Bigwig07

Stirling LS3/5a 11 ohms - Matching amplifier advce

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As part of my ongoing quest for meaty and detailed bookshelf speakers I've just managed to procure a set of these to play with (dating from 2012). I'm a box swopper.

Now the impedance is 11 ohms which has thrown me a bit. Stated power handling is 60w continuous, 110w short term. Sensitivity is 83dB

From checking on the internet it seems that most people use low power amps, vintage amps or tube amps with Ls3/5a's. I think despite the low sensitivity the 11 ohms means they are easier to drive, but I don't want to blow anything.

Now which of my amps would be ok or might work best ? (There's probably some maths here)

Roksan Caspian M2 - Probably my best amp, 125w into 4 ohms, 85w into 8 ohms, so about 60w into 11 ohms ?

Roksan Oxygene - Class D amp, lovely lush sound - 150w into 4 ohms, 75w into 8 ohms, ? into 11 ohms

Marantz PM 8200 - Great old midrange amp, c20 years vintage. 80w into 4 ohms, 60w into 8 ohms, ? into 11 ohms

I also have a Marantz PM15s1se rated at 90w into 8 ohms with a good phono stage but that will probably be too meaty

I listen to all sorts of stuff in a small/medium size room.

Thanks

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Super Wammer

It will be clipping that is more likely to damage the speakers, so do not overdrive the amp. I have some  8 ohm Ls35a's and have used 4 watt Valve amps and 200 wpc into 8 ohms solid state, all to good effect. In fact I have just got a new 500 wpc into 4 ohms amp, and cannot wait to try that with them. The B110 will usually bottom out when driven to hard, this you will hear!

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Super Wammer

I agree with greybeard. You won’t ‘accidentally’ overdrive them, assuming you’ve some mechanical sympathies! 

Actually, the PM15 Marantz would be fine, imo, though if you want period sound then tubes may be the answer.  That said, the 3/5as appeared when transistors were in the ascendant.  And they were meant to sound accurate, not cuddly!  

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8 minutes ago, greybeard said:

It will be clipping that is more likely to damage the speakers, so do not overdrive the amp. I have some  8 ohm Ls35a's and have used 4 watt Valve amps and 200 wpc into 8 ohms solid state, all to good effect. In fact I have just got a new 500 wpc into 4 ohms amp, and cannot wait to try that with them. The B110 will usually bottom out when driven to hard, this you will hear!

What he said - try em all and see which sounds best.  

Generally amps are about half their rated power at 16 ohms compared to 8 (I am no engineer but I do know that it is never guaranteed amps doubling their output when comparing 4 ohms to 8) so I would work on the fact that the value at 11 ohms is approx 25% less than the rated value at 8 ohms.

I would have expected the Caspian to give out about 63 watts

I would have thought the Oxygen would put out about about 56 watts   

I would expect the Marantz 8200 about 45 watts 

I would expect the Marantz PM15 about 67.5 watts.

That is provided i have done my maths right .. and my assumption of halving power to 16 ohms is correct.

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Thanks - so basically I'm ok if I don't push the volume up too much. How will I know when it starts to get too much ?

I'm looking forward to playing with them

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Super Wammer
2 hours ago, Bigwig07 said:

Thanks - so basically I'm ok if I don't push the volume up too much. How will I know when it starts to get too much ?

I'm looking forward to playing with them

A speaker driver has exceeded the physical limit of it's voice coil travel when it "bottoms out". Long story short: The loud clacking noise is the voice former (a short cylinder glued to the back of the speaker cone around which the voice coil wire is wound) slamming into the speaker's back plate after being driven out of the voice coil gap (cylindrical slot formed by the pole piece and magnet assembly) by too large a signal and/or a frequency below its operating bandwidth.

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6 hours ago, Bigwig07 said:

Thanks - so basically I'm ok if I don't push the volume up too much. How will I know when it starts to get too much ?

I'm looking forward to playing with them

The problem with an underpowered amp overdriven is it runs into distortion and the distortion burns out the tweeter.  With regards to the bass unit - it is possible to damage the driver by overdriving and hitting the backstop.  

The thing to remember is this loudspeaker is not made to be a high output monitor and so do not try partying with it, especially in a largish room as it will more than likely end up with damaged drivers..

Loudspeakers usually start to sound ragged and rough when they are overdriven - which is the warning but the problem is if you are at that level and then there is a massive bass transient, it is a bit too late to turn it back as by then it will probably have popped the bass unit.  However, if the amp is underpowered then when it runs into distortion you should hear the top end frequencies becoming ragged and distorted but there again you may not until the tweeter burns itself out and stops working.

At a show at Heathrow many years ago one exhibitor (Peter Marshall with his Profile 11 loudspeakers) was using an FM Acoustics amp (which was rated at over 200 watts a side) and was playing at very high levels in a very large hotel conference/function type room.  He left the room and his assistant put on a punters copy of Telarc 1812 at very high volume and all was fine ... until the cannon shots, where one bass unit broke (hit the back stop and tore the cone from the spider behind).   That was a large 3 way loudspeaker and we sold quite a few pairs and never had a similar incident I should add but i do not think any of our customers had them to use in a large conference room.. 

