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In Reply to: RE: Futterman Story w/ Ted Hammond posted by rhinohifi714 on July 18, 2012 at 21:27:27
Looks Good, I had just completed the alignment with no issues.
Edits: 07/18/12Follow Ups:
Topside of the amps we built, notice the gold plated top and bottom, sweet!!!
The pressure cooker that Julius Futterman used when making his transformers.
Ted reading up to make sure we didn't forget anything in the H3's...
Funny pic if you get it...
Fascinating. Can you comment on the sounds of the various amps? OTL vs H3aa vs
509? I can't help but wonder what you will do with all these tubes and amps. Would you be willing to sell some of the 6LF6's? Are they matched pairs?
If you are still interested in some matched pairs or a full set of 6LF6's let me know, I can get you a tightly matched set on my Amplitrex tester.
Thank you. Since I just bought a new cartridge (van den Hul Frog) I'm out of funds
for the time being. Is it hard to bias the output tubes? I have some handwritten
instructions from Ted and I find them fairly intimidating.
The alignment procedure can be a little frustrating, I use a stack of 5 simpson multimeters to monitor the bias, upper and lower screens, and upper and lower grids all at the same time, along with another meter you place in line with the bridge rectifier to monitor the Idle current. If you have all good tubes this process can be done in about a half hour, not seeing all the voltages at the same time makes it much more difficult. That's why I made up the stack of meters, when you do it this way you can get the uppers and lowers both screens and grids to match, I have been confused at times with the variations but since I'm quite anal about them being perfect I don't give up til it's right.
Which amps do you have?
If you have any questions I would be happy to help however I can.
Below is a pic of the alignment with all 6 meters.
That is truly cool, but clearly something I couldn't do. When I need it done,
I'll either send my amps to a pro or have him come here. Maybe you. Where do you live?
How could I contact you later? If you are anywhere near near me, it would be worth
your while to visit and listen to the Futterman Stax combo, while another pair
of Stax's is available.
I have NYAL OTL3c's (I think it is the c) with the meters. The meters
show the balance of the output tubes and the bias of the input tubes,
but not the bias of the output tubes.
not sure you got my reply, I made it on your Stax post in the planer asylum, I left my E-mail there along with info reguarding your amps.
.....N.I.C.E...... Bryan that is awesome!
I'll consider selling some later, I have 2 more pairs of OTL-3's to restore before I'll be able to think about letting any go.
The EL-509's in my sound room.
Hey Rhino I was hoping you might have a minute to answer a question or two regarding the JJ EL509 conversion on the H3aa OTL's.
Do the amps retain the original circuit design and just replace the output tubes? I am fairly familiar with the JF circuit from various rebuilds of H3's and NYAL OTL 1 & 3 rebuilds I have done in the past. Knowing that the original H3 circuit used many different tubes that had similar parameters as the JJ EL509's I am wondering what you did with those amps to make the switch? Less voltage? Reduced current? A completely new circuit?
Thanks Rhino for any info you might help with.
I don't know anything about the circuit design changes, but at some point George Kaye was offering to modify NYAL amps to use EL 509's. However he stopped doing this because (he told me) that the 509's he could get did not perform adequately.
Fortunately 6LF6's seem to last a long time...
Thx but I think the EL509's shown in the pics posted by Rhino are JJ Tesla EL509 which are different then say the Amprex version of the tube. GK was doing the Amprex tube version (max current to pass 1.4A). The JJ's pass 700mA max. Now I tend to think its not that big an issue as the early JF OTL's such as the H3 used tubes such as the 6HB5 that only passed 700 to 800mA but just wondering is Rhino could chime in here and offer up understanding on this???
as far as changes to the original circuit in the h3aa and the 509s version pictured there are several, and I only know a few, the addition of pots for alignment as in the otl-3's was installed for easy alignment, as well as hexfred diodes, several bypass caps on both power and speaker caps. also bypass caps on the 4-way bridge rectifier. but that's all I know, I have only played the amps a few hundred hours since I got them from Ted, I had planned to take them back to Croton and he was going to go over all the mod's with me. There is no complete schematic for that amp, only handwritten notes concerning the changes.
Since then Ted has been undergoing chemotherapy for cancer off and on for the last year and a half. Hopefully when he gets better I'll get copies of the changes.
Concerning the 509s tube:
I was there when Ted performed max output at clip, the amps put out 95 watts into 8 ohms, so as far as them being up to the challenge in that design they appear to work ok. One thing I noticed though was when doing the alignment that I was near the max settings to get the 300 ma idle current recommended in the procedure, I think that may be a sign of the lower factory spec on the tube. When I tested the tubes in my Amplitrex to the same setting as I use on the 6lf6's they all showed to be considerably low compared to good 6lf6's, the problem is that all I have is the tubes in the amps and 6 spares. I think that there is a chance that they were just off the shelf tubes not premium examples.
