tube fanatic Posted December 5, 2010 Share Posted December 5, 2010 Since this thread hasn't burned out yet (see what you started Joe!) I'll raise a question which, to my surprise, hasn't been discussed in the context of using low power SET amps- has anyone experienced a "spud" amp (i.e. a single pentode, directly driven by the source component)? This represents the ultimate simplicity in tube amp design- one tube per channel and minimal support components in the signal path. A couple of years ago I heard a demonstration of an Ah Tjoeb cd player (which can put out around 5 volts, as opposed to the typical 2 volts) driving an amp using one 6EH5/channel to around 700 mw output into Cornwalls. The sound was amazingly clean, with smooth mids and highs, and much tighter/fuller bass than is usually available from SET designs. Given the efficiency of the speakers, the guy was able to produce extremely high sound pressure levels (far greater than I could tolerate, in fact). For those who have source components which can output 3 volts or more, this may be a nice avenue to explore. Quote Link to comment Share on other sites More sharing options...
markgod Posted December 5, 2010 Share Posted December 5, 2010 Which camp ? It all depends on what I feel like listening to , variety is the spice of life . Why make a long term choice when you don't have to .It is nice to be able to mix it up ,when you want to . Craig, A little off the current subject, I wondered if you have tried the Shuguang "Treasure" Kt88 tubes in your VRD's yet . Or if you know anyone who has ? just curious Quote Link to comment Share on other sites More sharing options...
thebes Posted December 5, 2010 Share Posted December 5, 2010 Can you audit the Channel Islands D•100B Monoblocks? Clean low power that I think is better than SET and plenty of high power that is just as clean. Leo Leo, are these some form of T-amp? Their site does not make clear what type of circuitry they are using but from an inside shot it looks to be too simple for a solid state design. Quote Link to comment Share on other sites More sharing options...
leok Posted December 5, 2010 Share Posted December 5, 2010 The Hypex modules used in the Channel Islands amps are pwm, but derived from very high gain binary feedback instead of the traditional ramp/comparator approach. My take on it is that the advantage of feedback in limiting distortion is achieved, but feedback noise, which usually trashes the low power purity of a feedback amp, is shifted to the mid to high hundreds of KHz. What's left in the audio band is super-clean. I think the concept is brilliant and the sound of the modules, for me, is the proof. There are a few white papers on the Hypex.nv website. Look at the distortion: Under 0.03% from 60 or so Watts down to something like 3mW. That's about 5 orders of magnitude of power under.03% distortion. I don't know of another approach that can do that. By focusing on keeping low power distortion low rather than extending power to the KW range,the Hypex approach is optimized for efficient speakers like those made by Klipsch Leo Quote Link to comment Share on other sites More sharing options...
NOSValves Posted December 5, 2010 Share Posted December 5, 2010 Which camp ? It all depends on what I feel like listening to , variety is the spice of life . Why make a long term choice when you don't have to .It is nice to be able to mix it up ,when you want to . Craig, A little off the current subject, I wondered if you have tried the Shuguang "Treasure" Kt88 tubes in your VRD's yet . Or if you know anyone who has ? just curious Yes I have. I heard no difference between them and the standard Valve Art or Ruby Chinese tubes which is not surprising since beyond the black substance applied to the glass on the inside they are structurally identical in a visual sense to the VA or Ruby. I still think the best tube coming out of the Chinese factory is the Penta KT-88SC. In fact I prefer it to any other currently produced KT-88 or 6550 on earth. Quote Link to comment Share on other sites More sharing options...
joessportster Posted December 5, 2010 Author Share Posted December 5, 2010 It's not a set amp but the counterpoint np 220 comes pretty close it's a tube hybrid at 220 wpc plenty of power and not fatigueing at all on 105 db titans (typically a problem for ss amps) these had a bad rep back in the 90's but mike elliots revamp of the design and the parts used make them very stable now. I just swapped my coincident 300b's for one and I'm happy I did. Joe Quote Link to comment Share on other sites More sharing options...
