advertisement


Small(er) efficient speakers?

Lots of useful insight above, thank you.
Just to take two not very efficient speakers as a starting point:
The Harbeth P3ESR and M30 or in studio guise M20 and M30. The 30 is a bigger box with a bigger bass/mid and slightly higher quoted efficiency 85 vs 83 dB/W or thereabouts. Similar impedance and similarly designed to be an easy load.
So in the near field in a smallish room on the end of a low power valve amp how would they compare?
The 30 would go lower and play louder if required, but what else would be expected, are there ways in which the smaller, less efficient speaker would be better?
[For context, currently listening to JR149s with Sugden ANV50 in a room 4.5 x 8m and not near field at all, almost the other end of the room, sounds good to me.]
 
Load is key. A lot of very small speakers have really awkward reactive low impedances due to obnoxious porting etc and it is this that upsets low power amps, especially valve ones, not the efficiency.

To be honest the efficiency is largely irrelevant as no one wants a mini-monitor to play loud, so even one rated at 83-84db or so is fine as even a ten Watt amp will take them far louder than needed in their typical usage context. I’m sure is a key reason for the enduring popularity of the 15 Ohm LS3/5A, it has a very easy valve-friendly load that barely drops below 8 Ohms and can be driven superbly with a good 10 Watt valve amp. Certainly my Leak Stereo 20 or TL 12 Plus (10/12 Watt) monos take the LS3/5A or JR149 as loud as I would ever expect a speaker with a little 5” bass-mid to be driven. These are just not high volume speakers, but in the nearfield with amps as good as these they sound truly stunning.

Seconded. I noticed my amp running hotter driving LS50s than the supposedly amp-killing Magnepans @ 3.5 Ohms.
The latter act as a 3.5R resistor with no reactance to speak of.
 
Woofer size has very little to do with it.

As Hoffman's iron law says, there is a reason why very small speakers are very inefficient... and that is simply that they would have bugger all bass if they were efficient.

I've experienced Celestion SL6's from about 5' away with a 50WPC amp just clipping on peaks (a good, very dynamic recording) and a mate and myself were able to continue talking, albeit with raised voices ... we didn't need to shout as such, when stood next to each other.

Which doesn't preclude using say 10WPC amps with such low efficiency speakers but you need to use them near field ideally and have realistic ideas as to the limitation on volume.
 
Woofer size has very little to do with it.

As Hoffman's iron law says, there is a reason why very small speakers are very inefficient... and that is simply that they would have bugger all bass if they were efficient.

I've experienced Celestion SL6's from about 5' away with a 50WPC amp just clipping on peaks (a good, very dynamic recording) and a mate and myself were able to continue talking, albeit with raised voices ... we didn't need to shout as such, when stood next to each other.

Which doesn't preclude using say 10WPC amps with such low efficiency speakers but you need to use them near field ideally and have realistic ideas as to the limitation on volume.

Far too close for those, try from another room, or house.
 
I run the Proac Tablette 10 with either the little Denon d41 - 30 watts optimistically and a 1.5 watt single ended amp that uses the 45 triode tubes and it works surprisingly well. The amp is by Alan Eaton and was nicely described on the Glow In the Dark audio blog where he reviews low wattage amps.
 
Tony, there are so many variables in play that your statement has to be qualified. Among the small speakers I have and do own, with 5-6" drivers, the spl of clean audio yielded varies a lot. My MAD 1920S go VERY loud and clean in my space and can rattle the windows with their bass. They are 4 ohm, 90dB. The LS3/5a can't get close to that kind of volume, but they can still go louder than I can possibly tolerate at 12 feet listening distance.

I have heard many tiny speakers play at high levels, but never well to my ears. I always hear the compression, distortion, or just that weirdness you get from a driver bobbing in and out an inch or so and the mess that makes of the crossover region. I would never personally play a small speaker with dynamic peaks hitting above say 95db or so absolute tops at a metre (i.e. 80db or so median). If I want more level than that I’d always buy something bigger. It is basic physics; to go loud and deep a tiny driver needs to move a very long way, and that is never a good thing IMO. The magic of small speakers is in the nearfield, and there one doesn’t need high levels.
 
I've stumbled across this thread whilst pondering a change in speakers. I currently have a pair of Cheviots powered by a Radford sta 25. They sound very good to me a d I certainly wouldn't want to change other than space is at a premium amd the speakers dominate our front room. I was considering some Grahams- the LS3/5 or the LS5/8 (pushing it size wise I think). Considering what has been said here I think the Radford would drive either pair with ease if listened to near field and at modest levels. Am I right?
 
When I designed the Ergo-IX, which is a mini-monitor sized loudspeaker around 9L in enclosed volume, I chose bass extension over sensitivity. The non-boundary version barely registers 80dB/2.83V/m. Whilst the mid-woofer is a very accomplished 5.25" Scan-speak that can handle a continuous 60W, and can replay the fundamental note from the E-string on a bass, it will never play with the same ease or loudness as a pair of 90dB/W/m Yamaha NS-1000Ms. That's just physics. But at sensible levels under 90dB in room, you'd be hard pressed to tell which pair is playing if blindfolded. The main difference is the Yams will be sucking less than 2W each, whereas the E-IX will be drawing 20-30W each.
 
