GM70 SE 300B E80CC monoblocs

[gabdx]

Just saying if looking for alternative to AN, J&K Audio Design makes a tailor made OT Double-C for 880USD pair.

 

[claudiomas]

thanks Rajkom
i made a 6C4C PP driven by LL1660PP, E80CC and LL1540 input stage
this combination for 8W a 0,1% THD was excellent
PP 6B4G interstage DHT

 

[claudiomas]

Just saying if looking for alternative to AN, J&K Audio Design makes a tailor made OT Double-C for 880USD pair.

for output transformer i do not like coreC high impedance high voltage
but EI transformers. if standard OPT give - 2db 18/20 Khz
a perfect linear transformer price X3
so we are very happy with standard canadian OPT 1629SEA
if i find a flycase plenty of dollars i will buy better OPT
thanks anyway

 

[gabdx]

I looked your website and you build impressive audiophile amplifiers.

I liked the PPP kt88 and GM70 PP, very special.

I read your modification of the music angel 845, you did a very great work especially replacing the OT with Hammond! 3.5% thd to 0.5 is incredible!

P.s. I too have a stock of 5691 RCA NOS NIB , they are exceptional tubes! same with the 6sn7 too, very good section balance and a transparent sound the new tube completely lack off.

 

[zigzagflux]

I have experimented with, listened to, and measured various IT designs/topologies. Once I managed to find a design that allows bifilar winding design with appropriate DC interwinding voltages, I will never go back. I was never able to even remotely approach the bifilar performance with split bobbin or layered/sectionalized windings.

That being said, I also subscribe to the philosophy that IT topology is best implemented between driver and output stage, where impedances are optimized. Between input and driver stage, not so much; you are better off with cap coupled. Blocking distortion should be an output stage challenge; so fix it optimally with an IT. Only poor designs will suffer with blocking distortion between input and driver stage; therefore cap coupled is a very reasonable (and low distortion) solution.

Optimal device for the optimal stage, IMO.

 

[6A3sUMMER]

Claudiomas,

I may have given you the wrong impression, I am sorry.

I have used interstage transformers in single ended amplifiers, and they sounded great.
Some were c core, some EI.
One interstage was EI and bifilar, and I used it with 4-65 Tetrode.
I used a push pull interstage with a current source and a cathode coupled phase splitter.
I also used an SE to PP interstage transformer as the phase invertor in a push pull amp, that had good performance too.

Like you, I only used EI output transformers.

Keep listening.
Keep building.

 

[peteki]

They are a beautiful build but feel the need to comment that more recent technology using class A transistors such as the JLH or HIRAGA amplifiers will sound better, have a much better transient response, higher s/n ratio, and cost much less. Having started off with a SET nearly 60 years ago, my comment is not without some personal experience. Those thinking about valves in any configuration should read Self.

 

[Kris0603]

yes, of course Sakuma its the continuation of the old golden era
just have a look how things was going on before capacitors and penthodes take over the DHT sound
http://www.bunkerofdoom.com/xfm/UTC_1936/UTC1936.pdf

That is a sweet manual! Just read it cover to cover. Makes me want to run out and build some transformer-coupled SETs!

 

[claudiomas]

nice Kris
you can find old style input transformer and low level IT by Hammond 800/850 series, i use 850QA its really fantastic
you need alsop UTC transformers data, here linked:
http://www.dhtechservices.com/documents/SpecSheet/CAT_UTC_Transformer_Catalog_1963.pdf
or
http://www.bunkerofdoom.com/xfm/UTC_1951/UTC51PART.pdfhttp://

 

[claudiomas]

testing PP input stage by input splitter transformer to 6N6P to no gap IT
PP to paralleled secondary for 2A3 driver for IT to 845.
like this:
next amp?
edit:
124F only 5W so 20mA but this only for preliminary test with E80CC??