Building an amp to last 30+ years

[battradio]

I have been gathering parts for a tube amp build and want to build it to last for the rest of my life with out ever having to repair it other than tubes .
The power supply will be a potted UTC power transformer , a 5V4GA tube ,A poted UTC choke , one Angela 30 mfd 515 volt caps and two ASC 600 mfd polypropylene 500 volt caps and some bleeder resistors . The iron should be good for another 50 years as long as it stays dry and caps should be good as long as the end crimps / welds holds out , nothing to dry out or go bad except the tubes .





The output and input transformers are UTC potted LS series ,LS-57's for the outputs and LS_12's for the input transformers . The tubes wil be two 6J5Gt's and two 6B4G's . The alternate output tube would be WE300B's if i had the cash for them .The two coupling caps will be polypropylene and tin foil and the all the resistor will be over sized metal films except for the output tube cathode resistor which will be wire wound . Still looking for suitible by pass polypropylene caps for the cathode resistors .

The circuit will be a bridged version of a get set go amp with the LS-12's being the bridging transformers .
http://www.diytube.com/getsetgo/getsetgo_manual.pdf

[azazello]

It seems very good! Please, You can note, 6B4G works with current about 60-65 ma, 300B with about 90 ma and You can change cathode resistor to about 700 ohm, but You can try. First filtering cap is 20-30 uF, but for next caps You can use 470-600 /Nichicon, Rubicon/uF for better sounding. You can also use for heater filtering caps more 10000 uF for avoid hmm.
You can use cathode resistor Mils /the best - about 10-15 $ from Hificollective-England/ and cathode cap 1000 uF Black Gate, Nichicon or ELNA for 6B4G or 300B. Also cathode cap 1000-1500 uF the same brand for 6SL7.
Regards!

[DeathRex]

I'd use a 5AR4 instead of 5V4G. If you use a 5V4G I thought it said max first cap is 8uF?

[battradio]

Fisher 80AZ used a 5V4GA and the first cap was 40 mfd , i have 8 or 10 5V4's and not a 5AR4 in the place .Will wire UF4007 in series with the plates do most likely won't have any trouble .
http://audiophool.com/Schem_A/Fisher_80AZ_svc.pdf

The 5V4 is there for the voltage drop and the time delay .



Here is the sealed power transformer and one of the chokes .




The 600Uf cap is 3" in diameter and 5 1/4 " tall
next to it for comparison is a 1 3/8" X3" 4 section can cap 40, 30 , 10 and 20
at 450 volts , the 20UF is 25 volts .

[battradio]

Got the first chassis punched out will do the second one later today , the 2 5/8" chassis punch is hard on the arm when you have to punch 4 holes per chassis .

Mark

[Shannon Parks]

...the 2 5/8" chassis punch is hard on the arm when you have to punch 4 holes per chassis .

Looks like the amp will be hard on the back, too!

Shannon

[battradio]

Spent today mounting all the major componets , will do the other channel tomorrow . The woods just laying in place it will be the last item done after the wiring and tweeking .

[Blair]

Looks really nice!

The big cover is much bigger on there than I figured it would be. That looks more like 4 3/4" or so.

Too bad you don't have a thin acrylic tube to put under the cap. That would look sweet!

[battradio]

Got most of one amp wired , need lock washers for the filter cap posts of all things .There is one electrolytic cap in it across the cathode resistor of the 6J5GT's

[Shannon Parks]

Looks awesome, Mark!

Shannon

[battradio]

Thank You for the nice coments Shannon .

Here is how the schematic is at the moment .



Will add a slight amount of feed back when done tweeking it , its at 10 watts out with .325 volt signal in .

[battradio]

IMG]http://i650.photobucket.com/albums/uu227/battradio/6B4amp007_zps9d5291d1.jpg[/IMG]






The above photos are my second amp it is mirror imaged from the first one , and has had some minor changes from the first one so when this one is up and running will have to make them electrically the same .Of course the second one's wiring turned with neater

Changed the cathode by pass caps to 100 UF 200 volts Polypropylene , by passed by a 5.6 UF Polypropylene cap , got rid of the 100uf electrolytic caps , now the only electrolytic caps are in the filament rectifier circuit .

Picture of first amp



I let the first one run for 48 hours playing music , and the power transformer was just slightly warm to the touch with my fore arm .

[battradio]

All the B+ caps are polypropylene , all signal caps are polypropylene and foil , the cathode by pass caps are polypropylene , the only electrolytics in it are in the filament DC supply .Three chokes provide the proper B+ voltage drops to each section
Going to redraw the schematic , in the next day or so and repost it with the revision

The tube complement in each amp is two 6B4G's , two 6J5GT's and one 5V4GB .

Was trying to get 10 watts a channel , but only can get 8 watts , the phase inversion is provided by a UTC LS input transformer , the output transformer is a UTC LS 57 , the power transformer and large choke are UTC .