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Old 26th September 2008, 12:07 PM   #11
JandG is offline JandG  United States
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SE UL is very good indeed. I run a IT coupled 12bh7/6v6 SE UL. This amp is prefered over any of my DHT amps . Run batteries off cathode of 12bh7a & fixed battery bias on the 6v6. Just run the - battery bias supply up the secondaries of IT & all will be good. Also you'll get a dead quiet amp that just might make you chamge your entire thought process of DHT amps.
J & G
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Old 26th September 2008, 12:43 PM   #12
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I'm running a SE UL amp using an EF86 pentode driving a Shuguang EL156. It's pretty 'old school' with loop feedback, tube rectification and 'lytics too. I really like the way it sounds - extremely fast and detailed with good bass control too.
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Old 26th September 2008, 06:18 PM   #13
dtut is offline dtut  United States
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I've been running this one for about a year. Like it. Interesting different qualities from triode.
Doug Tuthill
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Old 26th September 2008, 07:03 PM   #14
dtut is offline dtut  United States
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I apologize for the lack of image. I'm having problems attaching attachments. I'll keep trying.
Doug Tuthill
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Old 27th September 2008, 02:49 AM   #15
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Check out my "Shrine" thread for a SE UL amp using a cascoded JFET input stage and a 1625 UL output stage. It uses a switching power supply for compactness, but there's no reason you couldn't run one with a linear supply. I like the sound, but I don't have nice enough speakers to get the most out of it just yet. Right now I'm using the bitty little Edcor XSE-15-8-5k output transformers. I'll be retrofitting with the corresponding GSXE transformers soon for more bass extension, and taking the little critter with me to Burning Amp, where I hope to introduce it to some efficienct full-range speakers.

This sort of setup would probably sound really peachy using the small size Transcendar output transformers, which are very beefy for their output rating. Gary will add a UL tap to a pair of these for a small fee. I woulld've gone that route except that the Transcendars are just a bit too large to fit in the space available inside my amp. The Edcor GSXE series have the same mounting centers as the XSE series, but with a thicker core stack of the same size lams... They'll fit.
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Old 27th September 2008, 03:08 AM   #16
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Does Tubelab's Simple SE count?
SE UL is a common configuration for Simple SE's and many have been built that way including mine. I have the ability to switch between triode and UL mode, and the ability to turn the NFB on or off.

I find that triode mode without feedback has more detail and accuracy. I use this almost always with my small near field monitor speakers and for some music on my big speakers. SE UL with NFB more than doubles the output power with a slight loss in detail. It is excellent when you want to rock. With the big speakers (Silver Iris OB) you can hear the bass inside the house across the street.
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
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Old 27th September 2008, 04:30 PM   #17
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Originally posted by maynardg
I built one from this schematic and it sounds very good.
Hi Maynardg,

Thanks for sharing... That circuit looks very neat... Do you have any idea if other tubes can be subsituted... I have some spare 8417 and 6L6 tubes laying around and I'm tempted to try them out.

Btw, do you know how much power are you able to get from your amplifer.
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Old 28th September 2008, 02:15 AM   #18
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How many watts does the Simple SE output, with a pair of KT88s a side, in triode and UL modes?
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Old 28th September 2008, 03:33 AM   #19
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Originally posted by otto88
How many watts does the Simple SE output, with a pair of KT88s a side, in triode and UL modes?

The Simple SE will make between 5 and 7 watts per channel using the recommended power tranformer. It depends on whether you have a 3K output transformer (7 watts) or a 5K output (5 watts). I think this is probably for the triode strapped configuration. I'd imagine the UL connection would make about 50% more power.

On my browser, the beginning of the page is blank. Scroll down a bit for the good stuff.
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Old 28th September 2008, 09:17 AM   #20
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Default I don't like it

Yes, I tested the so called UL circuit.
It oscillated and the reason was the bad quality of the output transformer.
To get 'ultra linearity' the phase and the voltage ratio at the UL tapping must be constant with the frequency.
Every little mistake of the output transformer will end in a big mistake in the so called UL circuit.
Don't forget the so called UL increases hum sensitivity from the supply rail and reduces output power.

Kind regards,
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