New or used? Are you looking for a warmer signature or something more neutral with just a bit of that tube magic?
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.
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+1 @Carlsbad. My Line Magnetic 518ia generated 22w and was a Stereophile Class a rec. More important, it was one of the best sounding tube amps I've ever heard. Try LM as well as Raven Audio products and Rogue. There're a host of good, tube products under $4k that do NOT need 100w. Although I guess it all depends on our speakers' Db rating. |
jperry is correct, two amps at 100wpc will not necessarily play at the same level unless the gains are also matched. You need to be able to control the gain of one of the amps to match the level of the other one. The two sets of binding posts on your speakers are not only for bi-amping but also for bi-wiring. The passive network is still connected to both drivers: low and high. To do bi-amping properly, you will need to disconnect at least the low frequency drivers from the passive crossover network. Since you are not ready to modify your speakers, you will not be able to enjoy the full benefits of bi-amping. You have all the necessary equipment. As your knowledge increases you can tackle the full mod later. Be advised, the difference will not be subtle. |
Thanks for the input so far. Yes, I am looking for a bit of that “tube magic.” Switching to a tube preamp has made the music seem so much more alive, with more depth, possibly due to hearing more harmonics from the various instruments. I now understand that I do not need anywhere near 100 wpc for the mids and highs, that probably 30 to 40 watts will be more than sufficient in our roughly 13 x 20 x 8 living room, open on one side to the dining room. A higher power tube amp would just give me power reserves I probably would never use; we like to listen at moderately loud levels—just beyond where the speakers “open up”—not very loud levels. Someone commented that the crossover will handle gain matching between the two amplifiers, which was a major concern. One thing I do not understand is the need to remove or disconnect internal crossovers when using an active external crossover. My speakers have two sets of binding posts, one for lower frequencies and one for mids and highs. When a manufacturer builds a speaker this way, do they not bypass at least the crossover divides the lows from the mids and the highs? (In the F702s, that would at 250 hz.). If not, what is the point of two sets of binding posts? Thus, it would seem to me that if I set the active crossover at 250 hz I am simply duplicating the internal crossover point and sending just frequencies below 250 Hz to the woofer, which is what the internal crossover does; frequencies above that are directed into the “upper” binding posts, and it seems to me that I would want to retain the internal crossover dividing the mids and highs (1.7 kHz in this case) because I am only bi-amping, not tri-amping. OR, are we getting into the “magic” of crossovers with the possibility of some undesirable interaction between the internal crossover at 1.7 kHz and the active crossover? Can someone explain. As you can tell, I am new at this, and I greatly appreciate your advice. My current system is far beyond what air replaced in the past year—Infinity Modulus satellites (the 1992 quality model with EMIT tweeter before Infinity went mass market) and a NAD C356BEE used as a preamp feeding into a McIntosh MC2125, of which for the latter I was the original owner. I am looking at tubes for the upper end to see how much better I can make my system without spending gobs more money. Many thanks, folks. Good listening to all. |
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Power: yes, less for just mids and highs, however, consider you might want to try just the tube amp for all, then, if more power is affordable, ... smaller means less heat, cost, and more placement options. Crossover does not equalize gain, just distributes these frequencies to this driver ... You need gain controls on at least one amp (preferably both), get them volume matched to each other at your favorite listening volume, then after that fundamental match, the preamp controls the volume to both amps. |
Your plan is misguided. Unless you perform surgery on your speakers to hardwire the LF input terminals of the to the woofer and the HF inputs to the correct circuitry traces for the upper crossover (MR/TW) you will be “double crossing” your speakers. Plus, an engineered product like the Fynes often have compensatory elements in their passive network that the electronic crossover won’t be able to match. Skip the electronic XO! It’s perfectly OK to just biamp into the terminals as is with the 2 amps as long as their gains are matched. 50W tube amp should suffice. I do this with my own DIY speakers to great effect with a SS woofer amp and EL34 based upper range amp. |
RE: the crossover discussion. No, you don’t need or want 2 crossovers. If your speaker is set up for biamping, then the crossover inside the speaker will split the signal at the frequency that the OEM thinks is best. Then you just need to figure out how to make it work with no external crossover.
