GM70 IT PP

[claudiomas]

i rebuilt the GM70 PP with smps professional psu,
two meanwell 24V and 12V and four airplane modules HT 315V500mA
few chokes and caps and power supply its very light weight.
audio the same ITdriver EL34 or 6E6P-E

 

[claudiomas]

image

 

[ncc]

Hi,

Very Nice amp.
What is the name of the HT smps power supply you're using and where did you get them?

 

[claudiomas]

keysight professional custom builds

 

[claudiomas]

mistake on post "41" to resume: input transformer to 6E6P-E triode mode to bifiliar IT to EL34 or 6P3S-E driving Sowter splitter IT for GM70PP to output transformer lather i change input tube to parallel 6N1P-EV so no capacitor link but input transformer and two IT , no feedback,floating output 4/8/16ohm only cathode caps on signal path power supply capacitors are Kemet and RIFA long life thanks for readings

 

[Bandersnatch]

Given your load, you will get a lot more power if you can make a swing into grid current territory. The parafeed drive on the last IT precludes this. Use a LTP, then drive the last IT with a pair of 801A...🙂
cheers,
Douglas

 

[claudiomas]

thanks but the amp its done, power was not the priority , SE driving DHT PP by IT , yes the 801A its good idea, you did GM70PP driven by 801A?

 

[Bandersnatch]

I have not played with power triodes. I like what comes from pentodes better. Type 813 and 4E27A for instance. I also prefer to stay Class A.
cheers,
Douglas

 

[claudiomas]

HV smps like these i use in my amplifier become available by
http://www.mouser.fr/ProductDetail/...5PRBMPTWcaQfhArPaNvLN50hhHX/7X/5Jl3Xv5N9FLg==
http://www.mouser.fr/ProductDetail/Mean-Well/HVGC-320-700A/?qs=sGAEpiMZZMt5PRBMPTWcaQfhArPaNvLN50hhHX%2f7X%2f5Jl3Xv5N9FLg%3d%3d
3 of thems in series you get 400/800/1200VDC 0.7A
just need a choke and few long life good caps and you can built your
GM70 GK71 845 813 etc
just see

 

[djn]

The last few years have been too lean to spend much on audio but I landed a great job, moved my wife and I to Albuquerque two months ago and just this weekend I unpacked my unfinished GM70. I need about 50 bucks worth of parts and we are both working full time so now I have the money but no time!!!

I vowed to spend at least an hour a night on it and how to have it up and running by the end of the month....but first I have to assemble my work bench and find my tools ;>)

Revising this thread has given me hope.

 

[claudiomas]

6E6P-E first stage sound very good but microphonics and gain too high
now with 6N1P-EV in CF gain to noise improved. no more microphonics
and noise.
output power higher also, 30Vrms/8ohm

 

[claudiomas]

finally the best IT driver its 6B4G dual black plate,
same GE 2A3 plates, and 6N6P input
no more problems and very powerfull and musical autority

 

[VladimirK]

As for me, 6B4G is a really good driver for GM70. Maybe, you could consider to avoid additional connectors at the input signal sockets. I consider the input connectors quality as a high priority issue.

 

[ErikdeBest]

HV smps like these i use in my amplifier become available by
http://www.mouser.fr/ProductDetail/...5PRBMPTWcaQfhArPaNvLN50hhHX/7X/5Jl3Xv5N9FLg==
http://www.mouser.fr/ProductDetail/Mean-Well/HVGC-320-700A/?qs=sGAEpiMZZMt5PRBMPTWcaQfhArPaNvLN50hhHX%2f7X%2f5Jl3Xv5N9FLg%3d%3d
3 of thems in series you get 400/800/1200VDC 0.7A
just need a choke and few long life good caps and you can built your
GM70 GK71 845 813 etc
just see

Hi Claudio,

interesting PS units you have found there. Just a fast question: the ones you linked to are specified for constant current output. Are yours constant current output as well, or constant voltage? Constant currents doesn't look right into this amp.

Cheers! erik

 

[claudiomas]

vladimir,input its on XLR to Klein Hummel input transformer,
so can be balanced or unbalanced and any way this do not degrade the sound at all
Eric"doesn't look right into this amp" ???
the smps work perfectly,the bias its for 90mA each GM70
one dedicated smps only for drivers

 

[ErikdeBest]

Hi claudiomas,

I am not doubting it works - I was just wondering because these two units are meant for constant current - while we actually "want" a constant voltage to feed an amplifier. I am curious how these units can be made to work as constant voltage PS.

Thanks! Erik

 

[claudiomas]

its for class A SE or PP not for AB
you do not need 0.7A!!!! so voltage its max at lover current
i do a proto SEP211 /2A3/45 stay tuned

 

[claudiomas]

wen finish i do new tread

 

[Shef]

Wah, a massive one! I think I will never (never say never) go for the big bottles, but yours looks impressive.
.. and accurate