6550/KT88 SET amp aka "Uber Beam Machine"

jrebman · « **Reply #80 on:** 10 Dec 2007, 09:47 pm »

Dan,

You posted as I was typing.

Thanks for the physical description

.

They sound beautiful.

-- Jim

DaveC113 · « **Reply #81 on:** 10 Dec 2007, 09:57 pm »

I'm sure many people can hear a difference, the quote from that website was a joke... making me feel better about not being able to afford them. The Hashimotos are out my budget. I'm rebuilding a Chevy 496 to sell for school money over xmas break, I'll have to skim a bit off the top to buy the parts... or maybe santa will bring them.

Dave

Dmason · « **Reply #82 on:** 10 Dec 2007, 10:34 pm »

Jim

These things definitely are about an iron enriched diet. They are much much bigger than I thought, perhaps close to 7 inches square and I would say they weigh about 12 pounds each. This is where the rubber meets the road. Floobydust has some shots of a 45 amp built with same size outputs. Maybe Kevin can load us up a shot of his Hashimoto irons....

As Robert is the only one tuned into this amp currently, and a professional guitar amp maker, he said use good iron to get the best, the TungSols are REAL monsters. So I did. Asikura san answered my emails really quickly, and I place a premium on professionalism and service with this kind of purchase.

I emailed Jack at Electra, and didnt get a response, called him and left a message, with no response. I am sure there were good reasons, and better ones to take a pass there. I wanted them NOW, and Mikey makes fabulous irons, I have a pair of little parafeed jobs in a Bottlehead SEX amp and that amp became a very very fine little amp of 2+ watts. With Mike, his business model dictates that you get your stuff when Mike sends it. Your ownership happens at an undetermined point in the future. I dont pay for that. I would recommend Bud Purvine with O-netics, and like Asikura san, with O netics, you get Bud in the deal. You get an education. You make new friends. I will be sending my Coral 12 inch Alnico widebands to Bud for eNaBL treatment and so Bud can try the drivers for himself, in return, I am paying Bud for the treatment and electron pool speaker cable. The Corals will be on the receiving end of the Uber Beam Machine.

jrebman · « **Reply #83 on:** 10 Dec 2007, 10:51 pm »

So which Hashimotos did you get? Those sound a lot larger than the H-20-3.5Us.

I sent a pair of Fostex F120As to Bud for EnABLing, and you're right, you get a new friend in the process.

-- Jim

Dmason · « **Reply #84 on:** 10 Dec 2007, 11:04 pm »

Jim,

these are H-30 30 watt rating.

JoshK · « **Reply #85 on:** 10 Dec 2007, 11:31 pm »

Quote from: Dmason on 10 Dec 2007, 10:34 pm

... Uber Beam Machine.

I love it! Maybe we should adopt that as the official project name. UBM is easier to type than 6550/KT88 SET amp.

Now you have me wanting to try those Hashi's. 7" square. Wow! You will need a big chassis. Are you going monoblocks or stereo?

Did surplussales confirm your PCR300 order? They told me I got the last one. Bummer cause I wanted two. I placed my order first but with some other items that they didn't have so I didn't confirm the order till mid last week.

jrebman · « **Reply #86 on:** 10 Dec 2007, 11:37 pm »

Guess that makes the PT decision just that much easier

.

Maybe that's why I couldn't find an "add to cart" button.

Is this amp really going to need a 30 watt OPT, or is this for PSE?

-- Jim

Dmason · « **Reply #87 on:** 10 Dec 2007, 11:59 pm »

Josh

I never received a confirmation, I just figured they wanted to ignore business from "Peruvians." no matter, the values for that can yet come. I will eventually need a link to the copper flat stock shingles you spoke of, and I hope I can get more of it in 15 inch squares to make matching mounting rings for the Coral CR12A's. I have a length of Cherry chair rail I got from ACE, I had my eye on it for a couple years, this way you can make a chassis of any size you please. Sand it and finish it. I think Steve Deckert looks to be using chair rail on his big tube amps. Like salami, cut to size, and consume.

Uber Beam Machine is actually a pretty apt name... Glad you like it...

Jim,

The big outputs have almost twice the mass, and only a hundred more. I am old fashioned in the attitude that big magnets means big headroom. You look at all the hotrod SET amps, the spendy retail jobs, like Sun Audio, or Shindo, and they all use gigantic outputs. For once, I wanted to forget about what may of may not be appropriate, and get some really f***ing BIG, nice, end of the road, output transformers.

