Audio Asylum Thread Printer
Get a view of an entire thread on one page
|For Sale Ads|
In Reply to: RE: Neither posted by Tube Tourist on January 23, 2012 at 04:06:15
(1) If you need a 845 or 211 to power your speaker load, you will do better with a really good solid state audio amplifier, one that is of high quality.
(2) For someone asking such basic questions as cap versus transformer coupling, I would seriously caution you againt building amps with ultra high voltages for lowest distortion. ONE mistake with 1,000 to 1,100 VDC will likely kill you. It is very quick, permanent.
(3) A DC SE amp with 845s, low B+ is quite possible - 5 Watts output. Triode connect a 7788 and DC connect it to the grid of the 845. It will be more transparent, being a two stage, and will creme all the three stage amps out there, handily.
My friend has just showing me a fellow in other forum named Dowdy has buit a 2 stages GM70, and I saw his amp on youtube as well. And the other guy has intended to build also GM70 with Emission labs driver tube DRD coupled to GM70 with step up input transformer.
Maybe you are correct about the distortion issue from big triode, but doesn't mean 2 stages is impossible to work on big triode. Especially all Emission Labs's driver tube are DHT, and DHT driving another big DHT triode is pretty interesting if the quality of the step up input transformer can do their job well.
I read something about Dowdy's amplifier as this is a 2 stages with some big tube at front and parafeed. A pretty interesting approach as well. look, the most expensive Audio Note amplifier is a 211 driving by 10Y with "step up", and the LAMMM GM70 SE.
IMO, whether owning those amplifier is suicide is another issue. I used to build 845 back in the 90s with my best friend and never got it right since we have to parallel and series the lytic caps in the supply. We tried different circuit including the Audio Note Ongaku and Gakuon.
I'll not say big triode never sounding any good since I have listened to some fellow putting exotic double C amorphous output transformer made in Europe, I guess a company called AE along with high quality oil cap with 2KV rating, sounds pretty damn good. It sounds very different between those low powered and big triode.
Don't you know that running the big triode in low voltage making the driver stage more tuffy to drive. It requires much lower impedance.......so many things going to happen!! And the distortion retains on high side if operating at low voltage on 845 or 211. Why not just put a 300B for low voltage??
I also heard the people say the difference between graphite and copper palte from GM70. Well....they also sound very different. I don't build anything since the late 90s cuz getting older. But I highly respect those tube builder's "attempt" on big triode and the refinement they've done.
Nice talking to you!
Dowdy is a LONG TIME friend of mine, and I have had his amp, with Jim there, on my speakers in my living room.
I personally do NOT like a low or medium mu driver tube in a two stage amp, it makes it lifeless unless pushed hard to my ears.
You can triode connect a 7788 and pull off a big tube Finals amp OK, but if you really need that power, you have the wrong speakers, and /or should be using GOOD solid state, because it will outperform amateur builds I have seen. Overall, I prefer a 2A3 amp.
What you mean by low and medium mu? 50 or 100 or higher?
The high mu driver (in a two stage amp) is dependent partialy upon the mu of the finals.
To have a lively sounding amp at low listening levels, with a mu equals 4 or 5 (typical DHT) as Finals, I like to see about a 70 mu to 100 mu front end tube.
If you use a mu of 20 tube, (of which there are many nice sounding tubes ), it will never have the JUMP factor that I like to have in a DHT amp.
I am not into tonally correct but lethargic amps. I do not want to only hear it correctly when the amp is pushed. I want the amp, for long term listening pleasure, to be tonally correct and as lively and vivacious as all get out.
I need an email from you so I can have an address to send you the new power supply design data.
The D3A I am using has a Mu of 70 in triode & a low plate resistance of 1900 ohms. Also seems to be more stabile than a 6C45n. The Pete Millet site have some interesting test data on the D3A. It has remarkable low distortion.
I am surprised I never seen a schematic with a D3A direct driving a 2A3.
Jeff, I like privacy- no face book, twitter, only Linkedin due to business ralationships. I was a ham radio operator just so I could experiment legally with a transmitted signal. I rarely ever called CQ, CQ, CQ. I communicated via aurora on 6 meters for the most part. I only socialize with women as I HAVE to to have one or attend business meetings.
Thats fine on privacy, I surmised that, thats why I suggested email(or snail mail) to a third party. How can I do that??
You, of all people, should read the grouping of posts.
Post a Followup:
Post a Message!
This post is made possible by the generous support of people like you and our sponsors: