Tweaking the TDL RTL3

[bostod]

Hi there.
i have a pair of TDL RTL3's from ebay. cost me £120 and sound great. I have seen various reccomendations for tweaking the RTL2's but very little on their larger brothers.
for those who are unfamiliar the RTL3's use 2x 6" woofers in a large transmission line enclosure. this creates a huge sound stage and amazing bass.
the only tweaking I have done so far is to replace the tweeter with a Morel MDT 30. this gave a great improvement to the treble and reduces the Tinny sound significantly.
from what I have read, the crossover can be improved easily by changing the capacitors to audio grade, the internal wiring can be changed to better quality and the cabinets can be lined to improve the sound.
has anyone got any experience of tweaking these monsters.
my aim would be to tighten up the bass somewhat and hopefully bring some extra clarity to vocals and the more subtle parts to the music.
Am I asking to much of these speakers, they are so much fun I would not want to completely change their sonic character.

Come on Dave R, I know you have some experience of these, get that grey matter working

[Techno Commander]

I had a pair of RTL-1s which I upgraded. My list of mods was as follows-
Morel MDT33 tweeters
Rewire with mil spec silver plated LCOFC cable
Replace caps with boutique polypropylene alternatives
Line cabinet with damping pads and refit the wadding.

The mods made a ton of difference and improved speed, clarity and definition. They did well for a couple of years and were then sold (for a good price) to fund some JBLs.

[DSJR]

I can't argue with the above, but the fundamental issues in the crossover don't appear to have been addressed with the wholesale wiring and tweeter replacements above.

The comments below apply to the original bubble-veneer RTL3 mk1's, not the nicer looking mk2's, which had dire things done to them to make them sound more like the popular Acoustic Energy competition.....

TDL in many of their speakers over the years (and some IMF's before) "featured" a recessed midband and the RTL3 was a classic in this respect. If you look at the crossover network, there's a resistor across the bass coil (IIRC) and I think from memory that it's 15 Ohms. All but doubling this value to 25 - 30 Ohms approx lifts the midrange back to a flatter level, DRASTICALLY improves the loading on the amp (which is around 4 Ohms across the whole midband otherwise) and enables the rather exposed tweeter to be far better integrated, the small soft-dome helping with the roll-in at the crossover point (a larger dome would probably extend the tweeter down to far I think).

The electrolytic caps MUST be replaced with polyprop ones, but I wouldn't go too exotic here in all honesty, as the rest of the speaker isn't really worth it. Now, if you were talking of the "proper" TDL Studio 3's (from which the RTL4's were derived IIRC), then I'd suggest going all out for a major update/upgrade.

Hope this helps a bit. I knew the driver and basic "RTL-model" designer well and we had endless chats about these and other TDL models. The late John Wright did the "voicing" of these speakers, together with all the TDL and previous IMF models and I also understand from memory that John also designed the Goldring G800 cartridge and its derivatives way back in the late 60's..

[bostod]

I have finally got round to sorting these speakers out. I had a chat to Wilmslow audio who supplied all the components needed apart from the 27ohm resistor.
first I unsoldered the old capacitors and soldered on a Supersound 5.6 ufd and a 10 ufd capacitor. I replaced the 15ohm resistor with a 27 ohm one as reccomended by Dave R.
I lined the cabinets behind each driver with bitumen deadsheets to reduce any vibrations and changed the internal wiring of the woofers with black rhodium disco cable again from Wilmslow audio.I have currently left the original wiring to the tweeters as some recommend that silver plated copper wiring can make these sound too bright.
before putting the woofers back in I bought some wadding from Dunelm Mill. it looks and feels exactly like the original stuff.I placed the original stuffing in the first chamber rolled up loosely as recommended by Mike Snowdon in a popular tdl rtl 2 forum. I also put extra wadding folded over in the entire rear chamber.
when replacing the Woofers i used no nails as well as the screws to make sure they were secure.
then I plugged them all back in put the music on low and went to bed to let them burn in a little.
when I listened to them the next day I was blown away. the bass was still there but tamed significantly. the midrange was much more evident. to be honest I did not realise what people meant by midrange until I heard the change in these speakers. the Detail was night and day. I just sat there all day listening to my music collection, hearing more clarity And detail in each track. I finally fell asleep in the chair after some whisky and that is where I stayed all night
this upgrade is well worth the effort and even an amateur like me had great success with it.
one little question remains. on my TDL 3 crossover there is a wire soldered on where the small resistor is usually located on the TDL 2 crossover.
Is this correct and what would happen if I replaced this for say a 1.8 ohm resistor? like the TDL 2
i will post some pics of the crossover later for reference.

[bostod]

hopefully here are the photos

[DSJR]

If you add a resistor in series with the tweeter, it will reduce the tweeter level perhaps a tad too much, especially as you've increased the mid now (and made the RTL3 easier to drive in the process ).

Why not just enjoy them as they are now, as doing what you've done may have really improved them. John Wright, who was very talented at designing and "voicing" his speakers (I understand he developed the Goldring G800 series of cartridges too), tended to reduce the midrange to emphasise bass extension, especially in his bigger models. This kind of balance can upset lovers of "fast" bass and a midrange which projects out of the box. Hopefully what you've done will be a great half-way point.

[bostod]

yes i am very pleased with the results. time to enjoy now
great tip changing that resistor.

[DSJR]

You can thank Clive Gibson (ex Elac, TDL and Musical Technology designer/engineer) for that. Before MF sadly disappeared (sold for peanuts to PMC), Clive built and repaired loads of 80's/90's TDL drive units the majority he designed as well (in John Wright's lifetime).

Glad you've givin 'em a new lease of life.

[bostod]

having listened to these speakers for quite a while now and given them time to burn in there continues to be a persistent problem. the tweeter still remains too bright. this is especially noticeable on the s and t's as well as the cymbals. how can I reduce this slightly without changing the overall sound of these speakers.

any ideas will be appreciated

[Stratmangler]

having listened to these speakers for quite a while now and given them time to burn in there continues to be a persistent problem. the tweeter still remains too bright. this is especially noticeable on the s and t's as well as the cymbals. how can I reduce this slightly without changing the overall sound of these speakers.

any ideas will be appreciated

then a proper burn in