Hi
Does anyone have experience of Wilmslow Audio crossovers and specifically the Wilmslow Audio Forte speakers. I have recently purchased, and rebuilt a pair of these speakers and whilst they are ok, they don’t sound to me anywhere near their potential (considering the drivers) and are a bit fatiguing to listen to – especially at anything over moderate volume.
The Forte is a 50 litre 3 way design using the following drivers:
Treble: Seas T25CF-002 Millennium
Midrange: ATC SM75-150
Bass: Scan-speak 25w8565-01
Crossover points:
500Hz
4kHz
The crossovers are designed by WA as part of the Forte kit, and to my relatively inexperienced eye look fairly basic for a 3 way design - containing Hovland caps in treble, SCR caps for bass and inductors only. There are no resistors in the crossover, padding on the drivers or sound equalisation that I can see.
When I stripped them down I was surprised at how little damping materials were used in the cabinet – Id say maybe 60% of the internal surface area was covered with bitumen backed acoustic foam panels – the rest was plain MDF. Before I rebuilt them they sounded a little boomy to me so when rebuilding them I added a small internal cross brace and heavy duty ‘deadsheet’ bitumen panels to most of the internal surfaces and reinserted the existing acoustic foam panels.
The cabinets are definitely better damped now, but to my ears the drivers still don’t sound optimised. With the drivers above these speakers should sound excellent, however whilst they are very clear the sound to me is a bit fatiguing and considering there are 10’’ bass speakers and 50l cabinets the bass sounds a little recessed at times compared with the midd / treble which sound a little too promient (especially compared with my other commercial speakers (Peak Consult Princess and AVI active ADM9.1).
I emailed Wilmslow Audio and asked about driver matching and how baffle diffraction loss (or baffle step) compensation was implemented and they said it was through the values of the capacitors and inductors.
I would be grateful for any views or tips as to what I can do to improve these speakers? Im fairly new to all this.
Does anyone have experience of Wilmslow Audio crossovers and specifically the Wilmslow Audio Forte speakers. I have recently purchased, and rebuilt a pair of these speakers and whilst they are ok, they don’t sound to me anywhere near their potential (considering the drivers) and are a bit fatiguing to listen to – especially at anything over moderate volume.
The Forte is a 50 litre 3 way design using the following drivers:
Treble: Seas T25CF-002 Millennium
Midrange: ATC SM75-150
Bass: Scan-speak 25w8565-01
Crossover points:
500Hz
4kHz
The crossovers are designed by WA as part of the Forte kit, and to my relatively inexperienced eye look fairly basic for a 3 way design - containing Hovland caps in treble, SCR caps for bass and inductors only. There are no resistors in the crossover, padding on the drivers or sound equalisation that I can see.
When I stripped them down I was surprised at how little damping materials were used in the cabinet – Id say maybe 60% of the internal surface area was covered with bitumen backed acoustic foam panels – the rest was plain MDF. Before I rebuilt them they sounded a little boomy to me so when rebuilding them I added a small internal cross brace and heavy duty ‘deadsheet’ bitumen panels to most of the internal surfaces and reinserted the existing acoustic foam panels.
The cabinets are definitely better damped now, but to my ears the drivers still don’t sound optimised. With the drivers above these speakers should sound excellent, however whilst they are very clear the sound to me is a bit fatiguing and considering there are 10’’ bass speakers and 50l cabinets the bass sounds a little recessed at times compared with the midd / treble which sound a little too promient (especially compared with my other commercial speakers (Peak Consult Princess and AVI active ADM9.1).
I emailed Wilmslow Audio and asked about driver matching and how baffle diffraction loss (or baffle step) compensation was implemented and they said it was through the values of the capacitors and inductors.
I would be grateful for any views or tips as to what I can do to improve these speakers? Im fairly new to all this.
Never used one but it is my understanding that the ATC mid needs a fairly complex xover to work at its best. IIRC it needs some eq and steep filter slopes, though to my mind 24dB passive filters are probably not the best idea.
May be someone can chime in who has actually used them with a passive xo as I could easily be wrong.
May be someone can chime in who has actually used them with a passive xo as I could easily be wrong.
Thanks for your comment, the wilmslow crossovers look quite basic, no resistors. I'll post a schematic when I can scan it in.
Unless someone comes up with a good crossover for these speakers, your best bet would be to measure them and design a new crossover - Or stick them on ebay.
Take them back to Wilmslow Audio. Neil??? should be able to suggest some crossover changes to tweak the sound to your taste.
