Search found 4546 matches

by Stevem
Wed Mar 27, 2024 9:53 am
Forum: Technical Discussion
Topic: Knight 600 valve emissions tester thoughts?
Replies: 5
Views: 121

Re: Knight 600 valve emissions tester thoughts?

Give me your mailing address and I will send you a few!😊
by Stevem
Tue Mar 26, 2024 10:07 am
Forum: Technical Discussion
Topic: Knight 600 valve emissions tester thoughts?
Replies: 5
Views: 121

Re: Knight 600 valve emissions tester thoughts?

These simple testers only test the emission level of the tubes cathode, so as such they are fine for testing out rectifier tubes but will not tell you how well a audio tube will amplify signal level. Like testing a rectifier tube these testers in terms a audio tube will tell you only how much life i...
by Stevem
Mon Mar 25, 2024 10:50 am
Forum: Technical Discussion
Topic: SZ13C zener replacement for 1964 JMI Vox T60? - UPDATE
Replies: 8
Views: 167

Re: SZ13C zener replacement for 1964 JMI Vox T60? - UPDATE

With the ability you have displayed in the great reserection of the chassis you should be able to make a cab for the head easy! You might check out North coast music, as they have,or had repro cabinets. No Zobel network added to the output stage for safety? It seems everything back then was rated fo...
by Stevem
Sat Mar 23, 2024 12:24 pm
Forum: Technical Discussion
Topic: Questions about popping noise
Replies: 9
Views: 161

Re: Questions about popping noise

That’s not what the first reply to your post was questioning.

You referred to a 12AX7 as a pentode when it’s not, in fact the whole large number of the 12A series of tubes ( 12ax7 av7, au7, at7 and others) are all duel triode tubes.
They can perform 2 separate amplification functions in other words.
by Stevem
Sat Mar 23, 2024 11:29 am
Forum: Technical Discussion
Topic: Is there a way to measure the amount of supply current in the 2nd tabs of the Power Transformer?
Replies: 6
Views: 152

Re: Is there a way to measure the amount of supply current in the 2nd tabs of the Power Transformer?

The main difference you would find with 34s is that the output stage will clip sooner . 34s have more gain then a 6L6, and of course this also translates into a tad more touch sensitivity. This may help to float your boat or maybe not? One other thing you can try is a set of Groovetubes 6L6 tubes . ...
by Stevem
Fri Mar 22, 2024 9:31 pm
Forum: Technical Discussion
Topic: Power filter schematic change help
Replies: 11
Views: 192

Re: Power filter schematic change help

It does not make a lick of sense to me other then two 50 Uf caps are likely cheaper then one 100 Uf and the same might go for all the 40uf and 8 Uf caps being cheaper then one 50 Uf, but I don’t know with todays prices! All of the added voltage storage area as with the way it’s drawn might make the ...
by Stevem
Thu Mar 21, 2024 10:02 pm
Forum: Technical Discussion
Topic: Bias range question.
Replies: 27
Views: 506

Re: Bias range question.

Tubes pull millamps when at idle, not mv even though your reading mv . Besides that, something does not seem right for the TS tubes to be pulling 50% more current yet the B+ dropping only 5 volts. Does your heater voltage change between having the JJs or the TS’s in the amp. Also note that the TS tu...
by Stevem
Thu Mar 21, 2024 9:54 pm
Forum: Fender Discussion
Topic: Can I use a Bassman 70watts PT and OT for a Deluxe reverb?
Replies: 10
Views: 253

Re: Can I use a Bassman 70watts PT and OT for a Deluxe reverb?

Yes, all the silverface 70 and 135 watt amps where Ul and as such not what you want it your looking for a true Deluxe playing feel and response .
by Stevem
Thu Mar 21, 2024 10:06 am
Forum: Technical Discussion
Topic: Is there a way to measure the amount of supply current in the 2nd tabs of the Power Transformer?
Replies: 6
Views: 152

Re: Is there a way to measure the amount of supply current in the 2nd tabs of the Power Transformer?

Let's look at the numbers. Four 9 pin preamp tubes need 1.2 amp of heater current, then add to that another 1.8 amps for the heaters in the 6L6 type tubes for a total of 3 amps. NOW Take the at same 1.2 amps of preamp tube current and add the 3 amps needed for the 34s and your needs are now 4.2 amps...
by Stevem
Wed Mar 20, 2024 10:35 pm
Forum: Technical Discussion
Topic: Signal mute when wiring is tied with cable ties?
Replies: 11
Views: 238

Re: Signal mute when wiring is tied with cable ties?

Yes, that’s another good possibility stated in the above post.

Use a clip lead jumper to go right to the output leg of a pot that might be suspicious.
by Stevem
Wed Mar 20, 2024 9:56 am
Forum: Technical Discussion
Topic: Signal mute when wiring is tied with cable ties?
Replies: 11
Views: 238

Re: Signal mute when wiring is tied with cable ties?

Simple continuity test that follows the signal flow Plath will tell you what's going on. I can tell you from my own experience and in fact more then once,( like 3 times ) it would not be the first time that what looks like perfect new wire had a break in it, or even in terms of stranded core wire wh...
by Stevem
Tue Mar 19, 2024 10:35 pm
Forum: Technical Discussion
Topic: Matamp R28 info - request for help
Replies: 8
Views: 155

Re: Matamp R28 info - request for help

Do a search on here, as I thought I recall some questions about a Matamp a few months ago, I forget which section though!
by Stevem
Tue Mar 19, 2024 10:19 pm
Forum: Technical Discussion
Topic: SZ13C zener replacement for 1964 JMI Vox T60? - UPDATE
Replies: 8
Views: 167

Re: SZ13C zener replacement for 1964 JMI Vox T60?

Hi RG! Oh yes I know, but with mine only kicking out the low 18 rms that it does I did not thank that the original where stressed all that much where a silicon would be a big advantage. Now in the bigger amps I know it’s a life giving up grade. And by the way, thanks for all the knowledge sharing yo...
by Stevem
Tue Mar 19, 2024 9:12 pm
Forum: Technical Discussion
Topic: SZ13C zener replacement for 1964 JMI Vox T60? - UPDATE
Replies: 8
Views: 167

Re: SZ13C zener replacement for 1964 JMI Vox T60?

Thanks for the schematic. Why not use a modern 220 type negative regulator for that 3 transistor section of the preamp. I put silicon type T03 outputs in my 66 reverb twin and found that the higher idle current needed only served to slightly reduce the amps RMS and peak output with really no improve...
by Stevem
Tue Mar 19, 2024 8:56 pm
Forum: Technical Discussion
Topic: Matamp R28 info - request for help
Replies: 8
Views: 155

Re: Matamp R28 info - request for help

I must say that to me I find this a strange post!

I think your just trolling for conversation, I mean if you love it so very much what do you need to know about it?

Are you going to build another one and need a schematic, if so I think you would have said such right up front.