"Complete" SE KT88

Sherman · 25th February 2005, 04:11 PM

Here are some pics of my newly "complete" single ended KT88 monobloc. (Still have to build the other one.) Please ignore the ugly temporary base. It is something I threw together this morning from some poplar I had laying around.

First here is the amp in front view-

Sherman · 25th February 2005, 04:13 PM

From above, spacing isn't as tight as the front view makes it appear.

Sherman · 25th February 2005, 04:15 PM

And the wiring. I like the quick connects on the caps and to the ground point because I can easily disconnect sections for troubleshooting.

Sherman · 25th February 2005, 04:28 PM

First I want to say thanks to everyone on this forum that helped me out. Particularly Mikael Abdellah whose schematic I used with only a very small modification, Frank, Sch3matic, SY, Dave (Planet10) and lots of others. This wouldn't have been possible without this forum! Thanks everyone.

So far I've only tested it with a cheap speaker. Input is from my preamp connected to a CD player. When the other one is finished and I have some proper bases I'll bring 'em up and test with better equipment.

First of all the amp is absolutely quiet. No hum or buzz whatsoever from the speaker, even with my ear inches away. Second the sound, even with my cheap test speaker is pretty amazing. Bass extension is excellent, highs are crisp and the midrange is very good. Diana Krall, even in mono sounds great.

Nothing exotic in the construction. 1/8" aluminum top plate sanded with 320 grit wet/dry sandpaper and sprayed with a couple coats of clear gloss acrylic. Power iron is a Hammond 273BX and a Hammond choke (8 henry) filtered with ASC oil caps. A .22uF Auricap coupling cap between the Svetlana 6N1P driver and the Valve Art KT88. Rectification courtesy of a 5U4-G (which looks great too).

The best part may well be the James 6123HS output transformer. I had a difficult time deciding between the James and a Hammond 1628SE but I am very happy I went with the James, even though it meant painting the Hammond iron to get some sort of match.

I'm anxious to get started on the twin so I can listen in stereo!

rdf · 25th February 2005, 07:22 PM

Thanks for the auditory report Sherman, looking good! I have a pair of James 6123HS hung up in the dimensional warp known as Canadian Customs right now, slated to replace the 1628se's in my amp. Haven't given up on the latter yet, going to try them Ultralinear SE with some spare 5881's.

rdf · 25th February 2005, 07:58 PM

Now this is ironic. The courier delivered the James 5 minutes ago. Pictures don't do the quality of construction justice, these are very nice looking units! Not sure you want to hear it but James is making them in black now.

Sherman · 25th February 2005, 09:02 PM

Quote:

Originally posted by rdf
...The courier delivered the James 5 minutes ago. Pictures don't do the quality of construction justice... Not sure you want to hear it but James is making them in black now.

Glad to hear you got them! My amp is connected ultralinear also.

The Hammonds I received had a very poor level of finish with some spots and runs. The bolts holding the bells on appeared to have been cut to length with wire cutters. Even if I had gotten black James transformers I probably would have repainted the Hammond iron.

You are right about the James units. The quality of the finish is superb and based on my limited listening so far the guts must be equally well done.

amperex · 26th February 2005, 03:30 AM

Very nice.

resident · 26th February 2005, 06:40 AM

Very very nice.Why you didn't post it to photo gallery?

What kind of wire are you using from the input RCA to first tube?
It's a shielded but brand?

Positron · 26th February 2005, 01:00 PM

Very nice looking Sherman. Congradulations!

25th February 2005, 04:28 PM	#4
Sherman diyAudio Member Join Date: Feb 2004 Location: Chicago area	Sound? First I want to say thanks to everyone on this forum that helped me out. Particularly Mikael Abdellah whose schematic I used with only a very small modification, Frank, Sch3matic, SY, Dave (Planet10) and lots of others. This wouldn't have been possible without this forum! Thanks everyone. So far I've only tested it with a cheap speaker. Input is from my preamp connected to a CD player. When the other one is finished and I have some proper bases I'll bring 'em up and test with better equipment. First of all the amp is absolutely quiet. No hum or buzz whatsoever from the speaker, even with my ear inches away. Second the sound, even with my cheap test speaker is pretty amazing. Bass extension is excellent, highs are crisp and the midrange is very good. Diana Krall, even in mono sounds great. Nothing exotic in the construction. 1/8" aluminum top plate sanded with 320 grit wet/dry sandpaper and sprayed with a couple coats of clear gloss acrylic. Power iron is a Hammond 273BX and a Hammond choke (8 henry) filtered with ASC oil caps. A .22uF Auricap coupling cap between the Svetlana 6N1P driver and the Valve Art KT88. Rectification courtesy of a 5U4-G (which looks great too). The best part may well be the James 6123HS output transformer. I had a difficult time deciding between the James and a Hammond 1628SE but I am very happy I went with the James, even though it meant painting the Hammond iron to get some sort of match. I'm anxious to get started on the twin so I can listen in stereo! __________________ --Sherman

26th February 2005, 01:00 PM	#10
Positron diyAudio Member Join Date: May 2003 Location: Morton, Illinois	Amp Very nice looking Sherman. Congradulations!

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25th February 2005, 07:22 PM	#5
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	Thanks for the auditory report Sherman, looking good! I have a pair of James 6123HS hung up in the dimensional warp known as Canadian Customs right now, slated to replace the 1628se's in my amp. Haven't given up on the latter yet, going to try them Ultralinear SE with some spare 5881's.

25th February 2005, 07:58 PM	#6
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	Now this is ironic. The courier delivered the James 5 minutes ago. Pictures don't do the quality of construction justice, these are very nice looking units! Not sure you want to hear it but James is making them in black now.

26th February 2005, 03:30 AM	#8
amperex diyAudio Member Join Date: Feb 2005 Location: MI	Very nice.

26th February 2005, 06:40 AM	#9
resident Account Disabled Join Date: Sep 2004 Location: Earth	Very very nice.Why you didn't post it to photo gallery? What kind of wire are you using from the input RCA to first tube? It's a shielded but brand?