• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

SE 304TL

making of :304TL SE - Google Drive
input on E80CC CF direct coupled to 6C45P-E nos bifiliar IT to 6BX7GT
+300/-280V CF direct coupled to 304TL
bias tuning from 6BX7 grids
best for tube life and sound quality 180mA @ 1200V
two set of 3X420V350mA smps in the lower 1U case
then two 5H300mA choke and two D-link dry 590uF1300V
50W A1 4ohm tap 8ohm load
THD1% @28W H3 -60db
 

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professional pfc HT power supply smps
supply 420V @350mA
tree in series make power source for one channel
1260V the six aluminium epoxy potted
device are in 1U lower case
i use also in GM70PP 211PP GM70SE 805SE etc from many years
just need a choke and cap
i bring my 211 PP to ETF 2018 to show and explain how to use thems
but there was not room no place so the amp left in the car
so i decide do not give other informations
i present few smps power supply amplifier in this forum from many years
sometime i put MOV 866A/816/RG3-250A etc etc between smps and choke
this time no room so a power switch do the job.
the 304TL heathers are on all day
2X 200W 5V pfc smps
the driver +300-280V transformer power supply and speed regulated papst 230V fans
by switch also
 
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for the smps HT on post 3 I have already answered
they are modules reserved for professionals
for heating mainwell RSP-200-5 one each valve
I mounted nine GM70 amps
this is completely different. others SE 304TL exist but often are limited in current and with a driver that does not allow full power in A2.
I made an amplifier that produces 28Watts in A1 with 1% THD with H3 at -61db
and @ full power A2 the maximum sinusoidal power is 28V / 8ohm 1Khz read 98Watts,
which must also be the limit of the output transformer
the making of: 304TL SE - Google Drive
 
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i am surprised that the isolation does not blow.

been looking into hammond 1300~ tr + 3b28 /866a supply (for a future project)
/hybrid bridge/ 724A Hammond Manufacturing | Mouser Europe

no blow , my 211pp working from 4 years
for gm70 monoblocs i use hammond 728 and for 100TH i use hammond 726
both make noise so i pour epoxy resin from the bottom window afther sealing covers with silicone and now perfectly silent.
the main problem for transformer psu its swing choke for 1Kvolts and more.
choke should be twice the current and should be potted
i also bypass them with hv capacitor +-0.47uf + serie resistor
 
What speakers do you have the amp hooked up to?

I don't build amps just to listen to music at home with fostex 208 blh
create dream appliances revive exceptional triodes. surprise and sweep away the preconceptions in a world full of false principles that have moved away from the original rules when at the time of the golden era it was an audio amplifier it was nothing more than a castle of triodes and transformers, admire the spectacle by bringing together noble handmade materials with the know-how of another era when humanity no longer put limits on achieving international communication routes
creating magnificent triodes with exceptional performances.
who are just waiting for people like us to reproduce the song of the artists and their musical instruments
 
one 304TL went bad becose plate heatsink was too close to glass so shiiiiiit..
i buy two 304TH, degassing heather only one week
modified bias supply but one tube fly over above 120W....overcurrent.....
i buy one 304TL from spain professional but bad tube air inside..
so let forget 304TL/H
modified bias supply and i put two matched 100TH each channel in parallel
nos nib beauty ... i have some more...
wonderful sound even more deep bass and over dinamyc response,
 

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