RM40s -- Why is mid-bass driver on top?

ctviggen · « **on:** 1 Apr 2004, 02:35 pm »

It just seems odd. Most speakers are tweeter, mid, mid-bass, bass. Why is the mid-bass driver on top in the RM40s?

Marbles · « **Reply #1 on:** 1 Apr 2004, 02:44 pm »

Just a guess, but I think that BC wanted the tweeter to be at ear level when a person is seated.

Since that positioned the tweeter in about the middle of the cabinet, BC then went for a symetrical layout of the drivers. That is Bass, m, m, t, m,m, mb from the ground up.

Again this is just my guess, and I could be totally off.

ctviggen · « **Reply #2 on:** 1 Apr 2004, 04:41 pm »

Sounds like a good guess (and idea) to me! Thanks.

Tyson · « **Reply #3 on:** 1 Apr 2004, 04:53 pm »

The top and bottom woofers BOTH do mid-bass (down to 80 hz), so the rm40 is really a giant D'appolito array from 80hz and up, with the bottom driver also doing low bass & couplling w/the PR.

ctviggen · « **Reply #4 on:** 1 Apr 2004, 05:52 pm »

That's an interesting observation. I like certain D'Appolito designs, like the Wilson Cub for instance (though the price is extreme -- 7,500 or so for the speakers and stands). (Speaking of Wilson -- anyone seen his sub? Two 18 inch woofers! 700 pounds! I guess you figure out where it goes and leave it there forever.)

errivera · « **Reply #5 on:** 5 Apr 2004, 05:20 pm »

I feel that this has been the RM40s weak point. Hanging the bass driver up away from the floor diminishes their mid bass response, and their low end response. I guess that is why many members have mentioned the lackluster midbass performance of the RM40s.

Excellent speakers none-the-less but I think that changing the driver configuration to put the 'mid bass' driver at floor level would do wonders for them.

Tyson · « **Reply #6 on:** 5 Apr 2004, 05:47 pm »

The lower driver does midbass too. I've heard them with great midbass and weak midbass. A lot of it was determined by the room, placement, and tuning, and front end gear. The 40's are transparent enough and tunable enough that they can end up sounding almost any way you want them to.

Redbone · « **Reply #7 on:** 5 Apr 2004, 10:18 pm »

If the lower woofer is doing mid bass then I've got peanut butter in my ears. Nothing over ~80Hz coming out of mine. Also consider that the bass low pass crossover supposedly cuts off at ~160Hz, I think mid bass covers frequencies a little above that.

Actually, if you look at the pictures Zybar took, the low pass bass crossover is a first order (6db) 2.8mH Inductor, which according to the manufacturer's website, provides a cutoff at 225Hz. But considering it's a first order, it will pass a fair amount of frequency above that. But even so, it's the NEOs that are handling mid bass, everything from 1kHz down to ~250Hz.

Explanation:

FST handling >7500Hz 2nd order (12db) crossover
NEOs handling ~7500Hz - 160Hz 2nd order (12db) crossover
Woofers handling ~20Hz - 225Hz 1st order (6db) crossover

The range from ~250Hz - 1000Hz is handled exclusively by the NEOs, which are great speakers, but not capable of the mid bass extension and impact that cones provide in this frequency range. It is my opinion, and only my opinion, that this is where some of us find a small weakness with the 40s.

errivera · « **Reply #8 on:** 6 Apr 2004, 12:25 am »

I keep hearing that on this forum, that the VMPS speakers can be tuned to sound any way you want them to. Is this correct???

I would rather the speaker sound the way it's supposed to. Do not add or take away anything from the original sound. I understand that everyone has their own personal tastes, that's all good. If this is true though, then why spend so much money on the 40s??? Bose makes a nice set of speakers that could be made to sound almost anyway you want with a cheap EQ.

That's a pretty extreme example but I hope I make my point. Speakers sould be true to the source. If you want to tweak to your own personal taste, great.

Redbone · « **Reply #9 on:** 6 Apr 2004, 03:46 am »

I don't get your point. Bose can't be made to sound like 40s, equalizer or no.

covermye · « **Reply #10 on:** 6 Apr 2004, 11:44 am »

Quote from: errivera

I keep hearing that on this forum, that the VMPS speakers can be tuned to sound any way you want them to. Is this correct???

I would rather the speaker sound the way it's supposed to...

What you're leaving out of the equation, errivera, is that the ROOM that the speakers are in have about as much to do with the final sound as the speakers themselves at times. Listen to a pair of un-adjustable speakers in my room and chances are they'll be totally different sounding in your room regarless of placement. It's a fact of physics. Mr. Cheney's designs allow you to tune the speaker DUE TO ROOM EFFECTS in order to make them sound consistently good regardless of the room.

It's this adjustability that DOES allow VMPS speakers to sound the way they're supposed to, regardless of room.

errivera · « **Reply #11 on:** 6 Apr 2004, 01:52 pm »

Yes... that is my point. I'm surprised that the sarcasm didn't show through.

There was a brief discussion on this just about two weeks ago. Some people feel that speakers should not contain any adjustments whatsoever. Others feel that loudspeakers should allow tweaks that help adjust the speaker to the listening environment.

Tweaking loudspeakers is a great idea except that as mentioned here on so many ocasions, the end users end up adjusting the speakers to their own liking; usually not a true flat response, or accuate to the original signal. Which is better???

I personally think that one should create a sound that is pleasing to oneself however, this is not the true audiophile representation. What can we do??? Heck, if I paid for the loudspeakers, then I will adjust them the way I like.

Let's see what others have to say about this.

errivera · « **Reply #12 on:** 6 Apr 2004, 02:12 pm »

As a quick note, Brian's speakers do not allow you to adjust the speakers to a particular room. The nulls and resonances that are created in a room are far more complex than a simple level adjustment of either the midrange or tweeter would would fix.

The pots on the VMPS speakers allow for level adjustment only. Am I correct? I see how this might help, but it will not allow the fine adjustments necessary to smooth the frequency response of a speaker in a room. Individuals spend a good amount of money taming their room to achieve a friendly environment for their speakers.

As you all can see from my previous posts, I have very mixed feelings about speaker adjustability. Let me summarize:

I love speakers that are designed to be as 'flat' as possible but I think that they should include controls that allow for adjustments to assist in room placement, like VMPS. Everything is a tradeoff, just as Brian has said in past posts.