Found this place while looking up PT15 valves . Looks like I may know some of the members here already from other forums or whatever I'm mainly an amp and linestage builder , have also built a few pairs of box speakers and a few ESL panels . I try to avoid conventional valves , it's getting the weird oddballs to work and sound good that I enjoy most . Got a nice pile to work through . Currently I'm playing with some odd old tx valves in class A2 and getting fairly good results .
Cool. I had a moment of sanity and thought to stop playing with silly valves, then I came to my senses and realised I had never tried anything by Eimac, looks like you are just the person to talk to
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
The valves are Heintz and Kaufman HK54 , similar sort of thing to the Eimacs with self-gettered tantalum anodes and a healthy 25 watt filament . Drivers are HK24 , these are only running with a small amount of anode cherrying at 8mA . Once pairs of filament chokes and heat disspating caps are located , these valves are fairly straightforward to use . I'm having fun anyway
Actually, I am a bit unsure where to go next with the valve amp side. I am happy with the A2 211, and I can see a big learning curve in front with the ideas for DACs. But I think a 572b A2 set might be fun. But then I do have the 3kv transformers from the last 211 and a big supply of 866 rectifiers...
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
A2 to me sounds very clear but also a bit bright no matter which output valve is used . The sound is very different to lower Ra valves in A1 , before I was using Eimac 4-65A , the speaker crossover needed to be tweaked with HK54 ! Bass is the main problem , I'm currently running the 16 ohm secondary in the cathode circuit of the output stage to add a little feedback . HK54 has Ra around 12k , the output transformer is 5k so damping a bass reflex loaded cone driver is a real issue . Next plan is to try zero bias with an 834 , I should really get a pair of the James HSF outputs with the feedback tap which would make life a lot easier
Ha! The Frankfurt School, Adorno et al. I did a special study about this many years ago. Basically Thoedor Adorno and his co-workers were studying how it was possible to be a total bastard Nazi in the day time job and go home to tea and be a normal dad.
How could anyone be 'normal' who ordered and or carried out the industrial slaughter than happened in the holocaust?
The findings, to cut a long and very interesting story interweaving Fruedian psycholanalytic theory with Marxism, short, was that Nazis were total bastards to their family when they got home too.
The Authoritarian Pesonality was a nasty type with no saving graces. They demanded order, they wielded power a whatever level in teh rigid hierarchy in which they lived and they got it. The offspring of such types were not happy well adjusted free thinking children.
and so on................
Authority now has a bad side to what it means and how it is used to wishy washy liberals such as myself but authority when applied to a tasty powerful amplifier ....... Yeah, I know what you mean.
71aSE - no.
300b, ever?
transmitter valves - yeah! should be.
I've got a couple of eimac valves in the shed. Heaters are 10 volts at 10amps. They light up a treat but I've never pushed the HT through them.
andrew Ivimey wrote:
I've got a couple of eimac valves in the shed. Heaters are 10 volts at 10amps. They light up a treat but I've never pushed the HT through them.
I'm mainly an amp and linestage builder , have also built a few pairs of box speakers and a few ESL panels . I try to avoid conventional valves , it's getting the weird oddballs to work and sound good that I enjoy most . Got a nice pile to work through . Currently I'm playing with some odd old tx valves in class A2 and getting fairly good results . 
