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Subs with electrostatics; is this a tricky one?

Years ago I tried to build an active sub for my ESL63s. It was based on a Goodmans Magister cabinet and 15" driver, and it was a failure. Fast forward to a couple of years ago, I got a car sub amp and XO, a couple of sealed box car 12" subs (Vibe brand IIRC) and bodged together a chunky 12V SMPS. Stuck it all on the carpet behind my ESL57s. It was only a bit of fun, I expected to throw it away after a play. Guess what? It integrates perfectly, the only debate is how much bass reinforcement is required. I favour very little, a pal of mine with monster Tannoys with 2x 15" HPDs *each* unsurprisingly favours a little more.

Maybe I just got lucky, but it works.
 
The relationship between bass and treble is a difficult one, or at least a confusing one. Many years ago I was using the Linn Acitv crossover with my Isobariks. Linn introduced the bingo modification that extended the bass response to be essentially flat down to 20hz in room. I installed the bingo board, and in those days I was only using vinyl - the improvement was immediately apparent, the midrange and treble clarity was dramatically improved - why?
 
JemHayward said:
The relationship between bass and treble is a difficult one, or at least a confusing one. Many years ago I was using the Linn Acitv crossover with my Isobariks. Linn introduced the bingo modification that extended the bass response to be essentially flat down to 20hz in room. I installed the bingo board, and in those days I was only using vinyl - the improvement was immediately apparent, the midrange and treble clarity was dramatically improved - why?
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As a former owner of Isobariks, my mind boggles that anyone would want to extend the subterranean bass properties of these speakers. I've had quite a few big speakers since, but have never come near the quick, deep, dry bass of the Briks. :) However, that was their one redeeming feature, i.m.o.
 
Mike Reed said:
As a former owner of Isobariks, my mind boggles that anyone would want to extend the subterranean bass properties of these speakers. I've had quite a few big speakers since, but have never come near the quick, deep, dry bass of the Briks. :) However, that was their one redeeming feature, i.m.o.
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Oddly enough, in the vinyl era, having the in-room bass flat to 20hz (in my room with the passive x-overs it was about 6dB down at 35hz - I think, this was 14 years ago!) - made relatively little difference to the amount of bass, but the increase in midrange clarity was quite a shock. A friend still has those speakers in a huge room in Paris and they still sound pretty good, but things do move on. I now use ML Summits and the bass is superior to anything Isobariks ever did active or passive and by quite a margin really.

Some good modern recordings have a lot going on in the 40hz zone and below so speakers able to differentiate bass frequencies with spot on timing are important. Jon Hopkins' Insides and James Blake's eponymous album are on my regular playlist.
 
JemHayward said:
The relationship between bass and treble is a difficult one, or at least a confusing one. Many years ago I was using the Linn Acitv crossover with my Isobariks. Linn introduced the bingo modification that extended the bass response to be essentially flat down to 20hz in room. I installed the bingo board, and in those days I was only using vinyl - the improvement was immediately apparent, the midrange and treble clarity was dramatically improved - why?
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Phase alignment between the LF and the rest. That's the main reason to extend bass very low.

You can get a similar effect by using the subsonic filter in for example a 640P phono stage. If you switch the subsonic filter in, most of the ambience disappears.
 
S-Man said:
Phase alignment between the LF and the rest. That's the main reason to extend bass very low.

You can get a similar effect by using the subsonic filter in for example a 640P phono stage. If you switch the subsonic filter in, most of the ambience disappears.
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Ah, yes, that rings a bell. I had a few records that made the bass cones on my 'briks pump quite alarmingly, so I built a switchable subsonic filter that reduced the levels below about 30hz. On white and pink noise it was completely inaudible, and it certainly stopped the wobbly cone issue, but everything sounded awfully flat.
 
That has more to do with the RIAA filters intruding into the audio range than any phase issue.
Most RIAA LF filters are audibly thinning bass output because the slopes used are too shallow and the corner frequency is set too high.

It's possible to build such filters keeping variation to around 1dB at 30Hz while still giving reasonable attenuation at and below 10Hz.
It does require more than a single pole filter though, and this tends to send some into unnecessary panic.
The intermodulation distortion and time errors caused by wildly flapping cones is the worse of the two evils IME.
 
JemHayward said:
- the improvement was immediately apparent, the midrange and treble clarity was dramatically improved - why?
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Imagine the following signal, which stands here as a model for playing a single note:

-a few seconds silence
-then 2 seconds of 80Hz sine (i.e. key on, wait, key off)
-a few seconds silence

Now what is the spectrum of that signal? How much does it extend below and above 80Hz?

