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Vikash 14th August 2003 05:32 PM

Rehousing speaker - TDL RTL3
I'm bored and can't afford the Seas drivers I want yet, but I do have a pair of TDL RTL3's collecting dust in the 'sound room' (my loft conversion). I love these speakers for what they are, but after seeing the flimsy chipboard cabinet and very poor looking crossover and internal wiring, I want to take out the drivers and use them in a new design.

A long shot, but has anyone got any T/S parameters for the bass driver? or perhaps done some mods on these speakers?

analog_sa 14th August 2003 05:42 PM

I once had the RTL4 (i think the bigger brothers to yours). No idea why i bought them; must have been high on something. Ah, yes, remembered - they were very cheap :) No matter how hard i tried i couldn't make them play music to save their lives - boomy bass and generally very annoying sound. Maybe it was my room or my valve amps but they simply didn't work. The cabs are terrible, the drivers - dirt cheap. Your best option is probably to sell them and buy some reasonable drivers with the money - i am sure you'll do a lot better.

Vikash 14th August 2003 06:17 PM

Your opinion is appreciated. But my experience with them is quite the opposite of yours. They were cheap, I think about 400 when I bought them, but they blew away the competition to my ears. They are known for their good bass, and the soundstage is nothing short of huge. I've put them next to a pair of Celestion A3's (quite in a different league) and they held their own in the bass and soundstage area. In fact the whole experiment was to try and identify what the Celestion's were missing.

Enough rant, back to measuring...

pinkmouse 14th August 2003 06:51 PM

Ah, I used to love my 3's, but you're right about the 4's they were rubbish in comparison. ;) But, saying that, the mistake most people made with all the TDL range, IMHO, was driving them with underpowered amps, they needed 80-100w minimum to really sing.

The drivers in the early RTL3s were Monacor SPH175, they had squared off sides. The later, inferior versions had Visaton drivers, sorry I'm not sure of the exact model, but as they had paper cones, I think they were probably the same as, or a variant of the WS17E.

I did have measured parameters for the Monacors, but I suspect they have gone to data heaven in a HD crash years ago, however if I find them I will post details.

Vikash 14th August 2003 07:14 PM

I have the drivers with the squared off mounts. Didn't know they were by Monacor though. I heard that TDL made their own drivers. Perhaps it was for their upper range TL's only.


Monacor SPH175
Thanks for the info. Let see what I can find on these...

pinkmouse 14th August 2003 07:24 PM


Originally posted by Vikash
I heard that TDL made their own drivers.

Yup, you are right, all the drivers made for the big TLs were custom, but the RTL range used off the shelf drivers for budgetary reasons. I learnt about this from a chat with John Wright, as I needed to get replacement drivers for the mate who bought my 3s from me. It was as they were just closing down, before the Richer sounds buyout, and as they had no spares in stock, and John thought it was all over, he had no problems with giving me the driver details. Nice Bloke. :)

Vikash 14th August 2003 10:00 PM

I found the Monacor SPH-175 driver and it does look very similar, although no exact from the pictured angle.

A couple of concerns. My measurements show Re = 10.9 (versus 5.7 on SPH-175 datasheet) and SW impedeance plot shows impedence = 150R at fs (versus ~93 on SPH-175 datasheet)

Where would you put your money? Almost certainly at a different revision driver right (my TDL's are at least 7 years old)? Or perhaps it was a modified driver just for TDL? Or maybe its my SW setup...but testing resistors is accurate.

pinkmouse 15th August 2003 10:45 AM

I would go with your SW measurements. I suspect that you are correct in your assumption that the driver may well have been "updated" since. ;)

Vikash 15th August 2003 12:32 PM


I would go with your SW measurements
meaning believe them, or the fault is in my set up?

I ran some quick tests: my jig v2 and SW exactly matched my DMM readings for every resistor measurement. (I went up to 2K7R)

Is it possible for t/s parameters to change over years through underpowering, overpowering etc?

I'll test the other three drivers to see if I get consistent results.

Vikash 15th August 2003 05:01 PM

2 Attachment(s)
Ok I've tested the four drivers using SW.

Does this look like an acceptable difference between four identical drivers? It seems a bit much to me.

Max differences between all four drivers:

fs: 6Hz
Qts: 0.11
Qms: 0.27
Qes: 0.13

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