Anyone that have the Troels Gravesen The Loudspeaker 1 or 2

[Niccob]

Have I realized any improvement in the HF? Well, quite a bit, though I don't think it had much to do with break-in.
As it turned out, the fellow who assembled the crossovers for me inadvertently followed Gravesen's instructions for the wrong super-tweeter, so the Viawave ribbon tweeter that came with my kit was getting too much attenuation. Once that was corrected, I noticed an immediate improvement.
Having said that, from a graph published on his website, it seems that Gravesen designed the TL-1 to be 4-5 dB down at 20 kHz when listening at a typical 3-4 metre distance. I don't quite understand why one would do that, but it is what it is. So, even now, the TL-1 doesn't have quite the vividness in the upper frequencies (most noticeable with cymbals, gongs, bells, etc.) that I enjoy from my other speakers.
Finally, it's also worth mentioning that Gravesen uses the same 18 Sound horn and 1" compression driver in a smaller 3-way system that's also on his website and, in his description of that design, he mentions that the 18 Sound driver/horn outputs to well above 20 kHz, but loses some linearity above 16 kHz (I can't hear beyond 14 kHz due to age). I even asked Gravesen if I could just remove the 9 kHz low-pass on the horn and disconnect/remove the super-tweeter, but he said that with the TL-1 crossover no such quick-n-easy modification was possible—and, understandably, he was not about to start doing a custom design for me!
Hope this helps! Regards, JT.

Thank you very much for your detailed answer! I am sorry for not having the knowledge to help, but following with interest. I guess that there may exist other TL owners with similar experiences.

 

[dr.joe]

According to the e-mail I received from Mr. Gravesen, modifying the crossover for a three-way system would be extremely complicated. He was most emphatic that simply removing the 9 kHz low-pass on the horn would NOT work.

 

[EarlK]

@System215

Tweeter Mod:

If in your shoes I would first see if I can get more listening satisfaction by simply turning up the tweeter a couple db ( I know that my almost 70 year-old ears would welcome this mod ).

One can do this by paralleling another resistor ( of similar value or greater ) to the existing resistor ( R1, seen at the "amp-side" of the UHF circuit ).

Horn//Driver Mod:

(i) Have you already done Troels recommended mod to get a couple more db to play with ( of adding an variable LPad after substituting a 10-12 ohm resistor for the existing 5.6R resistor found in R6 position ?? )
- This ( & more tweeter level ) may be all you need to do.

(ii) Levelling out the HF drope,

There's a very gentle downward slope ( Hi-Mids towards HF ) that is now-a-days considered "best-practice" when using constant-directivety horns, but it can be "levelled" at a few places ( here are two examples ).

• A 3.3 uF cap can be paralleled onto R5 for a tiny increase of HF above 8K.
• A 30 ohm resistor can be paralleled onto R3 ( this results in a very moderate increase in db in the overall presence area, say 3-8K )

The two mods combined give an overall increase ( as seen in the following response prediction made by XSim )

• Purple trace is Troels existing Hi-Mid response for the horn//driver combo ( as published ).
• Green trace is that same response with the 2 mods just mentioned.

I would really recommend against thinking that going 3-way is going to satisfy your aural observations.

I think you likely just need a wee bit more UHF ( and lower treble ), perhaps because you've "goosed" ( a bit too much ) the bass amp with its' user adjustable dsp section or you have an acoustical dry room or some other reason.

One final question; Are you sure you have built your crossovers to proper spec ( & that your TL1 is meeting Troels published specs ) ??
- Have you measured their frequency response?



🙂

 

[dr.joe]

EarlK, I very much appreciate your taking the time to suggest ways to improve the HF performance of the TL-1s.

Alas, for me the major reason for attempting the TL-1 project was that I thought—mistakenly it seems—that I wouldn't have to do all manner of "corrections" to get a flat response because the designer had already done the hard work.

I don't have time right now to carefully look at your suggestions—though I will—but with regard to measurements, my TL-1s are more than 20 dB down at 20 kHz, and that downward slope starts at 8 kHz.

And the reason I'm thinking of reverting to a 3-way system is that I've got a number of excellent 2- and 3-way speaker systems using 1" or 1.4" compression drivers that offer stellar MF and HF performance which, at least in its present configuration, positively embarrass the TL-1s. . .

Will probably have questions when I get into the nitty-gritty of trying to implement your suggestions.

Thanks again! Joel.

 

[darkmatter]

A quick question, how critical is the series notch filter on the passive bass crossover?
This series Notch Filter dampens bass driver resonance at its resonance frequency (fs)
Would removing it affect the bass driver x-over values?
Thanks