DIY speaker design, based on ATC SM75-150 mids

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Paulthefirst

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Hi,

My first post, so interested in responses!

My current speakers are ancient IMF Reference Monitors (I think the Mk III), which I bought secondhand about 15 years ago. Excellent bass - especially once when I had them in the garden: they really love to be free. But I am thinking of changing them a) to make them more "spouse friendly", and b) to update to modern drivers. And time to diy for the first time for many a year: so I would appreciate any thoughts as to how my proposed setup might sound, especially referenced to the IMFs, if anyone can venture!

My plan is for the following: Scanspeak R2904/710003 tweeters (chosen for their better dispersion than the ring version, ATC SM75-150 mid, and Scanspeak 22w 8851T00 bass, in asymmetric 27litre reflex cabinets (see pic), downward firing ports, stand mounted so tweeters roughly at ear level when seated. These partnered with one (spouse preference) or two (if needed) BK Monolith subs.

Wilmslow Audio have indicated that they can supply suitable crossovers matched to this setup (crossover points as recommended by ATC).

Many thanks,
Paul

Any observations?
 

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If you don't have the ability to measure and design your own crossovers, then I would strongly advise building from a proven design. The problems otherwise, are many.

There are lots of good designs around, although I don't know of any using the ATC mid. Still, if you are going to add a sub(s), then a good two way could be everyhting you need.

This one looks like one of the best standmount designs to me - http://www.zaphaudio.com/ZD5.html

Or if you prefer the other tweeters, you could build these with the standmount sealed cabinet he mentions. - http://www.zaphaudio.com/ZRT.html
 
Hi Paul

welcome to ZG. Good to see your first post BUT don't we have a diy section here?

Anywho, what you have is a drawing of a loudspeaker, the drivers you would like to use and a crossover supplier. This does not make for a good loudspeaker. A really good loudspeaker is more about design (internally and externally) and as you might know a lot of thought is put into the crossover design and how each drive unit reacts with it, not only that but how the crossover reacts with the cabinet design. We are not in the 1960's where companies threw together parts (well some still do) to make a loudspeaker. The chances are (maybe 99%) that if you go ahead and build it... it will fail on audio quality. The box might look nice though ;)
 
I'd run with the plan, looks interesting and fun, it's not rocket science, nobody will fall from space if it needs a tweak or two and would make for a great learning curve, i say go for it, you never know, could be that little bit of Magic...Good Luck.
 
I'd also suggest that if you have the creative urge you should run with it.

It might be worth thinking about going down the active crossover route - if only because they can be easier to tweak than passives.

At the end of the day you'll end up with something that satisfies your ear - the criteria would be different if you were making something for sale. I've made speakers in the past which have pleased me as well as commercial designs, and where the drive units have been the same as in those designs, the characteristics of the drivers come through. But getting where you want to be may not be a "cheap" option - don't be tempted to skimp.
 
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yeah go for it!

Also, I think an active crossover is likely to be easier for you to work with at first. That's the route I'm personally going down.

If you want to do it, go for it.
 
If you just want to have some fun playing with speakers then by all means build yourself something, but wouldn't it be a better idea to use less expensive drivers for your first design? Peerselss HDS, or Seas Prestige ranges are still capable of pretty stunning results if you do the design part right, and they cost a lot less than SS tweeters an ATC mids.

If you go ahead and build this, and expect to just drop in some crossovers from Wilmslow, you will be wasting about £1500 of your cash. I'm all for a bit of fun, but I don't want you to waste your money because you didn't know what you were getting in to.
 
Seriously folks....

All that time and money spent on the cabinets, getting the drivers, fitting them. Getting a 'general purpose' crossover...then finding out that is sounds naff and is drinking loads of power from the poweramps... learning curve:confused:
If you are electronics minded the learning curve will be steepish, but if not...WOW... good luck!

