new 50 watt build?

[rockgod212]

im going with a new 50 watt build this time. I have most of my parts sourced and ready to go. im going with classic tone transformers for this build, so what power transformer should I get? the 456 B+ or the lower 415 B+, not sure which way to go here. I know I could get the dual B+. maybe.

more details to come, as I sourced lots of nos parts for the build.

[Tazin]

Neither of those voltages are typical for a 50w Marshall PT. The Drake 1202-133 was around 440 - 450vdc I believe after rectification. The Drake 1202-118 was typically around 425 - 435vdc, and the later ('72ish) Drake 1202-164 around 390 - 400vdc.

[rockgod212]

I ended up getting the classic tone 1202-55, which after recto puts out about 456B+, I tend to like higher plate voltage's, so it will suffice. I also got a classic tone OPT and a 3H choke, I got some NOS 60's- 70's piher's for the plates and PI components, nos src and lemco mica's, AB carbon comps in select places, dual 250k PEC for PPIMV, F&T cap cans, the new sozo's through out, chassis and hardware stuff is all metro stuff. no shell yet. should be a killer amp.

[herbvis]

I am very interested to see what you think of the classic tone transformers. And the new sozos of course

[rockgod212]

I was sold after hearing this.

http://www.classictone.net/PaperVsPlastic.html

[herbvis]

That is such a great comparison video. I wish I would have known better before I bought my (MM) transformers

[rockgod212]

yeah I don't care for them much. i liked the heybour like the metro's I have in my 36, but the classic tone OT just has so much balls to it for a 50watter.

now, this build was supposed to be based on a weber kit, but I bought so many nos parts that I decided to build 2 50 watt amps, 1 will be a el34 plexi with the metro chassi and all the nos parts, and the weber will be a jtm 45 with the weber tranny's and kt66's. I got some 60's celestion alnico blues from a vox cab waiting for the jtm45. should sound great.

[awangotango]

i've got one from Merr en that has 3 taps, 425ish 465ish and one on the middle. I like his PT's even better than his OT's. don't know why but both marshall's i put his PT's in is grail marshall stuff.

[rockgod212]

im starting this build now, so I got the tranny's in so far, more to come.

[rockgod212]

well im just about finished with this build, im still waiting for my 1m push pull pots to come for the xtra cathode gain switching im doing. almost time to start testing and put tubes in, I got some nos rca, rft, brimar, and mullard pres, and some old stock used rft el34's, I would like some nos xf2's, but they are kinda pricey for me at the moment. eventually this amp will have a ppimv and im thinking of doin the RR mod to it with a switch, so I can still have a stock plexi- as I like to jump the channels from time to time.

[rockgod212]

heres a pic so far

157.jpg

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[Tone Slinger]

Did you use Classic Tone transformers ? If so, I'm interested in your opinion of them. I got a CT PT(Thanks Shannon ), but am a little hesatant about what I choose for the OT. I've heard VERY mixed opinions about CT transformers.

[rockgod212]

i haven't gotten to the point of biasing up tubes yet in this amp, almost there. but I love the classic tone tranny's I used in my jtm45, they rocks, so I expect no less in this amp build.

[rockgod212]

well I went to bias up these old stock rft tubes I got off ebay a while back while acquiring my parts for the build, as soon as I tried to bias them up they red plated, now when I first got them I told the seller one of these tubes has been red plated before and it is now toast, the seller refused to listen and said I tested the tubes and they are good tubes, then why did they red plate. so I stuck another set of Svetlana's in and they biased up perfect. now I gotta try and fight with the seller for him to pay to ship these back to Germany and get my money back, im already out 100.00 bucks for them. I'm pissed.

so back on to the build, I got the other set biased up, I'm running 436vdc on the plates biased to 42mV. I haven't been able to crank it yet, but it sounds real good, although the 4n7 bright cap's gotta go, its just too bright sounding with these g12-80's im using with it until I get some creambacks, then its time to finish off the RR one wire mod on a switch, so I can still have both stock plexi inputs, so I can jumper them when I want to, and I still gotta put the ppimv in too.

I used 1m spst push pull for vol's and bass pots. 1 pot switches a 1.5k over the 2.7k to make roughly 1k/.68u, then 1 pot switches the .68u over v2's 820r, then the bass pot switches another .68u over the .1u for the presence. right now its got a 300pf lemco over the 470k mixer and a 560pf lemco treble cap, I might have to change those, but I gotta get the master vol in first then decide if they stay or not. cool amp with lots of options, just like I like them.

[Tone Slinger]

Sorry about the bad tubes man. Its risky buissiness dealing with old, used output tubes. Going by the specs you've listed ( push/pull cathodes, PI couplers, etc,),your amp should really be quite versatile