Post by Steve Deckert on 01/07/18 at 05:19:46
It comes at a price, adding the OA3 regulation for each output tube that is... Rather than the two capacitors used in the power supplies of the SE84UFO and SE84UFO2, this uses a few more. The first cap comes off the rectifier tube just like the other amps but then the power supply is split into three separate filters, one for each tube. This adds 7 additional caps and nine additional poly film bypass caps. There was no option other than to spit it into three separate supplies due to the 30mA limit of the OA3 tube. And because the large gap beautifully slows things down, all of the caps have to be carefully bypassed to speed things back up. This stretch between speeds expands the transient playground to a very large window giving a more immersive sense of depth and complexity. The slow side of its personality creates unbelievable liquidity. The fast side of it's personality reveals stuff you had no idea was there, and that Zen duality creates an infinitely variable speed power supply that fills in the middle.
It's not real practical, but it is something you do when you're trying to not be practical, and voyage well beyond that point of diminishing returns, through the neutral zone and into heavy waves of total realism... something I think the little Zen deserves after being such a trooper for so many years!!
Who would have thought 25 years ago when Eric Barbor of Svetlana contacted me to see if I had any interest in an EL84 substitute called the SV83, such incredible effort would have ended up going into the amps for it. 25 Years ago it was a $4.00 tube. Who would have thought a $4.00 tube would justify a $2500 wholesale price pair of amps (and counting). The bizarreness of it from this perspective just makes it even more desirable to do, just to see how much further can we push the resolution of this amazing output tube, which is actually a Russian 6P15P-EB.
We've always known that EL84's are faster than virtually all 8 pin output tubes, be it pentode or triode wired, but the 6P15P-EB was nearly twice the bandwidth and subsequent speed and as a result nearly perfectly neutral. So there is no reason not to see how fast the tube actually is... just know it's expensive aka painful, but worth it. I predict it's going to hurt fairly bad until the moment it arrives. Most of the pain will go away in the first hour. I would say 90% of it. By the third week you will begin to understand that the amp is easily worth twice what you paid for it, and it's limited production ensures that it will always hold it's value and you will then become forever pain free.
Steve
Here's a picture of the prototype... don't worry I was just having some fun with the finish. The actual model will be done in a beautiful textured powder coat resembling a green patina with silver jacks, and white silkscreening for a really vintage upscale look and backlit meters.
The current tube compliment is presently a globe 80 rectifier tube with adapter, a pair of OA3's for the output tubes, an OD3a for the input tube which is a 7DJ8. So far the input stage is working out as a wonderful opportunity to voice your own amplifier. With 3 voltage regulator tubes ranging from VR75 to VR150, you can make any input tube sound three different ways. Powerful tool. The input tubes used and liked are 6N1P-EB, 6N23P, 6N11, 6922, 6DJ8, 7DJ8, 6N5P. I'm presently torn between the 7DJ8 and the 6N5P with the OD3A on both as to which should be the stock tube compliment... but that could change with more time.
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