Notice how people looking to bi-amp are usually folks that a lightbulb goes off in their head and it sounds like a good idea. and it can work. but if I were going to biamp I’d approach it like this: carefully pick the amp I live for mids and highs, try many amps. Let them drive entire speaker. then add a second ss amp to drive the lows only if the other amp was lacking. Jerry |
Another way to go would be to sell the benchmark and just get a tube amp so no need to mess with an external crossover at all. At 93dB and nominal impedance of 8 Ohms, depending on what the minimum impedance is your speakers might do quite well with a 70-100Wpc tube amp. That’s what I’d do rather than messing with external crossovers, volume matching issues, etc. Another consideration is that the woofer crosses over at 250Hz reaching up into the lower mids so there may be an issue of significantly different sound signatures of the Benchmark and a tube amp blending seamlessly in that area. Just some thoughts FWIW, and best of luck in obtaining more of that tube magic. |
@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. |
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Wise counsel from you, @lloydc @soix and others who caution against unwanted complexity. It seems to me that 1 quality tube amplifier would be idea with the Fyne speakers. But I understand, to each their own. Charles |
OP: This is the data point I was mentioning, right after the word "minimum." This tells you that these speakers don't need 100watts and would be fine with a tube amp. Impedance: 8 Ohms nominal (minimum: 5 Ohms, from 150-250Hz) |
Hi Mike;
I think this has been well covered here but my 2c worth is that bi-amping is a great way to have imbalance in your sound and your checkbook. "On paper" bi amping seems like it makes sense but in your listening room you are going to have a sonic disaster. If you are married to the idea of 2 amps use matched mono block tube amp but NOT bi-amping. Tubes are always welcome as they produce wonderful warm sound and a LOT of volume. Personally I’d go with a good used Audio Research stereo tube amp with under 1500 hours on it. They are built like tanks, sound amazing, are much more affordable than the new ones, and don’t loose value if you choose to trade up. (Of course sound is a preference like blondes vs. brunettes or French wine vs. California wine. Only you can choose what "sounds best") One other thing- ignore anyone who makes fun of what YOU like.
I have a great used Audio Research VT130 tube amp for sale for sale 3.5K It was my favorite "large format" amp until I put my hand up on a pair of Ref 250SEs (8K 1900 hrs plus nearly $500 in FedEx freight. Ouch!)
Remember the KISS principal- Keep It Simple, Stupid! Hope this helps!
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OK folks, you’ve convinced me to reconsider. I do not want to modify the speakers, so it appears—as is often the case I found in my nearly eight decades—that the simplest course of action is most often the best answer. I will, once I convince the wife, opt for a single tube amp; if something convinces me that I don’t have enough power, which is most unlikely, I could always buy a second identical amplifier or go to monoblocs. I know there are LOTS of options out there. Given my satisfaction with my Rogue preamp, I am considering either the Rogue Stereo 100 or the Atlas Magnum III and also the McIntosh MC 275 MKII, but the Cary CAD120S MKII also has caught my eye.
Any recommendations in the roughly $5000 and under range would be most welcome. I prefer new equipment, preferably not made in Mainland China, as I don’t like supporting totalitarian regimes engaging in nefarious activities.
