FE126En in MLTL

[slhijb]

Comments on using the FE126En in an MLTL (design with MJK’s worksheets).

Power = 1.5w SE-OTL, small 13‘ x 13‘ room, corner loaded with WAF concerns.

New Fe126En = 0.3 QTS, 93dB, Vas 8.5L

Good idea?

[rjbond3rd]

Hard to say more without knowing the dims / tuning. How much bass do you need? How close to the corner? Have you considered that a circuit is often (but not always) needed baffle step?

A bipole or at least a 1.5 solves a few problems. A horn can solve some of the same problems but will be bigger, more complex but can sound lovely. Using two drivers gets you there faster, usually with a smaller cab, arguably with a flatter and often deeper response (or at least more tuning flexibility) but, but, but -- less dynamic (in the bandwidth that the horn would have covered).

Both approaches are good though. Once you've heard good horns, the choice is much harder so don't listen to any

[slhijb]

Thanks for the quick response. Bass, although a concern, is not a major concern. I have a powered sub already along the back wall. Would like the speakers to reach around 40 - 60Hz. They will be located close to the corners, the back of the speakers within 6" - 18". Plan on using a (Paul Joppa, Bottlehead) variable passive line-level baffle step due to the limited power of the 1.5W SE-OTL amp.

Passive Line Level Baffle Diffraction Step Compensation

I love the idea of a 2-drivers for SPL reasons (takes the Fe126 to about 96dB), was even considering an MTM or TMM, but this is a different animal altogether.

Do you think in this situation, a thin tower FE126En MLTL will be really good?

I have also designed a pair of FE-167Es for an MLTL, but am worried they may be a bit too much for this small room. Opinion?

[chris661]

FH Mk3 might be worth a look here?

It's a reasonably simple horn design, the only difficulty being a large radius cut needed for the side panels...
There's been a lot of threads on the forum about it, so have a quick look around...

[hm]

Hello,
do you look the Xmax of 0,35 mm,
how much bass you will get?!

[chrisb]

Originally Posted by slhijb

Thanks for the quick response. Bass, although a concern, is not a major concern. I have a powered sub already along the back wall. Would like the speakers to reach around 40 - 60Hz. They will be located close to the corners, the back of the speakers within 6" - 18". Plan on using a (Paul Joppa, Bottlehead) variable passive line-level baffle step due to the limited power of the 1.5W SE-OTL amp.

Passive Line Level Baffle Diffraction Step Compensation

I love the idea of a 2-drivers for SPL reasons (takes the Fe126 to about 96dB), was even considering an MTM or TMM, but this is a different animal altogether.

Do you think in this situation, a thin tower FE126En MLTL will be really good?

Without a lot of help, even 2 of these in an enclosure of this type would likely have very limited performance at frequencies well above 60Hz. They really benefit from a horn - of which there are several designs that are known performers without the need for any BSC or EQ, particularly in small rooms - no need to reinvent the wheel (note that the Fostex hybrid design wouldn't be on any such list that I'd recommend)

in no particular order:

BIB / metronome / Buschorn MKI / Frugelhorn 3 - Scott Lindgren's double mouth Saburo or Valiant are great performers, but better suited to a larger room


While Paul's line level BSC doesn't "waste" power in the conventional sense, (i.e. as would a passive line level BSC), it's still an EQ that tailors the FR by attenuating the higher frequencies, which is exactly where the 126 is most sensitive.

A far more efficient use of the low powered OTL would be line level XO, drive the 126s directly, and add woofer(s). In this type of application, the higher into the upper mid-bass you can raise the turnover point of the XO, ( as high as 300 is not uncommon) the less constrained the 126 would be in terms of dynamics, and the lower the distortion. Above 80Hz or so, even in a small room, you'd need one bass driver per "full-range" channel.

edit: a line level HP filter can be as simple as adding cap to the amp input - it's been a while since I did this myself, and I let someone else do the math, but it was brain dead simple to install. Incorporate a bypass switch to run the amp full range - we're only talking about less than 1" of wire and less components and solder joints than any type of external passive EQ/BSC network

I have also designed a pair of FE-167Es for an MLTL, but am worried they may be a bit too much for this small room. Opinion?

this driver has been discontinued for a while now - if you have a pair in hand or available, they might well better suit your room if it can't accommodate the real estate for the FE126E to best perform its "magic" - i.e. some type of horn, or the addition of powered woofer(s) in combination with either a small ported box or Open Baffle.

As with horns for FE126E, there are any number of good designs extant for the FE167E - MLTLs among them. FWIW, even the factory recommended BR for this driver isn't bad - but it can certainly improved upon.

[chris661]

diyAudio Full Range Reference Project

I find those to go low enough to cross to a single subwoofer, though I expect you'd get more dynamics etc from a full-size horn, they're very good. I currently run them without a subwoofer (couple of THs waiting to be built though), and find it sufficient.

hm, the Fostex drivers, while having a very small linear travel (and there's many ways to define that), pass such that tiny amount with no horrendous nastiness to the sound. A couple of mm p/p, while doing no favours for the sound, will still sound acceptable.

Chris

[chrisb]

Originally Posted by chris661

diyAudio Full Range Reference Project

I find those to go low enough to cross to a single subwoofer, though I expect you'd get more dynamics etc from a full-size horn, they're very good. I currently run them without a subwoofer (couple of THs waiting to be built though), and find it sufficient.

hm, the Fostex drivers, while having a very small linear travel (and there's many ways to define that), pass such that tiny amount with no horrendous nastiness to the sound. A couple of mm p/p, while doing no favours for the sound, will still sound acceptable.

Chris

Chris - what freq your XO, and size of the room?

FWIW, I found the late FE127E much easier to get good sound from in boxes as small as (or smaller than) Tim's folded Voigt

[chris661]

Hi Chris,

Previously, I'd crossed them 1st order line level at around 80Hz, to a pair of 8" woofers in a sealed cabinet. As I said, now I run them full-range, and will continue to do so until these tapped horns are built. Then the XO will be ~80Hz again.
Room's small (typical UK there), ~3.5m by ~3.8m. Minus desk, drawers, wardrobe, a couple of cupboards for storing old amplifiers... And a big guitar amp. Leaves very little space.
Given a larger room (well, large for this cramped island), they really shine.
In here, there's usable output to 60Hz.
I also found I had to mess around with stuffing to get them at their best. Behind/around the driver helped, as did stuffing the tapered end reasonably tightly. Sounds very very nice now.

[chrisb]

thanks, Chris