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mikesnowdon 21st August 2007 07:18 PM

TDL RTL2 upgrades
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I won a pair of RTL2 on ebay for 5.50!

Decided to modify and upgrade them and need some help/advice please....

First step: Crossover, whats the best way to impove it?

Second step: Drivers. Ive been advised to go for Vifa M17WH-09-08 midbass and Morel MDT30s tweeters. Are there any alternatives which would work without altering the crossover?

Third step: Enclosure. I plan on lining every internal surface with self-adheisive Bitumen deadsheet. Im also keen to learn of any other materials I could use for damping. What about 'dimple foam' or 'acetate fibre'?
Finally im going to attatch a new front baffe over the existing one (click attatchment) and apply 'Birdseye maple' veneer....

Any advice, hints, or tips will be greatly appreciated!

engine 26th September 2007 02:00 PM

well done on your purchase, i thought i had a bargain paying 19.00 for a pair.great speakers as they are but i am interested
myself in upgrading the drive units in the future.i have been in touch with lockwood audio who can source mk 2 versions of the tweeters but can no longer supply the main drivers but can advise on an alternative make. birdseye finish sounds nice.sorry but can't offer much advice as i am new to this forum but good luck with your project, please let us know how you get on,engine.

mikesnowdon 26th September 2007 04:00 PM

Hi and thanks for the reply.

I thought id share a recent mod with you as it is really cheap and hugely sucessfull.

I changed the internal wire, QED siler anniversary XT for the midbass driver and the old silver anniversary (the standard twisted version) for the tweeter (I chose not to use the XT on the tweeter as I did this previously on a pair ofALR/Jordan speakers and it made the treble far too 'bright' for my taste). I first removed to original wire and solder with a solder sucker making sure I removed all of it. Before I did this I marked with a pen on the crossover to ensure the new wires went on the correct terminals and the drivers were in the correct polarity. Then I resoldered the new wires with a good quality silver solder (this gives a better electrical connection than ordinary lead based solder).

While I had the drivers out I felt it would be a good experiment to re arrange the 'stuffing' inside the cabinet. It was just stuffed in to begin with so removed all of it and took each individual piece (about 4 per enclosure) and folded each of them in half and replaced them around the cabinet walls. This is tricky when doing the lower front portion of the box (youll see what I mean) but with care can be done. The result your looking for is to have all internal walls (exept that of the vent section) lined with the foam stuffing leaving free space at the rear of the main driver.

The result: More detail, better dynamics, imaging, clarity, and most notably, alot deeper bass. A really sucessfull mod. Well worth the effort.

justblair 26th September 2007 04:35 PM

While you have the bass drivers out of it can I suggest a mod that improved my missions but should be universal.

I used no more nails, but others have used putty. The baskets are no doubt pressed steel on these speakers (my memory says so). Damping or strengthening the steel basket reduced ringing from the baskets and cleans up the sound. Expect to hear improvements in the midrange to mid bass range of the sound.

The particular area of interest is the gap between the magnet and the steel frame. Fill this with putty or no more nails. This reduces ringing.

Others have gone further and added bracing to the legs of the basket. I cant see this doing anything other than good.

I found it to be the most cost effective upgrade on a pair of speakers.

Oh and yes on the rewire. I used three strands of mag wire, twisted together on a drill for my bass drivers, 2 strands on the tweeter. (18guage wire I think) rewiring IMHO is almost always an improvement.

Another cheap upgrade is a couple of slabs to stand them on.

mikesnowdon 26th September 2007 06:55 PM

Sounds good, I'll give that a go. I read somewhere on the net a suggestion that covering the frame with Bitumen has a similar effect....

On the subject of cabinet stuffing. I intend to try out a product supplied by wilmslow audio. Its a composite of bitumen sheets bonded to acoustic foam on a self adheisive backing which you line the cabs with. This should improve things even further. Then I'm going to use varying amouts (in different locations) of lambswool stuffing (also supplied by Wilmslow) to 'tune' the sound to my taste. Will post results on this thread.

A note on the RTL2: The weakest links are undoubtedly the cabinet and the crossover. Folowing that its the tweeter, apparently the MOREL MDT30's brings a major improvement to this speaker. To improve the box im going to use 15mm dowel cut into lengths that run from front baffle directly behind the screw holes for the midbass, to the back panel. These will be srewed into the rear panel, then the midbass will be re-installed with slightly longer screws which penetrate the front baffle and go into the dowels. Again, will post results on this thead....

mikesnowdon 4th February 2008 08:22 PM

I got the Morel tweeters and they sound amazing!

I really like the sound, theres virtually no sibilance at all and they produce nice clean treble. Im really happy with the integration with the RTL2 midbass. The Morels seem to blend niceley.

Ive been advised that the Scanspeak 18W/8545-00 should work wel in the RTL cabinet. Ive seen a speaker design using this midbass with a D2905/9500 tweeter ( and the mesurements are good.

Im considering attempting to incorporate this design into the RTL2 cabs. I'll need to make a completely new front baffle for this and in doing so I can give myself a little more volume to the box. The RTL2 cab is 25.5 ltr's which is enough for this driver. I can get it up to 26 with the new front baffle.

For a cheap and easy upgraed just fit the Morel MDT30's and upgrade the wire. Also fitting the Deadsheet panels will solve the cabinet resonances. Link for 'Deadsheet': (

mikesnowdon 18th April 2008 09:30 PM

Heres a picture of the planned changes.

Existing cabinet is clad in 4mm Birch Ply exept front baffle which is cut out with a flush trim router bit. A new front baffle is made to accomodate the SS drivers in the layout suggested by Troels Gravesen:

(let me know what you think)

mikesnowdon 18th April 2008 10:03 PM

2 Attachment(s)
image below

mikesnowdon 11th May 2008 09:17 AM


I have since upgraded my mains cable to Lapp CY with silver connectors. Great results but has the side effect of highlighting the brightness of my system.

I have ordered Jantzen Cross caps for the tweeter, and new resistors of a slightly larger value to drop the treble a tad.

The original tweeter section cosists of:

6 uF electrolytic Cap.

1.5 ohm 5w Resistor.

I had to order 2x 5.6uf and 2x 0.39 uf, as this was the closest match I could find. For the resistor I'v ordered 1.8 ohm, may try 2ohm later.

Im going to first try installing only the 5.6 uf and see how that affects the crossover point. If theres a difference it will probably be subtle. We'll see.

Once ive dtermined what sounds best I'll be ordering new coils and better resistors and re doing the whole crossover. Ive decided to do this rather than modding the entire speaker and changing drivers etc, allthough I may still do the above mentioned at a later date.

There is another interesting thread on the RTL2 here:

Cheers, Mike.

Report coming soon.


SimontY 11th May 2008 08:33 PM


Originally posted by mikesnowdon
I had to order 2x 5.6uf and 2x 0.39 uf, as this was the closest match I could find. For the resistor I'v ordered 1.8 ohm, may try 2ohm later.
Sensible values to try. You might prefer the smaller value cap, and if it's a "better" cap, then it may want to be smaller anyway, as good caps can make the treble seem louder.

Look forward to hearing the results.


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