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Old 5th June 2005, 10:52 AM   #31
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Hi Stalker,

Did you finally found good speakers in Madrid? I am also looking for high sensitivity speakers.

Now I am using the KT88-SE design from Jean Hiraga: http://www.bonavolta.ch/hobby/en/audio/kt88_1.htm with Hammond 1627SE, but I'm not totally satisfied, so I am also going to try Mr. Abdellah's schematic. I suppose the 1627SE will also work for it.

Thanks,

Manuel
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Old 5th June 2005, 12:19 PM   #32
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Question What about a 6Sn7 driving a KT88?

What is your opinion about this idea?

It based on the "JE-Labs 300B" with the 6SN7 driving a KT88.

Cheers,

Manuel
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Old 8th June 2005, 09:54 AM   #33
Cassiel is offline Cassiel  Libya
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Hi, ping floid, no i didn't find a suitable speaker in Madrid. Fostex drivers seems to be only available from Germany. I'm searching for some in Ebay.


I like the schematic you post it...try it.

Cheers,


ÁLVARO.
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Old 8th June 2005, 12:18 PM   #34
Sherman is offline Sherman  United States
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Quote:
Originally posted by pingfloid
...so I am also going to try Mr. Abdellah's schematic. I suppose the 1627SE will also work for it.

Thanks,

Manuel

Manuel,

I have built a pair of monoblocks using Mikael's schematic. They sound great! I was struck by the simplicity of the design and felt it would be a good amp to experiment with. Changes if necessary would be very easy.

I used tube rectification with 5U4-G rectifiers. They feed into a 40uF ASC cap, an 8 Henry choke and then a 100uF ASC cap. The result is a very clean power supply. SS rectification would be smaller and less expensive but for this project I wanted to keep things "all tube".

Mikael's schematic calls for an OPT with a 5K primary. I believe the 1627SE is 2.5K. I think it would work and you would have somewhat more power and also higher distortion.

The Hammond 1628SE has a 5K primary but it reportedly has linearity issues. For my monoblocks I used James transformers (6123HS). Here in the US the price was the same as the Hammond 1628SE and most users reported them to be excellent OPTs. After listening for a few months now I have to agree! A real bargain.

Good luck with your project. I'm sure you will be happy with the result, Mikael did a great job with this schematic.
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Old 9th June 2005, 06:40 PM   #35
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Default KT88 SE PSU

Mikael, Sherman,

Since I got quite curious about the KT88 you designed/built is it possible to share the schematics for the PSU so we can see how you got your amps powered? Furthermore, can you elaborate about the input sensitivity? Thx in advance.
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Old 9th June 2005, 08:51 PM   #36
Sherman is offline Sherman  United States
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Default Re: KT88 SE PSU

Quote:
Originally posted by DocLorren
Mikael, Sherman,

Since I got quite curious about the KT88 you designed/built is it possible to share the schematics for the PSU so we can see how you got your amps powered? Furthermore, can you elaborate about the input sensitivity? Thx in advance.

Here is my PS schematic. Very simple and effective.

As for input sensitivity I haven't measured it but I would guess an input of about a volt would drive it to full power so sources like CD or DVD players or tuners would be fine. For my monoblocks I didn't change anything other than elminating the volume pot and substituting a fixed resistor. So technically they have more sensitivity than a power amp probably should.

A unity gain preamp would be fine as an input. I'm using a preamp with a gain of 5.6 and seldom move the volume control past 9 o'clock but everything works and they sound great.
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Old 24th September 2006, 08:28 PM   #37
JeroenR is offline JeroenR  Netherlands
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Quote:
Originally posted by Mikael Abdellah
I have built a wonderful SE KT88-amp.

http://213.67.45.220/se_kt88.gif

It's REALLY simple to build. I'm unsure how it would work with headphones, but maybe someone else can answer that for you.

I am realy interested in this but the link does not work. Can someone help me get the schematics?

Thanks in advance!!

Jeroen
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Old 25th September 2006, 12:20 PM   #38
JeroenR is offline JeroenR  Netherlands
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Quote:
Originally posted by JeroenR



I am realy interested in this but the link does not work. Can someone help me get the schematics?

Thanks in advance!!

Jeroen
Never mind, I found it. Thanks!!
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Old 25th September 2006, 12:50 PM   #39
Sherman is offline Sherman  United States
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Quote:
Originally posted by JeroenR


Never mind, I found it. Thanks!!

Jeroen,

Also search this forum for Mikael's KT88. There are now a few threads about this amp and it seems at least four people have built it. It really is a simple, great sounding design with good power output.
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Old 15th November 2006, 02:26 AM   #40
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Default Where to buy James transformers now?

It seems that Euphonia is no long selling anything at all as of October 17th. Does anyone have a source in the US? Also what are the voltages of the power transformer for Mikaels' KT88SE amp? Does anyone have a suggestion on what James power transformer would be proper for Mikael's KT88SE amp? I like the look of the potted transformers :-)
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