Speaker suitability for valve amps....

[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:



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.