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TDL TRL2

Hello, signed up mainly to reply to this thread! I recently bought a pair of these on fleabay and was immediately impressed by them, they have a 'different' sound quite unlike all the other speakers i've tried- and i like that about them.. but at the same time i can see their weak points. So far the only mods i've done are fitting some scanspeak 2010 tweeters, lining the cabinets with damping, and re-arranging the stuffing as per mikesnowdon's example. Happy so far... but this is what i've got planned by the end of the year:
1/ Build new replica cabinets out of 12mm birch ply- built to scale approx 20% bigger
2/ Either fit new, bigger mid/bass drivers OR: Make it a 3 way design
3/ Re-do the crossover

Any problems/issues/advantages with making this a 3 way design?? Any problems with increasing the size of the cabinet? By my calculations the new box will have an approx 50litre capacity... what does this mean in terms of driver selection? cheers guys
 
Hi Fraser.

I liike the idea but unfortunately its not so simple to re-design a speaker from scratch.

If you want to build a bigger box there are factors involved regarding the size of the cabinet and driver choice. For the box, the capacity is determined by the Woofer parameters etc. Port tuning is simmilarly determined by the main driver. And designing crossovers from scratch requires driver measurement equipment.

You could improve the RTL cabinet by cladding it with 1/4 birch ply and adding plinths for stability.

As for making it a 3 way its possible by building a new enclosure onto the top of the existing one and mounting the new midrange driver there. This would be simmilar to a MTM configuration (M-T-W actually). Doing this would require measurements of each driver in the enclosure. Then the new crossovers could be designed based on these measurements.

My opinion is that you should make improvements to the RTL2 by improving the cabinet and upgrading the crossover components. Fit better wire internally and experiment with different resistor values on the HF section. Try and get the max performance you can with the existing enclosure, crossover, and woofer. (Of course re-building the cabinet from birch ply would be great - but you would need to keep exactly the same dimensions). When you upgrade the caps you will be quite surprised at how good they sound.

Also its worth trying the Morel MDT30s tweeter as they go well with the existing crossover - just needs a resistor change from 1.5ohm to 2ohm for best results. Wilmslow audio tried many different tweeters and determined that the Morel was the best match to the RTL crossover.

If you want to build from scratch though take a look here:

http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

Mike.
 
Thanks fot the quick reply Mike- ok i guess i've been a bit optimistic about how easy it is to whisk up a decent sounding speaker LOL. To be honest, i don't really need a bigger cabinet- they are big enough for my listening area already! This was mainly for aesthetics- but seen as i already have some very decent, heavy ply sitting about i think i will still re-make the cabinets, but exactly to scale as the originals. The only difference will be to brace and seal them internally and strengthen the front baffle, maybe with steel for the driver areas...

Then i will look into crossover tweaks etc later. I already have some mundorf caps and tantalum resistors lying spare so i can experiment with some crossover tweaks as i work. I will post regular photos in this thread following my progress- please continue to help with suggestions and improvements!! regards

fraser
 
Thats great!

Looking forward to the pics of the new cabinets. Have a good look at Troels Gravesens website for tips on building good enclosures. Things like chamfering the driver holes etc. Are those Tant resistors rated above 5W by the way? (they should be for a crossover) I would love to build new cabs myself but I dont have the tools or expertise. What I'll probably do is have new front baffles made for me and then get a router to flush trim some 1/4 ply around the existing cabs.

I'll be getting some resin stuff soon to experimet with. As I said in an earlier thread I intend to fill the recess behind the flange on the midbass with it. Im also going to try gluing the maget. Another thing to try is a peice of dimple foam on the rear of the magnet - helps to break up standing waves inside the enclosure.

After that Im going to rebuild my crossovers in their own external box and seal them with resin. (I might incorporate them into some new pinths though)

I'll post pics as I go along like you are.

Its great that your here and Im happy that you also found out how great these speakers are with just a few tweaks.

Mike.

Edit: Make sure you maintain the same dimensions internally also, this is all critical to the RTL sound. Also keep the driver placing on the front baffle the same.
 
