Dear FR experts,
Presently I am using modded SI T-amp. I am thinking whether to build ML TL enclosure with Fostex FE207E, or DBR or BR enclosure with the same driver. ML TL seems to be too simple to be very good
Furthermore, I have read few comments that DBR or BR enclosure work very well with FE207E and T-amp...especially for bass freaks. My listening levels are from low to moderate (not loud).
Should I consider those types (DBR/BR) of enclosures, specifically having in mind that I like bass, and I have no possibility to put the speakers in the corner (the room is 20 m), or should I go with ML TL project...?
I would greatly appreciate your help.
Presently I am using modded SI T-amp. I am thinking whether to build ML TL enclosure with Fostex FE207E, or DBR or BR enclosure with the same driver. ML TL seems to be too simple to be very good
Furthermore, I have read few comments that DBR or BR enclosure work very well with FE207E and T-amp...especially for bass freaks. My listening levels are from low to moderate (not loud).
Should I consider those types (DBR/BR) of enclosures, specifically having in mind that I like bass, and I have no possibility to put the speakers in the corner (the room is 20 m), or should I go with ML TL project...?
I would greatly appreciate your help.
I have FE207E in 45 liter vented cabinets. I have 2 to 3 ohms (can't remember exactly) series resistance because of the large cabinet size.
If I were starting from scratch I would build something like Martin's project 5 MLTL:
http://www.quarter-wave.com/Project05/Project05.html
If you want something a little more "daring" in looks you could build a tapered version like project 6:
http://www.quarter-wave.com/Project06/Project06.html
I have spent close to a couple of years with these drivers; here are my suggestions based on personal experience:
1. Phase plug
I simply use the Decware mod, i.e. a wrench socket. Smooths out highs quite nicely:
2. Wall placement
My conjecture is that because of the inevitable beaming effect, full-rangers are happier with boundary placement than, say, the typical dome-tweeter "monitor" type speaker. With wall placement, you all but maximize the speaker's efficiency and you don't have to use baffle step compensation. Just keep clutter to a minimum between the speakers -- a soft piece of furniture like couch might work nicely, though.
3. Overtoeing
Even with the phase plug, the driver sounds best slightly off-axis. The best solution is the toe in the speakers so their axes cross in front of the listener. In a typical listening situation of the listener and the two speakers making an equilateral triangle, this means the speakers are toed in about 45 deg. This makes for a really nice, wide, stable stereo image.
4. Zobel
With the t-amp, you might want to experiment with a Zobel across the speaker leads; I'm certainly no expert, but the t-amp might be happier driving a zobelized load. I don't think the effect would be dramatic.
Have fun with the drivers. I think you'll be happy.
If I were starting from scratch I would build something like Martin's project 5 MLTL:
http://www.quarter-wave.com/Project05/Project05.html
If you want something a little more "daring" in looks you could build a tapered version like project 6:
http://www.quarter-wave.com/Project06/Project06.html
I have spent close to a couple of years with these drivers; here are my suggestions based on personal experience:
1. Phase plug
I simply use the Decware mod, i.e. a wrench socket. Smooths out highs quite nicely:
2. Wall placement
My conjecture is that because of the inevitable beaming effect, full-rangers are happier with boundary placement than, say, the typical dome-tweeter "monitor" type speaker. With wall placement, you all but maximize the speaker's efficiency and you don't have to use baffle step compensation. Just keep clutter to a minimum between the speakers -- a soft piece of furniture like couch might work nicely, though.
3. Overtoeing
Even with the phase plug, the driver sounds best slightly off-axis. The best solution is the toe in the speakers so their axes cross in front of the listener. In a typical listening situation of the listener and the two speakers making an equilateral triangle, this means the speakers are toed in about 45 deg. This makes for a really nice, wide, stable stereo image.
4. Zobel
With the t-amp, you might want to experiment with a Zobel across the speaker leads; I'm certainly no expert, but the t-amp might be happier driving a zobelized load. I don't think the effect would be dramatic.
Have fun with the drivers. I think you'll be happy.
Interesting words Dumbass,
I have been playing around with these drivers in Martin's MLTL and, as you say, it seems that corner placement negates the need for a BSC. I have recently taken out all the stuffing too and found that there is an improvement at low listening levels (I never have them above moderate levels)...think I'll put some felt on the walls later though.
