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Got a pair of 65 year old National Union 45 tubes. Shoot! They can collect SS and I have to wait......... Anyway, I had to try them before the DRD's arrived so on down I-71 to Ron's place. In his Yamamato A-08 they sounded less romantic than the similar vintage RCA's he uses but equally detailed and robust. It's fascinating to hear the marked difference between designs and even within the same family of amps. Like push-pull. EL-34 ELLA is clean and effortless on attacks and transients but lacks that "hear into the music" SET thing. Ron'e MAC 240, heard briefly last night has some of that but a bigger, meatier sound. When you first hear the Norh SE-9 you are struck by that "tube aura" that surrounds the music; the 'lushness' or 'tubiness' is so apparent and gives all your CD's or records an ambience that let's you hear into the venue or studio. Or is it a false kind of thing created by 5% or more distortion? Ron's 45 Amp has just a touch of that tubeiness but with better detail and air so there is more of a sense of 'reality' to it. The 45 tube also seems to have very well-defined attack on sounds like drum beats and brass staccato tonguing. That's what I hope to find after I build the DRD's. And the hot Capicola, Mortadella, Genoa salami and Ham on fresh-baked Italian bread at the neighborhood Sub and Pizza shop? Class "A".
That's cool, Bill. I might just have to build a DRD amp too. Seems like they were talking about one in the Group Build forum.
Mine is a Cap coupled amp with the high mu 417a driver tube driving a 45 in SET mode. Sounds sweet and gives adequate power for 95 db + speakers. BAss is atrifle muddy, even though the output impedance apprently is 1-2 ohms. I haven;'t measured it. May be more. Call me crazy, but I like my SETs old fashioned: one large output transformer as opposed to the parafeed or drd designs. Dammit, a SET output tranny is SUPPOSED to cost money & be hard to build...these little tricks like DRD or the parafeed designs are just ways to "weasel" out of the large cost of the output tranny! It's kinda like an old fashioned small block engine versus these new high rpm bangers. half kidding! -akhilesh
Here's a Spice model of a 300B DRD amp: 300B DRD Spice
Hi akhilesh FYI, last time I looked - admittedly a while ago now - DRD did require a conventional SE "large output transformer." IIRC, DRD has two "clever tricks": 1) recycles some output stage current for the driver (via a plate choke) and 2) uses a cap (oil preferably) from the top of the output cathode R to B+, ancient WE style. The means a little lower current draw on PSU, should be less heat in output bias circuit (I think), less PSU in signal path, and DC coupling. This should add up to more modern performance than ye olde RC coupled circuits with premium-ish parts at (probably) less cost. I would do things (only) a little differently than the DRDs I have seen however... I am in no way associated with those making $$$ from these designs - just willing to acknowledge something clever - if not all that new. Cheers Ray
Thanks Ray! I was just ranting! Thanks for listening. BTW, what does IIRC stand for? -akhilesh
cool link, Wayne! thanks -akhilesh
Hi akhilesh IIRC = If I recall correctly. It took me a while to work this one out I understand the need to rant on occasion - I like to listen. Better to let things out than bottle and depress. BTW, let us know if you ever want to sort out the muddy bass issue with your amp - I'm no expert but may have a couple of ideas. Given that you are using it in a triamped system - and if you are enjoying the way it presents music - then forget and continue to enjoy... Keep well Ray
Ray, Cool. thanks for the new acronym! When i said muddy bassI meant compared to a solid state amp or a powered sub. Most people may find thw bass adequate in the amp. I like hte triamped setup, I find it lets me have a bit of the cake and eat a slice too. thanks -akhilesh
Cool beans, Bill! Congratulations on the National 45s. I have a pair of engraved base, balloon bottle National Union 45s myself. They are some very nice sounding tubes, with a certain magic all their own. Enjoy your DRD amp! Thermionic
Hey-Hey!!!, Just had a bit of a grin reading your post. I must say that, regarding your opinion: >>>that "hear into the music" SET thing
Hay , dont put down those high revvers. My 600cc ninja puts out >100 hp. And on the parafeed, i am looking close at the SEX amp (may be just the name?) and giving gainclones a bit of a break. I figure with the 206e BLHs, 2 watts will do it. ron