JoshK · « **Reply #88 on:** 11 Dec 2007, 12:05 am »

I got the copper shingles off ebay over 2 years ago. I couldn't tell you who from. Onlinemetals has copper sheet but at a price. I'd search epay for copper shingles and see what comes up.

Dmason · « **Reply #89 on:** 11 Dec 2007, 12:23 am »

And if anyone knows a Millwright in San Diego that would be good. I know the other Coral 12 converts, Joe and Blake want circular metal mounting rings to bring the driver out to flush mount. Drivers HAVE to be flush mounted for OB to sound right.

The Corals are the nicest wideband single drivers I have heard, and I have heard ALOT of them over the last several years. They are not high efficiency, we opine that they are on the order of maaaybe 90db, and rated at 20 watts. One thing I learned working for Clair Brothers is that if you have a driver, or speaker or cabinet rated at X watts, it should be fed with X watts. This reason alone is a very practical one in considering the Beam Machine.

Robert Simpson says for those inclined, the TungSol 6550 also sounds really sweet in ultralinear and those inclined should consider a triode/UL switch and UL gives he figures maybe 15 watts, 7-9 in triode.

jrebman · « **Reply #90 on:** 11 Dec 2007, 01:03 am »

Dan,

I can't argue with that thinking on big transformers -- one of the reasons I picked the PP amp in my main system was because it weighed about 20 pounds more than other amps in it's power class, and that's all iron.

Those drivers should be amazing with the EnABLing. Actually, the whole thing sounds very tasty.

I'd have to think seriously about a two-chassis design with those trannys though.

-- Jim

Dmason · « **Reply #91 on:** 11 Dec 2007, 01:13 am »

Jim

Bruce the engineer next door to me here took one look at these beasts and said " you might want to think about separate chassis for each of these, and use a power chassis, and umbilical cords" ...as a Telecomm engineer he is all about refined power supplies and separation, shielding, etc. So yeah, I might have to think about that.

Glad you like the idea. I am pretty well hooked on the nice clean sound of open baffle, and the ridiculous simplicity of cutting a hole, screwing in a driver and you are done. The cleanest sounding alignment in speakerdom is also the simplest, easiest, and potentially least expensive. The Corals are really something, and came from serious Jap style home audio of the late 60s, early 70's and were originally in large acoustic cabinets, so high Qts, and bundled with PP 6BM8 amplifiers with Sansui (Hashimoto) transformers. The 6BM8 tube has for years and years enjoyed a status with Japanese audiophools similar to the 300B here. They value elegant design, and so the twin tubes, like these, or the TV oscillator tubes are VERY highly thought of there. The 12's I can easily think of as obscure Coral Beta 12s but with big Alnico magnet, and none of the usual nasties associated with wideband drivers, such as rising response, laser beaming, power compression, and whizzer weirdness, NONE of that. Joe and Blake are similarly impressed, addicted, converted, and have no plans to stray from these drivers. I am pretty sure all this will mean the kind of sound you just cannot buy from a store. Bud P believes that the larger diameter driver will elicit an even greater response/benefit from eNaBL treatment, and is sure of it. He went on the say that the healthy excursion capabilities make it a shoo in for his electron pool cables, and stout high quality single ended amp would be the icing on the cake. If I dont come back for x/mass, I will get Kyle to send the Corals over to Bud to play with. He can post his impressions and results.

nodiak · « **Reply #92 on:** 11 Dec 2007, 04:14 am »

Good to hear from you Dan. Love where you are (want to go there) and what you're doing.
Considering the transformers you've got I'd say I'm looking at an Uber Minor. Will use the Tubelab SimpleSE and considering Transcendar iron. Ditto on the new TS 6550. Picked up Coral Flat 6B, and will try with a 15 on ob at some point this winter.
Don

Dmason · « **Reply #93 on:** 11 Dec 2007, 04:27 am »

Don

If you are going to use a 15, I have an interesting design plan for you to look at, courtesy of Poinz, who just sent it.

I think nothing but good of the George board, and he was very diligent in its development. I intend to start there, with all this nonsense. If it stirs the Kool Aid, so much so's the better. The good news with this circuit is that it will play fine detail in finely crafted recording, but will have enough juice to be muy fun during drunken rocking nights on occasion.