I also found that dramatic over-toeing works wonders when you are trying to get the widest sweet spot....mine are crossing well in front of the listening position and the best spot is about 15' away where you get the reflections off the side walls of the room, especially for the base response.
I have Planet10's phase plugs and would always recomend that mod before anything else...what a difference!
Currently there is no series resistance or zobel between them and my Amp6 but there is further experimentation to come.....when I get the oportunity and time of course.
Lee
I have been playing around with these drivers in Martin's MLTL and, as you say, it seems that corner placement negates the need for a BSC. I have recently taken out all the stuffing too and found that there is an improvement at low listening levels (I never have them above moderate levels)...think I'll put some felt on the walls later though.
I also found that dramatic over-toeing works wonders when you are trying to get the widest sweet spot....mine are crossing well in front of the listening position and the best spot is about 15' away where you get the reflections off the side walls of the room, especially for the base response.
I have Planet10's phase plugs and would always recomend that mod before anything else...what a difference!
Currently there is no series resistance or zobel between them and my Amp6 but there is further experimentation to come.....when I get the oportunity and time of course.
Lee
Presently I'm ordering fe207e drivers from madisound to go in the ML TL enclosure, and I thought to order capacitors for BSC circuit. Do I really need to go for exotic and fancy caps such as mundorf/hovland 3uF, or solen caps will be more than enough? As I have read, polypropylene film caps are preferred over metallized polypropylene caps...
...in Lithuania we have a bit of troubles with quality caps, therefore I would appreciate your advise whether I should go for an expensive caps or 'regulars' would be fine for BSC circuit.
...in Lithuania we have a bit of troubles with quality caps, therefore I would appreciate your advise whether I should go for an expensive caps or 'regulars' would be fine for BSC circuit.
irss said:
Hi chaps, just to update, currently I have no stuffing except for some felt to deaden the box. I also added 3 ohms of series resistance on each channel using about 1 metre of 1mm nichrome wire.
No BSC or Zobel, removing them seemed to give clarity to the highs at such low levels (louder levels seemed better with the BSC)
This seems to be the best setup at low listening levels (so as not to waken the little 'uns).
The sweet spot is a good 6 metres away with generous toe-in. This is the best position to appreciate the base in my room which is long and narrow.
Thanks mates for your help.
Few Fostex experts (who have been doing enclosures for some time) asked me why wouldn't I go for fostex recommended Double Bass Reflex enclosure. Their arguments are simple:
1. Why to do something different, when the producer of drivers recommends the best option for driver, specifically taking into consideration the fact that the Fostex has done extensive research before recommending it? If Fostex considered ML TL to be the best choice, it would have recomended it.
2. Why would one go for enclosure (ML TL) which requires the correction circuit, when one can have a real fullrange driver system (that is Fostex recommended DBR) without any filters?
Well, and here I am...lost again
I shall flip the coin.
Few Fostex experts (who have been doing enclosures for some time) asked me why wouldn't I go for fostex recommended Double Bass Reflex enclosure. Their arguments are simple:
1. Why to do something different, when the producer of drivers recommends the best option for driver, specifically taking into consideration the fact that the Fostex has done extensive research before recommending it? If Fostex considered ML TL to be the best choice, it would have recomended it.
2. Why would one go for enclosure (ML TL) which requires the correction circuit, when one can have a real fullrange driver system (that is Fostex recommended DBR) without any filters?
Well, and here I am...lost again
I shall flip the coin.
Who says that the recommended DBR for the FE207E doesn't need a filter? Look at the response graph on the plans. It shows the classic baffle step response. It needs a BSC filter just like almost all other tall thin cabinets, unless, of course, you push the speakers up against a wall. I don't understand the concept that a thin sounding speaker with ear-bleed upper mids is preferable to a balanced speaker with a firm bottom end just to avoid a simple BSC filter.
Seriously, consider the 35 liter BR. Anything from 35-40 liters will work. I have a pair of these running right now that work pretty well without a sub, so long as you don't have to have THX levels.
Fostex does not recommend a MLTL because Fostex designers aren't into MLTL's. Look at their product line. They are into quasi-back horns, or as GM calls them, big mouth TL's. I've put 207's in MLTL's and they work just fine.
Bob
Seriously, consider the 35 liter BR. Anything from 35-40 liters will work. I have a pair of these running right now that work pretty well without a sub, so long as you don't have to have THX levels.
