Speaker suitability for valve amps....

[eddieedwards]

I'm getting a bit of an itch and might look to change speakers in the coming months/ year. I've been looking around for speaker to partner well with my Leben and something has got me questioning exactly what to look for when searching for a good match (I'll obviously listen first, and that's all that matters really!).

You often hear it said that "x" speakers are voiced for valves, or these "y" speakers only work well with solid state, but why is that? For example, Harbeth is often stated to be a good match for Leben/ valves, yet are only rated at 86db, ATC is also similarly sensitive yet are mainly viewed as solid state suitable, whilst others might be more sensitive, yet primarily recommended for solid state.

So what actually makes a speaker suitable or not, as it clearly isn't just sensitivity and impedance - does it relate to physical characteristics too then? :confused:

[Sherwood]

My Rogers LS35a speakers work well with valves as do two other speakers I own. My Reference 3a De Capo are high efficiency speakers and operate without a cross-over. My Omega Marathon is also a high efficiency speaker that uses a single Alnico driver. Depending on where you are in Derbyshire you might want to bring your Leben over if you wanted to hear them in the flesh.

[eddieedwards]

My Rogers LS35a speakers work well with valves as do two other speakers I own. My Reference 3a De Capo are high efficiency speakers and operate without a cross-over. My Omega Marathon is also a high efficiency speaker that uses a single Alnico driver. Depending on where you are in Derbyshire you might want to bring your Leben over if you wanted to hear them in the flesh.

Thank you Geoff, that's a very kind offer.

I suppose I'm asking why are some speakers considered valve friendly, or solid state preferable, when they appear to be similarly specced in terms of impedance and sensitivity? There must be more to it than meets the (non technical) eye!

[Sherwood]

I find that low impedance designs do not fare so well with valves. As a general rule, higher efficiency designs work well but my LS35a speakers are 15ohm and relatively inefficient and they are an excellent match to my valve amplifier.

[struth]

Depends on the output transformer, and thus the reflected load back. Turns ratio etc... sure one of our resident geniuss will have better info.

[Sherwood]

Depends on the output transformer, and thus the reflected load back. Turns ratio etc... sure one of our resident geniuss will have better info.

Clearly not all valves are created (or designed) equal. My first valve amplifier was a Rogers Cadet 3. Whilst this was not special in any way and relatively low powered, to my ear it sounded much better driving my Rogers LS35a speakers than my Rogers A75 ss amplifier.

[Bonky]

"Living Voice" speakers are recognised to work well with valve amps (and Sugden amps).

[Arkless Electronics]

Thank you Geoff, that's a very kind offer.

I suppose I'm asking why are some speakers considered valve friendly, or solid state preferable, when they appear to be similarly specced in terms of impedance and sensitivity? There must be more to it than meets the (non technical) eye!

Indeed there is... Much depends on what the valve amp is. Big push pull ones with plenty of feedback can be expected to drive pretty much anything ok. Examples are the likes of EAR 509, 519, Radford STA100, Papworth M100 and several Audio Research and Mcintosh amps. IE the more SS like measuring ones with plenty of power. At the other extreme are the likes of SET's with often only 8-15WPC output and a high output impedance. The lack of power obviously requires high efficiency speakers in order to get the required volume from so little power. The high output impedance means a poor damping factor (to over simplify a little, the ability to "grip" the speaker cone), which means speakers with good "self damping" properties are best. The high output impedance also means that the frequency response will tend to try and follow the impedance curve of the speaker so speakers with a fairly flat impedance are best.

Between such extreme examples are the many 15-30WPC mainly push pull amps with moderate feedback. As you would imagine speaker requirements are a bit more relaxed than for an SET, of course it could easily drive any SET friendly speaker, but would also handle ones with a bit lower efficiency and rather more awkward load. In this category are so many different models that, well, it's gonna have to be down to those sound detectors on the sides of your head!

[RothwellAudio]

It helps if the impedance curve is fairly flat, and also the phase curve. Actually, the two are closely linked anyway.
Also, it makes a difference how loud you like to listen and to what kind of music. Taking a low powered valve amp and trying to play Metallica at Metallica gig volumes would most likely result in disappointment. However, that doesn't mean you wouldn't enjoy other types of music at lower volumes.

[Macca]

We had Steve (Bourney's) Leben sounding magnificent through some JBLs at MiBO but I can't recall what model they were now, except they were '4' series three way stand mounts. Might not be too easy to locate some for sale though.

[RothwellAudio]

May I remind forum members that the OP's question was "so what actually makes a speaker suitable or not, as it clearly isn't just sensitivity and impedance", not a request for recommendations of brands/models suitable for use with valve amps.

[eddieedwards]

Thanks for the replies all.

Perhaps my original question was not well articulated. I apologise, if so. What I'm asking is why do apparently similarly specified speakers end up with reputations for being valve or solid state friendly? Take two quick examples:

Harbeth SHL5, often being cited as relatively valve friendly and good with Leben: 86db, 6 ohm

ATC SCM 40, often cited as solid state preferable: 85db, 8 ohm

To me, neither are really quite sensitive enough, and they are two examples pulled out of the air, and not options I'm considering. Why the different reputation, when specs look similar? Is there something else to it? For example, physical characteristics of materials used etc etc?

