MTM design

[chatziva]

Hi all

I own a Cygnet MK2 kit which I bought from madisound.
http://www.madisound.com/catalog/pro...roducts_id=379

Overall they are very good budget speakers but there some things that I dont like about them:

The bass sounds sort of paper-y, like tapping a cardboard box or something. I think this is the effect of the small enclosure.There is also lack of bass generally.

What I was thinking was to either ditch them and get some fostex 206E back loaded horns. I have never heard those this is a gamble. I have seen mixed feedback on those 206E's

Or I go crazy and buy another pair of woofers (Seas H511) and turn the existing kit into an MTM. Of course the enclosure and crossover will be replaced with new suitable ones. The risk with this one is that this paper-y sound wont go away as it might be the woofers characteristic sound. However with a bigger enclosure I should get better bass.

Which option do you think makes more sense?

[Glowbug]

Going from that to 206E BLHs would be a very different take on things...not saying it's better one way or the other, just different

You could always keep it as a 2-way and just design a floorstanding cabinet for it. If you don't have a lot of power available, the small box and wanting a lot of midbass is working against Hoffman's Iron Law.

[chatziva]

The enclosure has already the optimum volume for the H511 woofer (by using the calculator in lalena.com)

Would increasing the volume not make it sound worse? (still talking about the 2 way original cygnet kit)

I think i will go ahead and buy a second pair of woofers and make it a MTM. I have some questions though:

How do I redesign the crossover? Obviously by using 2 woofers in parallel the overall woofer impedance will halve from 8ohms to 4ohms.

So in the crossover calculator below do I just change the woofer impedance and that's all the change?
http://www.diyaudioandvideo.com/Calculator/XOver/

Also in the speaker box calculator do I just enter the thiele values of the original single woofer and then I just double the calculated volume? (effectively sticking two speakers together to make a new one?

Cheers

[infinia]

Hi
Can you post the crossover schemo. You might get some remedy by changing a couple of values there. How do you listen to them and room size and placement?

AFAIK doubling up with the same woofers with a changed alignment ie MTM, is very hard to do correctly esp with a 8" and 1" dome, at the risk of poor polar response and up to 2 times worse "paper" sounds you hear.

[chatziva]

This is my listening arrangement.

Possible known problems:
- Speaker stand too tall
- Distance between speakers and my ear is only 220cm
- The port has not been flared and the corners have not been chamfered / rounded


As an amplifier I use either a Sympatico or a UcD400. To be honest I can't hear substantial difference between the 2 when playing at the same volume levels. This leads me to believe that either I am deaf or the speakers limit my system.

In terms of crossover, I am afraid I don't know what the scheme is, as it's all closed now. I will have to remove one of the woofers to find out.

What surprises me is that this guy is very happy with the base:
http://www.audioasylum.com/reviews/S...rs/110538.html
I wonder what will happen if I change the woofer phaze...

Also this guy says that by getting rid of the polyfill and covering the walls he got better bass, i might try it
http://www.audioasylum.com/cgi/m.mpl...196&highlight=

[chatziva]

Here is the crossover picture but I am not sure how to reverse engineer it.

Could it be 2nd order or something?

[chatziva]

XO schematic

[Ron E]

That doesn't look like a very likely schematic.
You would have to take a pic of the back of the board also to see if there are any connections.

My suggestion, if the bass is the only issue, get a sub.

[infinia]

Hi the crossover is a series type with 1st order. Just as I suspected the madisound design doesn't have too much Baffle Step Correction. But your listening placement is with the boxes next to the wall and mostly near-field so it s/b OK. The only thing I can think of...off the cuff... of is a room mode is giving a null point at a key bass point. I could give you a new crossover to try... mostly a parallel type, 2nd order with lots more BSC (bass).It could be modified to your box and the tweeter level would have to adjusted to taste and your ear/room furnishings. But then it m/be too much bass for your placement and music?

Your comment of paper sound s/b investigated further with more stuffing first directly behind the woofer and away from the bottom vent. You can experiment yourself with variations of box stuffing and room placement before you decide.

[infinia]

Originally Posted by Ron E

That doesn't look like a very likely schematic.
You would have to take a pic of the back of the board also to see if there are any connections.

My suggestion, if the bass is the only issue, get a sub.

Yea it looks weird at first (series type). The only thing wrong is maybe the value 1R5 might be 15R. Chatziva can you verify that?