Monacor SPH-135/C and SPH135/KEV comparisons

[nmackie]

I have to replace the drive units in my Clements Reference 1 loudspeakers, one of which accidentally got burnt out. The Monacor 135mm units appear to be very similar in mechanical fit to the existing unit, but there are a number of variants available. The best available (I'm assuming) are the SPH-135C (carbon fibre cone) and the SPH-135KEP (Kevlar cone).

Details of the SPH-135C which is listed as a bass-midrange are here

while details of the SPH-135KEP which is listed as a midrange are listed here

There are some opinions on these drives here

And a useful table here comparing the drives here

To my untrained eye their specs are very similar, except for the cone material (carbon fibre/kevlar) and the fact that the Kevlar model has a phase plug.

Which should I choose?
I'd be interested in hearing from anyone who has compared these units by listening to them.

Regards,
Neil (J Mackie).

[isamac]

I have a pair of SPH165KEP

First important thing is that T/S measured where completly out-of spec from what Monacor claims. They were close to the ones from SPH135KEP, quite strange. Hopefully both units had same specs...

From the FR point they are really smooth up to 5/6khz, with a smooth rool-off, thanks to the phase plug maybe.

Second point, there is a gap between the phase plug and the voice coil. It makes some air noises at high levels. Not something important, but C version should not have this problem.

[bombardon73]

I guess the woofer also has to do a bit of midrange so the 135kep is a better option here. The 135c is usable up to 2.5khz but then you should use a steep filter (18db/oct). The 135kep has a very smooth frequency response up to 7khz withotu breaking up.
I did build a speaker with the 135kep and was very pleased with the sound.

[nmackie]

bombardon73 wrote

>>The 135c is usable up to 2.5khz but then you should use a steep filter (18db/oct).

I would not have guessed that from the Monacor frequency responses. The SPH135C looks reasonably flat to 5k while the SPH-135KEP looks OK to 10k. The SPH-135C does have a prominent peak at 6.5k though. The Clements Reference 1 have ribbon tweeters and your point does highlight the fact that I should know the cross over point before making a choice.

As for any adjustments for crossover, my intention was just to use the existing one to get the speakers back in use and then then at some time in the future go active and use a digital crossover to make the frequency response flat. However I'd still need to know where to put the crossover point which is something I'll have to measure.

The discussion so far seems to indicate I should get the Kevlar units. It makes me wonder why they produce the carbon fibre ones as the frequency responses seem similar at the low frequency end.

Thanks.

[bombardon73]

I do have some tests lying around from a german magazine. These tests show that the 135c should be filtered at aprox. 2 khz (crossover point will be 3 khz)

In your case I would choose the 135kep.

Another question, how big is the enclosure?
I just did a simulation in WinISD, and the 135 kep needs an enclosure of aprox. 7 liters. The -3db point will be at 60hz.

The 135c has totally different parameters, this one needs a enclosure of aprox. 13 liters but will go pretty low. The -3db point will be at 43hz!

So the choice is yours, want deep bass go for the 135c but keep in mind that you can't go higher then a xover point of 3khz so the question is, can the ribbon speaker go as low as 3khz (with some experimentation it probably will).