Sometimes there are just synergies that have no real grounding in specs - sometimes there are often repeated views based on one another's experiences, that become "truths"! No worries if there is no answer, it just confused me and I thought perhaps I was missing something.

Cheers!

[eddieedwards]

Thanks for the replies all.

Perhaps my original question was not well articulated. I apologise, if so. What I'm asking is why do apparently similarly specified speakers end up with reputations for being valve or solid state friendly? Take two quick examples:

Harbeth SHL5, often being cited as relatively valve friendly and good with Leben: 86db, 6 ohm

ATC SCM 40, often cited as solid state preferable: 85db, 8 ohm

To me, neither are really quite sensitive enough, and they are two examples pulled out of the air, and not options I'm considering. Why the different reputation, when specs look similar? Is there something else to it? For example, physical characteristics of materials used etc etc?

Sometimes there are just synergies that have no real grounding in specs - sometimes there are often repeated views based on one another's experiences, that become "truths"! No worries if there is no answer, it just confused me and I thought perhaps I was missing something.

Cheers!

[Scooby]

I don't have a definitive answer but I do think one factor is that the specs never tell all the story. Two similarly specced speakers can behave very differently. Nominal impedance isn't exactly reliable as impedance curves can differ greatly. Also, for some reason, quoted sensitivity and actual "in room" perceived behaviour can also differ.

[Firebottle]

Mathew I think the real (simplified) reason is the flatness or otherwise of the speaker impedance curve, as mentioned previously.

Here is a typical plot:

https://upload.wikimedia.org/wikipedia/en/thumb/7/72/Speaker_impedance.svg/1224px-Speaker_impedance.svg.png

If this was a straight line it would be an 'easy' load. As it is the load that the valve(s) will be working into will also vary to the same degree as shown on the plot (but at a higher impedance due to the output transformer).

When the impedance is non optimal the power output drops off at the higher impedance parts of the plot. Negative feedback is used in part to correct for this but there are limits dependent on the circuit and supply voltage used.

Hope that's a bit clearer.
:)

[Macca]

Thanks for the replies all.

Perhaps my original question was not well articulated. I apologise, if so. What I'm asking is why do apparently similarly specified speakers end up with reputations for being valve or solid state friendly? Take two quick examples:

Harbeth SHL5, often being cited as relatively valve friendly and good with Leben: 86db, 6 ohm

ATC SCM 40, often cited as solid state preferable: 85db, 8 ohm

To me, neither are really quite sensitive enough, and they are two examples pulled out of the air, and not options I'm considering. Why the different reputation, when specs look similar? Is there something else to it? For example, physical characteristics of materials used etc etc?

Sometimes there are just synergies that have no real grounding in specs - sometimes there are often repeated views based on one another's experiences, that become "truths"! No worries if there is no answer, it just confused me and I thought perhaps I was missing something.

Cheers!

The lower the sensitivity the less volume you will get, the sooner the amp will clip. So you can use a comparatively insensitive speaker with a low power valve amp providing you are happy with a fairly low upper limit on how high a volume you want to go to. In a smaller room, sat quite close to the speakers, this won't be a problem. Bigger room, sat a long way from the speakers, it might not work as well for you. This is true whether the amp is valve or not.

To generalise a bit, the typical UK listening room is going to be 14 x 12 or 16 x12 and the speakers will probably be firing across the width, so the listener is only 8 to 10 feet from the speakers at most. Add the room gain and the fact that the house is shared and volume cannot be at silly levels anyway, and that is why people rarely report an issue with lack of clean volume, even if on paper the amp/speaker combo looks like a mis-match.

[Sherwood]

May I remind forum members that the OP's question was "so what actually makes a speaker suitable or not, as it clearly isn't just sensitivity and impedance", not a request for recommendations of brands/models suitable for use with valve amps.

Various replies to this question have given technical explanations as to why a speaker may or may not work well with a valve as compared to a solid state design. Clearly the power rating of the amplifier, the sensitivity of the speaker and its impedance attributes are relevant, as are the listening habits of the user (e.g. moderate near field listening in small room). My experience is that one cannot determine the synergies between a speaker and an amplifier on a priori grounds. Yes many speaker designs work as one would expect with valve designs but that is not always the case so that it is essential to listen to specific combinations before committing to purchase. That is why in my response I gave examples of speakers that I have found to work well not just with one particular valve amplifier, but with several of markedly different designs. Unfortunately, my main speakers (Magneplanar 1.7s) do not perform well with any valve amplifier that I can afford as they require a lot of current and as i understand it, that requires expensive valve amplification to deliver.

I guess it all comes down to Matthews original question. I don't think it is helpful to merely generalize about design and performance parameters without illustrating those points with empirical evidence of good amp/speaker combinations (subjective as that judgement may be).

[SLS]

Had 35w mono valve amps made to try and drive Harbeth SHL5+ and was fine except a very wooly bass. In other words, didn't work.

My choice was the SHL5+ and more powerful solid state amplification.