Yes, Lima and coastal Peru are something. I never loved so many faces, and they have built some amazing places. This city is very cosmopolitan, it is a mature Latin American city and the food, South American cultural influences, and Pacific Rim genetic and cultural influences make Hawaii look stale. I strongly recommend Peru for a visit, and you can live like royalty on not much. There are a couple surf rats down here collecting the dole for a year or two, in British Columbia, and living here. Very well. And getting in and out of here are pretty easy with easy transfer in Mexico City downbound, and there are direct flights from Houston, LAX, Toronto.

nodiak · « **Reply #94 on:** 11 Dec 2007, 08:56 pm »

How are the cases on the James, Hashimoto and other transformers helpful? Keeps stuff out, any shielding qualities, electrical benefits, etc. ?

Dmason · « **Reply #95 on:** 11 Dec 2007, 09:07 pm »

Don

The Hashimotos are basically in another league altogether, in terms of fit and finish. Both are potted, the James in epoxy, I would imagine, but the Hashi's are embedded in pitch, ie: tar, and that stuff is well known to be totally dead, totally non-conductive. Vibration is one of the enemies of audio transformers, and the pitch filled pots address this to the n-th degree, in my opinion.

The James units are painted, and the paint is notorious for easily chipping and coming off, and basically should be wrapped up until the amp is finished, the Hashimoto's are finished in some synthetic material like a sort of stylish pigskin upholstery. They are very nice, and will come in handy when I decide to play, "Dazed and Confused."

JoshK · « **Reply #96 on:** 11 Dec 2007, 10:14 pm »

But in fairness to the James OPTs, they are $200/pr, the Hashimoto's $800/pr. So you'd expect (and get) a higher level of polishedness.

I'd say if the Hashimoto's are in your reach and this project is a good likelihood near the end of the line for you, then by all means jump. If you are like me and this is a project, learning, curiousity, whatever, then the James might be a better price/perf ratio balance.

FWIW, I usually try to keep my stuff wrapped till I am done working. I've pretty well scratched up my Aikido PSU project wiith all the reworking and learned a few things the hard way. Contact paper, like you would line a kitchen cabinet with helps to protect the finish while you are working on things.

nodiak · « **Reply #97 on:** 11 Dec 2007, 11:21 pm »

For me so far Transcendar gets the nod for $165/pr. delivered, and good reputation for sq (#1 issue). But I'm trying to decide if the potted/covered transformers make a difference in sq, longevity, shielding, just keeping windings clean, etc. If so that would be a good reason for me to up the budget, a little.
James for 215 + ship and good rep for sq. is probably as far as I would go. Cheapest potted Hashimoto is the H-20 ~ $530/pr., a little less than H-30, but I'm not sure enough to do it now.

JoshK · « **Reply #98 on:** 11 Dec 2007, 11:38 pm »

I am not sure about the transcendar, as I haven't heard enough about them. I heard a few things a ways back, but I can't remember if these were the ones that people were having issues with later on (after first few shipments). Maybe I am getting them mixed up with something else.

I am not sure potting has a great deal of added value, it may or may not, I have no idea. I certainly like the idea. It will add shielding at HF, but doubt it'll add a lot of shielding lower in freq. The HF shielding may be beneficial for EMI hash from SS diodes and such. It looks nicer. The epoxy may help with dampen, I don't know. I do like the connection compared to bare wire coming out of the transformers, as it lessens the chance accidental shorting, but that is a minor issue.

The down side is it is easier for the manufacturer to hide puny cores.

jrebman · « **Reply #99 on:** 12 Dec 2007, 11:38 pm »

Ok, I've been doing my "homework" as assigned a few pages back. Unfortunately, the BAS audio DIY nmag is an image PDF, not text, so I'm going to have to print them out and scan them to see if I can garner anything useful from them. Likewise the 6550 and KT-88 data sheets are scanned and not text, and I'm assuming mostly graphs and drawings, so printing and scanning won't do much good. I got the duncan amps software, but haven't tried it yet. I actually may have more luck with SE Amp CAD, but that won't do PSUs.

I have plenty of other resources to check out, so I'm sure I'll find something I can work with sooner or later, but the basic amp design stuff is coming back to me now, so I don't feel quite so stupid

.

Still considering trafo options though and will make a final decision once I have a couple different operating points established for different B+ and primary impedances.

This is what I call fun

.

-- Jim
,,