Aric Audio? First Watt? PrimaLuna?

I run my Unlimited with a First Watt F5. I find the sound completely addictive. I unfortunately have never had the chance to hear Aric's tube amps,however,after living with his pre,I'm sure they're magic as well. 

According to measurements performed by the National Research Council of Canada and published in SoundStage the sensitivity of the speaker is somewhat less than specified, at 85.4 db/2.83 volts/1 meter. Consequently I would be concerned that some of the amps you are considering won’t provide enough power. Possibly including all of the First Watt models, but especially the SIT-3 and the F6, which are unlikely to be able to provide enough power into the speaker’s extremely high impedance peaks in parts of the frequency range. (See the impedance curve near the bottom of that page).

Also, the SIT-3 has extremely low gain for a power amp, which together with the speaker’s low sensitivity might cause you to have to operate the preamp’s volume control at or near the top of its range, especially when using your phono source.

Also, given the wide variations of the speaker’s impedance over the frequency range I suspect that the very high output impedance of the PrimaLuna DiaLogue Premium would not be a good match in terms of tonality. From Stereophile’s review of that amp:

The output impedance varied widely, from an extraordinarily high 15 ohms with EL34s and 14 ohms with KT120s from the 16 ohm tap, both tubes in Ultralinear mode, to 2.4 ohms with EL34s and 2.15 ohms with KT120s, both tubes in Triode mode, from the 4 ohm tap. The output impedance from the 8 ohm tap was lowest with both tubes in Triode mode, at 4.6 ohms (EL34s) and 3.9 ohms (KT120s). Changing to Ultralinear mode raised these impedances to 7.9 and 7.4 ohms, respectively.

With these high output impedances, the DiaLogue Premium’s frequency response will be altered to a significant extent by the Ohm’s law interaction between these impedances and the manner in which the loudspeaker’s impedance changes with frequency.

I have no particular knowledge of the Aric Audio amp, although it appears that it would be sufficiently powerful in its higher powered configurations.

A very well regarded tube amp that I suspect would be a fine match sonically, **if** you feel confident that 35 watts per channel would be sufficient, is the Music Reference RM-10 MkII, purchased used. Its power tubes are not expensive, and according to the description at the website tube life is estimated to be "5,000 to 10,000 hours if the amp is played below clipping at the recommended bias setting." And while I see that you would prefer an amp with non-adjustable bias, in this case the adjustment pots and test points required to bias the amp are easily accessible, right on the top panel. And regarding heat generation, note that it consumes only 70 watts of AC when idling.

http://www.ramlabs-musicreference.com/rm10mk2.html

http://www.ramlabs-musicreference.com/rm10design.html

Good luck. Regards,
-- Al

Thanks rocray.  Can I ask what speakers you are using?

almarg, I was wondering about the power myself.  I rarely go over 12 noon on the volume.  I confess to not understanding this completely.  From what I have read 16w will produce 100db for 88db speakers.  Which is ....ok.  Not rocking out loud, but ok.  I read a review (audiophilliac) on the J2 where he used it  with 805D3's.  Similiar impedance from what i saw on stereophile.  But admittedly, I would HATE to plop down 3-4k and not have enough power.  Which is one reason why I posted.

Thanks to both!

Sorry, it was the F7, not the J2

From what I have read 16w will produce 100db for 88db speakers.

16 watts is 12 db greater than 1 watt, and 88 + 12 equals the 100 db figure you cited. However that is at a distance of 1 meter, and that assumes the 88 db spec is accurate, which as I mentioned it is not.

To get a better handle on that, I suggest using the following calculator, plugging in your listening distance, speaker placement, and using 85.4 db for the speaker’s sensitivity:

https://myhometheater.homestead.com/splcalculator.html

For example, based on 16 watts, 85.4 db, a 10 foot listening distance, two speakers, and speaker placement within 2 to 4 feet of the walls the result is a maximum SPL at the listening position of 93.8 db. And only 90.8 db for speaker placement further away from the walls.

Also, as I indicated the speaker’s impedance rises to very high levels at various frequencies (42 ohms in the vicinity of 2 kHz, more than 20 ohms in much of the upper midrange and lower treble, and 32 ohms at about 85 Hz), and comparing the 8 ohm and 4 ohm power capabilities of the F6 and SIT-3 suggests that they will not be able to supply much power into those high impedances. That will be compensated for to a significant degree by the speaker’s presumably greater efficiency at those frequencies, but still ....

Regards,
-- Al

I have never heard Aric’s preamps but I have the Aric Audio Transcend Push Pull. It sounds wonderful and powers my 85db, 8 ohm TAD ME-1’s with plenty of headroom.

