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Old 21st January 2010, 03:46 AM   #1
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Default Help finding parallel 45 SE schematic

I was once referred to a SE amp using 45 tubes in parallel here on the forums but for the life of me I cannot find it again. Anybody have an idea of the schematic I might be referring to?

Thanks,
Jeff
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Old 21st January 2010, 12:41 PM   #2
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Hello Jmillerdoc,

on Audiodesignguide site (complete description) :

New 2A3

perfect for D3a use.

Philippe
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Old 21st January 2010, 12:54 PM   #3
kmtang is offline kmtang  Canada
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Hello Jmillerdoc,

What is the point building a parallel? Why not just a simple 2A3? May be you have some 45 tubes in hand.

Johnny
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Old 21st January 2010, 03:31 PM   #4
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Default In the process of building 2A3, have many 45 in hand

Quote:
Originally Posted by kmtang View Post
Hello Jmillerdoc,

What is the point building a parallel? Why not just a simple 2A3? May be you have some 45 tubes in hand.

Johnny
I am in the process of completing a 2A3, Hagtech Clarion, and the JEL 300B dx too.

I happen to have many 45 tubes on hand, about 8 good ones. I am also in the process of building some Sachiko horns but I still would like to get a little more power than 1.5wpc. I guess I could (and likely will) settle for the lower power JEL simple 45 but still would like to see what is available in a parallel 45 SET. I have read some threads at Bottle Head about a parallel 45, at least the idea of one. Still can't find a schematic. Might just have to build and design from scratch.

Here is the 2A3 under construction:
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Old 21st January 2010, 05:50 PM   #5
kmtang is offline kmtang  Canada
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Hi Jeff,

Nice works of the chassis. I am now using the same amplifier for both 45 and 2A3. All I need to do is switching the cathode resistor between 750 and 1.5K. Also, the secondary tapping of the output transformer wired for 4 or 8 ohm with 8 ohm speaker. Then, the primary impedance would match 45 or 2A3 with 3.0K and 6.0K.

Even though the 45 has lower output power, it has very natural and warm sound from it. I just felt in love with it.

Johnny
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Old 21st January 2010, 06:25 PM   #6
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Default Chassis

Quote:
Originally Posted by kmtang View Post
Hi Jeff,

Nice works of the chassis. I am now using the same amplifier for both 45 and 2A3. All I need to do is switching the cathode resistor between 750 and 1.5K. Also, the secondary tapping of the output transformer wired for 4 or 8 ohm with 8 ohm speaker. Then, the primary impedance would match 45 or 2A3 with 3.0K and 6.0K.

Even though the 45 has lower output power, it has very natural and warm sound from it. I just felt in love with it.

Johnny
Thanks,
The top is actually 1/2" thick and made from laminating strips 1" wide of white Tiger Maple. I did it this way b/c the cut edge of the Tiger Maple has the best "tiger stripe" pattern. The base is Spanish Modena I planed down to 1/2" thick. I will try to take a few better pics, these were done with my web cam and do not show the grain of the wood at all.

I am wondering if I could do something similar with the Hagtech Clarion. It uses a 680R cathode resistor, maybe I could switch another in series somehow, or just switch to a 1300R cathode resistor and do the same with the taps on my James transformers. Would you then use the 4ohm tap with a 8ohm speaker to get a primary impedence doubling (5k)?

I was jst thinking of building the 45 Bugle: http://www.wavelengthaudio.com/bugle.pdf

Or, again, the JE Labs simple 45. The Bugle claims an output of 2.5 watts which I find a bit difficult to swallow. I believe the JEL version claims a 1.5 watt output which is more in line with what I understand about this tube.

I am also having my friend Bruce Heran who created the Oddwatt SIPP (Self Inverting Push Pull) design look into possibly making a PP amp design.

Still hoping somebody will come up with a parallel 45 though.
Jeff
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Old 21st January 2010, 06:57 PM   #7
DougL is offline DougL  United States
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Since a 2A3 is 2 by 45 in the same glass, you could use any SE 2A3 design.
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Old 22nd January 2010, 01:27 AM   #8
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Default For real???

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Originally Posted by DougL View Post
Since a 2A3 is 2 by 45 in the same glass, you could use any SE 2A3 design.
Is this for real? Is it exactly the same? Wow, that makes things very easy. So could you connect the cathodes together and run them into a single cathode resistor, maybe with each cathode connected to a leg of a 50R pot and the CT of the pot (wiper) connected to the cathode resistor...this would allow for some balance of current. Place another 1R under each cathode before the pot to check mV (mA) across each resistor and set the current via the pot using the resistor as a check point.

So, I could basically use the Hagtech Clarion and add this set up to it....hhhmmmmmm, interesting. I might just have to try this. Thanks alot, this is very cool.
Jeff
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