JTM45 Build with 6P3P output tubes and GZ34

[Spencerleehorton]

I’ll change the 12ax7 tubes first before I start taking things apart.

 

[Spencerleehorton]

Took all tubes out apart from GZ34 and checked voltages, B+ 460v.
Turned on standby and dropped a bit to 457v.
Then put OT in and 12ax7s.
Power on B+ 460v as soon as standby turned on B+ drops to 403v!!
Bias was set at 43ma.
I then dropped bias to 36ma (el34)
This then put B+ to 414v from 403v
Checked out other voltages across the tubes and although they looked low it all looked consistent.

I wonder whether the GZ34 is damaged?

 

[Spencerleehorton]

I think what I will try is to revert back to the original way that B+ was connected and see if it is the same.

 

[Spencerleehorton]

Yep same problem, choke is fine so it must be gz34, so I’ve ordered a new one.

 

[Accelerator]

@Spencerleehorton​

Man, ride out this shitty Radial 100 watt Output transformer and put in a proper & correct Output transformer for the tubes that you would like to use and at least use a matched pair of Output tubes …

If you would like to use a matched pair of EL34 / KT77 / 6CA7 Output Tubes, you have to install a Drake type JTM50 3200 ~ 3600 (A-A*) 50 watt Output transformer and you will have nearly 50 watt output…

If you would like to use a matched pair of KT66 Output Tubes, you will have to install a Radiospades type JTM45 8000 (A-A*) 35 watt Output transformer and you will have nearly 35 watt output…

The whole “Spartan spirit” of the Marshall 35watt JTM45 amp. it is NOT for you to makes this Grande cheapie B.S. with this Shitty & Uncorrected Radial 100 watt Output transformer in this amp., and then to add the one B.S. after the other B.S., like the idiotic dangerous & cheapie B.S. with the 6P3P output tubes, then the B.S. with the P.PI.M.V. to tame down your higher wattage that comes from your Shitty & Uncorrected Radial 100 watt Output transformer with your unmatched pair of your EL34 tube, and then the B.S. with the Dual bias to matched your unmatched pair of your EL34 Output tubes, and then the B.S. with the Fx loop and the list of your B.S. goes on and on and on, asking continues like an attention slut for someone to helps you or to save you from your continues and dangerous B.S.…

Before you make any another new B.S. and asking continues like an attention slut for someone to help you from your continues and dangerous B.S. make yourself a favor to educate yourself by spending a little bit of your time to read this book:

Designing Tube Preamps for Guitar and Bass, 2nd edition by Merlin Blencowe

I don’t care, I don’t give a F*kk and I don’t have any economical or any other effort if you buy this book, if you download this book by a “pirate” site, if you read it in your public library, if you steal it from a book shelf or whatever else…

You MUST READ THIS BOOK because ‘till this time you are an Uneducated and Dangerous Newbie for yourself and for everybody near you and for the whole DIY-er Community…

By the way, like any Marshall amp. lover here & out there I have to tell you, that the Marshall 35watt JTM45 amp., it is not a “polymorphic” B.S. amp. like any “Mesa Boogie”-like amp., with all of these “add ons” and “add ons” and “add ons” to mods and mods and mods to ruin the whole sound…

The “Marshall Roar” sound it is like a malt whisky that you drinking it straight, you don’t ruin it…