Hey fella's

If you really want to de-bug a TDL, try for some RTL 3 mk1's, or for cabinet freaks, the RTL4!!!

The 3 needs it's mid resistor across the coil changed (doubled in value?) to lift the mid and this smooths the mid to top balance. The cabs need tons of extra veneer/cladding/bracing to taste, but they're worth it IMO. The 4 was basically a cut-price Studio 2 and the box affected it severely......

Just a thought when you've all finished with your "2's."
 
Cheers for the input DSJR- definitely a thought for the future, if i'm not happy with the 2's by the time i'm done i'll keep my eyes open for a '4' version. I noticed when looking for the transmission line that the later versions- 3 and 4, were always a lot more expensive than the 1s and 2s which put me off a bit!
 
I've decided instead of starting the boxes from scratch to just go over the whole thing again with 12mm ply, glued and bolted tight. This will result in a very solid 23/24mm cab. When i've cut all the wood to size i'll see what i can make in the way of bracing with the leftovers.

p.s. I was surprised by the cheapness of the wooden finish! I tried sanding it off before realising it was just stuck on and peeled off quite easily :p

Here's one cab completely stripped- i sawed the connection in the middle of the port off- i have a cunning plan to finish this bit off later. I used filler to go over all the screwholes left by drivers and the cabinet covers, and filled in the cut0out for the tweeter. This week i'll sand it all down to get an even surface and start work on the ply
DSCN0642.jpg
 
Go to edit - advanced - Insert image - copy paste the URL of the image into the box that appears. I wanna see these pics!
 
Go to the photo you want to add - right click - properties - 'copy' URL - in advanced edit follow above instructions. When you paste your URL into the dialog box make sure yout dont have the http// twice.

Mike.
 
I've decided instead of starting the boxes from scratch to just go over the whole thing again with 12mm ply, glued and bolted tight. This will result in a very solid 23/24mm cab. When i've cut all the wood to size i'll see what i can make in the way of bracing with the leftovers.

p.s. I was surprised by the cheapness of the wooden finish! I tried sanding it off before realising it was just stuck on and peeled off quite easily :p

Here's one cab completely stripped- i sawed the connection in the middle of the port off- i have a cunning plan to finish this bit off later. I used filler to go over all the screwholes left by drivers and the cabinet covers, and filled in the cut0out for the tweeter. This week i'll sand it all down to get an even surface and start work on the ply
DSCN0642.jpg

looks like your doing waht I originally planned. Good work - nice one. How was it removing that plastic veneer? Did it rip out much of the wood particles? For bracing the internal partition you just want a length of dowelling (bit of broom handle will do nicely) between it and the front baflle glued in place. Got any plans for a plinth yet?

Mike

EDIT: Have you got a Router with a 'flush trim' bit? You need one to trim off the little lip around the front and rear baffles and to get a nice join when you add your birch ply cladding. Will you be flush mounting the tweeter? If so you need a router for this also. Mike.
 
The veneer came off quite easily once i got the hang of it, took off a thin layer of chip with it- but no harm done :) For the internal bracing i was either going to use some leftover ply or maybe get a rod from here: http://www.theplasticshop.co.uk/clearance-stock-3311-0.html they do some very strong engineering plastics which i've used before

I lent my router to a neighbour who then moved about 300 miles away without telling me :confused: i never got round to getting another as i rarely used it. For this job i've just got some very coarse sandpaper and went wild round the edges. I've got an idea for mounting the tweeters- all will become clear later!!

Some rough photos so far- here's the completed sanding; some ply cut to fit the lids and the base of the cabinets; and a spare cut off of aluminium mesh grill i have lying around. This was from an old marshall guitar cab project where i replaced the vinyl grill with this industrial looking stuff. I'm going to cut a rectangle out of it and use it to cover the port. Should be cool :cool:

http://i14.photobucket.com/albums/a329/fraser1985/DSCN0647.jpg
http://i14.photobucket.com/albums/a329/fraser1985/DSCN0645.jpg
http://i14.photobucket.com/albums/a329/fraser1985/DSCN0643.jpg
 
Hi All,

I finally found the time to add bitumen damping to the midbass frame and up the attenuation on the Morel tweeters to a 2 Ohm again (I started with 2, dipped to 1.8, got tired of it being so 'glarey'and went back to 2 Ohm - much better balanced). The frame damping DID make a difference, but not quite what I was expecting... In fact it tightened up the midbass which was, I suppose a nice benefit but I was looking for something to tame the 470Hz(ish) ringing. In the end I did achieve this, but only accidentally when I re-glued all of the crossover components I had fiddled about with. I've yet to understand quite why my capacitors and resistors being unglued did this but there you go - I'm learning more about this non-exact science as I fiddle. I'll post a schematic of the crossover next week once I've put it in a format suitable for use here.

