SET for 88 dB 4 ohm loadspeaker

My room is 400 sqf and I listen mainly jazz and rock

Which loudspeaker??
Judging by yr info, go for any 40+W rms /4ohm, spec'd amp fm any reputable manufacturer (Wavac, Nagra, Kr Enterprises, ??). 8 series tubes or 211 tubes or 610 tubes. That's quite a choice... whether they'll play music with yr particular spkr is another matter. They'll drive it though:)

88db's not very efficient. Are you married to the SET topology? Have you considered triode tubes wired in PP configuration or pentode tubes wired triode mode? This might be an acceptable compromise for you if your speakers are a constraint.

I had used Antique Sound Labs Explorer monoblocks (about 45 watts SET based on the 805 triode) to good effect with Spendor SP 1/2E's in a small room (156 sq ft). The Spendor's are 88 dB sensitivity. I never ran out of volume with that combo. I play mostly classical including large orchestras at realistic volumes. This amp was given a very positive review by Art Dudley some time ago in Stereophile. A good and relatively inexpensive way to try out SET. Good luck.
Mark

I doubt this is a good idea.

Won't work. You need push/pull tube. Either KT90 or 6550. Just curious, the speakers are they Theils, Vandersteens, Von Schwikert or Tyler?

speakers dali helicon 400

i can not understand the Nagra VPA model's specifications "Pure Class A Push-Pull Triode Monoblocks" how can a pure class A be PP at the same time? Is this ultra liner?

"03-15-07: Monomithos
i can not understand the Nagra VPA model's specifications "Pure Class A Push-Pull Triode Monoblocks" how can a pure class A be PP at the same time? Is this ultra liner?

Class 'A' refers to the bias condition.

I use a 12 wpc SE tube amp to drive 88db/mtr efficiency speakers and can achieve quite high volume levels.

Regards
Paul

Pauly; it may not be very apparent in your system due to room size, music type, etc. but, the issue is usually frequency response and bass control. You may hear some frequencies really loud but, low power doesn't really control a 10in woofer well enough to move a room full of air appropriately.

Monomithos,

Power requirements are so dependent on one's listening level and size of room, it is hard to say whether any SET amp will be sufficient for your needs. I would say don't overlook pushpull amps; many sound fantastic and some don't even give away any of the "magic" of SET (just ask those who listen to ruinously expensive, but incredible sounding Western Electric amps).

Personally, I don't like most higher power pushpull amps based on pentodes, like the 6550, KT-88, etc. Some pentode amps based on EL-84s actually sound good to me, though they don't have that little something extra of low-powered SET amps.

My absolute favorite is low-powered SET amps (based on 45 or 2a3). But, my speakers are reasonably efficient (99 db/w, have a high impedance, and I don't play them very loud). I do think you give up something with higher powered SETs, but some are very nice sounding. A friend had a Wyetech that used 211 tubes that sounded very good.

Now, for something completely different. While I really do like the way SETs reveal fine textures and detail in an unforced manner, there is a quite different magic that is available from OTL amps. OTLs are incredibly dynamic and lively sounding. The compatibility issue there is that they work best with higher impedance speakers. Still, I've heard them on a wide range of speakers and really liked the sound too.

Hi Pawlowski

My speakers respond well down to the 30’s (I believe the specs are –3db at 34Hz ) and the amp does provide a very deep and controlled bass. I have measured response down to the low 20’s, although that must be down 10-20db at those low frequencies.

The most critical thing for a tube amp is a speaker with benign impedance curve. Given that, you’ll be surprised how little in power is needed to provide high(ish?) volume levels.

I think 88db is a bit low for a 300B based set, but I am sure an 6C33, 805 or 845 based set will do well. I have a 22wpc 6C33 SET and it will blast my walls down if I turn it too high.

Regards
Paul

Thanx Paul. I stand corrected.

Another consideration is a set of SET amps based on a 13E1 tube. I think it's a tetrode running in triode and still produces 30+ watts

>Won't work. You need push/pull tube. Either KT90 or 6550<

No, that is bad information. An SET amp such as the NAT Se2Se will drive that load without breaking a sweat. These amps are push pull SET, Class A, and output 70WPC into a 4 or 8 ohm load.

I have no affiliation with NAT.

Audiofeil, I don't think you can have a push-pull SET. Do you mean push pull with a triode tube (e.g. 300b)?

Pawlowski,
I meant SE push pull.

My typing got in front of my brain.

My bad.

Sorry.

Audiofeil,

One of us is confused here. What do you mean by SE push pull? Aren't the two designs, single-ended and pushpull inherently different? Single-ended means that one tube (or set of tubes in parallel) reproduces both halves of the wave form (by modulating DC current flowing in the primary). Pushpull means that tubes reproducing the opposite halves of the wave are connected to the opposite ends of the primary, with the DC voltage at the center tap.

I don't know anything about the amp you mentioned, but it could be a triode, class A, pushpull amp. But I don't see how it could also be single-ended.

KR Audio produces a number of higher power SETs, that output 20-100 Watts SET depending on model. I have their SXI integrated on order with 50W output from the Kronzilla tube. I currently have a Ming Da with an 805/300b combo that puts out about 45 Watts and still has a lot of nice attributes of the SET sound -- not the last word, but not bad for the money. Other amps I was considering were the New Audio Frontiers with about 25W and the Mastertone 845 Ref with about 40W/channel.

oops, I meant Mastersound 845 Ref. As a banjo player, I think about the Gibson Mastertone whenever I write mastersound.

100Watt SET???? Something doesn't smell right here...

Tvad,

Thanks for the link. The amp shown is a parallel SET. It has two output tubes per channel, but it is NOT pushpull. Rather, the two tubes are hooked up in parallel. Not only does this increase output, it lowers the output impedance of the amp.

I know there are a lot of SET purist who say that configuration does not work well. I have no idea if the drawback of this configuration outweighs the advantages. What I can say is that my amp (Audionote Kageki) is a parallel SET (2a3 tubes) and it sounds great to me.

The KR Kronzilla DX monoblock has 2 T-1610 Kronzilla tubes in parallel for a total output of 100Watt SET. Here is a review: http://www.enjoythemusic.com/superioraudio/equipment/0506/kr_audio_dx_monoblock.htm
The Kronzilla SX and SXI stereo versions output 50W each.

I own the NAT Audio Symmetrical preamp and the SE2se power amps. These are one of the most incredible sounding products I have heard in my life. Well worth the money.

Any amp that is designed to deliver the current neccesary for your personal level of musical enjoyment...ie Manley Neo 250 (EL34) or 500 (KT88) in ultralinear (SET) mode and others come to mind ...

Usa:

I have the NAT Symmetrical preamp as well. It has unbelievable transparency and very musical.

What cables are you using with it?

I think Audiofeil meant parallel single ended for the NAT amp; it uses 2 211 tubes in parallel but it is not push pull, else it could not be a SET.