Need help

Lostcause

Member
2005-08-02 3:46 pm
NW UK
Hi gents, I've been surfing this forum for only a couple of days and I've probably picked up more information than I can handle!
I really need some guidance on a suitable speaker set up for a sprused-up Sonic T-amp.
After starting in the loudspeaker forum it now seems that I should be looking at more sensitive drivers and Fullrange Fostex seem to be the order of the day?
My budget is around £200 not including the enclosures which again, I will need some help on.
Room size: 3 x 5 M approx.
Music volume: Low/medium
Music: Easy listening (jazz, pink floyd, Damien rice etc)
Disgression is also on the menu (nothing too big), with stands or floor standing?
If you can give me any sugestions on designs they will be greatly appreciated, I have been surfing but I'm finding it difficult to match all the perameters without some guidance.
Thanks in advance.:confused: :xeye:
 
Ypu have a few options here here: what you go for depends on whether you want a small, medium or large driver.

Small driver = (say) Fostex FE103E. A Zigmahornet would be high on my agenda, and there's another simple design here too lower down:
http://audionova.nu/docs/KVARTSVAG.HTM
A couple of more complicated designs are here:
http://diyaudio.8m.com/Solo/solo.html
http://vicdiy.com/products/tqwt/f_sekkei.html

With a £200 budget, using a medium sized driver, if you can cope with a very tall, (but slim and elegant) box, and you don't mind deviating from a flat response in favour of heftly bass, you could try Terry Cain's Bigger Is Better box, but use the Fostex FF165K or perhaps FE167E. it measures better than it simulates. The design's here: http://melhuish.org/audio/DIYTQ8.html
Top choice however at this price (& you could just about manage it) would be Martin King's simply wonderful ML TQWT. It's probably far more obtrusive than you want though which is a pity as they look rather good when complete: certainly a conversation piece! The design is here: http://www.quarter-wave.com/Project02/Project02.html Use the FE167E in this: it's a straight swap for the now superceeded FE164E Martin used.

With a large driver, you wouldn't have much budget left for an enclosure, so I'd simply get a pair of Fostex FE206E 8" drivers and stuff them into a 45L vented box as shown in the Fostex site. You could then upgrade to an MLTL cabinet at a later date.

Whatever you go for, good luck!
Best
Scott
 
Scottmoose, thanks for the lowdown, but I think they need to be more discreet...
With a large driver, you wouldn't have much budget left for an enclosure, so I'd simply get a pair of Fostex FE206E 8" drivers and stuff them into a 45L vented box as shown in the Fostex site.
This sounds like the best solution and seems to be the recommended way to go as they are very efficient drivers. Which box is it your looking at?
The T-amp seems to be geared towards this..
15W @ 4Ù, 10% THD+N
10W @ 8Ù, 10% THD+N
High Efficiency
81% @ 15W, 4Ù
90% @ 10W, 8Ù
Dynamic Range = 98 dB
Do you still think this is a good solution for say 80db listening?
I like the look of the solo 103's but dont know if the drivers are efficient enough?
 
Scottmoose said:
With a large driver, you wouldn't have much budget left for an enclosure, so I'd simply get a pair of Fostex FE206E 8" drivers and stuff them into a 45L vented box as shown in the Fostex site. You could then upgrade to an MLTL cabinet at a later date.
MLTL cabinet is just as easy to build as a bass reflex. Plus, bass reflex cabinet requires a stand anyway, MLTL doesn't and has a nice small footprint. Plus MLTL has superior bass quality.

I recommend either the FE206E or FE207E in Martin's project 5:
http://www.quarter-wave.com/Project05/Project05.html
 
Agreed 100% with the above. The reason I didn't suggest them however was because the additional cost in extra cabinet materials and the BSC circuit would take it well over the £200 budget. That said, the considerable benefits would be well worth it. I've built several of Martin's MLTLs 2 pairs of his FE164[7]E ML TQWT and 2 of his FE206[7]E MLTLs that you've mentioned, and love them, but the typical cost of the latter, done properly, in my experience starts at around £250. Personally, I'd stretch the budget if possible!

A bass reflex is not really a favoured choice of mine, but some people do like them, and it's at least cheap and you get some frightening transient response. If you do this, I wouldn't look at any particular box: just make something that's got a volume of 45L, add a 3" x 3" vent, and stuff the 206 into them. The shape is up to you: a large stand-mount would probably be best, though you could try a small floor-stander with the front baffle sloped backward to aim the driver up at the listening poistion. Up to you really. If you look on the Fostex site at the recommended back-horn for the FE206E, you'll see a vented box diagram lurking in the corner. Alternatively, you could try the FE207E in the double-bass-reflex enclosure; the Fostex 'recommended' design on their site. Both would fall into your £200 budget. You'll find them here:

http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/206e_enclrev.pdf

http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/207e_enclrev.pdf

I doubt you'd have too many problems running the solo 103: just remember that the way forward with these would be to slam them right up against a rear wall, and tell yourself you never liked low frequencies anyway. You won't get much action below 150Hz in practical terms out of a small driver in a tiny shelf-mount design.

Best
Scott
 

Lostcause

Member
2005-08-02 3:46 pm
NW UK
Now we're talkin'....thanks Dumbass and Scottmoose.
This is the kind of insight a apprentice like myself needs!
The £200 budget was really just for the drivers and I still would need stands anyway so....The floor standing MLTL with Fostex drivers seems to be the one to go for.
I realise that I can alter the correction circuit to balance things out but will these be OK if placed in the corner of the room?
Also, does the cabinet design alter depending on the amp powering it?
I can see that I'm going to get addicted to this..........
 
