Recommend a good tube power amp in the 100 wpc range for under $4k


Folks, 

 I am looking to bi-amp my Fyne F702 speakers, with a solid state amp for the low end and a tube amp for the mods and highs.  The Fynes are floor standing 2.5 way units with 93 db sensitivity and 100 wpc rms power handling capacity.  My preamp is a Rogue Audio RP-7, and my current solid state power amp is a Benchmark AHB2 at 100 wpc.  My goal is not so much more power but to put a tube amp on the middle and highs.  The Fynes have two sets of binding posts, one for lower frequencies and one for mids and highs.  I am looking to go active bi-amping with a Sublime Acoustic K231 Stereo 3-Way Active Crossover.

  In addition to an amplifier recommendation, what else do I need to consider?  For example, if I buy an amplifier with wattage output similar to the AHB2, what other factors do I need to consider?  Because I do NOT want to modify the speakers in any way, do I need to consider a gain control to match level differences resulting from other factors, such as impedance differences? Or, can I just hook up the crossover between the preamp and the two power amps and enjoy the music, which is what it is really all about anyhow?

 

Many thanks for any and all comments.

mike4597

I own the Fyne F704s and feel you are adding too much complexity to your system for no good reason.  Just get one good tube amp. No need for 100 watts unless you have a huge room.  One good tube amp will sound best. 

@soix is spot on regarding the sonic blending of the two amps on the mids. No reason to add this problem to your system. 

Want a great integrated amp for your F702s? Get the Circle Labs A200 hybrid Int amp.  Tube preamp section coupled with SS output.  Your Fyne speakers are a great match for the purity of this amp.  This one amp will greatly simplify your system and give you the best sound.  Better sound than the two amp approach you are contemplating. 

As others pointed out, gain matching will be an issue. In most cases, tube amps will have higher gains that SS amps of the same power rating. Sometimes MUCH higher. This is because they use less feedback, and also the typical input tubes like 12AX7 / 12AT7 / 6SN7 / etc provide a lot of gain.

A Rogue Atlas II (or III the current one?) Magnum is a good 100W tube amp well within your budget. There aren’t too many other budget options like this without going to a no-name Chinese amp (I’m taking about stuff named like Quin-Poo or whatever, not the PrimaLunas which are good).

Your Benchmark has 3 gain settings which helps, but even its highest gain will have trouble keeping up with a 100W tube amp. It looks like the Atlas will be a couple dB hotter than Benchmark’s high gain mode (see Stereophile measurements of Atlas - and they even comment that its gain is lower than usual for a 100W tuber amp!). So you’d need to either insert an additional volume control (and calibrate by ear and/or SPL meter), or re-think your strategy.

Personally, I wouldn’t try bi-amping unless I had two of the EXACT same amp. I’ve even had two of the "same" stereo amp, but there were minor internal differences on the units (made about a year apart), and bi-amping didn’t convince me of any benefits versus running either amp alone. The very slight sonic differences between these units seemingly worked against a cohesive musical whole when bi-amp’d.

I have lots of experience with Tannoys, similar to your Fyne (I used to own Kensington SE that were also 93dB), and the Rogue Atlas did a great job powering them alone. The Rogue amps are not "typical" tube amps in that they have great bass power and dynamics with a drier midrange. So they’re really kind of like a tube amp with SS persuasions. If you went with the Rogue, I would run it full range.

I also ran those Kensingtons with 20 - 35 Watt vintage tubes amps (Heathkit, Eico), and those very much have that "classic" tube sound, but the bass response was a bit softer and I play loud so I definitely hit their clipping limits at (rare) times. I later got the Rogue Atlas (version I, non-Magnum), and I did NOT hit any limits with that amp (except once totally by accident on a Sheffield Direct-to-Disc of Firebird Suite) :)

Incidentally, I later moved on to Rogue Apollo tube monoblocks, 250 Watts/ch, and their gain is absolutely INSANE (not always a good thing with efficient speakers). I don’t think any SS amp on earth would match it. The bass response on those amps is crazy good though :)

@mike4597 

Your speakers are designed to be bi wired not passively or actively bi-amped. That said, bi-amping or bi-wiring speakers should not be undertaken without first asking the manufacturer’s advice.  See Fyne F702 speaker, crossover below: 

Mike

Crossover type Bi-wired passive low loss, 2nd order low pass, 1st order high pass, cryogenically treated