Speakers for triode tube amps


I have a Luxman CL 38u SE tube preamp and matching MQ 88 SE Triode tube amp rated at 25 wpc. I m using ProAc Anniversary Tablets at the moment and I’m wondering how I can upgrade to a speaker that can be driven with 25 Triode watts. Any recommendations on a high quality 8 ohm speaker that is easy to drive?  I know Wilson Tune Tots are out of the question (impedance/ sensitivity issues- they were my first choice.  Not interested in horn loaded speakers.  I Love the Harbeth P3 but I already own a pair of 40.1s in my main system. Any suggestions??
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Showing 8 responses by larryi

It would be useful to know a bit more about your specific requirements-- budget, size of room, how loud you listen, whether the current 25 watts into Tablette speakers sound good (if not, what are the sonic problems), speaker placement issues (do you have limitations on where the speakers can be placed, etc).

I tend to think that most people over estimate the amount of power they need for most of their listening.  Although tube gear manufacturers tend to give their amps a quite high output rating (relative to the amount of distortion at that rated output), it is still the case that most amps rated at 25 watts can work with relatively easy to drive speakers.  I've heard such amps with most of the Harbeth lineup and I would consider only the 40.1 to be out of consideration.

Any of the Audio Note speakers will work a 25 watt amplifier.  My favorite local dealership carries ProAc, Harbeth and Audio Note.  What is interesting is that he says that,, by far, most of his new customers come in looking for Harbeth speakers, and more than just a few end up with the Audio Note speakers; those who initially bought Harbeths often end up buying Audio Note.  
The main concern with a speaker with a low nominal impedance, such as 4 ohm, and tube amps has to do with frequency response changes due to the relatively high impedance of the amp interacting with the impedance of the speaker.  While 4 ohms might be the nominal impedance, the actual resistance at each frequency is probably quite different, which means certain frequencies will be emphasized more than other depending on the speaker's actual resistance at that particular frequency.  If a 4 ohm rated speaker had a perfectly flat impedance curve (resistance at all frequencies the same) the impedance match of the speaker and the amp would not matter.  But, all speakers have a pretty wide ranging up and down curve regardless of their single number "nominal" rating.  Hence, all 4 ohm speakers are not the same when it comes to how they will react to the impedance of the amp as far as frequency response change.

Ideally, the amplifier's output impedance will be so low compared to the speaker impedance that there will be not much in the way of frequency response effects.  A tube amp with a 4 ohm tap will have enough enough of a turn ratio in the output transformer so as to lower the output impedance to make it work reasonably well with a 4 ohm speaker.  But, there is no free lunch, so this means a sacrifice of some power that can be delivered to the speaker.  If the amp only has an 8 ohm tap, it may not have a low enough output impedance to avoid major effects on the frequency response when working with a 4 ohm speaker.  Whether or not this effect is severe enough to disqualify the amplifier depends on the particular impedance curve of the speaker, the actual output impedance of the amp and the particular taste of the listener.  I've heard a number of supposed mis-matched speaker and amps that sounded quite nice.
I do wonder how Tekton has become such a polarizing brand.  Is it the looks, is it the over-the-top ravings of fanboys?  While the sound of the speaker may not be to everyone’s taste, I have heard several models and there is nothing “extreme” about the sound—it is well balanced, smooth, dynamic and engaging—and I cannot see how it’s sound could evoke such disliking.  The prices charged are also quite reasonable for the level of performance.

I do suspect that some of the critics of this speaker have not heard them.
Samuelg,

I hope some of the suggestions above have been helpful.  It is a bit hard to give focused advice, given that we don't know some basics, like a price range for instance, but, you are probably looking for a wide range of options.  For example, I like the suggestions of the Devore speakers, but, I have no idea if they are in your range as a choice. 

I know you mentioned that you have the Harbeth 40.1s, so you are not looking at Harbeths, but, I think that their other models sound substantially different from that speaker and the other models are MUCH easier to drive than the 40.1s (these are particularly demanding speakers that can sound dead or flabby with the wrong amplifier).  Perhaps the 30.2s  would be a candidate.

