Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Swampertech on January 03, 2019, 03:40:20 pm
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I'd just like to thank Steve Luckey for his correction of my understanding of where to ground the preamp section of a 5E3. Being my first build, I had read all of the available info on grounding from Aiken, Valve Wizard, Rob Robinette, and of course Doug. Since I bought my chassis, amp components, and board from Doug, I tried to follow his rules and drawings. Luckily, Steve corrected my preamp grounding scheme to reflect that the grounds of the input connectors should be attached to the chassis close to the connectors. Also, my initial design was to implement RR's cascaded channels using a relay. Big mistake! Besides being a bit too ambitious, it introduced a ton of buzz, hum, and noise. After removing the relay and it's drive components, and re-wiring all preamp lines with shielded cable, I ended up with one of the quietest amps I've ever heard. It was a Christmas gift to my son-in-law, and I think he is still in shock.
So, again, thanks Steve!! And since I have a couple of matched pair KT66's (Genelex Gold Line) laying around, I might just tackle Steve's Dual 50.
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Glad it worked out for you. Good to have another Alabama boy on the team!
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So Steve, I'm looking at a Fender Princeton cabinet and chassis in which to fit this new build. My reasoning is that Peter Mather, who made my 5E3 Tweed cabinet, said the Princeton Reverb cabinet is pretty close in size to the Tweed. And if I again use a Celestion Gold 50W speaker, I'm hoping the resonance of the cabinet is close to the Tweed. Haven't done all the homework on holes or spacing yet, but the Kt66's will fit that chassis, right? I see you have a turret board design for the dual 50 on Doug's web page. I'll probably stick with the TP40D and TO26 Heyboer's (assuming they fit the chassis and that I have enough 6.3VAC current. Also, I would like to use the GZ34 instead of the diodes (call me old school, and yes I know Marshall used diodes). That Dual 50 is interesting since the preamps are voiced to both a Fender and Marshall response curve. And, you have a switch for Plexi/JCM 800. NICE! The long tail pair PI will also be new for me, but since everybody uses them................. Another interesting feature is the TMB tone controls. Are you using a Marshall choke in the PS?
Enough questions for one day. Thanks again!
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I never built a dual 50 amp. Several people on the forum have. Those that stuck close to the layout were pleased. So, you're thinking about putting a dual 50 in a PR box? That's gonna be like putting a 5 gallon bucket of shit in a quart jar! Measure twice. Cut once. Could get stinky! :icon_biggrin:
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:laugh:Ah, great advice, and with a smile. I know your turret board on Doug's site looks a bit long for the PR chassis. I'll have to do some research on that. Now, your GND #1, #2, #3, #4, are they tied up to that buss wire?
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So, you're thinking about putting a dual 50 in a PR box?
Well it would work if it were a Ham Radio... Just put a fan in it with a safety switch if the fan went out..
silverfox.
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Swampertech and Sluckey, sorry for the loss tonight.
Here is a photo of the Princeton Chassis.
I don't see why the Dual 50 couldn't work, but here is what I would consider.
1. Figure out if you can use a laydown transformer or a standup based on the room you will need.
a. I would get a stand up and use the extra room below.
2. If you have Mather build a Princeton cabinet, please make sure it is the Tall Boy with a 12" speaker. The Tall Boy provides enough clearance for the OY to hang without interference.
I am using a Princeton Chassis (custom Chassis) for a Deluxe Reverb build. I have the Princeton Tall Boy cabinet for reference.
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Thanks purpletele. Yeah, we just got outplayed by a better team.
I'd like to use the TP40D Heyboer PT, but still looking at pre punched PR chassis dimensions. I would definately use Peter's tall boy cab to afford the 12" Celestion spk. Silverfox hinted at maybe some heat problems. Not sure about that. I would again design for low/high power situations by changing the power tubes and rectifier, and maybe a switched fixed/cathode bias arrangement. The 5E3 I just finished (my first amp build) sounded fantastic, and my son in law said it was the first time his Strat sounded really good. I think he leans toward Les Pauls though. I'll also again install send/return jacks like my 5E3. I'm looking at using one 12AX7 for the FX loop to control levels.