Failing that, ship them off to Troels, or some other experienced designer, for them to make you a bespoke crossover (not cheap inc shipping).
Or, you could buy a Berhinger DCX2496, and a 7.1 reciever and go active. In fact this would be the best way to find out whether you can get a nice sound out of the cabs (I am sure that you can). Buy second hand units of ebay, then flog them afterwards. You would likely not loose any money. One of the Pioneer recievers, the 912 (I forget the other model letters) was touted as being a giant killer when used for audio, so this should not be a bottleneck in term of quality. Many would say that the Behringer unit needs some modifications, but for a speaker sound tweaking experiment (finding a right balance) it should be fine. If you are on a DIY website, you should be able to bypass the crossover easily enough.
Let us know how you get on.
Failing that, ship them off to Troels, or some other experienced designer, for them to make you a bespoke crossover (not cheap inc shipping).
Or, you could buy a Berhinger DCX2496, and a 7.1 reciever and go active. In fact this would be the best way to find out whether you can get a nice sound out of the cabs (I am sure that you can). Buy second hand units of ebay, then flog them afterwards. You would likely not loose any money. One of the Pioneer recievers, the 912 (I forget the other model letters) was touted as being a giant killer when used for audio, so this should not be a bottleneck in term of quality. Many would say that the Behringer unit needs some modifications, but for a speaker sound tweaking experiment (finding a right balance) it should be fine. If you are on a DIY website, you should be able to bypass the crossover easily enough.
Let us know how you get on.
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schematic for Wilmslow audio forte
Hi Ive posted a photo of the crossover schematic here:
P1030455 | Flickr - Photo Sharing!
Any thoughs as to the suitability of this crossover for the drivers Ive listed and whether members concur that there is no baffle correction or driver spl matching would be appreciated, also any quick tips to improve them.
Thanks again, really appreciate any help!
Roger
Hi Ive posted a photo of the crossover schematic here:
P1030455 | Flickr - Photo Sharing!
Any thoughs as to the suitability of this crossover for the drivers Ive listed and whether members concur that there is no baffle correction or driver spl matching would be appreciated, also any quick tips to improve them.
Thanks again, really appreciate any help!
Roger
Without any measurements it's quite a challenge to predict exactly how the crossover will perform. But from a few quick simulations, when looking at the filter transfer functions, it's clear that the loudspeaker might not be perfect for everyone.
The full space sensitivity of the scan bass unit is only ~82dB. Now its position in the loudspeaker could increase this depending on how close it is to the floor, but nevertheless you'd be looking at around an end system sensitivity of around say 85-86dB, re 2.83volts. The fact both the mid and the tweeter are run full tilt would probably give the loudspeaker an output that rises with frequency and as a result would explain why they could be fatiguing.
The full space sensitivity of the scan bass unit is only ~82dB. Now its position in the loudspeaker could increase this depending on how close it is to the floor, but nevertheless you'd be looking at around an end system sensitivity of around say 85-86dB, re 2.83volts. The fact both the mid and the tweeter are run full tilt would probably give the loudspeaker an output that rises with frequency and as a result would explain why they could be fatiguing.
Thanks for your input. The quoted sensitivity for the scan-speak is 88db - I guess this must be half space then? It sounds like as I suspected wilmslow haven't included very much driver spl matching or baffle loss correction, despite their reply to my query statin that the inductor and capacitor values accounted for this. The speakers don't sound awful, they sound clear and precise at low volumes and can produce bass as would be expected with 10" driver and relatively large cabinet. It's the midd and treble esp upper mid that become excessive and fatiguing particularly at medium volume upwards. Do you think l-pads on the midd and treble would improve them? Another poster indicated that the ATC midd needs steep slopes and some EQ to sound it's best - both of which I think are missing in the current crossover. It's a shame I think the drivers have potential!! Unfortunately I don't have any means to measure them (other than my ears)
Thanks again!
Thanks again!
The drivers most certainly have a lot of potential, both in their performance and in the bandwidths they are capable of producing.
The SEAS tweeter can be used down quite low due to it's generous linear xmax (linkwitz uses it down to 1440hz with 4th order acoustic slopes), whilst at the same time the ATC mid-dome can be used up to around 3.5khz, so there's plenty of room for experimentation.
The Scan unit should be capable up to around 800hz with the ATC wanting around 400hz as it's lowest, again there's a decent amount of room for playing around there.
Personally I would go for 4th order acoustic slopes between the bass and midrange and at about 400-500hz. This would keep the demands placed on the ATC quite reasonable, while probably using the Scan unit within the better part of its bandwidth.