I have heard many tiny speakers play at high levels, but never well to my ears. I always hear the compression, distortion, or just that weirdness you get from a driver bobbing in and out an inch or so and the mess that makes of the crossover region. I would never personally play a small speaker with dynamic peaks hitting above say 95db or so absolute tops at a metre (i.e. 80db or so median). If I want more level than that I’d always buy something bigger. It is basic physics; to go loud and deep a tiny driver needs to move a very long way, and that is never a good thing IMO. The magic of small speakers is in the nearfield, and there one doesn’t need high levels.
100% true !
 
Putting the issue slightly differently: what are the major differences (assuming for now that build quality doesn't put one at a disadvantage) between 15W of T-amp chip type power and 15W of valve power?
Granted there are now lots of chip amps and equally (still) lots of ways of doing valves, but from the point of view of the speaker/amp interaction is there an obvious difference?
(Last time I did anything like this it was a T amp into a pair of Goodmans Magnum K2 in a village hall, fine but just didn't go loud.)
 
Putting the issue slightly differently: what are the major differences (assuming for now that build quality doesn't put one at a disadvantage) between 15W of T-amp chip type power and 15W of valve power?
Granted there are now lots of chip amps and equally (still) lots of ways of doing valves, but from the point of view of the speaker/amp interaction is there an obvious difference?
(Last time I did anything like this it was a T amp into a pair of Goodmans Magnum K2 in a village hall, fine but just didn't go loud.)
Alot depends on the individual amp, my experence with t amps is they don't like low impedance speakers, but apart from that it's your choice
 
I had a TPA3116 amp, not very good with JBL Control 1's, tried a Topping PA3, again not a success but changing my speakers to Mark Audio Cesti MBR's and the Topping works fine, didn't get chance to try the chip amp, the power input connector was faulty so I cannot say how well the Cesti's would work with that, but I'm sure they would be ok with 6-10w of valve amp. This is what it says on the website, but not my findings, same as speaker positioning, they say start with them placed 1mtre away from the wall, but I have them placed 26cm from the wall

AMPLIFIER REQUIREMENTS:

These recommendations can only be used as a guide. Over-driving the loudspeakers risks damaging the drive units


Class A/B @ 8 Ohm Per Channel:

50W to 100W

Class A @ 8 Ohm Per Channel:

12W to 25W

Class D @ 8 Ohm Per Channel:

30W to 60W

They a a lovely sounding speaker, but I would also consider the Klipsch mentioned above.
 
I had a TPA3116 amp, not very good with JBL Control 1's, tried a Topping PA3, again not a success but changing my speakers to Mark Audio Cesti MBR's and the Topping works fine, didn't get chance to try the chip amp, the power input connector was faulty so I cannot say how well the Cesti's would work with that, but I'm sure they would be ok with 6-10w of valve amp. This is what it says on the website, but not my findings, same as speaker positioning, they say start with them placed 1mtre away from the wall, but I have them placed 26cm from the wall

AMPLIFIER REQUIREMENTS:

These recommendations can only be used as a guide. Over-driving the loudspeakers risks damaging the drive units


Class A/B @ 8 Ohm Per Channel:

50W to 100W

Class A @ 8 Ohm Per Channel:

12W to 25W

Class D @ 8 Ohm Per Channel:

30W to 60W

They a a lovely sounding speaker, but I would also consider the Klipsch mentioned above.

I'm afraid the above is just rubbish! 15W is 15W whether it comes from valves, transistors or little cotton bags of magic beans...
 
Well you could be correct Jez, but it often seems to me that valve amps seem to give more, only my feeling when listening
 
Well you could be correct Jez, but it often seems to me that valve amps seem to give more, only my feeling when listening
As ever it depends. Just taking the example that Jez gave of a 15W amp. If that amp is driving into say a 6Ohm resistive load than yes he is absolutely correct. However speakers are a reactive load and different speakers present different loads over their frequency range.

My speakers have a nominal load of 6Ohms but over the treble frequencies this drops to around 2Ohms. Now there are different ways to design and then build amps and one may handle that 2Ohm load and others may clip and distort. Another factor is phase angle. With a resistive load the current is proportional to the applied voltage but with a reactive load the current may lag or even lead the Voltage. What this means in practice is that as the angle between Voltage and the current drawn increases less power is used to drive the speakers and more is wasted as heat in the amplifiers output devices. In which case that 15W amp doesn't deliver 15W into the speaker load all the time so may clip and overheat.

Its a difficult subject as the loading of loudspeakers varies enormously and to build an amp that can cater for all possibilities would be a big and costly exercise. Hence the range of different approaches to amplifier design that we see.

I am afraid that with speakers its a case of suck it and see. First does the speaker work into the room and then does the amp drive them to your satisfaction. Another approach is to take an all-in-one such as the Meridian DSP system where everything has been designed to work in harmony. However this is not a cheap option and also needs the physical space.

Cheers,

DV
 
15W is 15W at the end of the day.

What I'm not prepared to do is spend a great deal of time going into the endless in's and out's of every possible load and amplifier type.
 


advertisement


Back
Top