Fostex does not recommend a MLTL because Fostex designers aren't into MLTL's. Look at their product line. They are into quasi-back horns, or as GM calls them, big mouth TL's. I've put 207's in MLTL's and they work just fine.
Bob
Bob has addressed argument #2. Argument #1 is merely an appeal to authority.irss said:
The internet-connected DIY community does far more "extensive research" of enclosures than Fostex could ever do. The Fostex-recommended designs were not handed down by God, they were drawn up by human beings at the time a particular product was rolled out. These designs need to appeal to a broad range of customers, specifically not take up too much space.
irss said:
So far our experience with Fostex recommended enclosures is mixed. FE103 horn was not great, FE126e BR/TL hybrid was OK with muddy bass. FE167 BR is OK but we improved the tuning....
I have a pair of 207s on the way, i'm thinking of Onur's 206 horn for them (reports are that 207 is better than 206 here), or see if i can get a Big *** Fonken to work. But for quick & simple it is hard to beat Martin's ML-TL.
dave
That would be my automatic choice too. Or buy Bob's plans, which are a little more refined, as you'd expect, it being a quasi-commercial product. DBR has potential, but that doesn't necessarily mean that the Fostex designed enclosure is the ultimate expression of it for that driver. I'm betting improvements could easily be made. I'll look into it when I get a moment. Unless Bob, Martin, GM or someone else beats me to it first of course...
Bob, what do you reckon for ~40L -large standmount?
Best
Scott
Bob, what do you reckon for ~40L -large standmount?
Best
Scott
Scottmoose said:
I took a look at DBR's, but I never found anything that would remove the discontinuity where the little box hands over to the big box. I get better results with a MLTL, and the sizes are almost the same. I think of the DBR as an interesting sidelight, but nothing to actually pursue.
I settled of 36L, to make up for all of the stuff that has to go into the box. I feel that this is large enough to get f3 below 40 Hz and still keep some control over the cone down to 30 Hz. Going larger only exacerbates the excursion problems you get with a single driver full-range speaker. I'm in the process of establishing the port tuning and designing the BSC/zobel. I'll report back when I get it nailed down.
Bob
http://www.zillaspeak.com/fostex207e.asp
Not sure what i would do with this driver actually...
Probably a Voigt Pipe
http://www.melhuish.org/audio/DIYTQ11.html
Peace,
Godzilla
Not sure what i would do with this driver actually...
Probably a Voigt Pipe
http://www.melhuish.org/audio/DIYTQ11.html
Peace,
Godzilla
Godzilla said:
Not enough Vb to do it justice as is. However, if you junk the original large vent (seemingly set to the Sd of the PM6C it was aparrantly designed for) in favour of a 3in diameter, 3in long port 4in up from the bottom, you'll get an extra 20Hz of LF extension and kill the worst of the the ripple, at the price of loosing a couple of db efficency. Good trade off IMHO.
A better bet if you like the TQWT look would be Martin King's classic trunkated ML TQWT cabinet, with a 3in diameter, 4in long port. The cabinet design is here. http://www.quarter-wave.com/Project06/Plans_Option_1.pdf
This is the response you could expect -I wanted the slight rise to compensate for room-gain. You can flatten it by shortening the port to 2in, at the expense of a small peak at cut off, which can add weight if you don't go too far. This is Ye Olde Wharfedale response, and it works as well today as it did when Gilbert Briggs was still running things.
Best
Scott
Attachments
Incidentally, I just got a photo of one of my FE207E cabs uploaded. You will see:
(1) wrench socket phase plug
(2) 45 degrees toe-in
(3) speaker stand made with two cinder blocks, three Moray-James-designed "isolation feet", a bit of bluetack, and a spiked wooden platform
(4) custom-designed cabinet resonance control
You will not see:
(1) 3 ohms series resistance to account for relatively oversized cabinet
(1) wrench socket phase plug
(2) 45 degrees toe-in
(3) speaker stand made with two cinder blocks, three Moray-James-designed "isolation feet", a bit of bluetack, and a spiked wooden platform
(4) custom-designed cabinet resonance control
You will not see:
(1) 3 ohms series resistance to account for relatively oversized cabinet
An externally hosted image should be here but it was not working when we last tested it.
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