nonsense but the concept is innovative.
Sweet chords at the end, thank you for sharing
They were limiting themselves a bit with that 60FX5 pentode output tube.
I wonder if anyone built a series-string amp with a pair of 25C5s in push-pull like Bell & Howell had in some of their projectors.
Love your videos! Had a question for you if you have a few moments - in researching adding a power isolation transformer to a Harmony H400C (Canadian version of H400A I believe) I've seen at least one guide express concern about using the N68X transformer since the 35W4 rectifier is only half wave, leading to the transformer being saturated too quickly. I'm curious if you think this is a valid concern? Sorry to ask for specific professional technical help via a youtube comment 😇 .
Did you find out if its an issue? I am planning on adding to an amp that also uses the 35W4.
When adding the isolation transformer, I see many refer to the Death Cap and removing it. In this schematic, I believe it is the .04 ceramic disc cap attached at the volume pot along with a resitor. Is there a reason you did not remove it? Is it an option, basically has the isolation transformer made it irrelevant so you can leave it in or out or by removing is there a potential issue. If it is OK to remove, should the resistor be removed as well?
Brad. Thank you for your stance on current affairs. My question: Would a wireless guitar system isolate the player from a series-filament widow-maker amp? Would the wireless transmitter act as an isolation transformer?
A wireless would isolate, of course.
Hi Brad, love your videos. Speaking of isolation transformers-- a lot of folks recommend using isolation transformers when repairing old radios and transformerless tube amps. Is there any advantage to using one when working on modern tube guitar amplifiers such as Fender or Vox--or could I be in more danger plugging such amps into the isolating transformer while troubleshooting?
Isolation just means you're isolating yourself from the full wall 120VAC. Putting something between yourself like an isolation transformer just helps ensure if you get shocked, i.e. bridge the 120VAC to ground with your body, there might be a chance you'll survive because you can't receive the full wall current across the gap between primary and secondary transformer windings. If you are interested in safety, an isolated variac transformer and current limiter are probably good purchases. The kind of variac I use is not isolated because it's an autotransformer, meaning there's only one winding.
Wow, that truly is a minimal parts count amp
Hi Brad,
Merry Frippus.
Where do you sell the amps you buy and sell ?
I hope it's on Reverb .com and not E-Boo.
Also...how do I get in touch with you outside of writing messages here ?
I won't correspond and refuse to deal with anything involved with Farcebook.
Yes, I spelled it like it should be spelled but that's just me trying to remain a low profile under the radar.
Craigslist and Facebook is where I list my stuff: louisville.craigslist.org/search/msa?query=773+1103
You can reply to one of the listings there and get me that way.
If those sites work out for you I wish you all the best.
Personally after years of selling on e-Bay, Reverrb.com was a breath of fresh air and they only charge 3.5 %
commission vs. e-Boo's !0 % ....A no brainer for me.
Only 2 top amps Marshall and Laney BRITISH quality
3. Matamp
Brad don't you have other CZcams channel?
Thomas Tommy I do, but I don't use it for anything.