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Multi-Way Conventional loudspeakers with crossovers

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Old 28th October 2009, 11:56 AM   #1
edross is offline edross  United Kingdom
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Join Date: Oct 2009
Location: Bath, UK
Default New UK Member - first project

I am about to start my first DIY speaker project so I thought I would join here and say hi.

My project:

I have been thinking of a project for while now and have been tempted by some of the offerings at Wilmslow Audio. I currently have Proac 2.5's with a proac sub driven by Musical Fidelity 308 kit (cd, pre and power) but I have thought that some larger speakers with a bit more punch would be the way to go. I have always loved ATC 50's and 100's but are very expensive, even second hand so that has led me to the DIY route.

My problem with DIY has always been the aesthetics of the cabinets as I am about fussy about how they would look in my living space and have never been that confident that my efforts would be that attractive! The answer to my thinking would be to find a speaker box that I liked and modify it to take the drive units and crossover for my needs.

Sound; I really love the sound of the ProAc's its clear and well defined but lacking in the upper mid and bass departments so I want something that is going to give me an ATC like sound but without paying ten grand.

So far I have found a pair of boxes. They are 100ltr 3 way ported design and were a pair of studio monitors (EV interface C's) but they were custom made with burr walnut veneer so will look good. I know its not the full DIY process but it may well provide me with the sound and looks I am after.

Drive units

High
Peerless 810921 HDS
or
ScanSpeak D2905/970000

Mid
ATC SM75-150 Midrange

Bass
Volt B2500.1

One think I know nothing about is crossover design so any pointers would be great.

I will post some pics of the cabinets when I have cleaned them up.

What do you think? Any comments advise welcome.

Cheers

Ed
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Old 28th October 2009, 12:57 PM   #2
edross is offline edross  United Kingdom
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Join Date: Oct 2009
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Here is a pic of the cabinets.

They measure
D 28 cm
H 74 cm
W 51 cm

The bass mounting is already sized for the Volt, Tweeter will fit OK. I will need to make a mounting plate for the ATC mid as the hole is 235mm.
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File Type: jpg Pair - front view.jpg (98.6 KB, 390 views)
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Old 28th October 2009, 01:19 PM   #3
Ian J is offline Ian J  United Kingdom
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Ed,
Is that combination of units used in one of the Wilmslow kits? If so, have you heard it? If the answer to those two is yes, then you could save a lot of work by buying the crossover that they use, though even here there may be issues if the width of the baffle is very different. IIRC the ATC is a sealed unit? This means you wont need the mid-range chamber in the boxes you have. How does the volume and tuning (ie reflex/sealed) of the box compare to that used by Wilmslow? If it's different it will affect the quality and quantity of bass.
If you're keen to develop your own crossover then you'll need to acquire basic measurement tools and software. Sorry if you're aware of all of this, but you say it's a first project and thus you might not be...
It sounds ambitious for a first go, are you ready for many iterations of it 'not being quite right'? Personally I'd try a 2 way for a first project and go on from there...
Hope this helps,
Ian
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Old 28th October 2009, 02:13 PM   #4
edross is offline edross  United Kingdom
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Hi Ian,

Thanks for the reply. Wilmslow dont do a kit with the same drivers although the ATC clone kit has the same Peerless tweeter and ATC mid. Its also a ported design. The bass hole will take the Volt B2500.1 and it also looks like the Volt will integrate well with the ATC mid.

I was going to make an external crossover test bed so I could get the sound right before making the final unit but any help anyone can offer is welcome.

Thanks

Ed
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Old 28th October 2009, 09:01 PM   #5
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I admire your enthusiasm - I haven't tried a 3-way yet.

I'm not sure about your driver choice - the price for the tweeter is way below the mid and woofer, which would lead to a mis-match in quality (meaning the drivers (potentially) won't be as well matched as ones from the same price bracket).

It seems like an awful lot of money to spend on a project that will be chopped and changed around a lot (this happens with lots of projects), but that's probably me talking from a teenager's point of view.

Have you modelled the bass response in various boxes for the woofer? winISD is a good, free tool for this, if you haven't.

When you decided on a 3-way speaker, what else did you consider? I'm curious about how you arrived with the conclusion that 3-way is the way to go.