Ah. well, life suddenly becomes easier. If that's just the driver budget, then Martin's MLTL is easy!
In response the the two questions, yes, and no. They'll be fine in corners as they are front-vented, and no, the cabinet design would not need to alter a jot if you were powering them with 212 transmitter-valves. The BSC circuit might though.
Now then, as you're running an SI T amp, I would strongly advise the FE207E, not the FE206E. Martin generally favours the 206, using heavier BSC to tame it's rising response, because the larger magnet provides a touch more detail. However, with 0.1% distortion being the limit of audability in an amplifier, you're going to have to keep the eficiency of the drivers as high as possible, which means less BSC, so the 207 would be, in my view, the better choice.
Also, check Bob Brines website, specifically here:
http://www.geocities.com/rbrines1/Pages/LT-2000/Main.html

Bob, like Martin, is a great man to talk to, and the acknowledged master of refining transmission-line systems. He can sell you a set of plans of truely spectacular detail -cutting diagrams, the works, for a not unreasonable $25, which might be worth doing. You can also upgrade to Lowthers at some point in the future with both Bob's and Martin's designs (Bob's are based on Martin's MathCad software).

Best
Scott
 
Fantastic.....within two or three posts/replies my prayers have been answered!
207's it is then, with the MTLS's and less BSC.
I like the look of those Brines cabs, the driver doesn't look as lost as it does on Martin's. Think I'll introduce some similar 'external' additions.
The 'stuffing' is interesting, wonder where I can get some of that locally?
I see Lowthers are £...........crikey they must be good.
Certainly a thought for the future.
Thanks again chaps, I'll drop a few photo's in once I've finished.

PS I was looking at Wilmslow Audio for the drivers, any sugestions on a cheaper source?
 
Lostcause said:
Are there any better drives that would be around that £200 budget?
Probably not. The Fostex drivers are a great value.

Go to this page for Bob's discussion of and plans for a folded version of Martin's FE164/FE167E design:
http://www.geocities.com/rbrines1/Pages/Proposals.html
It models down to 40Hz, would be a right nice design IMO.

For stuffing I would just use polyester batting (from any fabric store) or Acousta-stuf.

For a TL, airtightness and stuffing location/density are of the essence. The stuffing details should be tweaked to taste.

Regarding the FE206E/FE207E design, even if you don't use the BSC, you still need to put a series resistor in for proper tuning. Nice non-inductive resistors, however, are not expensive. It's the coils and boutique caps that get kind of pricey.
 
Lostcause said:
Is Bob's internal design the same then except for the foam?
Or has he tweaked the sizes of Martin's so there is a definite difference?
Seeing as I'm within budget on this one....yes you guessed it..
Are there any better drives that would be around that £200 budget?


No, it's quite different. There is a general relationship in terms of dimensions, as you'd expect, but Bob's are a more refined piece of engineering. They aren't based upon Martin's project you see: Martin simply licenced his MathCad software to Bob, who uses it to design from scratch (as do the rest of us MathCad types, but as a hobby) what are basically production speakers. That's not to say Martin's are poor however -quite the reverse. The fact that I've built two pairs will probably give you a good idea of how highly I rate them. For the price, I would go so far as to say they are the best speakers in the world in many respects. Bob's are a slightly more refined commercial product -he does this for a living remember, so they cost more as they are more complex to build.

Beware of external baffles etc. by the way. You can do unpleasent things to the sound quaility unless you are very careful. If you look at the gallery on Martin's site, you'll see plenty of FE206/7E MLTLs built to his design, and the driver looks quite at home.

Best
Scott
 
Beware of external baffles etc. by the way. You can do unpleasent things to the sound quaility unless you are very careful
That sounds a little worrying....Does that mean I have to follow the design exactly, with 3/4" ply and no more additions?
Bob's have a nice esthetic addition to the front, do you mean it is accounted for in the calculation, and the design does not work without it?
I'm asking because I thought I would break up the plain appearance and integrate it into our room by adding some laminates etc. (well bonded of course)
If I modelled it up (I am a 3D CAD engineer) could I put it through some sort of simulation (Ansys or something) to prove it?
Are Bob's superior then? (however slightly).
 
Lostcause said:
That sounds a little worrying....Does that mean I have to follow the design exactly, with 3/4" ply and no more additions?
Bob's have a nice esthetic addition to the front, do you mean it is accounted for in the calculation, and the design does not work without it?
I'm asking because I thought I would break up the plain appearance and integrate it into our room by adding some laminates etc. (well bonded of course)
If I modelled it up (I am a 3D CAD engineer) could I put it through some sort of simulation (Ansys or something) to prove it?
Are Bob's superior then? (however slightly).
As long as inside dims are same, you will be fine. Just ensure that driver is securely mounted.
 
Bob's are slightly superior designs; as I mentioned, Bob is the master at refining things. There won't be a huge amount in it however.And no, you won't have to stick with the plywood, MDF is just as good in this application; if anything, it'll be slightly superior in that it's less resonant and easier to work with. So you can cheerfully use this without problems.

External baffles are a bit of a problematic area, but not one you should really worry about with what you're planning, so go ahead with confidence.

The baffle, strictly speaking, is the front (and rear) panel of the speaker, but the word tends to be used to describe an external addition to this panel, like those oval shaped pieces attached to the front of Bob's (excellent looking) speakers. Those are there both for appearance, and because they provide worthwhile additional damping to the speaker cabinet. The major problems generally occur when people go too far, with wide baffles sticking out over the edges of the main speaker cabinet. That's when you run into diffraction issues. It's just something to be aware of really. Martin's site has a link to some baffle-step simulation software.
Best
Scott