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Re: 6Ah4 Amp [message #11336 is a reply to message #11330] Mon, 17 July 2006 04:24 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey-Hey!!!,
I'd suggest the 2A3. While it won't teach you about super-silly HV, you'll learn much from the DH cathode. Go for a bit more load than 2k5, you'll still make your 2W.

Then again, I am currently palying with TX tubes, and I am just leaving the voltage spec of vintage AB1 commercial amps. Super high B+ is not a requirement.

If you get a custom SE output, say from Jack of Electra-Print, a 5k/80 mA 15W version would be useful for a lot of tubes. Up to an 845 at 7-800V. Very versatile, good for 300B, and even a high load 2A3.
cheers,
Douglas

Re: 6Ah4 Amp [message #11337 is a reply to message #11335] Mon, 17 July 2006 14:24 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
I have a couple 6Bm8 circuits from Svetlana. I have no way of knowing how anything other than what I have heard will sound; thats why I picked a cheap tube; the 6h4a. I look at it like this; the transformers are interchangeable; most of the passive parts are useable and the chassis are useable; so whats the risk in trying?
See I have heard lots of amps and they all sound different and they all sound good in the right situation. So I am intyerested when someone describes a good sound with a particular type of system.
I figure the one watt would work with the 96 db monitors and have a 7K primary on the OPT that I could use with another SE design. What do you think?

Re: 6Ah4 Amp [message #11338 is a reply to message #11337] Tue, 18 July 2006 19:18 Go to previous messageGo to next message
Forty2wo is currently offline  Forty2wo
Messages: 163
Registered: May 2009
Master
It sounds like you are trying to talk yourself into it.
Go for it!
Like you say you can always transmogrify it into something else.

BTW. DIY Hi fi still sells the output transformers from there ‘Lady Day’ amps. these can be wired from 2.5K to 7.5K and are a steal at $190 a pair shipped. Look under ,accessories / magnetics…John


Re: 6Ah4 Amp [message #11339 is a reply to message #11338] Wed, 19 July 2006 07:21 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Now you are talkin'! I had pretty much made up my mind to go with the Sansui from EIFL for about 250$ pr with shipping; they can use either 5K or 7K. Let me look at the DIY units.
As far as talking myself into this; it's finding the time to do the grunt work that matters, the parts will all be re-used. Drilling and cutting chassis and mounting tubes and transformers is work. I would love to find someone who has streamlined that process. Thats a guy I would buy even two sixpacks for sharing that knowledge.

Re: 6Ah4 Amp [message #11340 is a reply to message #11336] Wed, 19 July 2006 15:08 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Thanks Doug; let me say this and hope it doesn't sound rediculous. The 2A3 is such a common circuit; there are so many models and designs that it would be much easier to just succumb and build one tof the standard well designed circuits available on the net.
But my question then would be which one is best? Why are there so many variables instead of a few good designs using that tube? It has been used to the most extent that you would think by now there would be two or three designs proven to be the best out there. Yet we see many new trials and changes to existing circuits. So I have to ask why people feel they need to re-do this type of amp on such a constant basis?
Is there really a fundamental change for the better in each example?
So I have to believe that people aren't happy with that tube as it rests in the existing designs.
Why?
I would want to try a PP 2A3 amp if I did use that tube if only to not follow the usual suspects and try instead something a little different.
So is this a silly post on my part?
Anyone looking to do PP 2A3?

Re: 6Ah4 Amp [message #11341 is a reply to message #11340] Wed, 19 July 2006 17:27 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey-Hey!!!,
There is nothing stupid about the points you've made...or the questions you ask. If there were one single best, most of us would probably build it.

Building something that is a bit different, and inovative is a lot of what makes this fun. Just because the general population hasn't recognized something as good, does not mean it's not. Perhaps even excellent, yes?.

The Galahad schematic is still on my build list. I figured a way to combine my next two amps into one convertible just so I could do some more varied building. I don't think I would change anything about it. One of the attractions of the pentode front end is its nearly constant output Z with signal level. The plate Z can chage a lot, and the whole thing will still be dominated by the plate load resistor. That's probably a good thing...:)

I do suspect that part of the multitude of 2A3 amps is due to the value of personal experimentation. I know you can relate with the "I'll build it myself and see" mentality. Probably also because it work well too.
cheers,
Douglas

Re: 6Ah4 Amp [message #11350 is a reply to message #11326] Fri, 13 October 2006 08:45 Go to previous messageGo to next message
j.luis cruz . is currently offline  j.luis cruz .
Messages: 154
Registered: May 2009
Master
Hy .. do you could share the link to this amp. thanks

Re: 6Ah4 Amp [message #11361 is a reply to message #11326] Sat, 25 November 2006 16:08 Go to previous message
Gerard is currently offline  Gerard
Messages: 1
Registered: May 2009
Esquire
Hey....I have a Dehavilland Ultraverve preamp. It uses 2 6ah4's following one 6sn7 (Long live the glorious 6sn7!). It also uses a big rectifier (5aw4). It is a great example of a 6ah4 design and I recommend anyone building an amp with this octal tube get their hands one. They are around 2 grand. I'm writing because I am having a hard time finding good 6ah4's. I have 2 great Sylvania's in the preamp now, but would like to start collecting them. Any advise? I have quite a few 6sn7's, and would like to begin a collection of really good 6ah4's. Thanks everyone...Gerard

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