Chris

PS - where abouts in the UK are you?
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Old 28th October 2009, 10:22 PM   #6
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100 L is too big for those woofers, you'll get boomy bass. Unibox gives me 40L @ 35Hz, and that's slightly EBS.
The mids are 3dB more efficient than the woofers, and would need padding - I don't think thats a good idea. To match them you'd need 2 of those woofers, without taking into account BSC.
I'd choose a more efficient woofer, and one whose Vas is appropriate for that box....
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Old 29th October 2009, 10:08 AM   #7
edross is offline edross  United Kingdom
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Quote:
Originally Posted by PeteMcK View Post
100 L is too big for those woofers, you'll get boomy bass. Unibox gives me 40L @ 35Hz, and that's slightly EBS.
The mids are 3dB more efficient than the woofers, and would need padding - I don't think thats a good idea. To match them you'd need 2 of those woofers, without taking into account BSC.
I'd choose a more efficient woofer, and one whose Vas is appropriate for that box....
Hi PeteMcK

The actual volume is about 90l I was going on dimensions given by the guy I am buying the boxes from but they were external. The Volt website quotes 70l figures and I was thinking that as a Volt DVC250.1 has already been used in the boxes a similar but higher specification drive unit would be fine. Fitting 2 drives isn't an option nor is fitting a larger drive unit due to the format of the box. Can't divide the box internally either because of the port location. The guy I am buying the boxes from said the port and crossover had been modified to suit the Volt's. Could you explain a little as to why it wouldn't work, I am just starting at this. Thanks

Regarding your point on drive sensitivity matching, I think you are basing your figures on the "s" version of the ATC mid. The standard one is 91db and the volt at 90db.

Thanks, Ed
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Old 29th October 2009, 10:22 AM   #8
edross is offline edross  United Kingdom
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Join Date: Oct 2009
Location: Bath, UK
Quote:
Originally Posted by chris661 View Post
I admire your enthusiasm - I haven't tried a 3-way yet.

I'm not sure about your driver choice - the price for the tweeter is way below the mid and woofer, which would lead to a mis-match in quality (meaning the drivers (potentially) won't be as well matched as ones from the same price bracket).

It seems like an awful lot of money to spend on a project that will be chopped and changed around a lot (this happens with lots of projects), but that's probably me talking from a teenager's point of view.

Have you modelled the bass response in various boxes for the woofer? winISD is a good, free tool for this, if you haven't.

When you decided on a 3-way speaker, what else did you consider? I'm curious about how you arrived with the conclusion that 3-way is the way to go.

Chris

PS - where abouts in the UK are you?
Hi Chris,

I don't think the cost of the tweeter is really the point but its quality and match to the mid. I did a fair bit of reading on here regarding tweeter options and the peerless was always very highly rated. It's also used by Wilmslow Audio in combination with the ATC mid in their ATC 50 and 100 clones so a good pointer that they should sound good.

I decided on a 3 way as I always fancied some speakers based around the ATC mid as in my listening experience they sound exceptional.

I have winISD but I am not sure what I am looking at so some pointers as to what the curves should and shouldn't look like would be a help.

Thanks, Ed
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Old 30th October 2009, 01:10 PM   #9
Ian J is offline Ian J  United Kingdom
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Ed,
Would be worth talking to Wilmslow about what you're doing (are you buying the drive units from them?). They can certainly help as they have experience with the ATC. Though they would charge for a crossover design, it will be small compared to the cost of the drive units and xo parts.
Ian
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Old 30th October 2009, 02:17 PM   #10
edross is offline edross  United Kingdom
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Hi Ian, Yes I am going to buy from Wilmslow and I did see that they will design the ox for 75, which as you say is nothing compared to the cost of all the drive units. I am collecting the cabs tomorrow but there is quite a lead time on the ATC mids so my target is to be done by xmas. I am quite keen on learning the dark art of speaker design so I am going to buy a book (Loudspeaker Design Cookbook seems to be rated) and to start with and then will design and build my own centre to match.

The cost of the build so far is 1,370 for the drive units and 350 for the cabs so under 2k for the completed speakers. Quite a lot really but hopfully they will sound awsome.

Cheers, Ed
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