Sound System Discussions


I asked a CDT authorized dealer for the required equipement for Sonic Bed. I’m forwarding the emails he sent because the products you asked for are not available and I’d like you to approve what he suggests to me. First, as you will see, CL61 are replaced with CL62. Second, I can’t buy Massive Audio here in Canada. He suggests CDT subs instead, please read his explanations below. Third, Genesis amps are not available in North America. He suggests Kicker amps instead. I’ve read the specs and it seems very interesting but it’s not the exact specs you gave us, hence I’d like to know if it’s ok with you.

If you have any questions or comments, please feel free to email me. I’d like to have an answer the fastest you can so I can order the parts and start building the bed.

Best regards,

Meriol Lehmann Directeur technique


Begin forwarded message:

From: “CarAudiophile” Date: 24 novembre 2006 2:27:05 pm HNE
To: “‘Meriol Lehmann'” Subject: RE: CDT CL61


Yes the EF-120’s are rated up to 400Hz… however they’ll do a much better job than 90% of subwoofers rated to 1khz… remember a rating is something that the company publishes, no solid guidelines to it.

However even then I do not suggest running them up to 1kHz… or any 12” driver for that matter… it’s simply impossible to create a 12” driver that can accurately reproduce that high… it’s the physics of audio, something that no manufacturer can change.

The reason being that the wavelength of the frequency is about the same size as the cone itself, one should never output a frequency that produces a wavelength greater than half the diameter of the cone.

“The upper limit for high frequencies of a driver is where wavelengths become smaller than the speaker diameter. This causes node and lobe distortion within the cone (chaotic resonances). Dispersion narrows to a beam and the frequency response becomes chaotic, sounding harsh and screechy.

So even if a manufacturer “claims” their 12” has some crazy frequency response … it does not mean that it will reproduce it linearly or with a proper dispersion pattern, let alone cleanly… CDT is an audiophile level company, they want their ratings to show this.

The SQ line from CDT will do 1khz better than the EF 12’s … they have a much lower Qts, which means more control over the cone and thus higher frequency performance… but I still don’t suggest using them… mainly due to the diameter/wavelength issue… if quality output is a #1 priority, forget the 12” up to 1khz.

Best idea would be to use the EF-8 8” driver… these have amazing transient response and will hold together well right up to 1khz… as for subsonic performance, the 4 12” drivers you’re already running will more than handle that. J

They’ll have no trouble at all taking the amount of power she wishes to use, in fact they could handle almost double.

Also, they’ll be easier to install, and cheaper… it’s a win win situation.

How will the speakers be crossed over though?

The 6.5’s in the component sets are great from 100Hz up to be honest… maybe there is a reason she wants the 12’s to run up to 1000Hz? Big midbass duty? If so, the EF-8’s will do it better.

I’m also concerned with phase issues and group delay… seeing how speakers could be overlapping in frequencies.

A 3-way setup could be a better idea (3-way crossover)

As for the KX600.1’s… I can offer them for $xxx more each.

However, they do about 780wRMS-810wRMS from those I’ve seen tested… compared to the profile1’s which push about 550wRMS… the KX400.1’s push closer to this power level.

Also the EF-120’s are MUCH more efficient than the Massives… which means less power needed.

I have no problem selling you a bigger amp though. 😉

Well that’s enough of a novel for you to read already.

Let me know if you have any other questions… I’m very interested in this project.

Thanks again,

-Ross Aikin

From: Meriol Lehmann Sent: Friday, November 24, 2006 9:44 AM
To: CarAudiophile Subject: Re: CDT CL61

Hi Ross,

I checked the specs this morning and here’s a couple of questions:

1) The EF-120 are rated 10Hz to 400Hz. It is essential that the range is at least 20Hz to 1kHz. What do you suggest? (I think I already asked this question in my previous email but I’m not sure)

2) The Kx400.1 seems a little underpowered, what about the KX600.1?

Thanks, Meriol

On 23 nov. 2006, at 7:21 pm, CarAudiophile wrote:


The CL-61 however no longer exists, it was replaced with the CL-60CV set and CL-62 set this year.

The CL-61’s were in between these two sets.

As for subwoofers I’d suggest keeping with CDT and go for the EF-120’s… these are CDT’s version of an RW12 sub basically… 400wRMS, 2” voice coil, similar excursion etc.

However the CDT comes with a cast aluminum basket… which is a hefty upgrade from the RW12’s… also the CDT’s will play a good bit cleaner, the “Massives” will be a touch louder, although almost inaudible and worth the difference in SQ and linearity. (which is VERY important if you’re running them up to 1khz… however I strongly advise against this as it will hurt your stage and cause a good amount of resonance unless install is perfect)

For amps similar to what you’re looking for I’d suggest Kicker.

KX400.1 mono amp


Also these amps are a good bit underrated… you’ll see about 25% more than rated power… something that kicker is known for doing.

Thanks in advance,