What would happen if that signal were subject to a mild high-pass at 40Hz, say a 3rd order (which is more bening than reality, from microphone to eardrums)?
 
Robert, you may be right, although my experience is that the more poles you add to the filter, even below the lowest audible frequenices, the more the sound is affected. This leads me to conclude it is the phase that is affected not the amplitude.
I have not done enough measurements to prove it though.

Whatever, I seek to have the lowest order LF rolloff I can throughout my entire system and I am pleased with the results.
 
S-man - I had a very similar experience experimenting with the two LPF through my system varied over a 10:1 range where even the highest was well below the speaker cut-off (rolling-down from 16Hz to 1.6Hz for example). Changes were far more audible than than the expected, modelled odd dB variance in the bottom octave or two.
 
S-Man said:
Robert, you may be right, although my experience is that the more poles you add to the filter, even below the lowest audible frequenices, the more the sound is affected. This leads me to conclude it is the phase that is affected not the amplitude.
I have not done enough measurements to prove it though.

Whatever, I seek to have the lowest order LF rolloff I can throughout my entire system and I am pleased with the results.
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I would agree generally, partly because high order filters simply aren't necessary in many parts of the system interface, but I make an exception for LP replay because the potential for sonically damaging sub 20Hz crud impacting everything that sits above is greater IMO.
 
JemHayward said:
I now use ML Summits and the bass is superior to anything Isobariks ever did active or passive and by quite a margin really.
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That's interesting, Jem, but hardly credible comparing one 10" in the ML (??) against the two big KEFs in the Briks. However, as you say, things move on and memories tend not to be too accurate !:)

I was seriously toying with Summit Xs as an alternative to the 2905s, but cost and placement considerations (and that they're not British) steered me to all electrostatics. Wouldn't mind trying out some hybrids like the Summits, though.
 
Mike Reed said:
That's interesting, Jem, but hardly credible comparing one 10" in the ML (??) against the two big KEFs in the Briks. However, as you say, things move on and memories tend not to be too accurate !:)

I was seriously toying with Summit Xs as an alternative to the 2905s, but cost and placement considerations (and that they're not British) steered me to all electrostatics. Wouldn't mind trying out some hybrids like the Summits, though.
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Speaker size has no exact relation to bass output properly set up considering many factors room size the kit too etc small speakers can sound amazing & do big tight bass my Proac studio 100s are superb on their dedicated target R1 stands they are super fast highly detailed too I have got a good room solid brick walls :)
Also I feed mine though a Bryston 4B ST good amps need current to drive not necisarilly big watts but it does do wonders have tried the smaller 3B ST no where near the head room so I sold it.

Ok so some of you may question saying what do I know ? well having heard many hifi's at shows round people's houses etc been disappointed too many times given the money spend then you get the wow kit that really shines & I am talking about set ups that cost around £15000 to £50000 +

It's all too easy to be mesmerised by something thinking it's better without looking at the whole picture which is where many of our hobbies go inc this hifi one :D
I've got a few Ks worth in lounge but spent time tweaking it & will continue to do so cos it evolves but not changed any kit for over 4 + years the mistake box swappers do you never know how good it can be ? I just get stuff that sounds good & works well with each other then take time to get the best out of it.
 
Mike Reed said:
That's interesting, Jem, but hardly credible comparing one 10" in the ML (??) against the two big KEFs in the Briks. However, as you say, things move on and memories tend not to be too accurate !:)
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Look underneath the Summits - theres another 10" driver down there and a dedicated power amp and electronic crossover. I was looking for something that at least got close the the bass quality of active isobariks, but in reality, the MLs are better, though I will say I've not used them in the same rooms.
 
Mike Reed said:
That's interesting, Jem, but hardly credible comparing one 10" in the ML (??) against the two big KEFs in the Briks. However, as you say, things move on and memories tend not to be too accurate !:)
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A B139 is about the same radiating area as a 10", and "Isobarik" loading doesn't give you the output level of two woofers, since they're in acoustic series.
 
Mike Reed said:
That's interesting, Jem, but hardly credible comparing one 10" in the ML (??) against the two big KEFs in the Briks. However, as you say, things move on and memories tend not to be too accurate !:)
.
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The finger of doubtful credibility points firmly in your direction, Mike, given the amount of utter tosh you continually post on this forum

Mark
 
Well said Mark the big problem with many 'enthusiasts' is that they try to create solutions for problems that needn't exist in the 1st place why mess about with electrostats with no bass then need to piddle around for weeks/months with subs to correct them (subs are for cinema really anyhow) if the speakers you've got are 'top proacs' already thus they should be very good any sound related problems exist elsewhere in the system wrong room type the components,wiring and/or isolation how the kit is physically setup !
 
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