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Single End Parallel Class A amps.

72.197.33.49
Posted on February 12, 2014 at 16:18:31
Cougar
Audiophile

Posts: 4574
Location: SoCal
Joined: June 25, 2001
 Hello,
I came across an amp that has KT-120s. It's a Single End Parallel Mode Class A amp.

How does this configuration compare to a SET amp?

Will the sound be like a tradition SET amp?

Thanks

 

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Warning, rant ahead., posted on February 12, 2014 at 17:05:25
Tre'
Industry Professional

Posts: 17296
Location: So. Cal.
Joined: February 9, 2002
 A KT-120 is not a triode, even when wired as a triode.

Parallel tubes should give more power but IMO the whole point of SET has been thrown out with the bath water when you use triode wired beam power tubes (paralleled or not).

Direct Heated Triodes are very linear compared to triode wired beam power tubes.

IMO the term "SET" means only one thing, Single Ended Direct Heated Triode.

Here's what's wrong with push pull IMO.

You're counting on the two tubes being perfectly matched.

You're counting on the drive signal to be perfectly out of phase at all frequencies and having the exact same amplitude.

You're counting on the two halves of the primary winding of the output transformer to be perfectly matched at all frequencies.

When any of the above are not matched the signal gets degraded to some degree or another.

I know you're not talking about push pull but unless the two tubes in a single ended parallel amplifier are perfectly matched some of that same type of degradation will occur.

You won't have the purity of a true SET amplifier. (not to mention the lack of purity of a triode wired beam power tube to begin with)

If you want a SET amplifier, build or buy a true Single Ended Direct Heated Triode amplifier. That's the only way you'll know what all the fuss is about.

End of rant.

Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"

 

Perhaps am off track here but when I see 'SEP'; I 'think' single-ended pentode.~nT, posted on February 12, 2014 at 19:37:18
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 ~!
The Mind has No Firewall~ U.S. Army War College.

 

I believe what he's proposing would be SEPP, single ended parallel pentode, posted on February 12, 2014 at 20:08:07
Tre'
Industry Professional

Posts: 17296
Location: So. Cal.
Joined: February 9, 2002
 Or, if wired in triode, SEPPT, single ended parallel pseudo triode.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: 'Scuse me, while I shoot myself ;-}, posted on February 13, 2014 at 05:09:19
amioutaline?
 About a biscuit away from being done with these "Soloist 88s", Push-Pull KT-88 mono blocks from Diyaudio.com. Mullard 5-20 designed by Tubemack, breathed on by Johan Potgeieter, Eli Duttman, Steve Brown, et. al. Professor Brown is showing me, by e-mail, how to build the schematic.








I currently alternate between a direct-coupled 45 SE (Schmalle/Tucker) and a triode wired, KT-88 SE (George Anderson). The purity of tone of the 45 is undeniable but the larger muscles of the KT-88 are seductive too. Listening to Steve Brown's Allen Wright inspired Push-pull a few years ago convinced me that a push-pull belongs on my shelf.

Going from 1.8 to 6 to 50 Watts is an eye-opener!

 

RE: 'Scuse me, while I shoot myself ;-}, posted on February 13, 2014 at 12:31:34
Tre'
Industry Professional

Posts: 17296
Location: So. Cal.
Joined: February 9, 2002
 Nice looking amps there!

With two 97db speakers and 1 watt going into each you have 100db in the room. I doubt you are using any more than that.

Any differences you hear between the 1.8, 6, or 60 watt amps is the difference between those amps in the first watt or damping, etc.

Did I mention my first post was a rant? :-)

Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: 'Scuse me, while I shoot myself ;-}, posted on February 13, 2014 at 15:38:41
Stuben
Audiophile

Posts: 669
Location: Guber Ohio
Joined: December 30, 2005
 I understand the rant but....everyone who really loves the sound of reproduced music has their own idea and taste of what sounds good to them.

Not everyone can afford an SET that can drive the average speaker...or can they always afford a speaker that works well with SET amps that might have a more palatable price....with that said, there is definitely a range where we would all agree...maybe this discussion should happen on the DIY venue.

At this very moment, I'm listening to an EL84 triode strapped RC coupled power amp driven by a 5687 parafeed preamp with LL1674 opt all DIY driving DIY back loaded horns using Tangband drivers that cost 30 bucks apiece.

My IT coupled 50 mono blocks are down stairs and I'm happy to sit a listen to the EL84 rig..upstairs...

Hat's off to anyone willing to put the time into a design and build what makes them happy...

amioutaline? put your stuff on the DIY forum...

Stuben

 

What you need is a Bigger SET...., posted on February 13, 2014 at 17:18:07
drummerwill
Audiophile

Posts: 965
Location: St Louis Mo.
Joined: January 7, 2003

...I love the sound of a 45 ,,,, but I'm seduced by the sound of an 845..

JMHO..


Have fun
Willie

 

RE: OK, 845 next, but...., posted on February 13, 2014 at 18:24:23
amioutaline?
 ....you hold the test leads to check the 1200 Volt B+

 

RE: 'What DIY Forum?, posted on February 13, 2014 at 18:27:40
amioutaline?
 You mean the one with Clocks, Crystas and Telephone Calls? That one?

 

RE: What you need is a Bigger SET...., posted on February 13, 2014 at 19:00:49
RC Daniel
Audiophile

Posts: 1922
Location: Brisbane
Joined: November 3, 2002
 I'm with Willie and Tre in principle. Unless speakers demand high damping factors or simply need to be played at a SET-precluding volume. I'd opt for a higher power SET amp in preference to PP.

Interestingly, over the years I have read comments suggesting that despite their high-ish efficiency and over-damped bass response, the 4Pi speakers used by Bill seem to benefit from more oomph than one would usually expect.

