Telecaster Guitar Forum http://www.tdpri.com/forum Building or modding your amp? Then use this forum to discuss the process and show your pride and joy. en Sat, 21 Nov 2009 05:15:11 GMT vBulletin 5 http://www.tdpri.com/forum/images/misc/rss.jpg Telecaster Guitar Forum http://www.tdpri.com/forum Schematic/PT Questions http://www.tdpri.com/forum/shock-brothers-diy-amps/186464-schematic-pt-questions.html Sat, 21 Nov 2009 04:12:00 GMT
Quote:
Originally Posted by BlueJim (Post 2146216)
Ah I see. And a little later they went to solid state rectification. Apparently they didn't like sag in the Fender Twins.
Yes back in those days the goal was to make amps that didn't have any distortion, hence they kept getting more efficient rectification and higher voltages as time went on, up to abut the mid-late 60's when the pendulum started swinging in the other direction.

You can see the evolution in their amps from 5Y3G in earlier tweeds to 5U4 in later ones (and in some blackfaces) and 5AR4 last tweeds and in some browns/blondes and diodes in lots of blackface and silverface. When you use two rectifiers in parallel (like in the tweed twin), the 5V winding has to be rated for 2 rectifiers (e.g. 2 x 5U4G would need a 5V 6A winding) ]]> tubeswell http://www.tdpri.com/forum/shock-brothers-diy-amps/186464-schematic-pt-questions.html Got my amp kit http://www.tdpri.com/forum/shock-brothers-diy-amps/180580-got-my-amp-kit.html Fri, 20 Nov 2009 22:31:38 GMT ---Quote (Originally by tubeswell)--- Yep that other mica cap will be the 450pF in place of the other (500pF) tone stack cap. ---End Quote--- Ooops, I meant 470pF of course
Quote:
Originally Posted by tubeswell (Post 2143613)
Yep that other mica cap will be the 450pF in place of the other (500pF) tone stack cap.
Ooops, I meant 470pF of course ]]> tubeswell http://www.tdpri.com/forum/shock-brothers-diy-amps/180580-got-my-amp-kit.html Elevating heaters with off-balance CT? http://www.tdpri.com/forum/shock-brothers-diy-amps/186093-elevating-heaters-off-balance-ct.html Fri, 20 Nov 2009 21:19:17 GMT If I read your schematic correctly you are rectifying 500 volt in a diode bridge which will give you something like 700 volt for B+.The right way to wire this transformer is to ground the center tap and use diodes in series and get something like 350 volt for B+.You can find examples on the Fender Amp Field Guide. If I read your schematic correctly you are rectifying 500 volt in a diode bridge which will give you something like 700 volt for B+.The right way to wire this transformer is to ground the center tap and use diodes in series and get something like 350 volt for B+.You can find examples on the Fender Amp Field Guide. ]]> limbe http://www.tdpri.com/forum/shock-brothers-diy-amps/186093-elevating-heaters-off-balance-ct.html Modding Heathkit 20watt Push-Pull Design - Worth it? http://www.tdpri.com/forum/shock-brothers-diy-amps/186427-modding-heathkit-20watt-push-pull-design-worth.html Fri, 20 Nov 2009 21:17:05 GMT Agree with bdgregory's comments.

I'd buy it and use it for its original purpose - a hi-fi or stereo amp. Get it now, recap it and look for a mate. Then run 'em both for stereo. Tube audio rules.

If you're looking for a cheap old hi-fi amp to turn into a guitar amp, find something from a console or find a PA amp. An old Heath, Eico, etc., will make a very fine stereo amp.

Just my .02. I run a Dynaco ST-70 as my main stereo amp, fwiw.

-Kevin ]]> Crawfish http://www.tdpri.com/forum/shock-brothers-diy-amps/186427-modding-heathkit-20watt-push-pull-design-worth.html Tube Bias http://www.tdpri.com/forum/shock-brothers-diy-amps/186491-tube-bias.html Fri, 20 Nov 2009 20:35:05 GMT Many manufacturers set bias points much lower, especially in MV amps. IT all depends on how one wants a power tube/s to work and what kind of preamp thign is going on, I suppose.]]> I hear you, SCott. With a wall voltage of 122VAC as a norm and variances in tolerances, one could see mcuh higher voltages, right? ONE must take readings at each bias voltage settings and figure that dissipation factor to really know what is what. IF I ever set a fixed biased amp at 90% of plate dissipation, it would be at the insistence of the amp's owner and with a disclaimer....no tube warranty, no user claims on tranformer failure due to tube failure, etc. IN other words: At your Own Risk. IT seems that it can be done, but it is not a general thing, ime. IMe, a fixed biased amp running at that dissipation factor is beyond what I want a power tube to do for my personal preferences. Setting by ear and checking, I usually find that I like things in the high '50's to the high '60's. Everybody's mileage varies, IIRC> Many manufacturers set bias points much lower, especially in MV amps. IT all depends on how one wants a power tube/s to work and what kind of preamp thign is going on, I suppose. ]]> Wally http://www.tdpri.com/forum/shock-brothers-diy-amps/186491-tube-bias.html forget tweed..here is my paisley prototype http://www.tdpri.com/forum/shock-brothers-diy-amps/182411-forget-tweed-here-my-paisley-prototype.html Fri, 20 Nov 2009 12:58:10 GMT Not much work being done..or much guitar playing the last few weeks.
While travelling on my real job my father passed away so I had to hustle back home to Toronto.
He was 81 and lived life to the max so sudden exit is the way I hope to go also.
I have done a little work on my "deluxe" test build and here are the photos.
Baffle is baltic birch, a cheap Emminence Legend 1218, and 100 % linen grill cloth like the earliest tweeds.
I have most parts for the "brain" and once the hands settle down (too much Laphroig at the wake) I will get back on the projects I planned.
iggy
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]]> IggyT http://www.tdpri.com/forum/shock-brothers-diy-amps/182411-forget-tweed-here-my-paisley-prototype.html Dead amp :-( http://www.tdpri.com/forum/shock-brothers-diy-amps/186469-dead-amp.html Fri, 20 Nov 2009 08:12:30 GMT Unfortunately, you're probably going to have to take it to a repair guy. Troubleshooting over the net is sketchy at best and the problems your amp is exhibiting could be as simple as a bum preamp tube (user "repair" means plugging in a good tube) to something more complex (user repair could mean discharging caps and soldering stuff). ]]> JohnnyCrash http://www.tdpri.com/forum/shock-brothers-diy-amps/186469-dead-amp.html