Lance

your speakers look like they demand a high current amp and I'm not sure any of the First Watt products would work....contact Pass direct. I own a Prima Luna integrated and I think, but I'm not certain PL would have enough oomph. I'd contact Upscale Audio and they will be able to advise you without pushing product.  Good luck in your search. IMO the amp-speaker interface is most important after getting the listening room "right"

Hi jgoldrick, I rotate speakers. Nola Boxer 2's, Graham Chartwell LS3/5's, Hornshoppe Great Horned Heils, and occasionally a pair of Caintuck Audio The Betsy.  
     I have a small dedicated listening room,9x13. I also don't listen at ear bleed levels. 

"My "listening room" is my garage, unheated and uncooled..."

Out of curiosity, is this garage dedicated/converted to a listening room, e.g., furniture, room treatment, etc., or is a "multi-purpose" garage with car(s) and also used for music listening? Safely assuming the former, is it a one car or two car garage? I think the size and the nature of the use environment will play into what will work better in your application.
As you know, the Unlimited has a separate (from volume control) gain control that can be adjusted to deliver up to 5 volts of output. That may allow you some flexibility in selecting the amplifier and its associated gain. For comparison, my Unlimited (using 12AX7 tubes) is driving an 18wpc Aric Audio SE KT88 amplifier into 93dB/1w/1m speakers and I have to keep the gain control way low to allow for a reasonable range on the volume control and I still rarely go past 12 o'clock. 

Yep, the former. I park my wife's car in it at night and the other half is my shop/office.  Saws, benches, computer, etc.  Hence the cabinet for protection and my speakers are mounted high about a foot off the ceiling and a foot off the wall, also for protection,   and skewed slightly downward.  The environment is not the best, but it works.

Right now I have RCA 5751's in the Unlimited to keep the gain down.  I have the rear gain turned off the lower limit, but not by much.  I still generally set the volume between 9am - 10am.  If I turn the rear gain all the way down, the sound becomes flat and two dimensional.

I recently did a measurement with REW and a minidsp mike, but I have not taken that any further.  Honestly, I am not sure how to apply it to room treatments, so if there is a link with some noob info that would work, I would appreciate it.  I have thought about trying to setup a DSP (brutefir), but I haven't gotten any further with that either.  it would only affect the digital, as turning analog into digital and then back again somehow doesn't sit right with me.

I will contact Pass and Upscale Audio.  Good suggestion!

Hi lance, do run it in linear or triode mode?

Jgoldrick:   I love garages, saws, cars and music.  There are many amps that will sound great. What you should do is build one. Anyone who has the interest to ask these questions and owns tools can do it. I recommend an Aleph j or an F5 of Nelson Pass’s design. You can build one for around $1000 dressed very well. See diyaudio.com.   Build guides and a lot of help can be found there. Nothing will sound sweeter than an amp you built and biased yourself. 

The Pass XA-25 would be nice. It should have enough oomph!

@jgoldrick, I run mostly in triode mode. I’m using Sophia Electric EL34ST tubes. I have a quad of KT150 but the EL34 sound the best.

Lance

As Al mentioned,  your speakers aren't ideal for tubes. Why don't you change speakers first? You could look for some that are friendlier with tubes and then have a much less restricted assortment to choose from.
FWIW, I have b&w 804s and McIntosh MC275, so also like tubes. 

Also include Linear Tube Audio in your list of amps.

Yes, Sixfellas. D-I-Y !!!  D-I-Y !!!

I have the PL 40w/channel integrated amp auto bias. One thing about them I like is the 80 watt limitation.  I told the Marten Speaker rep that I don't need an  800 hp at the wheels car to drive 45mph to work.  If you listen at normal levels I think that gets lower power amps in the sweet spot where the tubes actually work.  I have not attempted to prove that though. Its driving Vandersteen speakers beautifully.  Not sure how the PL would match up with your speakers.  

Well, the First Watt is definitely out.  I never heard back from pass, but Moon audio and Reno Hi-Fi both said my speakers are not efficient enough.  Glad I asked on here and thanks for your wisdom. You saved me from a possibly expensive mistake.

I am looking at the xa25 Pass, but it's out of my price range. If I can't find it used I'll have to pass on that, pun intended!

Upsacale Audio will absolutely try to push their product...they are as self serving as they come.  I own both Aric Audio gear and Pass gear and will recommend with no hesitation reaching out to Aric at Aric Audio. I have his Motherlode pre, and have heard several of his amps. And when the wife is in a good mood as it relates to my esoteric audio hobby, will have him build some bespoke mono amps for me as well. 