And, once again, thanks to all for your comments. They have been most helpful. Mike |
Rogue Stereo 100 with a 93dB Tannoy or Fyne will be pretty bomb. It will give you all the bass slam and dynamics, so you shouldn’t miss that from SS :) Throw some sweet NOS small tubes in there to get a good balance of tube & SS archetypes. Rogues really respond a lot to tube rolling, and the stock tubes (other than KT120) are often mediocre. Several years ago I auditioned the old Stereo 90 on my Kensingtons, and it was a really solid step above Atlas (at the time with EL34). But that made me so rabid for upgrade, I placed an order for Apollos instead :) Of course the other amps you list should sound good too - I just have no experience with them. I’ve long heard Manley and Tannoy (therefore Fyne) are a particularly rockin’ combination. I should have tried them too; get slight pangs whenever I see a used pair of Snappers for sale :) There's definitely something about the EL34 sound I really like. |
👍 Aric Audio could build an excellent tube amplifier with the stated budget. Charles
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I think you’d be hard pressed to get a better tube amp in your price range than this VAC Phi 200 that delivers 100Wpc. Heres a review fyi… Best of luck in your search. |
@soix A very good amp for a great price. |
I currently have a pair of VAC 200iQ and Rogue Apollo Darks (along with my solid-state Phison A2.120SE). That's an upscale analogue of the Phi 200 versus a Rogue Stereo 100. The Rogue will be more dynamic and have better bass. The VAC will be more refined smooth and sweet, especially in the midrange. Choose your preference! But I really start to miss some dynamics & slam when I go from a pair of 200iQ monos to a single 200iQ in stereo mode. |
5K USD allows for some formidable amplifier choices as the numerous recommendations thus far have show. Lots of push-pull tube suggestions. This Fyne is 93db sensitivity and an 8 ohm speaker impedance. I’d think that the Line Magnetic 805ai is a viable consideration. 48 watts of pure class A provided by one psir of 805 tubes.Something to think about. |
@mike4597 + 1 on Raven Audio and you have 45 days to test drive it for relatively low risk (7% restocking fee + shipping). They sell direct only so you get better bang for the buck IMHO. |
I'm not a fan of the Raven amp aesthetics (looks like a run of the mill Chinese amp to me), but I do remember that 6L6GC kind of sound (vintage Heathkits - 5881 and 7581A) sounded absolutely wonderful with my 93dB Tannoy Kensington. Classic tube sound. That kind of tube & sound in a more modern form factor (binding posts, connectors etc) with a little more power (40 - 50 Watts at least) would be hard to beat. Haven't heard the Ravens myself, but probably not a bad choice. KT88 and KT120 seem to need a lot more power and brute force behind them to sound "whole" the way those 6L6 amps do. |
Hey Mike4597, Mix a tube amp with a SS unit for bi-amping & you’re GOING TO HAVE PHASING ISSUES. OK, before you throw out the baby with the bath water, all you MIGHT need is a few tweaks. To sweeten up that mid-range, swap out the 12AU7’s in your pre-amp, swap out the stock tubes for · NOS RCA Clear tops. Interconnects, try the entry level XLO’s, $275/pr (consider used). They’re not forward, but I find the mid-range timbre more transparent. Bi-wire your speakers. Try Kimber’s entry level wire. If yea just have to have a new Amp, consider Antique Sound Labs Monsoon (http://www.uptownaudio.com/as/as.htm), or better yet the Canadian company, Coincident Technology (https://coincidentspeaker.com/). Their 211 PUSH PULL DRAGON amp is to kill for. (Consider used).
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@mike4597 I'm considering listing my Music Reference RM9 MK II with newer Siemens (RFT) EL34's, refurbished for me by Roger Modjeski in 2017. Let me know if interested. It's a classic amp that runs under the radar. Also allows tube rolling of many varieties of power tubes... KT66, KT77, EL34, KT88 and 6550. https://www.stereophile.com/content/music-reference-rm-9-power-amplifier-rm-9-mkii
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I recommend the Rogue Audio Atlas Magnum latest version. .Basically the power amp section of the famous Rogue Cronus Magnum III, sounds so transparent and refined with excellent open midrange that sounds better that the up range Stereo 100 IMHO. The 100 can be too burnished and dark. Save some cash too, a great match with your preamp and speakers. There is good reason why the Cronus Magnum is a giant killing integrated amp- he sound ! |