There is a seller on e-bay that I contacted who said he could match sextet's of them and would guaranty they met the factory spec for mutual conductance, I need to make sure he is testing them using fixed not autobias settings to achieve those numbers.
Not sure I told you anything that will help you out.
Greatly appreciate all your time!!!!
Thx for the update on Ted's health. Please wish him all the best from all of us and I am sure we all understand how a guy like himself has been so helpful to the hobby!!!!
So I understand you correctly could you please let me know if the EL509 tubes are 8 pin versions or 9 pin version?
Reason I ask is that the 8 pin version would be the JJ Tesla EL509 tubes which is what they look like in the picture you posted. Also in that picture one is missing and it looks like the socket is an 8 pin socket. Could you possibly clarify?
It is an octal base, JJ el509s, the tube missing is one I was testing.
I think that explains the difference on testing you are seeing. 6lf6 1.4A, JJ EL509 700mA MAX! Could be wrong on that but that is just my guess.
I was wondering when you do the testing and amp alignment are you still adjusting to the voltages JF gave for the H3AA amp in his testing and Alignment papers? Or are the voltages different now that the output tubes are different?
My guess is no, meaning you are holding the original JF voltages...
Would be interested to know.
Ted said Julius knew what he was doing, yes original voltages were observed, 300ma idle current. 85v bias.
I can't argue that.
Hi, I would really like to send you a note on this topic, but it is of commercial interest. Let me know if I may contact you via email? I see you do not accept direct email messages.
Here is the second page for those who are interested
Thx Again Rhino!
I have uploaded the test socket voltage measurements sequence from JF. Are you getting a measure of 360V at the test socket as described in number 1? Also are you getting the 180v measurement at the test socket as described in number 2 & 3?
Your 85v front end measurement is lower then the JF papers I have so I was wondering of the other two measurements.
Jonesy sure misses Ted...
If you need some 6LU8s, I got 'em.
I was once or twice in Julius' "factory", on 72nd St near Broadway, in the late 70s. The fumes in there from cooking transformers could kill a horse, but Julius and his co-worker were unfazed. New transformers were literally hanging on a clothesline to dry. Crates full of NOS 6LF6s were everywhere to be seen.
Don't need any 6lu8's got over 40 GE's nos, 6fs5 is the only tube I would consider buying, would like to have seen those crates full of 6lf6's.
Julius, bless his heart, would sell matched and tested 6LF6s for $5 each. Not to mention that my brand new pair of H3aa's cost me about $800 in 1979. Later, Harvey wanted $50 for an unmatched single 6LF6. To be fair, by that time they were becoming a little less available (but not THAT unavailable).
I think I paid $400 for a set of twelve (6 matched pairs) from Harvey in 1986.
How much does a set of tubes for an Audio Research Ref 310 cost these days?
Good point, they weren't Chinese or Russian crap either, I'm glad those 2 countries never made a 6lf6.
Since you now own the world's largest stockpile of 6LF6s, it is easy for you to say that. What about some other poor shmo who owns an OTL3 or H3aa and is out of output tubes? He would be far better off, if there were a Chinese or Russian copy available.
No insult to Harvey was intended by my previous post. He was a business man and had to make a profit. I was just sayin'...
If a person is watching e-bay he could stockpile a good quantity of 6lf6's in less than a year, that's how I aquired more than half of the ones I have, they are out there, many ham suppliers have them too.
Also Roger Modjeski, RAM TUBES probably would be the best bet for getting a great matched set, they won't be cheap but they will be the best available period.
Good to know that for those in need. Please know also that I have no issues with your stockpiling a bunch of 6LF6. I use 7241 triodes in my monoblock Atma-sphere amplifiers, and I had to do the same as you, but 7241s are even harder to find and much more expensive. It took me a few years to find 23 of them, 2 or 3 of which are nearly worn out. (One wonders why they are expensive; there is virtually no use for them in audio except by weirdos like me. It's kind of like Yogi Berra's lament, "No one goes there anymore; it's too crowded".)
However, if there were a readily available copy of the 6LF6 or if the EL509 had not been discontinued, there might be more R&D going on in the realm of OTL tube amplifiers and more new interesting products out there.
I agree whole heartedly, I have also been collecting the 6336a in the last year as well as some 6c33c's I try to have a nice stock of any tube that I use in my equiptment. I just picked up a lot of 50 6lf6's that are all same manufacture, date and lot, they are made in japan and look just like the amperex version of the tube, they should be here in a few days then I'll break out the Amplitrex analizer I bought befor I went up to Ted's a few months ago and see how many matched sets I can come up with. I plan to keep a set of 12 for myself and sell the rest in matched sets for futtermans or counterpoints.
The tubes are out there, you just have to be commited to the search, soon as you think you wont find anymore you find more than you can afford.
Geart info....cool dog....thanks an goodluck
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