joessportster Posted December 5, 2010 Author Share Posted December 5, 2010 For good sound, first and foremost you need good speakers. They need to be properly located in a room with no glaring acoustical problems. The recording needs to be as clean and high quality as possible. The electronics are last in importance. If you are going through gear left and right and are still not happy with the results, maybe it's not the gear? amen buddy som are never happy matterhow much they spend in $$$ . For some of us part of the joy in this hobby is Hearing various equipment and we get to learn alot along the way !!!!! Joe Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted December 5, 2010 Share Posted December 5, 2010 "I still think the best tube coming out of the Chinese factory is the Penta KT-88SC. In fact I prefer it to any other currently produced KT-88 or 6550 on earth." Agreed. Love these so much I got a stash of 30 all matched up. I like the older VA KT100 too (basically a stout KT88), but the Pentas are very good....enough so that I don't look for NOS anymore (just too cost prohibitive). Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 6, 2010 Share Posted December 6, 2010 Since this thread hasn't burned out yet (see what you started Joe!) I'll raise a question which, to my surprise, hasn't been discussed in the context of using low power SET amps- has anyone experienced a "spud" amp (i.e. a single pentode, directly driven by the source component)? This represents the ultimate simplicity in tube amp design- one tube per channel and minimal support components in the signal path. A couple of years ago I heard a demonstration of an Ah Tjoeb cd player (which can put out around 5 volts, as opposed to the typical 2 volts) driving an amp using one 6EH5/channel to around 700 mw output into Cornwalls. The sound was amazingly clean, with smooth mids and highs, and much tighter/fuller bass than is usually available from SET designs. Given the efficiency of the speakers, the guy was able to produce extremely high sound pressure levels (far greater than I could tolerate, in fact). For those who have source components which can output 3 volts or more, this may be a nice avenue to explore. I have a quad of Mullard ECL86 from a Penncrest console stereo receiver. I've pondered a ECL86 PP amplifier circuit using the original Penncrest receiver output transformers, or a SE spud amplifier. But I'm not sure what the proper primary impedance would be for a SE output transformer when using ECL86. I guess I could try it with a SE 6BQ5 OPT, and see how it would work out... Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted December 6, 2010 Share Posted December 6, 2010 I have a quad of Mullard ECL86 from a Penncrest console stereo receiver. I've pondered a ECL86 PP amplifier circuit using the original Penncrest receiver output transformers, or a SE spud amplifier. But I'm not sure what the proper primary impedance would be for a SE output transformer when using ECL86. I guess I could try it with a SE 6BQ5 OPT, and see how it would work out... The ECL86 is a nice tube to use as a single ended "spud." You could run 250V on the plate and screen with the bias set by a 270 ohm cathode resistor (I'd bypass it with around 1000uf). The load impedance would be 10k. I doubt that the transformers in the Penncrest would be up to real audiophile standards (and you would have to measure their impedance to know if it is compatible with the voltage I specified). A nice choice, if you're not looking to spend a fortune is the Hammond 125ESE. Although it's rated frequency response doesn't look that wonderful, in reality it's capable of producing truly amazing sound, and significant bass output down to 35-40 Hz. Or, if you have some bucks to spend, the Hammond 1638SEA is truly excellent. I would also consider contact biasing the voltage amp section in this application, for simplicity sake. If you need any other info, send me an e-mail and I'll do my best to help you out. Quote Link to comment Share on other sites More sharing options...
jcmusic Posted December 6, 2010 Share Posted December 6, 2010 Well Joe my Vintage system is PP and my modern system is SET. So I sorta have the best of both worlds, the Vintage system has a tonal quality that is just hard to beat. I guess that's because of the old iron they used back in the day, I am into the SET world because of the midrange and the way it makes music sound so real. Jay Quote Link to comment Share on other sites More sharing options...
Marvel Posted December 6, 2010 Share Posted December 6, 2010 I personally am very happy with my Moondog 2A3 amps driving my LaScalas, but have a bedroom setup with some Heresy IIs and HK430. Obviously no comparison between the two systems, but I hear music out of both of them and they don't hurt my ears. Bruce Quote Link to comment Share on other sites More sharing options...
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