Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jatchley on November 26, 2020, 04:20:08 pm
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Hey guys before i go drilling holes all over my chassis, i wanted to check with you all about my trafo orientation. i know 90 degrees for stand up OT with Laydown PT is right. i guess ive concluded as well the choke is better oriented with the OT but what about the reverb driver? i determine the length of the lams to be what im working with. and this reverb driver has the leads coming out of the side and not bottom and is also a stand up. attached is a pic of what i think is correct but wanted to double check with you all. thanks!
p.s. i know the chassis is a little bit tight but i think with proper orientation and good lead dress it shouldnt be an issue. the trafos specifically are a Hammond Super Reverb PT and Classictone Vibroverb OT. many thanks.
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I'm not seeing any help except to hold off on holes.
trying to get 20 gallons of barn waste in a 5 gallon bucket takes finesse :icon_biggrin:
I would be inclined to hang the choke upside down inside
I would put the reverb T on the back - maybe
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You're gonna have a hard time wiring the tubes to a noiseless level too if they are going to sit that close to each other. Those grid wires will almost certain touch other wires...
Just thinking...
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You're gonna have a hard time wiring the tubes to a noiseless level too if they are going to sit that close to each other. Those grid wires will almost certain touch other wires...
Just thinking...
100%
If first build, I'll go to a bigger chassis, too much headache
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What size chassis? L x W x H
Schematic?
Board size and layout?
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the board is 11"
the chassis is 16x8x2
theres exactly 1/2" between each preamp tube socket shield a little bit more between each big bottle.
this is for the single channel 6g15 into ab763 with 6g16 trem
schematic and board layout is in a different post from a week or so ago.
in hindsight im sorry for creating another post when i should've just posted this in that thread.
V1 verb return.
v2 verb driver
v3 buffer
v4 preamp
v5 PI
v6 OT1
v7 OT2
v8 rectifier
not my first build. more like 15th build. but this is my first not a clone build.
i once fit a 6g2 in a 12" chassis and that was VERY tight. but that worked and has been problem and noise free for over a year and has survived a 15 day tour getting 3 hours a night.
when i ordered the chassis i was under the impression it was 17x8x2 but when it arrived it was 16" so i know it'll be tighter than a stock fender but i've also worked on tighter than this so im not worried about tightness. i know space is my friend in this case but i gotta work with what i have.
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ooooweee good thing i didnt drill yet i forgot a whole dang tube! might need to get another chassis.
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power tubes & rectifier tube are much too close to one another. that's setting up for a premature power stage failure. humbly suggest another chassis. or wrap the preamp tubes around the right side and use can caps.
the chassis shown is 8"x17" the bar stock at the end is at x=16" the blue can cap on the right by the reverb trans is ideally a J&J 40/20/20/20 - it is for power amp g2/tremelo, PI, 6G15 B+ and last 20UF rest of preamps. the board up to the bar stock is 12" long and is 3.125" wide.
--pete
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What would be best practice spacing for rectifier and power tubes? I was unaware that having them too close would induce early failure . . .
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What would be best practice spacing for rectifier and power tubes? I was unaware that having them too close would induce early failure . . .
Fender Blackface, the best made amps, use 2 3/4 to 3 inches from center to center for these tubes.
From my Tremolux, Bandmaster and Vibrolux reverb
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I used 1-3/4" centers for my big tubes and 1-1/4" centers for little tubes in my 6V6 Plexi. I would never use this spacing if the chassis would be put in a cab unless using a fan to move the hot air.
(http://sluckeyamps.com/6v6plexi/P-6V6_06.jpg)
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More space between tubes = easy wiring
Too much space = too long wires = noise
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Also try and rotate the big tubes so that any 'anode holes' face each other, as that face of the anode is the coolest, and so the glass nearest that face is coolest. The anode holes are the typically large cut-outs that allow the internal grid supports to be seen. Some anode structures don't have those cutouts.
The rectifier will likely have coolest glass where you can see through between the two anodes.
The aim being for the coolest glass faces to 'face each other', such that the hotter glass faces get the most access to free air, and for thermal radiation from the plates to either go in to the room or hit the transformer.