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Old 24th March 2006, 01:44 AM   #1
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Default Single Ended EL-34?

Hi, Anyone have any experience listening to single ended el-34 amps. Thinking single ended for first project and I have a bunch of EL-34's. I got the idea from a schematic on Angela. I would probably mate it to some 1982 Heresy's I have and use either a stock pas 3 or older H-K preamp until I could buil a phono pre. Oh by the way I listen almost excusively to bluegrass, usually female voice. Thanks in advance for any and all opinions or advice.
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Old 24th March 2006, 02:25 AM   #2
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Before you build any SE amp with EL-34's, read this:

http://www.lundahl.se/pdfs/claus_byr...ifier_8wse.pdf

I have built a similar design on a breadboard. I have been torturing sweep tubes in it and will eventually get to EL-34's. It sounds really good with $3 sweep tubes.
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Old 24th March 2006, 03:33 PM   #3
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I built a bastardization of the Angela El34 and the
http://www.lundahl.se/pdfs/claus_by...lifier_8wse.pdf

Tube recification, CLC filter, I sprung for the Lundahl OT's, used the cathodes tied to the OT scheme, no feedback, and didn't need the Ultralinear connection as the amp is used to power a pair of efficient LaScala's (ALKs Crossovers). I used 440 ohm resistors to set the bias insead of 880 ohms, this sets the bias at 61 ma. The Hammond OT's Angela suggest are kinda crappy. The Lundahl's give really deep bass extention which you will appreciate wth the Heresey's.

BTW if you use the cathode through the OT connection, you MUST ground the negative side of the output trannys.

I would use a stouter PT than the Angela build as it gets very hot at this bias setting.

I gave the amp to my brother as a vacation house warming present and it is very nice, may have to do one for myself.

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Old 24th March 2006, 10:16 PM   #4
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Thanks men, What a great paper! I'm going to have to read it a couple more times to soak more thru the bony part of my head, but I new it was good from the first page where he talks about the advent of stereo and how it affected circuit and build quality. I'm one of those who beleives technology does not always go forward. Can someone point me to a good place to get the Luhndahl? opt,s. I think I have a ipt that may work, I just have to dig for it. A couple more ?s I have are 1) Is there anything wrong with building this on a homebuilt copper chassis? 2) I think I have enough NOS western electric capacitors and 1% resistors for this amp. They are all in sealed military packaging from the late 50's. I acquired a huge box and everything I opened and tested so far is right on the money, but I know caps can degrade. Last thing is the final schematic was kinda washed out looking when I printed the paper off and I can Hardley read it. I wandered if this was done on purpose and maybe it would somehow be wrong to use it. (intellectual property?) This probably sounds like a stupid question but I won't be sure if I don't ask Anyhow thanks for all the help. I may have actually found a mentor, I went to look at a large lot of tube test equip. today and met the owner, a 91 year old gentleman who worked as an electronics tech for armed forces and then had a TV shop after retiring. He suffered a stroke and can,t do much with his hands anymore but is still sharp as a tack. He said he would love to show me how to operate the different equip. (sig gen. , scope, etc etc.). I think it will be great for both of us! Thanks Again, Jay
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Old 25th March 2006, 12:11 AM   #5
arnoldc is offline arnoldc  Philippines
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Lundahl in the USA is KandK Audio.
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Old 25th March 2006, 04:40 PM   #6
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Here's the link to the higher resolution schematic from the Lundahl site: http://www.lundahl.se/pdfs/claus_byrith/cb_seamp.jpg

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Old 25th March 2006, 08:25 PM   #7
kopite is offline kopite  New Zealand
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If you model the power supply for this amp with psu designer II it does not look good. Has anyone built it with a different power supply or have any comments on the power supply?
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Old 26th March 2006, 01:35 PM   #8
arnoldc is offline arnoldc  Philippines
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Default Re: Single Ended EL-34?

Quote:
Originally posted by jaymanaa
Hi, Anyone have any experience listening to single ended el-34 amps. Thinking single ended for first project and I have a bunch of EL-34's.
Yes I did. A unit from TS AUdio in Thailand and being re-sold by NORH - http://www.norh.com/products/se9/index.html

It sounds good enough, but still needs a higher sensitivity speaker.
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Old 27th March 2006, 12:45 AM   #9
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I am sure the Lundahl transformers sound great, but if you are doing this on a budget, consider the Edcor XSE-15-8-5K it only costs $18 and sounds pretty good in UL with cathode feedback.
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Old 27th March 2006, 11:35 PM   #10
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My EL34 amp, power supply is a 5AR4, 20 uF motor run cap,
10 H choke, 400 uF cap, 379 volts B+, right on the money.

Click the image to open in full size.

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