Tubed Monos for Focal Aria 948s


I'm considering a pair of tubed monos for my Aria 948s. Given that their efficiency is at 92.5 it seems that I could swap the 130W SS monos for the warmer tube sound in the 40W range and not have any issues. Any ideas how much bass would be lost? Do I need to factor gain into the equation? Already have a tube preamp and like the way that sounds, even like the the way the SS monos sound but since the Focals are so clear my thought is that tubes would pair very well.

Thanks
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A nicely restored pair of Dynaco MkIII's would work well. About 70 watts from a pair of KT88/6550's. I have a pair in my collection. Still among the best tube amps ever!
The biggest issue with similar speakers, and Focal in particular, is they tend to have an impedance dip right where you don't want it, around 100 Hz.

This makes them "discerning" of amplifiers, meaning that they will require a low impedance amp to drive them without loosing bass drive.

This is not the same model, but it is typical in this range for Foral:

https://www.stereophile.com/content/focal-aria-936-loudspeaker-measurements
Sorry, I never got to my point.  My point was that when auditioning amps, listen in the lower to mid bass for any weakness. Decide accordingly.
That may be a 92.5db/w/m speaker but it's a crossover intensive, multi-driver speaker. Few modest-power tube amps will resolve that Focal's problems (or challenges) and you don't want the mega-massed-tetrodes/pentodes 200w+ tubes monsters. What can you actually spend on amplification? I'm a tube loyalist but sometimes you have to accept a solid state alternative. IF you can afford to, the SST Ampzilla 2000 Second Edition (temporarily $5200/pair on promotion) would give you tube warmth and scintillating solid state resolution + faultless bass control. Magnificent on that speaker. Also the SPL S800 stereo power amp.  And for much less, the m2tech Crosby, either as a 60/60w stereo power amp or as 180w monoblocks (8 ohms), would obliterate most tube amps on that speaker. The Crosby is $1300 for stereo, $2600 for a pair of energetic, high-grip monoblocks. Tube smoothness with transistor assertiveness and control in an 8 lbs. per monoblock compact package. What are you game for?

Phil
Thank you everyone for the replies. As I expected, there is a good bit more to understand before making a selection and your information cuts down on research time.

@erik_squires I was wondering where that part of the signal went. I love the sound of these speakers but always felt that they needed a little something extra. Thank you for defining the problem.

@213cobra I was under the impression that the crossover design made it easier for amps to drive the speakers. If that is incorrect then I will have to take that into consideration. I was looking at a pair of Prima Luna Dialogue 7 monos ($4800) or the EVO 400 which are twice as much. The 7s I could get in a month, the EVOs would be 4-6 months but I am going to look into your recommendations now. I have the Odyssey Kismets hooked up at the moment so SS is not a deal-breaker at all. I'm looking at tubes just to see if I can warm things up a bit but as Erik pointed out, whatever I choose will have to compensate for the 100Hz dip.
Check out Quicksilver's new 120 watt mono amps...
@oddiofyl You are the second person to recommend the Quiksilver 120. I will send a message to the company and explain what I have. Erik_Squires mentioned the 100 Hz dip so now I'll be focused on that as well.

Again, thank you everyone for the information.
+2 for Quicksilver Mono 120s. Got some too. Love them :)

Also, I helped my sister to acquire Focal 948s and for her we chose a simple 100w Peachtree integrated (with tube input) for her family room. Goes plenty loud, and I’m certain QS Mono 120s would be plenty, I’ve heard them with large 7 foot tall IN-effcient electrostatic and large multi-driver speakers. Mono 60s could work too, with a bit less grunt than Mono 120s. 948s are known to be bass heavy so pick your poison with QS Mono amps.

Mono 120s are what I use for my own multi-driver electrostatics in my main system now. Takes a while for tubes and caps to burn in. Once that happens, they really take on a nice smooth sound.

Mono 120s have the finesse of lower power amps with large transformers and proper circuit and plate voltage to drive the KT150s.
I’m a 40-year mosfet solid state amp guy and love these amps. Mike did a really nice job on them, switch on the front and AC/speaker on the back, with KT150s and quality build and I’ll say it again, large-quality transformers in a well known proven circuit design. They run 12AU7 input and 12AT7 drivers, so tubes are not crazy expensive if you want NOS or boutique tubes. I’m running NOS 1960s Mullard input/drivers elevating the sound to true high-end, totally 3-dimensional, nice midpoint sound stage, dead quiet. Again, need to burn them in 200+hrs.

Mike’s standard Linestage preamp (non-remote) version is a nice preamp for them, great value too. However, I run a different 6SN7 based preamp (already had it), and it pairs sooooo nicely with these Mono 120s. Comparable CJ KT150 based amps are $19k, over 4x the price. I’d put these up against it all day long. Value$ !!!

