Hey everybody,
I just picked up a Futterman H-3 stereo block which has been modified to use 4 x 6LF6's per channel. It originally had either 4 or 6 x 6FW5's per channel. The reason I say 4 or 6 of the FW5's is because the chassis has 6 holes punched per channel for the FW5's but I know Futterman was a then an now kind of guy so he may only have installed 4 per channel as the attached schematic shows. Also he used many different tube types for the H-3 although mine has the 6FW5 printed on each hole the attached schematic shows the 6HB5 as the output tube of choice.
Now the H-3 I picked up pretty much has the front end shown on the attached schematic. Once you get to the output tubes it starts to become a NYAL OTL3 which uses the 6LU8 as well as the SS TIP 50 for regulation.
In the end the workmenship on the wiring is terrible inside the amp. I mean a mess!!!!! The sockets suck and are ready to give up the ghost as well as several key parts. I touched a metal oxide 1 watt resistor in one of the reg circuits last night with a hemostat and it crumbled.
So a rebuild is what is up and coming. Starting like as soon as I make some choices and there is where I am looking for help from a few of the members here who have experience with this amp.
Should I go back to the 6FW5's or 6HB5's?
Should I stay with the 6LF6's?
What about 6 JJ Tesla EL509's per channel? Current wise that will match the 6FW5's since they have a max of 550mA and the JJ's are 500mA. 6 replaced by 6 does not cause me a transformer issue. The 6FW5's are octal as are the JJ's. Heater current is higher but I could take care of that with a small additinal trans I tuck inside the box as it is large and once the birds nest of wiring is fixed all will be good under the sun
Thought???
Thx in advance.
I just picked up a Futterman H-3 stereo block which has been modified to use 4 x 6LF6's per channel. It originally had either 4 or 6 x 6FW5's per channel. The reason I say 4 or 6 of the FW5's is because the chassis has 6 holes punched per channel for the FW5's but I know Futterman was a then an now kind of guy so he may only have installed 4 per channel as the attached schematic shows. Also he used many different tube types for the H-3 although mine has the 6FW5 printed on each hole the attached schematic shows the 6HB5 as the output tube of choice.
Now the H-3 I picked up pretty much has the front end shown on the attached schematic. Once you get to the output tubes it starts to become a NYAL OTL3 which uses the 6LU8 as well as the SS TIP 50 for regulation.
In the end the workmenship on the wiring is terrible inside the amp. I mean a mess!!!!! The sockets suck and are ready to give up the ghost as well as several key parts. I touched a metal oxide 1 watt resistor in one of the reg circuits last night with a hemostat and it crumbled.
So a rebuild is what is up and coming. Starting like as soon as I make some choices and there is where I am looking for help from a few of the members here who have experience with this amp.
Should I go back to the 6FW5's or 6HB5's?
Should I stay with the 6LF6's?
What about 6 JJ Tesla EL509's per channel? Current wise that will match the 6FW5's since they have a max of 550mA and the JJ's are 500mA. 6 replaced by 6 does not cause me a transformer issue. The 6FW5's are octal as are the JJ's. Heater current is higher but I could take care of that with a small additinal trans I tuck inside the box as it is large and once the birds nest of wiring is fixed all will be good under the sun
Thought???
Thx in advance.
Attachments
Here is an underside shot of a Futterman H-3 using either the 6HB5 or 6LF6 output tubes in a chassis with only 4 holes punched per side for outputs. We know this because it is a 12 pin socket so it has to be one of the two or maybe even some other 12 pin tube Julius liked.
Attachments
adason said:Before you attempt any rebuild, you should read Harvey "Gizmo" Rosenberg's book "The search for musical ecstasy". Good one third of the book is about Futterman amp story.
is it about the amp and how it was built, etc or is it his normal rambling?
In the end the workmenship on the wiring is terrible inside the amp. I mean a mess!!!!!
From the picture you attached, its a rather neat wiring. Definitely not a mess. Supposedly Julius bent parts and wires to eliminate oscillations.
adason said:
From the picture you attached, its a rather neat wiring. Definitely not a mess. Supposedly Julius bent parts and wires to eliminate oscillations.
that is not my amp that is one i found on the net
Desperate,
From personal experience, I would keep well away from the JJ EL509.
They are nothing like the real TESLA EL/PL509, looking more like a EL34 than the massive internal structure of the real EL509.
I had a whole string of them just blow up.even though run well within ratings.
I strongly suggest you stick with the original design tube, and even then, wish you a "Lot of luck!"
Regards, Allen (Vacuum State)
From personal experience, I would keep well away from the JJ EL509.
They are nothing like the real TESLA EL/PL509, looking more like a EL34 than the massive internal structure of the real EL509.
I had a whole string of them just blow up.even though run well within ratings.
I strongly suggest you stick with the original design tube, and even then, wish you a "Lot of luck!"
Regards, Allen (Vacuum State)
Allen Wright said:Desperate,
From personal experience, I would keep well away from the JJ EL509.
They are nothing like the real TESLA EL/PL509, looking more like a EL34 than the massive internal structure of the real EL509.
I had a whole string of them just blow up.even though run well within ratings.
I strongly suggest you stick with the original design tube, and even then, wish you a "Lot of luck!"
Regards, Allen (Vacuum State)
thx Allen,
i hear you on the jj's except the orig design of the H-3 used a tube with the same max current rating 1/2 an amp? so why not? were you able to take a look at the post schematic? any furthe thoughts based on that?
thx again
adason said:...mostly rambling, but mainly a warning not to rebuilt...
its already been rebuilt and actually sounds good you can just tell its tired. what was the warning about? the theory that you can not build it as good as JF and HR himself. Remember HR was a bit of a marketing guru by most accounts
Michael Koster said:Desperateaudio,
Why don't you come to your senses?
Stop thinking past tenses,
and rebuild that amp...
Surely Julius would approve of experimentation
I absolutely agree i just want to try and get some good feedback on a direction from those who have done it if at all possible. Rebuilds are time consuming and i really only want to do it once well.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Tubes / Valves
- Futterman H-3