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Posted (edited)

My Dad had some old Brahms floorstanders (anybody remember those ?) in the seventies and he used to turn it up, probably after another argument with my Mum, and I remember hearing the cannons from the 1812 overture about 100 meters up the street !

Anyway I am beginning to think that the LS3/5a s might not be for me, but I’m tempted to buy and try anyway

Edited by Bigwig07
Typo

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Super Wammer
1 hour ago, Bigwig07 said:

My Dad had some old Brahms floorstanders (anybody remember those ?) in the seventies and he used to turn it up, probably after another argument with my Mum, and I remember hearing the cannons from the 1812 overture about 100 meters up the street !

Anyway I am beginning to think that the LS3/5a s might not be for me, but I’m tempted to buy and try anyway

Have you ever heard the 3/5a?  If you haven’t then imo you’d probably be better trying a mini monitor of a more modern design, like various Harbeth, Rogers, KEF, ProAc models.  Personally I like KEF LS50 but not everyone does. 

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2 hours ago, Nopiano said:

Have you ever heard the 3/5a?  If you haven’t then imo you’d probably be better trying a mini monitor of a more modern design, like various Harbeth, Rogers, KEF, ProAc models.  Personally I like KEF LS50 but not everyone does. 

Yes I used to own a pair of KEF LS50's - excellent with a lot of music but I found them a bit 'hit and miss'. I suppose I just want to try the LS3/5 a because of its reputation. I also own some other nice standmounts to compare with it

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Posted (edited)
10 minutes ago, Bigwig07 said:

Yes I used to own a pair of KEF LS50's - excellent with a lot of music but I found them a bit 'hit and miss'. I suppose I just want to try the LS3/5 a because of its reputation. I also own some other nice standmounts to compare with it

There is too much nostalgia on LS3 5As.  They are a great little speaker but if you want to play led zep at volume and get meaty bass this is not the speaker for you.  To my ears there were other small loudspeakers that did the job so much better (KEF 101, Jim Rogers 149s etc).  I always think of them as "headphone" loudspeakers where you need to play music at low levels when everyone is in bed and you do not want to wake them up.

It is also a misnomer to call a hifi speaker a bookshelf as invariably if you used them on a book shelf they will never sound at their best.  That means getting appropriate stands (another feat in itself finding the ideal ones for you and ones that the missus thinks do not look like an industrial structure not to be seen in the lounge).  In most cases a pair of neatly dimensioned floor standers take up the same footprint and if you choose well, in most cases will provide even more of what you want.  A pair of Totem floor standers will surprise many with the bass extension they achieve for such a small footprint. 

Personal view is find a pair of well designed great sounding floor standers unless you live in a bedsit and you really have to use a bookshelf speaker on a bookshelf.

Edited by uzzy
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Posted (edited)

I’ve got a pair of Stirling LS35a.  An easy drive. I was using mine with a Leak St20.  They work particularly well with valves.

Amp matching was the easy part. Finding the right stands and positioning was what took time to get right.  The position and stands are basically the only things to fix the treble. Stands can be transformative, unlike other larger BBC ‘speakers.

I enjoy mine massively but agree LS3/5a are overrated in comparison to contemporary ‘speakers like this BC1 or SP1.

I certainly prefer Stirling to vintage LS3/5a. 

Edited by HectorHughMunro

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On ‎09‎/‎06‎/‎2019 at 00:11, HectorHughMunro said:

I’ve got a pair of Stirling LS35a.  An easy drive. I was using mine with a Leak St20.  They work particularly well with valves.

Amp matching was the easy part. Finding the right stands and positioning was what took time to get right.  The position and stands are basically the only things to fix the treble. Stands can be transformative, unlike other larger BBC ‘speakers. 

I enjoy mine massively but agree LS3/5a are overrated in comparison to contemporary ‘speakers like this BC1 or SP1.

I certainly prefer Stirling to vintage LS3/5a. 

Thanks - how did you resolve the stands and positioning ?

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Posted (edited)
1 hour ago, Bigwig07 said:

Thanks - how did you resolve the stands and positioning ?

There is actually a LS3/5a community on Yahoo. The consensus there is to place in free space away from walls (ie not how the BBC did it).

For stands, IFDesigns Tallis were the gold standard but these are not manufactured now and change hands for silly money but if you’ve tried them, you’ll understand why.  Foundation Designer II are next on the list; these are particularly prized in Asia where they weren’t able to get the Tallis.  After that, open frames like the old Linn Kan stands or Something Solid XF.  LS3/5a are more stand dependent than other, larger BBC ‘speakers.   Partington Dreadnought are also well regarded. 

Edited by HectorHughMunro

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1 hour ago, HectorHughMunro said:

There is actually a LS3/5a community on Yahoo. The consensus there is to place in free space away from walls (ie not how the BBC did it).

For stands, IFDesigns Tallis were the gold standard but these are not manufactured now and change hands for silly money but if you’ve tried them, you’ll understand why.  Foundation Designer II are next on the list; these are particularly prized in Asia where they weren’t able to get the Tallis.  After that, open frames like the old Linn Kan stands or Something Solid XF.  LS3/5a are more stand dependent than other, larger BBC ‘speakers.   Partington Dreadnought are also well regarded. 

Thanks I have some Partington Dreadnoughts. Job done

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