I can see what the others are saying but lets all be honest.... is it really that simple making a really good loudspeaker? If so, why isn't everybody and his dog doing it? Neat, Naim, Linn and a whole load of other manufacturers have to their disposal thousands of pounds worth of test equipment when designing their loudspeakers BUT they can't even do it. There is a whole lot more to a really good loudspeaker than a nice looking cabinet, drive units made by ????? and a crossover.
 
Hi,

Thanks for the initial responses - so many so soon is a good welcome for me!

For clarification, the WA crossover is their design for this specific speaker combination (so they say), noting that the ATC has particular demands, and is not a simple 'off the shelf' one that simply has appropriate XO frequencies.

I was tempted the active way, triamping with a Boehringer active XO - but the cost of the extra pair of amps rather puts it out of the equation for now.

My first home-brew designs (circa 1969 -1974) using both reflex and a simple folded rear horn were less than impressive, though I hope I have learnt a lot since then! Personal preference based on experience (smaller IMF TLS50s before their top of the range) is would have been to go for TL loading - but that would defeat a primary consideration, namely size: with smaller standmounts the main pair will be - smaller - and will look so - while with greater freedom of flexibility in the sub placement should enable it to look like a nice coffee table, in an odd place...

I expect the mid-high to be better than my IMFs on the basis of the drivers, but am wondering about the bass, in the absence of TL loading, and using smaller cabinets supplemented with a sub (probably from about 60Hz). Is the message just suck it and see, so to speak, playing with stuffing etc? Maybe also mounting the XO externally to be able to tweak it? Anyone have any experience of this bass driver in a similarly sized bass reflex cabinet? Or of this sub?

I should also have clarified musical requirements: Heavy rock, classical both chamber and dramatic orchestral, and opera, and playing a sampled piano.

Paul
 
Paul,

The problem is that you have to design an xover in intimate relationship to the speaker. The thing Wilmslow are offering is guesstimated. It isn't going to give you anywhere near the best from these expensive drivers.

Please don't advertise your products in the main forum, use the trade rooms that are provided for that express purpose. It expressly states this in the AUP

Moderating
 
robM said:
[... deleted ...] is it really that simple making a really good loudspeaker? If so, why isn't everybody and his dog doing it? [... deleted ...]
Click to expand...

One weapon of the manufacturing industry is FUD (fear, uncertainty, doubt). Tell people "only we know how to do this".

I'd suggest there's also the question of personal ambition and goal. It's quite a different proposition for someone to decide to learn about speakers and from there start making items for their personal enjoyment and satisfaction (the journey may be more interesting than the destination) - as opposed to setting up for commercial manufacture.

And - as hinted at above - it's probably not cost-effective to make a single pair of speakers. If someone can find what they want readymade, that will probably cost less.

Researching, designing, and building a reasonable speaker takes time, money, skill and experience - not everybody wants to get all of that together. But it isn't rocket science.
 
Dick Bowman said:
I'd suggest there's also the question of personal ambition and goal. It's quite a different proposition for someone to decide to learn about speakers and from there start making items for their personal enjoyment and satisfaction (the journey may be more interesting than the destination) - as opposed to setting up for commercial manufacture.

And - as hinted at above - it's probably not cost-effective to make a single pair of speakers. If someone can find what they want readymade, that will probably cost less.

Researching, designing, and building a reasonable speaker takes time, money, skill and experience - not everybody wants to get all of that together. But it isn't rocket science.
Click to expand...

Totally agree. I built my own speakers from a kit to run active with my own crossover and was told by people (who happen to make & sell speakers) that I would be getting into all sorts of things I couldn't understand and would make a mess of it and would be unhappy as a result.

Utter tosh - I got good results (to my ears) reasonably quickly and fairly easily and, most of all, the experience of building the speakers was great fun and a great learning opportunity. Add to that, the personal satisfaction of seeing and hearing my own handywork reproduce sound in a very musical way was very very satisfying.

So, go for it!- don't let the naysayers put you off.
 