I’ll add to my previous comments that Iike Coachpoconnor I too own and am delighted with an XA25, and although I use it with speakers that are much more sensitive than yours I too believe that it would be a fine match for your speakers. Stereophile measured its maximum power capability as being 80 and 130 watts into 8 and 4 ohms, respectively, much greater than its specified 25 and 50 watt ratings which are apparently based on its capabilities before leaving class A operation as well as on distortion percentages that are much tighter than the reasonable percentages Stereophile uses in its evaluations.

I say all of that as someone who has traditionally used tube amplification over the years.

I hope you can find one used, at a price that fits your budget.

Regards,
-- Al

Thanks, almarg.  I asked Reno HiFi what they thought and if they had one in my price range.  They do, but he says  

"My experience is that your speakers need an amp that is at least 60 WPC, as I mentioned previously. Through my own personal experience as well as the experience with my many clients who use these amps in their own systems, I agree with Nelson Pass’ power rating of the XA-25 amp. And when the amp is pushed beyond it’s official power rating, the amp doesn’t sound it’s best."

Hmmphh.

jgoldrick, I'm not pretending to be an expert within the First Watt and PrimaLuna arena that you are working within, except to say that they are among the top flight choices. I can however address some of your concerns about going with a tube driven amp -- especially one that comes off Aric Kimball's bench at Aric Audio. I have two of his systems. First the heat issue: it's not an issue. Tubes get hot and the amps get warm, but they are designed to do so and with your cooling fans running and the cabinet doors opened, there is going to be no net effect. He builds his amps auto-bias so there is no longer the need for a tiny screwdriver and a multimeter. Believe me when I say that if I were replacing power tubes every two years at $600/per, I would be in search of another passion. Tubes last a long, long time; some of the best are Vintage or NOS from the 40s through the 60s and while I know it's possible to spend any amount you set out to spend on any thing, I have never approached those numbers, and won't.

But above all else is how they sound. It's why we do this. After looking over your system specifics, I would encourage two courses of action. One, talk to some folks with tube gear who will doubtlessly validate what I'm claiming here, and then secondly but most importantly, get next to one that you can listen to -- with ample time, with your music, in your comfort zone. The sonic difference is staggering. You're in this deep, I believe you owe it to yourself to not leave this decision to the guesswork and opinions of others.  Godspeed.

Why not have Klaus upgrade the Khartago? Depending on budget you could go full Kismet as monoblocks.

Getting in on this rather late... I’d have to agree with Almarg... The Pass XA25 is a terrific amp and well designed/implemented. I have the Pass XA30.8, a little bigger than the XA25 but very similar implementation. I also have a First-Watt SIT-2 and a nice 18-watt 300B SET amp. My speakers are Living-Voice OBXRW’s ~93-db with ~6-ohm impedance and are very tube and SIT-2 (8wpc) friendly, so not a good comparison to your speakers. I’d shy away from the First-Watt unless you have a fairly benign impedance and fairly efficient speakers. The SIT-2 is the most transparent and best sounding solid-state amp I’ve heard on my speakers. At moderate listening levels, it’s terrific and definitely on-par with my 18-watt 300B SET. I also love the sound of the Pass XA30.8 and I believe the XA25 would have the same sonic traits.  While not as minutely resolving as the SIT-2 on my system, it is very satisfying.  And on the 30.8, I've seldom ever seen the meter-needle move even playing at LOUD volumes!  It never seems to run out of power.  All the Pass and First-Watt stuff I've purchased have been through Reno Hi-Fi.  As far as I'm concerned, the best Pass/First-Watt retailer in the U.S.  

Thanks All for the feedback.  I am still waffling.  Since these speakers seem to require a good dose of current, I am wondering if I want to stay on this path or head to the high efficiency path.  Which is a good thing.  If I decide to stay with the B&W's in the long run, then I need to stay with amps that can push them properly.  Otherwise, I need to consider different high efficiency speakers. 
At least, that is where my head is at right now!

I think that’s the way to go. Get as highly efficient speakers as you can that you like and you’ll be able to use whatever amp you want. Took me a while but I’m glad that’s where I’m at now.

t_ramey, got any suggestions?  My wife loves the B&W, if they aren't as good as those I will be in hot water.  The searches I have done don't bring up alot of efficient speakers and reviews are somewhat hard to find.

You are looking at very esoteric amps that don’t do well will low impedance loads and do not have much dampening. I have owned The F5, Aleph J and F6 as well as SET amps (the 18 watt 300b referenced above must be Parallel Single Ended, because a single 300b can only output aroun 9 watts at about 10% THD).

your speakers are anathema to those types of amps. If you really want tubes, you will need something in the push - pull variety. I’ve owned Prima Luna and think they are only ok, but they will drive your speakers. You can look at Audio Research if budget allows.

otherwise, you can get different speakers. I own Kef LS50’s and B&W’s and have owned PSB and Salk among others. My favorite speakers are Zu Omens- which work perfectly with those small wattage amps.