Help tuning my FE127e fullrange ref MLTL

I have recently completeted a pair of Diyaudio fullrange reference MLTL monopoles.

I am not blown away by them, and I am wondering what the fuss is about fullrange loudspeakers. Maybe they need tuning?

See photos.










I have lined the cabinets with traditional felt (10mm est) on the rear of the cabinets, and synthetic felt (2x5mm est) on the fronts. I have stuffed the top 3/4 of the cabs with three layers of MDM3.

I have made the vents 50.8 mm long x 51mm diameter.

Ouch. ****, ^^^^, """", !!!!!!!!. I have just noticed from the original drawings that the monopoles should be 38.1 diameter. This is very annoying as I spent hours cutting the holes to 51mm (dipole diameter) with about 20 sessions each using a specially purchased Forstner bit. The idea was to avoid plastic tubes.

Is this likely to be responsible for the muddy sound?

The top end is good.
ouch, that is a lot of time & materials to invest in a project that leaves you underwhelmed.

As best as I can recall, there were many variations on enclosure dimensions, driver placement & vent tuning this series. Of the few that I built or heard, my personal favorites were the folded monopole which I made into a short, angled floorstander for my mom, and Scott Dunn's bipoles.

Yes, if your port is oversized, the tuning will definitely be off. How are these mounted? If the vent is downfiring, you could possibly line the inside of the port with a cut length of ABS pipe, hot glued in place - out of sight, etc......
Your hole is too big!

Yes you have a bit of a pickle here.
I was thinking the same thing as Chris. A liner to reduce the tuning diameter of the port will solve the problem.
Another thought once you get that dimeter solved is how is the port loaded I have a sneaking suspicion that the presentation does not load the floor or a wall. If this is the case the bass might be a little thin.

Also these speakers do like a current source more than a voltage source. Nelson Pass has a good paper on this topic that is worth the read. A Tube amp or an F4 ( or other current source) are quite wonderful. There are other amps that perform quite well, these are the ones I know about.

Good luck
These are designed to be wall mounted with the port facing down.

I have already been to the plumbing shop today, but it was closed.

I will insert a piece of pipe of the correct length and internal diameter and fill the gaps with silicone, and report back.

Perhaps we can get on with tuning after that.

SCD. these are to be used with my digital amp based system, see below. there is a pair of subs to follow.
Hmm, it's a bit late, but I calc'd an alternate driver position if anyone's interested, though with such small cabs it's debatable as to how audible the difference might be:

Monopole: 11.09"
Bipole: 12.09"

One thing's for sure though, even wall mounted the monopole will still probably need some BSC at this low tuning (for the driver).


I am struggling to find some pvc or similar tube with 38mm (1.5")internal diameter. 35mm is the nearest in the UK, so far.

Should I keep looking, or adjust the length accordingly. If so please could someone do the calculation for me (with 35mm tube) or point me to the software, so that I can have a go myself.
dublin78 said:

I am struggling to find some pvc or similar tube with 38mm (1.5")internal diameter. 35mm is the nearest in the UK, so far.

Should I keep looking, or adjust the length accordingly. If so please could someone do the calculation for me (with 35mm tube) or point me to the software, so that I can have a go myself.

Just adjust the length. All you are doing is looking for the correct volume of the tube. If the diameter is narrower then make the length longer. Look for a volume calculator on the web that calculates the volume of a cylinder.
Well I have found some 1.5" pvc pipe and now the ports are the correct size. See Below.


I still think that there is some work to do on the tuning. There is definitely something missing - low mids, I think. The sound is very promissing though, and I am more encouraged about the whole FR thing.

Sound is very hard to describe, but I would say that they sound slightly hollow and dull, cold even.

I have lined with felt and filled about 3/4 of the cabinets with three layers of MDM3 stuffing from the top.

What is the effect of the filling?
What happens if there is too much stuffing?
What would they sound like if there was none?

For reference this is the design:
Hi Dublin78,

No replies showing so I'll try one suggestion.

Take all the stuffing materials out and add to taste rather than
filling up the box with material. You can always add some.

From a base of zero the next step would be to pack some wadding above the driver.

I am pretty satisfied with that style in the GM MLTL (plus a variation on the port length and placement.) When first building that version of the MLTL and 127e I ran the box with nothing inside. That will surely give a difference to the 'dullness.'

Other enhancements include flush mounting the driver.

Driver tweaks are various from non invasive and reversible to
permanent mods.

A/B testing with some test tones on different speakers will also reveal the differences of the way units sound from what you've heard and your new ones.
I have not had a chance to play with the stuffing yet, but I had a brainwave and I moved the speakers into my main set up and AUTO EQd them with a Behringer DEQ2496. Here is the eq that is meant to flatten them:


As you can see, the DEQ2496 is boosting the low mids (160-400hz) and reducing the areas between 500 and 2.5K.

Does this mean too much stuffing, or too little? Or something else entirely?
Without taking any scientific measurements I would say that EQ pic is exactly what was needed when I had the FE127E in some fonkens. Also the sound you're describing is pretty much what I heard too - which ended up with unsatisfactory level of bass and a tendancy to treble harshness. Ultimately not something you could live with long term.

