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Old 28th June 2006, 03:40 AM   #1
Steveal is offline Steveal  United Kingdom
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Default Confused - Can You Help?

First off, let me say I'm so impressed by the knowledge displayed on this board. I feel like I'm observing the cutting edge of speaker design...
The problem is, that I've read SO many messages recommending so many different speaker designs that I am lost as to where to start my speaker building.

Here's my situation:
I have a 9W/ch SET amp on the way.
My room is about 18ft x 11ft x 8ft high. I'll listen on my sofa positioned along the short wall.
There is a walk in cupboard (4ft x 5ft) at the other end of the room, therefore I cannot have the speakers against the back wall.
I like acoustic folk and jazz music, small scale "classical" and solo piano. I'm not too fussed about high levels. I'm not too fussed about extreme bass, either; although appropriate levels of bass are appreciated.

Where so I start? Should I choose a driver and then find plans for a suitable enclosure. Should it be the opposite, or should they go together?

Any guidance would be most appreciated.

Thanks,

Steve
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Old 28th June 2006, 03:52 AM   #2
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Budget is often a good place to start. No point entertaining something that will cost 10x more than you can afford to spend.
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Old 28th June 2006, 04:33 AM   #3
ScottG is offline ScottG  United States
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Quote:
Originally posted by AudioFreak
Budget is often a good place to start. No point entertaining something that will cost 10x more than you can afford to spend.
Oh yeah!

additionally.. what size limitations?
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Old 28th June 2006, 08:36 AM   #4
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For the love of heaven don't buy a pair of drivers and then decide what to do with them! Exactly the wrong way to go about it! What you need to do is look at your own circumstances in as great detail as you possibly can, and decide what it is you require of a speaker system. Note I say 'speaker system' -it's better to think of them potentially as that, rather than as a plain set of drive units, given that that is what they'll ultimately become.

The guys have identified a couple of points you need to look at. Firstly, price. No point in us advising something you can't afford! Next, space: how large can you go? As a rule, a good big speaker cabinet will be ultimately more capable than a good small speaker cabinet, so best to aim toward the largest you can fit into your domestic circumstances. (That doesn't necessarily mean larger drivers BTW)

You've already stated the type of music you like to listen to, and the volumes you aim for. You now need to tell us if aesthetics are important for you. It's all very well for some of us to say &%$ the looks, speakers are supposed to make music, not look good. But it might be important for your own domestic harmony to have something that looks attractive.

You then need to think about construction -how good are you at building things? A complex enclosure might be a thing of beauty in appearence and sound, and might be 'better' for you in terms of sound. But it won't do you much good if you find that you simply don't have the time, space, tools or personal ability (yet) to make the things.

A couple of things I can offer straight off: I'd advise a 6 1/2in or 8in driver. 4in and 4 1/2in units are lovely, but it's a bit of a stretch to get them to produce realistic acoustic bass, and they'll need more juice to get them singing too. To me it sounds like you're after decent response down to about 40Hz -a 6 1/2in unit will give that. You say you've got a 9wpc SET: can I ask which it is? What THD does it throw out at full power? And at half power? And where is this distortion greatest? If it's 2nd harmonic, that's innocuous, so you can go for a slightly less efficient speaker, but if it's 3rd or greater, then as high an efficiency as possible will be necessary. I would say you'll need a speaker efficiency of 91-92db minimum, or you'll be in trouble.

Regards
Scott
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Old 29th June 2006, 04:23 AM   #5
Steveal is offline Steveal  United Kingdom
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Default More Details...

Chaps,


Cost

I'm a moderately good woodworker, so I anticipate building my own cabinets (as against buying a kit of parts). Within reason, therefore, I assume the size and complexity of the speaker won't have too much effect on cost (an extra sheet of MDF/plywood). The main other cost will be the drivers. 100 each or so would be acceptable, but 500 each would make my eyes water.
So say 200 for drivers and another 150 for cabinet materials etc.??

Size

My room is 18ft x 11ft, or so. I can't lose a pair of Tannoy Westminsters in there. However, the room is actually my "office", which I'm in the process of doing up. This means whatever I make isn't disfiguring the lounge and so I can get away with something a little bigger than I could in the lounge (this is a wild assumption on my part - I haven't actually confirmed this with the boss; but lets go with it).
When I see photographs of Jericho and J-Low horns, I think they are too big for my requirements.
Buschhorn (sp?) and Mr Brines' FT-1600 look very acceptable (but if someone told me I could have a MUCH better speaker, for slightly more size, I would be tempted).

Style

I've spent many hours recently scouring internet sites and studying speakers. One that made a big impression on me was the Cain Abby. I got all fired up with that until I saw:

1. The UK importer wants 1500 a pair ($1500 in US)
2. There is much negative opinion about "Voight pipes".

Other than that, the nicest looking speaker I've seen is this:

http://www.lowther-america.com/

the Alerion (I've attempted to attach a picture). Alarmingly, this cabinet is also made by Mr Cain... Maybe I just like Maple (Sycamore) speakers?

The amp I'm buying is a Chinese job off Ebay with very little of the sort of distortion information you mentioned (bought on looks and price and 300B valves, I'm afraid).

Hope some of this helps.

Steve
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Old 29th June 2006, 09:32 AM   #6
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That's a help. OK, if you like Terry Cain's Abby, which is an ML TQWT, then take a look at this: http://www.quarter-wave.com/Project02/Project02.html You can also use this enclosure with the larger 8in Fostex FE207E -just increase the port length to 3in. An excellent cabinet -most flexible I've ever known.