Paul

If your first homebrew was circa 1969 -1974 you should have learned by now that a crossover design isn't just about marrying the drivers but the marriage of the drivers and cabinet volume, shape, rigidity and resonance. I don't know anyone with a pair of Wilmslow loudspeakers - and I can see why now.

My first home brew was circa 2003 and I realised straight after dropping in a 'very well designed' crossover and messing around with a piece of software called Mellisa (I think that was what it was called) that the relationship between drivers/cabinet/structural rigidity/baffle design/volume and about 50000 other things all made too much of a difference.
 
Sorry, it seemed related. I just meant to say that for the same money these drivers cost, you could buy some very serious speakers that will be better designed and have resale value too.
 
Go For It

Hi Paul,

First off - go for it!

Second off (?) - if you don't want to get into the theory, assembly and testing of xover units then think of something else! As alluded to in the previous replies, there's much more to that black art than meets the eye! If it interests you then great, if not, then heap big trouble lies ahead. If you buy something and it isn't quite right then you're a bit banjaxed, if you're not confident that you could identify, re-calculate and change the offending component(s) yourself, then you're equally banjaxed. Not :cool:

I went through this thought process a couple of years ago. For me, it was the cabinet construction that fired me up. There was no way that pooring over circuit diagrams held anything for me but horror - just not interested in investing the time to learn it! So I opted for the 'full range' route. In the end I bought Lowther EX2's and built the Lowther Bicor 200 box as my first project. That did it for me - thoroughly wonderful sound. I sometimes feel a sub would be nice, my son says I need a sub.:D Whatever, the investment in the drivers is a one off, the fun is in 'upgrading' the cabinets!

There are a few diy designs out there for Lowther drivers and gazzillions for Fostex drivers! Coupled with a sub for the rock/orchestral stuff, a full range driver offers a very realistic route for enthusiastic diy'ers. Wire the amp straight through to the drivers and you can leave the circuit pounding to those that like and love such things! Very, very good 'full rangers' can be had for the money you have available and you can spend years bulding all sorts of wierd and wonderful boxes to put them in.

My next project will be to build the Lowther Fidelio cabs and after that to have a go at some seriously BIG horns - hours of fun and not a crossover in sight! (Many smaller designs are out there, to suit your standmount preference).

My main point would be, research the existing diy designs that suit your purpose and buy the drivers to match them. IMHO therein lies much less grief;)
 
Dont listen to the nay sayers,build the buggers,but hold fire on the crossovers,bring the wiring out of the box so you can experiment.There's loads of free software (or good old pen paper and a few good old fashion equations) out there that will calculate the component values for the crossover,buy cheep components and build a prototype,listen for a few days and tweak the bits that need tweaking until your happy,then leave well alone,If your really keen you can even wind your own inductors.
 
Dont listen to the nay sayers,build the buggers,but hold fire on the crossovers,bring the wiring out of the box so you can experiment.There's loads of free software (or good old pen paper and a few good old fashion equations) out there that will calculate the component values for the crossover,buy cheep components and build a prototype,listen for a few days and tweak the bits that need tweaking until your happy,then leave well alone,If your really keen you can even wind your own inductors.

A crossover isn't about calculating component values... it's about vectors, delays and power. It's not easy..and to do it on paper is effing hard. Calculating baffle step delay is not for the faint hearted and incorporating a working crossover into that is not joke.

Go ahead with it but if you think it sounds poor.... don't blame the crossover as it could be any one of 100 things to do with your design.
 
Again, thanks for continuing responses.

No observations yet on expected or experienced performance from these bass units in this size of reflex box, nor of the subs. Anyone have anything to offer?

Meanwhile, thinking about XO: For £100 more than the WA design (parts only) I could get a Behringer DCX2496 3-way active XO, and a pair of secondhand amps such as Samson Servo 170, and go for triamping with easy control over XO frequencies/slopes/EQ. How does that sound as an alternative?? (I've no knowledge of these amps other than the specs, and only outline info on the DCX2496) I've always liked the principle of triamping, but cheap amps are a bit of a departure. For info current amp is a Musical Fidelity P170.
 

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