I've compared these as they stand with my Linn boxes and a pair of ribbon tweeter floorstanders from HTD and they fit my tastes better. The Linns seem so relaxed I could fall asleep listening to them and the HTD's are a smidge too toppy but suffer no ringing at all, in fact they sweep VERY cleanly for cheapy speakers - great for movies!

I'm into seriously diminishing returns here, especially as my pair is 'rosewood' finish which(as DJSR, I think, pointed out) looks rubbish. I really do think a complete rebuild is in order as I have the woodworking tools to achieve it. Watch this space for some clones using the original midbass driver in the new year.
 
rumplestiltskin: That's weird about the caps and resistors gluing having an effect?? Maybe some impedance issues if they weren't in properly? I'll definitely try damping the driver if it has effect though- thanks

Mike i have no idea what my ply is- i've had it lying in my bucket for around 3 years- finding it is what made me re-do these boxes. If i'd known it was so rubbish i would have just bought some new stuff tho- it's tricky to work with- pretty cheap... Still brainstorming about the plinth- where did you get yours? They look quality.

I've never used covers before on any speakers, i prefer the open look so won't be bothering with them, unless my paint job is so awful that i have to :D

Today i glued and screwed the tops, bases and side baffles onto one speaker- it now weighs in at about 20 kilos, pretty good for an empty unfinished cab!! I've had to apply a fair bit of putty to smooth over the shoddy ply (and my woodworking skills!) but once the front and rear baffles are fitted it should look pretty decent, and the paintwork should complete it nicely. Here's a photo of semi-finished cab and the mesh which will fit into the port:

http://i14.photobucket.com/albums/a329/fraser1985/DSCN0648.jpg
http://i14.photobucket.com/albums/a329/fraser1985/DSCN0650.jpg
 
Fraser those are coming along nicely mate, love the mesh idea.

My plinths are Sainsburys chopping boards. I stuck on a square of bitumin about 1cm shy of the edges, then screwed the new plinths on. Install the threaded insets and add some spikes. Job done for 10 quid!

I think you definately need bi-polar caps but dont use eletrolytics. Go for some decent ployprops, you wont regret it. Regarding the resistor value: That depends on the tweeter your using and your taste really. Try a variety from about 2.2 to 1.5 see what suits the balance of you system and taste. Anything above 7w should be ok.

rumplestiltskin,

Thats a good discovery on the lose XO components causing the ringing. Im even more into the idea of the resin compound now. Trouble is I have no idea where to find it. On John Ekels site he calls it '2 component resin' but Ive tried google and theres so many varieties its hard to know which to choose. Like I mentioned before, I want to use it to fill the recess around the mouting flange on the midbass also. I wonder what difference that would make? If I had measuring equippment Id try it with blu-tak and see what the results were. Also dont forget the glue mod around the magnet where it meets the basket, I've yet to try it myself but it shouldnt do any harm to give it a go.

Mike.
 
Fraser,

I forgot to mention. You can tweak the HF response a litttle by trying different cap values in he crossover. I had 5.6uf and later went for 6uf - the same as the original crossover. It depends on your tweeters really but you might want to try tweaking the values a bit. I wouldnt go too far either way from the original 6uf.

The best way would be to get some measurements done by someone who knows and has the proper gear. That way you can optimise the crossover to suit the Scanspeak tweeters. I went for the Morel's because Wilmslow audio had tried various replacement tweeters for the RTL2 and found the Morel MDT30S to be the best match to the standard crossover.

How are the cabs coming along?

Mike.
 


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