SET recommendations

[ALF in AUS]

I'm on the horns of a dilemma, as they say ... (I've never known what that really means, but that's where I am).
I have been solid state for decades.
I am moving over to the glass side.
I am in decision making mode.... still thinking, still auditioning.
At present I am wavering between a KT88 based SET and a B300 based SET ...
Now, I'm hoping that you guys who have had experience with / lived with one or the other (or both?) would like to chuck in a few observations ... bits of advice ... caveats ... etc ...
I'd really appreciate it.
My amp maker is poised with his tranny winder in hand, and my wallet is warming.

ALF

 

[Bas Horneman]

What speakers do you have?
What is your budget?
What kind of music do you listen to?
What kind of sound do you like?
How big is your room?
At what levels do you like listening to your music?
Why do you want to cross over to SET?

 

[ALF in AUS]

Hello Bas


What speakers do you have?
I'm running Visaton B200s in open baffle ...

What is your budget?
Well, I have enough - I have decided on the builder, I'm not shopping around.

What kind of music do you listen to?
I am eclectic ... Jazz, folk, classical, rock ... no rap or bluegrass!

What kind of sound do you like?
I like detail, but at the same time I like it to be musical - warmish, but not too laid back.

How big is your room?
Ah, well ... this is a bit of a movable feast ... at present I have a 4.5 mt wide ... open at the back so it's irregular - minimum 7 mt long ... under 3 mt high...
But - I will probably be relocating next year and I don't know what I will have until I have it ...
The room in my real home, to which I'll retire in 10 years time, is 7 X 15 X 3.75 mt.

At what levels do you like listening to your music?
Fairly loud, but not deafeningly loud...

Why do you want to cross over to SET?
After decades in denial, I have decided that I like the SET sound ... it has a presence and naturalness I like...
and I'm getting old - time for a mid-life crisis, and buying SETs is one of those things we middle agers do I guess

I really just want a few very subjective opinions from anyone who may have a single ender with these particular valves ... and I guess EL34s, because I can roll them into the KT88s without too much angst (I think)

ALF

 

[Bas Horneman]

Since you have listened to SET amps. I have to give a boring answer and that is you choose on the basis of your preferences. The KT88 has a slightly fatter sound...the EL34 more neutral..and the 300B even more neutral. (I've never heard a 300B that sounded overly warm and bloated as many say.)

Since the amp is going to be custom. You might even get an amp that uses a switch or two to switch between 300B and KT88/KT77/KT66/EL34. (an output transformer for a 300B and KT88 have virtually the same requirements)

 

[Sherman]

I built Mikael Abdellah's KT88 SE (it is in UL mode not triode, so it isn't SET). I have been listening to it for about a year and a half and still love the sound. Search here for Mikael's KT88 and you'll find several threads.

 

[Bas Horneman]

I built Mikael Abdellah's KT88 SE

A yes. I helped Mikael with that project. It is quite amazing how popular that project has become. Built by a newby who was guided by a newby. Just goes to show how easy building great sounding SET amp can be.

 

[ALF in AUS]

Thanks Bas and Sherman ... that has been helpful.
Bas, please don't think your reply was boring - because it wasn't ... if you want to wax lyrical on SET sound, please do ... I'm sure we'd all love to read it.
Cheers
ALF

 

[ALF in AUS]

Well, a wee change in thinking ...
On the weekend I am going to audition a 300B SET...
I'm told this will change my life!
I'll post my impressions in a few days...
ALF

 

[sgerus]

Alf, Bas, Sherman

I just posted a similar question
(see help with amp#2, 300B or 6550)
but didn't get any replies, so I would be very intersted in learning what you think after listing to the 300B

Since the amp is going to be custom. You might even get an amp that uses a switch or two to switch between 300B and KT88/KT77/KT66/EL34. (an output transformer for a 300B and KT88 have virtually the same requirements)

Good Idea... But here are some of the issues
1. different sockets, 4 pin vrs 8 pin
2. different cathode voltages = different cathode R for the same current
3. different filament voltage

The only thing that I know is that kt88/6550 are about 1/3 the cost of the 300B, and offer the same power with less of an input voltage.... but no idea how the sound compairs!

 

[Bas Horneman]

Yes, 2 sockets per monoblock obviously. And either 2 filament supplies or a filament supply that switches in the right voltage dropping resistor. Then ofcourse a seperate cathode resistor for the 300B and the KT88. The rest stays the same.

The thing is that you can only really optimize it for one tube. The 300B needs more drive than a KT88. So when in 300B mode you won't be able to get the full power...but who cares. One could use that for certain types of music or late night listening. And switch in the KT88 for parties.

 

[gingertube]

ALF,
I see you are in Melbourne. Give Hugh Dean (AKSA) a call. He and a fellow in Mt Gambier have developed a Parafeed KT88 SET Amp. He can probably help with a schematic and local parts sources.
Cheers,
Ian (in South OZ)

Else there is this thread
http://www.diyaudio.com/forums/showthread.php?s=&threadid=41821

 

[Sherman]

... And either 2 filament supplies or a filament supply that switches in the right voltage dropping resistor. Then ofcourse a seperate cathode resistor for the 300B and the KT88. The rest stays the same.

... The 300B needs more drive than a KT88. So when in 300B mode you won't be able to get the full power...but who cares. One could use that for certain types of music or late night listening. And switch in the KT88 for parties.

Maybe use a 12.6V filament trafo and switch between separate voltage regulators to supply either the 5V or 6.3V depending on the tube being used at the moment.

I'm sure that someone could sit down and draw a schematic to allow full output with either tube but without switching things in the driver stage you'll only optimize for one or the other.

A KT88 can be driven with 32-33V swing, more than double (IIRC) that for the 300B. Maybe set up to drive the 300B to full output and use less of the volume control for the KT88? Or as BAS says, you won't get full output from the 300B if the driver is optimized for the KT88.