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PostPosted: Oct Thu 26, 2006 1:53 am 
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Sal,
I had seen the one from AES, but I don't know how to judge what would be good and what wouldn't. I was a litte leery after hearing comments about the AM transmitter they sell. If I remember they weren't all good. Probably one of the reasons I built the AMT3000. Seeing as how you've built others, what do you think about the AES one? Would the sound be clean?

Michael


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PostPosted: Oct Thu 26, 2006 2:47 am 
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You could modify the power transformer slightly by removing the back shell and then mount it horizontally. It will still maintain the distance from the output transformers but will give the needed 90 deg. displacement and won't take up much more real estate on the chassis. Of course, I'm such a purist I would probably not take my own advice and leave it as is. :D

Scott Todd


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PostPosted: Oct Thu 26, 2006 3:19 am 
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Michael,
So you mean the transmitters I built or tube amps. If tube amps, this is the first one I am building, if transmitters, I built 3, the Lil'7 which works pretty good, I gave that one away, the 3 tube one which used to work real nice but I tried it 2 days ago and it sounds very tinny so its time to open it to see what went wrong with it and the Vellerman ($30 kit, not the better one) tried it but never put it to use.

Alan,
What type of tube amp did you build? Which tubes?

Scott,
As Alan said, when I breadboard it I will try different placement of the transformers, I was thinking to order a new black Hammond chassis so I can buy a wider one and mount the transformers 90 degrees from each other.

Regards,
Sal Brisindi

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PostPosted: Oct Thu 26, 2006 1:29 pm 
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I was thinking, I could turn the 2 audio transformers 90 degrees instead of the power transformer. Here is a photo, what do you think? Does it look ok?

Regards,
Sal Brisindi

Image

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PostPosted: Oct Thu 26, 2006 5:20 pm 
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I used 6BX7s, 3 watts per channel, but the output trannies are 20W rated.


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PostPosted: Nov Wed 01, 2006 6:33 pm 
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Alan Douglas wrote:
I used 6BX7s, 3 watts per channel, but the output trannies are 20W rated.


Alan,
Thats the key, use larger output transformers than the tube can handle, I may be on the fringe with my tube amp..


Thanks,
Sal Brisindi

PS: I just ordered a Hammond 12"x10"x2" black steel chassis for this amp from AES.

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PostPosted: Nov Fri 03, 2006 12:36 am 
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So, I guess this is kinda what you are talking about with using the largest transformers you can? Note, output tubes are 6BQ5!!!

(HH Scott 222C Amp)

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PostPosted: Nov Fri 03, 2006 6:03 am 
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Please, guys....keep the electrolytic can as far away from those hot tubes as possible. And space the tubes away from the transformers as well, to allow free flow of cooling air.

A cool amp is a long-lived amp!

--Chuck


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PostPosted: Nov Fri 03, 2006 3:57 pm 
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Chuck is right. Those Scott amps always need the electrolytics replaced (except the bias caps that have low volts on them). Heat is the enemy. I was looking at some Muffin Fans recently at the local (make that only!) electronics store near me. They are rather expensive and you can't tell how loud they will be so I didn't get one yet. Lots of 5-Volt ones there cheap. I suspect they are replacements for computer power supplies....

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PostPosted: Nov Fri 03, 2006 4:00 pm 
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Alan Douglas wrote:
I used 6BX7s, 3 watts per channel, but the output trannies are 20W rated.


Alan,

I tried to lookup a 6BX7 and could not find it. What is it please?

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PostPosted: Nov Fri 03, 2006 4:13 pm 
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Don Cavey wrote:
So, I guess this is kinda what you are talking about with using the largest transformers you can?


No, more like this Leak Stereo 20:
Image
Oops, the transformers covered up the tubes. :wink: Here's a better view:
Image
Tubes in the front row from left to right are 12AX7, 12AX7, 6BQ5, 6BQ5, 5AR4.

-Steve W.


Last edited by BPlus on Nov Fri 03, 2006 4:16 pm, edited 1 time in total.

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PostPosted: Nov Fri 03, 2006 4:14 pm 
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6BX7 is a dual power triode - 6BL7 is similar.

http://www.nj7p.org/Tube4.php?tube=6BX7GT


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PostPosted: Nov Fri 03, 2006 5:35 pm 
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BPlus wrote:
Don Cavey wrote:
So, I guess this is kinda what you are talking about with using the largest transformers you can?


No, more like this Leak Stereo 20:
Tubes in the front row from left to right are 12AX7, 12AX7, 6BQ5, 6BQ5, 5AR4.

-Steve W.


Steve,

Looks more and more like "The War of the Transformers!" Thanks for the pictures

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PostPosted: Nov Fri 03, 2006 5:41 pm 
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Tom Bavis wrote:
6BX7 is a dual power triode - 6BL7 is similar.

http://www.nj7p.org/Tube4.php?tube=6BX7GT


Thanks Tom. I did a search but didn't think to put the "GT" behind the tube number. So if I get this correct, you use the two sections in the tube as push-pull? Sounds like a neat thing to do. I like things that are different. And, I always did like the 6BL7. The only thing that I have on in is the Sprague T0-6.

Who has plans for an amplifier using this tube as a PP output? Better question, where would you get that output transformer?

Thanks guys,

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PostPosted: Nov Fri 03, 2006 6:44 pm 
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6BX7 Amp

and lots more results from Google.....

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Last edited by Terry Judkins on Nov Tue 07, 2006 7:38 pm, edited 1 time in total.

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PostPosted: Nov Fri 03, 2006 7:38 pm 
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Wow,
Nice transformers! If I bought transformers that large, that would have added $200 to this amp I am building, besides, size doesn't matter, right? Thats what my wife always says... :oops:

Regards,
Sal Brisindi

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PostPosted: Nov Sat 04, 2006 2:47 pm 
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Hey, Sal, something you might want to consider...

I once modded a Dynaco Stereo 70, and was never satisfied with how noisy it was. I converted it to DC on the filaments and the only way you could tell it was on was to look for the glowing filaments. Made a significant (albeit small) difference. You might want to consider that for your amp.

Tom


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PostPosted: Nov Sat 04, 2006 4:36 pm 
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Location: Austin Texas USA
Sal...

Nice project (!) and interesting discussion so far...I must say the attention to the appearance of modern tube amps built by commercial builders today is quite impressive...A page as it were, from the philosophy that apparently existed long ago at E. H. Scott.

Maybe you should get a steel chassis and then get it and all of the topside components plated in dazzling chrome...Just thinking of how to spend more of your hard earned cash. <grin>

Bruce
WC5CW


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PostPosted: Nov Sun 05, 2006 4:27 am 
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VetPsychWars wrote:
Hey, Sal, something you might want to consider...

I once modded a Dynaco Stereo 70, and was never satisfied with how noisy it was. I converted it to DC on the filaments and the only way you could tell it was on was to look for the glowing filaments. Made a significant (albeit small) difference. You might want to consider that for your amp.

Tom


I know you guys get tired of me talking about Scott amplifiers, but... they use DC on the pre-amp tubes and like Tom says, you have to feel the top of the unit if you can't see the tubes because it makes it dead quiet. Might be a good thing to consider. However, they used the 40 or so volt tap on the power transformer to create the bias for the output tubes as well as the filament voltage for the pre-amps. 12AX7s were wired in series....

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