I'd then crossover somewhere between 2-3.5khz between the ATC dome and the SEAS tweeter, again with 4th order acoustic targets. I'd be aiming for the best phase integration between the two drivers and due to the large area of where a possible xover could exist, this shouldn't be too difficult.
You are quite right when you say the loudspeaker doesn't appear to correct for baffle step losses and yes, the 88dB is into half space.
It is possible that the midrange and tweeter integration is perfectly acceptable, the filter on the ATC does provide a downward sloping response profile, some of that would be necessary to correct for the hump in the ATCs upper end response (I seem to remember it having one from Shinobiwan's measurements) so it could bring the midrange in line with the tweeters 89dB sensitivity figure.
I think that the filters used by Wilmslow audio will probably do a decent job of integrating the drivers, but on what would appear to be a budget. Considering what the ATC appears to need to get the most out of it, a simple 4 element xover probably isn't going to cut it and as the ATC dome is supposed to be the stand-out driver of the system, it's odd that it's potential, most likely, hasn't been fully realised.
Steep slopes would imply 4th order acoustic targets. A 2nd order electrical filter used at the upper and lower ends of a drivers response will usually be enough to arrive at 4th order acoustic targets.
Lpads are unlikely to be of any use as they will also affect how the filters interact with the drivers, we are assuming here that they do a decent enough job already. If you wanted to try attenuating the drivers a bit I would use a series resistor placed after the xover, although not perfect it should allow you to have a play around without affecting the frequency response too badly.
If you have a second integrated amplifier handy one thing you could try is powering the mid/tweeter section from that amp and then the bass driver from another, this would allow you to increase the bass output, it might have a pleasing effect. The trouble with baffle step compensation though is that it is designed into the xover for the drivers, so usually, altering the level of the bass wouldn't help correct for the lack of compensation. You could try a PLLXO, that is a passive line level cross over, between your CD player and your amp etc, that would correct for baffle step losses.
Passive Line Level Baffle Diffraction Step Compensation
The SEAS tweeter can be used down quite low due to it's generous linear xmax (linkwitz uses it down to 1440hz with 4th order acoustic slopes), whilst at the same time the ATC mid-dome can be used up to around 3.5khz, so there's plenty of room for experimentation.
The Scan unit should be capable up to around 800hz with the ATC wanting around 400hz as it's lowest, again there's a decent amount of room for playing around there.
Personally I would go for 4th order acoustic slopes between the bass and midrange and at about 400-500hz. This would keep the demands placed on the ATC quite reasonable, while probably using the Scan unit within the better part of its bandwidth.
I'd then crossover somewhere between 2-3.5khz between the ATC dome and the SEAS tweeter, again with 4th order acoustic targets. I'd be aiming for the best phase integration between the two drivers and due to the large area of where a possible xover could exist, this shouldn't be too difficult.
You are quite right when you say the loudspeaker doesn't appear to correct for baffle step losses and yes, the 88dB is into half space.
It is possible that the midrange and tweeter integration is perfectly acceptable, the filter on the ATC does provide a downward sloping response profile, some of that would be necessary to correct for the hump in the ATCs upper end response (I seem to remember it having one from Shinobiwan's measurements) so it could bring the midrange in line with the tweeters 89dB sensitivity figure.
I think that the filters used by Wilmslow audio will probably do a decent job of integrating the drivers, but on what would appear to be a budget. Considering what the ATC appears to need to get the most out of it, a simple 4 element xover probably isn't going to cut it and as the ATC dome is supposed to be the stand-out driver of the system, it's odd that it's potential, most likely, hasn't been fully realised.
Steep slopes would imply 4th order acoustic targets. A 2nd order electrical filter used at the upper and lower ends of a drivers response will usually be enough to arrive at 4th order acoustic targets.
Lpads are unlikely to be of any use as they will also affect how the filters interact with the drivers, we are assuming here that they do a decent enough job already. If you wanted to try attenuating the drivers a bit I would use a series resistor placed after the xover, although not perfect it should allow you to have a play around without affecting the frequency response too badly.
If you have a second integrated amplifier handy one thing you could try is powering the mid/tweeter section from that amp and then the bass driver from another, this would allow you to increase the bass output, it might have a pleasing effect. The trouble with baffle step compensation though is that it is designed into the xover for the drivers, so usually, altering the level of the bass wouldn't help correct for the lack of compensation. You could try a PLLXO, that is a passive line level cross over, between your CD player and your amp etc, that would correct for baffle step losses.
Passive Line Level Baffle Diffraction Step Compensation
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