|
|
Post by LeftyMeister on Jun 21, 2022 15:20:45 GMT -5
I decided to splurge a few months ago and put Mullards in V1 and V2 of my Maz 18. I liked the tones, however, the amp had no sound on Sunday morning for church. I decided to use a spare amp and troubleshoot it later.
Today, I swapped out the Mullards for the backup JJ's and it worked. I reinstalled the Mullards one at a time with a JJ in V2 and it worked. So I installed both Mullards and it wouldn't work. As an experiment, I swapped positions in V1 and V2 and it worked. Will the amp work if there's a bad tube in either V1 or V2 but not the other?
Also, can anyone recommendation a decent tube tester?
|
|
|
|
Post by Leftee on Jun 21, 2022 15:54:36 GMT -5
You own a spectacular tube tester.  I'm a bit cornfused... Do the Mullards work in at least one socket? |
|
|
|
Post by LeftyMeister on Jun 21, 2022 15:58:15 GMT -5
Ha!
Okay, I figured out the amp will work with the bad Mullard in V1 but not V2. Even then, the tone is compromised.
|
|
|
|
Post by Leftee on Jun 21, 2022 16:49:32 GMT -5
Bad Mullard!
BAAAAD MULLARD!
|
|
|
|
Post by LeftyMeister on Jun 21, 2022 17:19:48 GMT -5
LMBO!
So much for spending big money on premium tubes. It barely lasted a couple of months with light use.
|
|
|
|
Post by larryguitar54 on Jun 21, 2022 17:22:15 GMT -5
Hickok 600A can be had for about $400 to $500 on Ebay. It's great to have one but it's not a necessity. Assume you will need to do some repairs. You are buying something built in 1960. The caps can be changed but the components would be really had to get. I bought one for $475 and am happy with it. It forced me to learn about micromohs and transconductance and such.
|
|
|
|
Post by LeftyMeister on Jun 21, 2022 17:24:54 GMT -5
Larry, that's a bit outta my price range. I was thinking maybe $50. lol!
|
|
|
|
Post by Vibroluxer on Jun 21, 2022 22:18:24 GMT -5
I have a B&K Mutual Conductance tester and they can be had on Ebay for $125 or so if you're patient. This is the one I have. It doesn't test every tube known to man but it does test all guitar tubes that I know of. www.ebay.com/itm/175245064669?chn=ps&mkevt=1&mkcid=28 |
|
|
|
Post by larryguitar54 on Jun 21, 2022 22:37:06 GMT -5
Larry, that's a bit outta my price range. I was thinking maybe $50. lol! Yup don't blame you. It's not a necessity. The recent tube shortage created a panic drove the price of vintage tube testers to ridiculous levels. |
|
pdf64
Wholenote
Posts: 557
|
Post by pdf64 on Jun 22, 2022 5:05:00 GMT -5
Just use a cheap digital multimeter to measure the VDC at pins 1,2,3 (anode grid and cathode of one triode section) and 6,7,8 (anode grid and cathode of the other section) for V1 and V2 with a good valve in place, and note the values.
Now try with the bad valve.
I expect the bad valve to have significantly different readings with at least one of its sections.
Might the bad valve still be in warranty?
|
|
|
|
Post by LeftyMeister on Jun 22, 2022 6:42:29 GMT -5
Thanks, PDF. I'll check.
|
|
pdf64
Wholenote
Posts: 557
|
Post by pdf64 on Jun 22, 2022 10:43:42 GMT -5
I seem to recall that some DrZ models use the triode sections in parallel on their input stage V1, ie 1 linked to 6, 2 to 7, 3 to 8.
If your amp is like that, a bad section would act to somewhat hobble the good section, but the stage may still kinda work.
And many amps use a direct coupled cathode follower circuit, typically uses both sections of V2.
Russian made valves can have a problem with that circuit, Chinese or vintage production are a much better bet.
|
|
|
|
Post by Seldom Seen on Jun 22, 2022 15:57:11 GMT -5
The Orange DIVO Vt1000 matched my technical capabilities. It's all I've ever needed.
|
|
|
|
Post by bluzcat on Jun 25, 2022 21:23:10 GMT -5
LMBO! So much for spending big money on premium tubes. It barely lasted a couple of months with light use. I bought a NOS 12AX7 that went microphonic soon after getting it. There’s always that chance of course but when you drop good $$ you hope to get some good life out it. |
|
