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Need help evaluating 2A3 transformer coupled designs

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Eric

Eric

Pass DIY Addict
Joined 2000
sites.google.com/bucknell.edu/ericshometheater/erics-home-theater
Paid Member
Hi Everyone,

I'm rather new to tube circuits and for some reason seem to be drawn to 2A3 based designs that feature interstage transformers for coupling. I suppose it is their simplicity that attract me...

I mainly listen to classical, pop, and jazz music at low volume levels, so I'm not concerned with low power output and cost is not really an issue.

Anyhow, I really have no idea how to evaluate the design itself and was wondering if a few of you who have more experience can help me. I found a nice looking design posted on the web by Ralph Powers that I find interesting:

An externally hosted image should be here but it was not working when we last tested it.


I was wondering if anyone has any comments about or critique of this design or a reason why I should not build it.

thanks!
Eric
 
A

Andrewbee

Member
Joined 2002
the 417A has I think 4 grid connections or pins on each tube so what "G" means is to solder one 200R resistor to each of the grid connections (on the tube socket of course :) and then twist together the 4 leads on the unsoldered side of the resistors and then you connect your input here.

BB
 
A

Andrewbee

Member
Joined 2002
None:whazzat:

The has been pulled apart for awhile because I wanted to redo the chassis plate. I was using a 1/8" thick piece of steel and originally 6B4G's. Then I changed to 2A3's and of course had to open up the holes so I used a dremel tool and file and it did not look as good as the originally machine shop punched holes:)

Anyway, at the time I was using a pair of "Afterburners" which are Thorstens idea, which are for lack of a better expression a
"Super 12 clone" and also Jerico horns. Both speakers worked very well but I prefered the Jericos'.

BTW I prefered the 6B4G's to the 2A3's, both are Sovtek.

Everyday at home when I go into my office / workshop I see the transformers for the amp on a box next to the doorway and say I should get busy with the chassis but I have been listening to a gainclone for the last couple months and .....

Andrew
 
Eric

Eric

Pass DIY Addict
Joined 2000
sites.google.com/bucknell.edu/ericshometheater/erics-home-theater
Paid Member
Andrew,

I'm familiar with the Afterburner project, I have looked at that as an alternative to the Super 12s.

You left me hanging at the end there :confused:

Would I be correct to interpret your comments (sometimes dangerous) as an indication that you like your gainclone better than the tube amp?

Is there some reason that you would not recommend this particular 2A3 amp?

Thanks!
Eric
 
A

Andrewbee

Member
Joined 2002
Would I be correct to interpret your comments (sometimes dangerous) as an indication that you like your gainclone better than the tube amp?

Short answer is yes.
Long answer is the gainclone is better overall from lows to highs. I am presently using Jerico horns so you know the speakers being used.
Gainclone excels in bass solidity and control, the mids are I think more real or accurate and the highs are there and sweet unlike many SS amps I have heard. The gainclone "sound" is very smooth yet very detailed at the same time. It likes easy loads like single drivers and no crossovers. It played okay on the afterburners but it did not sound as "happy" I also tried it on my Scanspeak monitors which use a Scanspeak 9900 Revelator and 18W8545 (I think it is) which uses a simple second order crossover and some resistors to balance the tweeter output and it did not like those either.
The 2A3 had no problems with the afterburner but of course had fits on the monitors as to be expected.

The 2A3 amp excels in the midrange and in imaging especially, it has (had) bass but not with the control of the chip amp and the highs were not as extended or clear but the mids are very "rich or creamy".
The imaging is my favorite part for that amp, its unreal, sometimes you hear an image 8 feet above a speaker or way out on the side almost surrounding you. I will look for an old picture of it on my HD and post it so you can see. i thought it was very beautiful to look at and listen to.

Is there some reason that you would not recommend this particular 2A3 amp?

On the contrary, I would recommend this 2A3 amp, it is the favorite of all the valve / tube amps I have built. A 5V6 U.L. S.E.
is a close contender though.
I have found like with most things in life as we get older our tastes change, presently I am really enjoying my gainclone and will most likely find something else at some time in the future. I want to try a OTL amp. I believe in listening for myself first otherwise I would not know personally but depend on the opinions of others and my opinion is the one that counts;)

Many people will probably say I am nuts to say I prefer a gainclone over the I.T coupled 2A3:bigeyes: but I only care about what I think and hear.
You could always build a gainclone as well just to see if you think I am nuts ;)
Here is a pic of it
[url]http://www.decdun.fsnet.co.uk/gcgallery4.html[/url]

Look for Andrew in the Cayman Islands.

Andrew
 
fdegrove

fdegrove

diyAudio Senior Member
Joined 2002
Hi Andrew,

Okay Frank, good idea but how do I post pics here.
Click to expand...

Whenever you reply to or start a new post you see a browse button at the bottom. This allows to brows your local hard drive(s) for the pic you want to post.

The are format limitations, I think BMP, JPG and GIF are accepted.

There are size limits as well, 800 x 1000 or something like that, can't quite remember.

The thing not to do is use the preview option as that somehow loses the links to your pic.

Don't worry once the local forum accepts them they will be stored on the host here.

As far as I know you can only post one pic at a time too.

As you have a server service running you could link the images there directly as well but in your case I think Yahoo won't let you somehow, I've seen that happen before.

Hope that helps you out,;)
 
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