Scanspeak mid/bass and tweeters??

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Hello there, new to the forum and looking for some help and advice from some you learned gentleman.


I have a pair of Acoustic Energy Radiance Ones, I bought them as seconds from AE on Ebay and they were really cheap. Less than £300 the pair.
Anyway about 12 months ago I swapped out the tweeters for Scanspeak D3004/660000 Tweeters - Illuminator. I'm really pleased with this upgrade, it works really well with no modification to the XO. Now I am looking to swap out the bass/mid units to a pair of 15/W4531GOO. These are the undoped 4 ohm version. The reason I have picked the 4ohm is because the AE mid/woofer has 5 ohm stamped on the magnet.
My question is this, will the existing XO be suitable with the upgrade I am planning. Physically the units are a perfect fit and I've seen speaker kits using about the same cabinet. All I know about the AE XO is that it's a 2nd order 12db and crossover at 2500khz. I suppose the obvious thing to do is to try them and see how they sound. On the face of it, they should be fine. However as you might expect having spent a fair bit on top quality units I don't want to compromise their performance for the sake of spending a few bob on a new XO.


Thank you to all in anticipation of your responses.


Ron


 
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Not really, it's just a 1st order electrical + notch on the midbass and a 2nd order electrical with Fs impedance notch (to prevent chronic distortion) on the tweeter with a series level padding resistor. The additional system impedance notch is optional.

As noted, those are superb drivers of their type and trying to wing it with a filter that is not designed for either their impedances (impedance is not a nominal: it varies with frequency, and is different for all drivers) or inherent frequency responses on a given baffle (ditto) is a recipe for not getting the best from them, or even half-decent results. Would that it worked that way: unfortunately it doesn't. You can try it, obviously. Your money, your life, your choice. You may even like the results. But you won't know what they can really do, and will be sacrificing a lot of performance in doing so. Brutal, but honest. Seriously, the advice above is good. Those are superb drivers. Don't waste them, your time and money. Do it right. You'll thank yourself (and maybe even those who advised you to do so ;) ) in the long run.
 
If you are set on winging it, then you could probably get close to a reasonable result by poaching another design using 15W4531 and a "similar" tweeter.

However, as Scottmoose says, there is more to it than matching simple characteristics such as efficiency. Several variables including impedance (not nominal) need consideration.

I have a XO for 15W4531 and R2904/70000 if you would like it. I haven't compared the R2904 tweeter with yours. You can do that!
 
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I have found some reference to an AOS kit using 15W4531 and D3004/660000, but it is not on their website. It may have been a special one-off.

Get in touch with Axel at AOS. He is a nice guy, and speaks good English. If he has designed a crossover, then I suspect that he would want you to buy a completed one from him. It is his business after all.

Scan-Speak
 
Job's a good 'un.

Is there a (standard ) crossover I can buy for these two units working together?

No. Short version:

-All loudspeaker drive units possess an inherent frequency response that is different from other loudspeaker drive units.

-The above frequency (and phase) response changes when you put it in a loudspeaker enclosure. How it changes varies (significantly) depending on the size and shape of the enclosure baffle, and where the driver is positioned on said baffle.

-All loudspeaker drive units possess an inherent impedance response that is different from other loudspeaker drive units. It varies with frequency, and is not a flat line with a fixed value (a numeric nominal figure).

-The above impedance response further changes when you place the driver in an enclosure. How, varies (significantly) depending on the type of enclosure, its volume, tuning etc. This is therefore even less of a flat line with a fixed value than it was under basic test conditions.

There is no such thing as a 'standard' crossover. There are a number of off-the-shelf generic filters that use fixed values for a fixed electrical slope. However, these take no account whatsoever of the massive frequency response variations mentioned above, which instantly alter behaviour, and further assume that impedance is a fixed flat line, which as also mentioned above, it isn't, and further massively affects the end result. Note that when I say 'massively' I don't mean 'a tiny little bit here and there'. I mean potentially gigantic deviations and fluctutions in behaviour. This is why quality speakers have crossovers designed for them, rather than a few generic values dropped in, a British-Leyland 'that'll do', slurp of tea and wander back to the picket line. ;)

If you wish to use these drivers properly, and don't want to spend a long time learning how to measure loudspeakers and design filters (neither of which is a short process) then as has been advised, your best policy would be to build a quality existing design that uses them. Anything else and you're at best wasting their potential. None of which is meant to be discouraging. What we want is you to succeed and get a good speaker. Hence the reason we try to warn people about pitfalls; it's better to know them in advance. If you're struggling with building a filter from a given circuit diagram, there are people who may be able to / can help on that front.
 
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This is the existing crossover and the cabinet. Does this mean anything to anybody?
 

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If you are set on winging it, then you could probably get close to a reasonable result by poaching another design using 15W4531 and a "similar" tweeter.

However, as Scottmoose says, there is more to it than matching simple characteristics such as efficiency. Several variables including impedance (not nominal) need consideration.