The problems you've heard about Voigt (no 'h' -P.G.A.H. Voigt you know ) Pipes is related to the Lowther Club of Norway VP cabinet, which is a truely duff effort. It has two problems: a) it doesn't have anything like enough volume to do most of the drivers that find their way into it justice, and b) the vent is far too large. Restricting the size of the vent to a 3in x 3in port will flatten the massive ripple and give an extra 20Hz of bass extension. Still not ideal though -avoid. A properly designed ML TQWT like the one I link to above has none of these problems.

Alternatively, here's a straight MLTL for the 207: http://www.quarter-wave.com/Project05/Project05.html

Bob Brines has a slightly more refined version of this latter that he sells plans for, or complete speakers etc. Only trouble in the UK is getting hold of the stiff acoustic fibreglass he uses to line the enclosure walls with. http://www.geocities.com/rbrines1/Pa...2000/Main.html It's very similar to Martin's free project -detail improvements for the most part, and of course, a much better finish as it's a commercial product.

My only concern with these lies in your new amp. Chinese valve amps for the most part have duff output transformers, so they really hate driving all but the lightest of loads (the bass goes to pieces). All of these designs require some form of compensation circuit to counter the effect of baffle-step diffraction., which will reduce their efficiency a bit. That said, a 5w t-amp powered my own 207 based MLTLs without batting an eyelid, so I doubt it'll be a problem -just something you need to be aware of.

A 207 in this (they found the 207 was better than the 206): http://www.yildiz.edu.tr/~ilkorur/sp...tex_fe206e.htm could be good.

Hope that's given you a few options to think about. There's plenty of others, so if you don't fancy any of the above, do let us know.

Cheers
Scott
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Old 30th June 2006, 01:02 AM   #7
Steveal is offline Steveal  United Kingdom
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Scott,

Thanks for the guidance. The ML TQWT is most interesting, although I don't like the drivers positioned in the tapered "side" of the cabinet; I prefer them in the flat face as MJK originally had them - I presume this is just a matter of what looks best to the builder?

Using the BSC reduces the sensitivity rather a lot, so would the FE207E be a better, more sensitive bet (as well as for bass)? Somewhere, recently I saw a great table comparing the sensitivities of all the fostex drivers. Can someone remind me where I saw this?

The straight MLTL (and Mr Brines refinement) seems like a fine, conservative option, but the yildiz job seems rather challenged in the looks department, even to me...

The quality of the output transformers on the amp is beyond my control or knowledge. I can tell you that the transformer cases look BIG, but there may be lots of air in there...
But never mind the quality - what about the weight? This thing is supposed to weigh 29 kg (64 lbs in old money), I'm figuring I can recoup a fair slice of my outlay at the local scrap merchant if the sound isn't too hot...

Steve
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Old 30th June 2006, 01:47 AM   #8
ttan98 is offline ttan98  Australia
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try this site for almost all Fostex drivers--

http://www.lautsprecher-shop.de/hifi/index_en.htm
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Old 30th June 2006, 04:17 AM   #9
ScottG is offline ScottG  United States
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I'd stretch the budget a bit more and do something like this:

Are you (open) baffled yet?

(i.e. Kuei's/Thorsten's 215 Bicone sig. dipole)

I think that Nuuk's baffle looks better (..the glass "wing" version with the oak veneer baffle):

http://myweb.tiscali.co.uk/nuukspot/...speakers2.html

Drivers here:
http://www.supravox.fr/haut_parleurs/215_SBIC.htm

Your distributor listed here:
http://www.supravox.fr/contact.htm

Of course there are a few Euro distributors that will ship to you..

(note that he has tried a LOT of types of speakers over a fair stretch of time and seems to think these are some of the best.. He also uses 300B based amplification.)
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Old 30th June 2006, 10:10 AM   #10
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Quote:
Originally posted by Steveal
Scott,

Thanks for the guidance. The ML TQWT is most interesting, although I don't like the drivers positioned in the tapered "side" of the cabinet; I prefer them in the flat face as MJK originally had them - I presume this is just a matter of what looks best to the builder?

Using the BSC reduces the sensitivity rather a lot, so would the FE207E be a better, more sensitive bet (as well as for bass)? Somewhere, recently I saw a great table comparing the sensitivities of all the fostex drivers. Can someone remind me where I saw this?

The straight MLTL (and Mr Brines refinement) seems like a fine, conservative option, but the yildiz job seems rather challenged in the looks department, even to me...

The quality of the output transformers on the amp is beyond my control or knowledge. I can tell you that the transformer cases look BIG, but there may be lots of air in there...
But never mind the quality - what about the weight? This thing is supposed to weigh 29 kg (64 lbs in old money), I'm figuring I can recoup a fair slice of my outlay at the local scrap merchant if the sound isn't too hot...

Steve
Yes, you can mount them on any side you like, providing they stay at the same point on the line, it won't make any difference to the response.

Don't know about the table, but the 207 is the better bet in any of these cabinets. However, it will still need baffle step compensation, same as the 206. There's 2 issues at work here. The first is baffle step. That's nothing to do with the driver per se, but do do with the losses caused by the cabinet, which usually causes a ~3db loss below the 600-800Hz, depending on how wide it it. The 206 in these boxes often requires further correction, typically done by adding further series resistance, unless driven by a SET, because many amplifiers over damp it due to it's very low Q. It also has a rising response, which can be sorted in this way, and by listening further off-axis than usual.

Onur's horn's a good- 'un. But I admit it's not as it stands, the most attractive I've seen. That said, I think it'd be possible to finish them to a mich higher standard than the pictures on his site. Out of personal preference though, I confess I'd rather see a version with a flush front, but there you go.
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