I couldn't sort it with stuffing or using a BSC. In the end I have kinda given up and gone to a different box. I have to get a friend to check my boxes just in case I have some measurement off, but at the time I worked to +/-1mm.

Sorry to be the bearer of a "downer"!

Hi Fran

Yes this news is a bit of a downer - The fonkens are meant to be the best sounding box for the FE127E around, and indeed they were my back-up plan.

I will play around with the stuffing of these when I have time.

I had planned on treating the cones with Planet10s original mods, but then the enabling thing came along, and I am not brave enough to attempt that.

I will inevitably buy a set of FE127eN off Dave when I get round to it, but in the mean time, I wanted to get these right.

All suggestions are welcome...
Check out the 3D spiral horn thread over in loudspeakers forum. Its a more complicated build, but you get good bass levels. I'm making a pair of the AG180Z models for the FE127 so I will report back in a few days with more listening etc.

What I can't understand :confused: , and why I'm doubting my build is that loads of people come back with great reports on the fonkens. Mine certainly aren't that so either they are all delusional or I have something wrong!! Easier to believe that I have something wrong innit?:rolleyes: Bear in mind that I made botht he regular fonkens and the slim tower ones and both have the same result, with the regular fonkens sounding a bit better.

What I would really love is a pair of jordans to go in there, but funds would need to be approved for that!!!

Fran: I agree with you. It is strange that the fonkens do not suit your tastes.

Perhaps there is something in your system that does not suit the Fostexes? Perhaps they are damaged? I am sure that your build will be good. +/- 1mm will be fine.

I noticed this evening that the driver frames of my FE127Es are not flush with the MLTL baffle. This will be because I have over-braced them from the rear. This is easy to sort, but I doubt this will be the cause of my problem, as there is a reasonable foam washer to seal them.

I should have a chance to remove all the stuffing tomorrow and start tuning from scratch.
I am very eager to find out why Fran's experience with the Fonkens is what it is... he is the 1st one with anything but pleasure to report (around here i don't know how many times we hear -- it is good but it isn't a Fonken)*. Admittedly low bass is MIA, this was one of the design compromises (i can say that with the FonkenWoofTLs there is no lack of bottom :D -- still working on XO)

We will build the 3D spiral/TL just to see how it does ... which brings up the JX92 -- are jkeny's from the recent group buy? So far i am having a hard time warming up to mine.

*for instance from a recent email (... but am finally feeling better this afternoon and thought I'd kick on some music.

The selection was a local southern gospel group whose vocals consist of two sisters, along with a bass singer on a few tracks. I just wanted to tell you that IMO, the enABL'd Fonkens do female vocals as good or better than any speaker I've heard. On this album especially, they effortlessly reproduce all the harmonic content of the vocals, that many other speakers seem to miss. And, they do it without sounding harsh, an ever present problem with soprano-range female vocals, as you know.

Although these two sisters harmonize together flawlessly (there's an old saying in southern gospel music, "There's no harmony like "blood harmony"), it's still only two-part harmony, not the more common 3 or 4 part harmony, and as a result it sounds thinner. But nevertheless, on the Fonkens, it sounds round, full, and 3-dimensional.

Also, the banjo on the CD's opening song extends to about 2 outside the left speaker, something that doesn't happen on my other speakers. Besides the great imaging, there's just something "right" about the tone, and one could never find fault with the coherency and focus only a point-source can provide. But, it doesn't stop there. They sound good with pretty much whatever you can throw at them. Acoustic jazz, cool/mellow electric jazz, fingerstyle guitar, and various categories of classical ranging from full symphony to string quartets all sound phenomenal.

I just want to say thank you once again for these terrific speakers. ...)

I'm hearin' what you're sayin' Dave!!

That was why I went for both the fonkens right out of the box and even went for the enabled drivers too. Not a single bad report. In fact so unanimous was the praise that I built both the regular fonkens and the slim towers at the same time.

And I know its not the drivers because I've had them in the 3D box and they are fine there.

The jordans are not from the group buy, AFAIK, jkeny bought them a few years back. Very smooth presentation and no need for BSC with them. He is pretty happy I think.

I have made another set of the 3D horns for the FE127 and hope to fit the drivers tonight so I'll post again when I listen a bit. I also want to double check all the stuff about the fonkens and see what I did wrong.

Right. I have now removed all the stuffing and have adjusted the bracing so that the drivers are nice and flush with the baffles. N.B. They are not flush mounted with a recess, just placed on the surface.

I auto EQd the MLTLs again and here is the EQ that the DEQ2496 came up with to flatten them:


This looks a lot better, however there seems to be some loss of detail now which is a shame, and that hollowness is still there, but to a lesser extent. I may just be getting used to it.

After EQing, I mounted the speakers in their intended location. see below. The bass is very pleasing and there is no shortage of low end. I am not rushing to get my subs completed anyway.



Now I need to tune with stuffing a bit more, to get the detail back, and to try and loose that hollowness.

Stuffing suggestions?
Add some felt to rear of drivers?