The Amp Garage

[quote="M Fowler"]Bypass caps read 25uf/25v to my eyes and that is the value I used to build my Zwreck.[/quote]


That's correct Mark.
250mF 50V on bias resistor bypass.


Z

Yes it is a 3.0 amp winding on the 5 V filament of the DR-5001 PT.

Actually all my Tranformers with 5 V taps are rated at 3 amp for the use of a 5U4 rectifier.

Z

Nice job Mark.

I bet it sounds great.

Z

My experience has been that a slight DC voltage across a pot will cause it to scratch. You may have a leaky coupling cap or more often a 12AX7 with DC grid leakage. Swap V1 with a known good one.

DR.Z

Nice job Tim on the Airbrake, but a couple of observations if I may. First the grey wire off of the varable res. end , the one that feeds the pot is touching the var. res. I might ty wrap that wire up with the purple and other grey to get them up out of the way of the HOT res. Second the stand off f...

Mark it's been over 15 years since I built up a AO-35, my memory is a bit fuzzy. I have an original one at home I will look at it and and share some notes. Most of the multi caps were good but some did leak and remember using the CE replacements ( or original Fender /Mallory ). I did open up V1 and ...

Sorry Mark, I ment the 20 uF X 4 , like the ones used in the Princeton's. Yes 40 X 4 would be too much filter. I'll have to look at an old OA-35 mod but I believe I doulbled up two 20's for 40 uF on plate , one 20 for the screen, the PI has it's own fixed DC bias and plate voltage supply, and the fi...

[quote="M Fowler"]Doc,

I wired up the board for the Ghia AO-35 does this look right? [/quote]

Close Mark , but no cigar...

Looks like a Matchless, Ha.

Z

Nice score Mark. That 35 looks in good shape. Couple of notes: That internal horz, can cap looks to be a added repair, remove it and replace the bad multi with a Antique Electronic copy of a Princeton 40 by 4 cap. You'll need that space for your pots. I used the exsisting board by removed all the in...

[quote="M Fowler"]Is the original Rx also parallel V1? Also it appears to have split load bias for the EL84's but one resistor is 50R and the other is 50R or am I way off on this point? Mark[/quote] No Mark I used a single 50 ohm cathode bias res. on the original RX. You know to get that great "CLAS...

[quote="tubeswell"]Got them now thanks. The prescription ES topology is not too far removed from what I thought it might be. I wonder how it would go using that spare triode for a parallel triode in V1?[/quote]


Look at the values for the plate and cathode, it is a parallel troide in V1.

Z

Hey guys my dad was taken into Hospice care this week.
He has renal failure as well as a few other ailments.
I will be out of pocket for a week or so.
Mark I would be happy to get you an assembly drawing of the Original RX
for you to post.
E-mail or call me in a couple of weeks.

Z

[quote="jcat5503"]Z - could the maz gt be made with a loop?[/quote] Not really. The cascaded gain of the GT doesn't allow for a simple Series loop, signal is TOO high way above line level for the Send. A buffer loop might work but could also alter the tone. The GT is a simple one tube gained up pre-...

Cool question let me give my .02 . I believe being a musician HELPS in guitar amp building. Engineers design Stereo Amps to meet or exceed specs and reproduce recorded music, guitar amps are built to be instruments and make music. The knowledge of mixing sounds in a band context is important to an a...

[quote="billyz"]Hey Dr. Z, Bill Zumwalt here . remember me? from Alaska. Great to see you here. I moved to Austin a few years ago and setup shop. I just worked on a Maz jr some idiot did some funkyness to. It is sounding Killer now . 8)[/quote] Great Bill welcome back to the lower 48. Thanks for fix...