I have a XO for 15W4531 and R2904/70000 if you would like it. I haven't compared the R2904 tweeter with yours. You can do that!




Thanks, have you got a pair and how much do you want for them?
 
Actually it does. See the legend below the graph. Black is on-axis frequency response under anechoic IEC test baffle conditions, with green and red 30 and 60 degrees off axis respectively under the same conditions. These will change significantly when you place them in an enclosure. Blue is the free-air impedance; this, most notably at lower frequencies, will also change significantly when the driver is mounted in an enclosure.
 
Thanks for that Scott, I thought it might be that. Looking at the frequency response of the drivers I'm using, it looks like there are lots crossover options depending on what type of sound you want.
There seems to be quite a bit of latitude on both drivers to play around with.
Anyway, I've decided to try my upgrade out first using my existing AE crossovers.
It a simple 2nd order12db/octave crossing over at 2500khz, hopefully it will be fine.

I ordered my drivers on Monday and they still haven't arrived so I e-mailed them regarding delivery and the question I asked about the crossover. They told me they had just got them packaged and ready to ship, but they still haven't shipped them yet and when I asked about the crossover, they said.


Hi Ron, sorry we get about 400 emails a day, it's hard to keep up and we sometimes mis one!
We've just packed the Scanspeaks for shipping.
On the crossover, if it's just ( as I would expect) a simple 2nd order without any notch filters, I'd see what the results were before diving in.
If you need crossover advice, we unfortunately don't have the time to be able to offer design services any more, but we can put you in touch with a colleague who is a whizz at this if you need this service.

Hope this is helpful.

Best wishes Jerry


I e-mailed them straight back and asked for the contact for the whizz kid, but they didn't reply.
Personally I think this is poor service, if they had the items in stock like they said, it shouldn't take four days to get them in the post. When I do get them I'll be sure to post my finding, good or bad.


Ron
 
Job's a good 'un.



No. Short version:

-All loudspeaker drive units possess an inherent frequency response that is different from other loudspeaker drive units.

-The above frequency (and phase) response changes when you put it in a loudspeaker enclosure. How it changes varies (significantly) depending on the size and shape of the enclosure baffle, and where the driver is positioned on said baffle.

-All loudspeaker drive units possess an inherent impedance response that is different from other loudspeaker drive units. It varies with frequency, and is not a flat line with a fixed value (a numeric nominal figure).

-The above impedance response further changes when you place the driver in an enclosure. How, varies (significantly) depending on the type of enclosure, its volume, tuning etc. This is therefore even less of a flat line with a fixed value than it was under basic test conditions.

There is no such thing as a 'standard' crossover. There are a number of off-the-shelf generic filters that use fixed values for a fixed electrical slope. However, these take no account whatsoever of the massive frequency response variations mentioned above, which instantly alter behaviour, and further assume that impedance is a fixed flat line, which as also mentioned above, it isn't, and further massively affects the end result. Note that when I say 'massively' I don't mean 'a tiny little bit here and there'. I mean potentially gigantic deviations and fluctutions in behaviour. This is why quality speakers have crossovers designed for them, rather than a few generic values dropped in, a British-Leyland 'that'll do', slurp of tea and wander back to the picket line. ;)

If you wish to use these drivers properly, and don't want to spend a long time learning how to measure loudspeakers and design filters (neither of which is a short process) then as has been advised, your best policy would be to build a quality existing design that uses them. Anything else and you're at best wasting their potential. None of which is meant to be discouraging. What we want is you to succeed and get a good speaker. Hence the reason we try to warn people about pitfalls; it's better to know them in advance. If you're struggling with building a filter from a given circuit diagram, there are people who may be able to / can help on that front.
This post should deserve another read...
The crossover you have already will be pretty much useless for your new drivers.

Shure it will do something, but you should make a crossover that fits the drivers + enclosure. You pay for the drivers. Make sure they can do their work properly. Lots of people around here that can help you achieve that.
 
Ok the speakers arrived and I popped them for a quick sound check. The bad news is they don't sound good. Far too much high frequency and mid range. I've spoke Paul at Reference Fidelity Components and he is trying to help me, but he thinks if I use an 4ohm mid/woofer with the four ohm tweeter, the final product might not be easy to drive and he thinks I would need a more powerful amp. This speaker DIY is far too complicated for me so I'm looking at other options. Has anybody on the forums listened to Wharfedale Diamond 11.2?


Ron
 
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Hi Ron
Don't give up.
As stated earlier, contact Axel Oberahge at AOS-Lautsprecher.de he speaks great English and is very helpful. He specialises in Scanspeak designs.
Click on: Scan-Speak
Axel sells a DIY design and kit for the Studio 10GL, which uses your exact drivers in a very similar cabinet. He will sell you a pre-made crossover.
I have had his Studio 12XL and regretfully sold them when crawling babies arrived at home. they were sublime.
 
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