I again mention the Audio Note speakers.  It is interesting that you have ProAc and Harbeth speakers, because one of my favorite dealers has ProAc, Harbeth and Audio Note as his primary speaker lines.  He also has Nola, although for some reason, they are not that popular (the cheaper models sound good for the money to me).  This dealer, DejA Vu Audio (Northern Virginia) only sells tube amplification, so their speaker preferences are matched to this type of amplifier.  Most often, when someone comes in looking at all options (i.e., they did not come in looking at just one specific model), they end up with an Audio Note speaker.  

If you can stretch a bit in price, Charney Audio makes terrific speakers that are in the 99 db/watt and higher level of efficiency and they are fantastic as long as one is not interested in extremely deep bass. 
It is interesting that Magnepan is mentioned here, because it represents what is supposedly one of the least compatible speaker model for low-powered tube amps.  Maggies supposedly demand high-power high-current amps.  I've heard Maggies (cannot recall the model) with a tube amp, which was probably a 40-watter, and the combination sounded quite good in a smallish room.  The time I heard an obviously incompatible Maggie setup involved a friend hooking up a single-ended 45 amp (1.5 watts/channel) to 3.5 Maggies just for laughs--it sounded quite good at lower volume, but the sound fell apart at volume levels approaching a normal listening level.  

There is enough wiggle room in Russ69's comment that it is not unreasonable.  First, "play loud" is not defined, and it IS the primary factor in whether or not a modestly powered amp will work with a given speaker.  The other bit of hedging is "just about any" which means there are indeed some speakers excluded.

I listen at modest levels.  All three of the amps I own are adequate, in terms of power output, and the highest rated output is the parallel single-ended amp rated at a whopping 6.5 watts/channel.  I have heard this amp used on much less efficient speakers than I own (my speakers are around 99 db/w efficient), so I know it has plenty of power for my purposes. 

Even at less than quiet listening levels, and even with low efficiency speakers,  peaks that would challenge a 25 watt amp represent only a small fraction of time.  Whether or not the compression or distortion at these peaks are so unacceptable that the amp is disqualified is a personal matter.  I would live with occasional problems at extreme peaks if I otherwise liked the sound, others might not. 

A 25 watt tube amp, particularly one with a higher output impedance, might not be the best choice for listening at even modest levels with some speakers, so there might be an increased probability of incompatibility.  But, matching an amp to a speaker involves so much more than having adequate output, decent damping factor (low enough output impedance), etc.  There is no way to really know until the combination is actually tried.  The Original Poster mentions having Harbeth 40.1s, which, from hearing it with around six or so different amps, I think it is a challenging speaker.  But, interestingly, it happened to sound best, to me, with two amps that had lower output than 25 watts, while the 100 and 200 watt amps did not sound as good.  Yes, both of the lower powered amps compressed a little at high volume peaks, but, for the vast majority of the time, they sounded terrific.  
If you are a fan of the Harbeth P3, I think you will like the Falcon version of the LS3/5A.  I have heard it, the original BBC 15 ohm Rogers LS3/5A, the P3 and the ProAc Tablette in the same system.  I like all of these speakers, but, I slightly prefer the sound of the old Rogers and the Falcon (warmer and better midrange than the other two).  I know both are quite inefficient, but, they are an easy 15 ohm load and I heard them with low-powered amps; in fact, in one comparison session, the Synthesis Roma 96 amp was used and it is rated at 25 watts/channel.  If a small monitor is in your plans, the Falcon is something to consider.  

Another reasonably priced, very efficient speaker to consider is the Rethm Bhaava.  This speaker has a built in powered woofer, so your amp will only be required to driver the very efficient main driver.  This is a quite lively sounding system that is a nice change from the sound of the Harbeth 40.1s.  
I have not heard the specific model of ProAc speaker you are looking at, but, I've heard several other models, including stand-mounted speakers with the ribbon tweeter.  I really like the ProAc ribbon tweeter speakers I've heard.  This is one of the rare brands that successfully pull off the integration of a ribbon tweeter with conventional dynamic drivers--there does not seem to be an obvious difference in the character of the sound above and below the crossover point.

Because the K-1 has a dedicated stand, to me, it is really not that much different from a smaller floor-standing speaker, so I don't know why you have ruled out floor-standing speakers.  But, I will note that several years ago, I heard a stand-mounted ProAc (I believe it was the D2R) and another ProAc speaker with what looked like the same drivers in a floor-standing configuration; the stand-mounted speaker being cheaper in price.  I liked the stand-mounted speaker more, and the dealer noted that, when you added in the price of a good stand, the two models were comparably priced.