Cheers.

"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

How about an EML 1605? nt., posted on February 13, 2014 at 19:04:08
RC Daniel
Audiophile

Posts: 1922
Location: Brisbane
Joined: November 3, 2002
 .
"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

It looks like this topic went in a different direction., posted on February 14, 2014 at 08:29:10
Cougar
Audiophile

Posts: 4574
Location: SoCal
Joined: June 25, 2001
 All I was asking was how would that type of single ended amp with the KT120 as the output tube would sound compared to a True SET from those here that may have had the opportunity to either hear or build. I haven't been into (True) tubes amps ( hybrid was the farthest) and haven't had the opportunity to listen to all these different types of SET amps (300b, 211, 845, GM70) to know which will fit MY listening need/s. The only Tube amp I have had an opportunity to hear but it was in a Push Pull configuration was Dynaco ST-70 and maybe a BAT.

So this is the amp I was talking about in the OP. It's a Musical Paradise MP-501 V2 KT120 Single End Parallel Class A tube amp. from what the info on the site says it's not a Push Pull configuration. So that's why I was asking how would the KT-120 in this type of configuration sound compared to a TRUE SET amp from those who had heard it in a SET config.

Btw, I'm currently ordering my parts for a 2 stage with 845 output tube/s in monoblocs. I have about half the parts and will be ordering some MageQuest output transformers. I wanted to use Edcor but their top limit is 1000Vdc and that's right at the point where I'm going run the 845's.

The Musical Paradise MP-501 V2 KT120 amp sounds like a great bargain for a Single End amp and even tho I wanted to build my 845 based amp from scratch I just didn't want to pass up what may be a great deal for a Single End amp without the normal Single End cost that a great SET would cost me if the amp above was right there in sound with a SET. Also if I could get that output power in a Single End amp that would be awesome!

Thank You Tre and everyone else for your info and Opinions.



 

RE: 'What DIY Forum? (vs SET forum), posted on February 14, 2014 at 13:04:49
zarniwoop
Audiophile

Posts: 590
Location: NY
Joined: November 28, 2002
 maybe i'm missing the humor, or I just don't get the reference.

It is my understanding that the SET forum is for commercial SET amps, not diy discussion primarily. There is a TubeDIY forum for diy amp builders. Yes, it has been polluted by capacitor and low-DCR power supply babbling but I think most people can sort thru that stuff. I'd rather just browse thru one diy forum on AA then have to sort thru the SET and DIY areas, personally.

 

.. I like the sound of an 845....., posted on February 14, 2014 at 21:34:08
drummerwill
Audiophile

Posts: 965
Location: St Louis Mo.
Joined: January 7, 2003

running about 700v plates and pulling 80ma..

Like a 45 on steroids..!


Have fun !
Willie

 

RE: Warning, rant ahead., posted on February 15, 2014 at 13:59:57
ElWoodrow
 Truer words may never have been spoken.

 

RE: It looks like this topic went in a different direction., posted on February 16, 2014 at 18:17:47
RC Daniel
Audiophile

Posts: 1922
Location: Brisbane
Joined: November 3, 2002
 I think Tre covered it below. The SEPP will not sound like a true SE(DH)T amplifier, though it might sound single-ended-ish at a gross level. That said, some SET amps DON'T sound like what people think SET amps should sound like, so go figure.

Cheers.

"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

RE: It looks like this topic went in a different direction., posted on February 17, 2014 at 19:25:25
Paul Joppa
Industry Professional

Posts: 7295
Location: Seattle, WA
Joined: April 23, 2001
 There is not enough information available to make a good educated guess. If it meets the 55watt per channel specification, then it is not being run in triode mode, and since is says there is no global negative feedback one must assume there is local feedback around the pentode-mode output stage. There are very very few examples of such an approach, so you won't see many reports of direct experience with it. I personally think it has some real promise - but that's just speculation. For what it is, the cost is peanuts at around $20 per pound - if you get it, please post impressions!

 

RE: It looks like this topic went in a different direction., posted on February 19, 2014 at 19:57:01
Cougar
Audiophile

Posts: 4574
Location: SoCal
Joined: June 25, 2001
 Hi Paul,
I will post back if I do get this amp. Seems too good of a deal to past up. :)

 

RE: Single End Parallel Class A amps., posted on December 17, 2014 at 07:47:13
TAdams
Audiophile

Posts: 11
Location: Vancouver Island
Joined: January 4, 2014
 I heard the MP 501 about a month ago on my single driver speakers. The gent brought it over to my place so I could here it in my room on my system. It's a monster amp and super heavy, well built. Seems to be a good bet if you need the power but I couldn't put the volume past 8:30 on my speakers. It sounded good but not really much better than my $200 PP EL84 if any. There was nothing really SETish about it to me as far as the sound went.

 

RE: Single End Parallel Class A amps., posted on January 9, 2015 at 16:22:20
PaulF70
Audiophile

Posts: 1403
Location: Midwest
Joined: June 30, 2006
 I don't know this amp but I have owned a couple SE amps running KT88s, either one or two. The latter were Audiopax Model 88s, and the former a custom amp from a builder I cannot recall. Both sounded very good. The Audiopax, in particular, are among the most natural-sounding amps I've heard, seemingly completely free of electronic artifacts. However, they don't have that "DHT-glow" thing, and if one is looking for that, they likely won't satisfy.

(FYI, in this forum, you'll pretty much find anything but a DHSET frowned upon.)

(IMO, if one is to go PP, one out to go OTL as well, to avoid hysteresis loss of detail which is inevitable with any TX-coupled PP output stage.)

 

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