Amazing, the man who designed the amp takes us thru a troubleshooting routine ! Only Dr Z ! Thx Doc, simple stuff but essential for us weekend warriors!
Good to know and thanks. I hope to add a Dr. Z amp to my collection in the near future. I bought a new Matchless Lightning 5 years ago and the 1st week the TAD rectifier tube went up like the Fourth of July. Owner of the company sent me a new one and it's still hanging in there. Had a JJ EL84 crack after 1 year. I replace all tubes every 2 years except for that 5 year old 5a4 rectifier tube. My 20 year old Marshall only likes the Winged =C= Svetlana EL34 power tubes that came with it.
That was a great idea! I know the troubleshooting guide is on the website but watching you go through it just made it so easy to understand . Thank you! Just out of curiosity, when doing that kind of checking you don't need to put a load on the amp?
While in this video the amp does not have any power connected to it, when powering your amp on, yes, be sure there is a load on it. Always have a load connected when turning your amp on. When troubleshooting your amp, be sure you are setting it up in the exact way you would be if you were playing it as to avoid any variables in the troubleshooting process.
Thanks for the lesson, one question, is it safe to do these tests without a speaker connected to the amp throughout the procedure or the opposite is essential?
Amazing channel! I need further help. I just finished the stewmac 57 amp kit. All the values for the tests they reccomend are within spec. But I get no sound! When I do a test the speaker pops but that is the only sound I have ever heard from this thing. How do I go back from the input Jack to find the problem w my Multimeter?
Marc Horel it shouldn’t. If it’s humming with nothing plugged in then the filter caps are probably let going. If it hums only when you plug in, try swapping the first preamp tube with the second.
hello doc, what is your opinion on touching power tubes with bare hands? I noticed you grab them without any gloves in the video. I recently replaced power tubes in an amp but the spots where I grabbed the tubes, with my bare hands, formed a black mark that looks like a burn mark.
Hi Caige, as long as the power tubes are cool, you can touch them. The burn mark you are seeing is not from your hands but from the normal wear of the tube's getter flashing beginning to burn. It's a normal occurrence. The outside of the glass doesn't get hot enough to cause any charring or, as some people will claim, "hot spots" from the oils in your hands. Still, it is best to have relatively clean hands in general when dealing with electronic equipment, and to handle them when they have cooled off.
I have a question! My Maz 18 blows that 1/2 amp HT fuse from time to time, but only occasionally, like once a year in the middle of a gig. I always have spares so it's usually just a mild inconvenience. I use a fast blow fuse because that's what it came with. There's a slow blow in the 3 amp position and that's never blown. Is this normal to occasionally randomly blow that HT fuse or is it indicative of a problem? My rectifier is a NOS RCA 5V4GA, which was recommended to me by an amp guru as a suitable replacement for the 5AR4. I blew fuses way more often with the original rectifier.
Cam Sutton you may have an intermittent power tube that is arching but not blowing. Contact repairs@drzamps.com and Don may have other suggestions for this problem.
I have a question. Is this the same process to follow for a Peavey AMP MH Mini Head? As you have to bias the amp later apparently. At present, I have a fuzzy noise coming from the amp and then, it settles down after being switched on and off a few times.
Hi Mike, I'm sorry to bug you with one more questions about valves for a Mesa Boogie Tremoverb 100 watt amp I bought back in 1994. I had two adjustable bias pots put on my amp. These amps normally use two 5U4 rectifier valves in the rectifier mode. The amp also has a switch to put it into solid state rectification. Well I thought about using two GZ34 rectifier in this amp, but I'm not sure if that's safe to do. The plate voltage in solid state rectification is 450 volts on the plates. My question is that for example on my Marshall Bluesbreaker JTM45 amp the plate voltage is 440 on the plates.it only uses 1 GZ34 rectifier valve. So wouldn't 2 of these GZ34 rectifier be two much power For this Tremoverb amp at a 100 watts? Any advice on this would be greatly appreciated. Thanks from Michael Newell from Niagara Falls, Ontario, Canada
Plate voltage is not supplied by the rectifier tube, so making a comparison of the tubes in your Marshall vs. your Mesa and their plate voltages is not comparable. Plate voltage is determined by your power transformer and the filter section. A 5AR4/GZ34 has about a voltage drop range of 5-15 DCV. So it will drop your plate voltage more than a solid state rectifier, but less than a 5U4 tube. Expect less compression and sag using a GZ34. It might not even be noticeable comparing it directly to solid state rectification.
if you purchased it new, the amp and tubes are still under warranty. Email me at media@drzamps.com and we will attend to this. It's likely a tube fault.
Dr Z Amplification Hey Dr Z!! I’m a dumba$$ .... the jewel light was loose ... I had two amps going so I jumped to conclusion when the light was out ... I was thinking it was not working.... I had just looked over when I was unplugging and shutting down ... anyway amp is fine and awesome and I appreciate you reaching out to help problem solve!! This amp is beyond perfect to my ears and customer care is second to none!! I will always have a Z in my arsenal!!! Take care! James
Ive got this USA fender blues junior. put new tubes in it and when I turn it on it goes "BBBRRRRRRRRRRRRRRRRRRRRRAAAAAAAAAAAAAAAAAA!!!!!!" not a clue whats going on.
@@ryanacosta3491 it is very possible. New tubes do not indicate good tubes. The problem with new production tubes is that they are very shoddy and unreliable, so please buy from a reputable dealers that insure the tubes. But your problem could also be power tubes. Please follow the exact instructions as listed here and in the video to isolate if one of the tubes is arching or redplating.
I recently bought a tube amp for my headphones and every time I've used it, I haven't able to hear much of the mid-range frequencies (or very quiet). Any idea of what the issue could be?