Keep the bias at 40ma and they run COOL! Any of my former Class-A, or better Class A/B solid state amps ran warmer than my Mono 120s. The more I listen to the KT150s, the more I really like them, more than I thought I would and I tend to generally like EL34 sound. The KT150s have more top-air, more bottom end, and the right amount of midrange without being syrupy in these amps. Mike nailed it with Mono 120s for my custom speakers.

Not sure what your budget is, but Rogue Audio's monoblocks are fantastic. I have the M-180s. No experience with those speakers, so can't say how they would match up. When I had my Legacy Audio 20/20s (94db efficiency if I remember correctly), it was intense! They're great with the Harbeths I have now also. 
@decooney I agree with bass on the 948s. I thought Focals were a bit light on the bass by nature but not these. I'm using a Prima Luna Dialogue HP for the preamp and love the sound.

@big_greg I figured that I would need around $5k for a good set of tubed monos so the Rogues are possible.

Just read a post about speaker impedance and amps which should help. Looks like a lot of math but that should narrow the parameters considerably 
@zyphryx

"OP: "I could swap the 130W SS monos" ...

------

@decooney I agree with bass on the 948s. I thought Focals were a bit light on the bass by nature but not these. I'm using a Prima Luna Dialogue HP for the preamp and love the sound."

zyphryx, 
Are you running 130W SS amps or Prima Luna Dialogue HP now?

What are you not getting out your current amps you hope to get out of new tube monos respective to your Focal 948 speakers?

@decooney I have a Prima Luna Dialogue HP pre amp that is connected to a pair of Odyssey Khartago mono blocks. They sound fine as is but the Focals are so clear that it sounds a little lean in the bass. As erik_squires pointed out, there is a dip in the upper bass range so my thinking is that the warmth of the tubes may help the tonal balance. Is this is incorrect?
...my thinking is that the warmth of the tubes may help the tonal balance. Is this is incorrect?

No, not incorrect but I will say there may be other areas to mess with before jumping to tube mono amps to remedy the leanness. Sure a pair of tube mono amps with smooth sounding EL34 tubes can "round off" the highs a tad to accentuate the bass some but you may have other options to try before you try other amps... tape a paper towel over your tweeter on your speakers as a cheater simulation test...: heheh.

I took a look at your amps, torroid transformer, notable power quad caps and while don’t know much about your amps sonically - but know a few locals with them that did go to tube amps later but for sonic reasons OTHER than adding the weight and fullness you seem to be looking for (below 200hz) with your Focals. With that said, I think you might look at some other areas if you want to keep your Odyssey amps. They are kinda nice. Perhaps restarting with 1) your preamp/upgrades, preamp tubes, preamp caps and 2) maybe even some softer and more rolled off interconnect cables next to cheat some...a tradeoff some times (chat via private message), gotta few ideas there too from my own hybrid tube preamp / ss combos. And, if you have not already done so. 3) maybe look at adding a little REL subwoofer is a nice cheater fix to fill in that dip. They can sound nice. I build my main speakers and custom subs and a good sub can help fill that void particularly for low volume level listening and permit your mains (to work less hard) to resolve better too in a large room. Look at what some of the more expensive Wilson Audio speakers are doing the past decade, see the lower half of he speaker :) Just a few other thoughts, feel free to send a private message. Gotta a few other questions for ya. Your preamp has the triple 12AU7s per side, correct - or older version. The new PL labeled input tubes in those preamps look like rebranded PSVANE tubes, sort of. Also noting the Mundorf caps in the newer version pre - I run those same caps in a tube DAC, but there are other caps that are warmer, less tinny, the EVO supremes are fuller, IMO. You may have other areas to work on IF you keep those amps you have now.


To the extent this is helpful - 

I used 60 watt per channel Allnic 300B XLS amps to power Focal Sopra 1s, and it worked like a dream, more bass than I ever would have imagined. I could play it loud. However, I never cranked it alllll the way.

I currently use a pair of Conrad Johnson's that put about 180 watts into 8 ohms, and they power my Sopra 2s perfectly. Extension in both directions, more than enough power to play very loudly.
@gmercer I'll bet that sounds great. If the Sopras sound half as good as they look you must be pretty stoked. I heard a pair of Kantas at a dealer's home and that's what got me hooked on Focals. The clarity and detail was like nothing I've ever heard so when an opportunity to score some 1.5 year old 948s came up at the price they did, I jumped. I figured they would be lean in the bass like the Kantas but they are not at all. They just need that something extra to push them across the finish line.