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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.
1. Should I go back to the 6FW5's or 6HB5's?
2. Should I stay with the 6LF6's?
3. 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
Thx in advance.
It's possible that there are more than one Anthony Naso's interested in audio, but I'd urge anyone planning business to use caution.
I traded some of the Steve Bench crossover boards with an Anthony Naso back in 2004. I never received anything in return - and once the tracking indicated that the boards had been delivered to him all emails' stopped. My losses were about $85 at the time.
I shipped to
271 Ridgebury Road
Slate Hill, NY 10973
I suppose there could be more than one Anthony Naso - but a word to the wise or a cudgel to the obtuse.
A couple more relative links regarding our Mr. Naso:
You were not the only one screwed by Anthony T. Naso in Slate Hill NY. I, along with many others, am out a lot more than $85.00. Most of us were taken for between 1 and 1.5K for mono amps that never materialized.
Stop your complaining Gary, You got the trans I sent you in trade. Sorry you did not like it and that it did not live up to your expectations but you asked for the trade not me. I owe you nothing.
Nothing was ever sent, or received as you are aware.
If anyone would like to see the "less polite" response Anthony sent directly to me I'd be happy to share it.
If it's truly an H3, it is very old. I mean maybe more than 45 years old. Does it say Harvard Electronics on it anywhere? That was the name of Julius Futterman's company during the brief period that he was in business. Otherwise, there were three iterations of that amplifier, the last two of which came later, when he was building amps on a custom basis in NYC. The terms are H3a and H3aa. I owned a pair of H3aa monoblocks that he built for me in 1979. They used six 6LF6s per side. Another hallmark of the H3aa is the use of several small photoflash-type electrolytic caps for output coupling. JF discovered that those sounded better and faster than single large size lytics he used for output coupling in earlier amps. If your lytics are still original, you will obviously want to replace those too, and I recommend bypassing them with good film caps. It makes an instantly audible major improvement. I recommend Panasonic TS-ED or the like for the lytics. 6LF6 is very hard to find now and expensive when you do find it, which is why more recent Futterman-type OTLs used the EL509. I think it's a better choice in this day and age, just on the basis of cost and availability. I know nothing about the other alternative output tubes you mention.
Julius had built me the last of the H3aa Mono amps prior to selling his intellectual property rights to Harvey Rosenberg of NYAL. This was late 1979-1980. He did use the photoflash caps in these amplifiers. Seems like only yesterday.
Yes it says Harvard Electric on the back edge and all the silk screening is there. It say H-3 but was modified from have either 6 x 6HB5's or 6 x 6FW5's per channel but since I started this info I have received tells me that it was now most likely the 6HB5's which is a compactron tube as well as I now believe the tube sockets to be original and the are 12 pin. The 6LF6's I have are in good shape and yes they are hard to find and the old el509s are also hard to find but not as expensive. Since it turned out after the mods to be half a H-3 and half a NYAL OTL-1/3 I think I will just build it back as the OTL-3 Spoke to George Kaye at Moscode this morning and he said that is what he would do.
My Acoustat Servo Tube amps use 6HB5 as well from the factory.
But I can use and I am, 6GE5 tubes with no modifications, it was a drop in replacement and prices for these tubes are very reasonable.
Post a pic when you can?
George Kaye is da man. Sorry I forgot to mention his name earlier. You will have a nice amp when you are finished. I think the H3 was a stereo amp (i.e., two channels on one chassis). I saw one once back in the day. First thing is to change out all those electrolytics.
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