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#327631 - 11/05/10 01:33 PM Crossover mod for M40ti to remove upper mid dip?
Wuchak Offline

Registered: 12/18/09
Posts: 42
I just posted a review on the M40ti's I've been living with for a few months now. I would like to know if there is a way to modify or upgrade the cross over to eliminate the dip in frequency response they have between 2khz - 5 khz. Any guidance or advice on how to achieve this would be greatly appreciated.

Here's an excerpt from my review for some more info on why I want to do this mod.
"The "laid back" sound others have described with these speakers I believe is due to a dip in frequency response in the upper midrange between 2khz and 5khz. You can see this in the Listening Window graph from the review at SoundStage This gives the sound a bit of a veiled character in the vocals and pushes them towards the back. If you look at the graph from the review of the M22 which is described as being more forward sounding you see it has a bump between 2khz and 5khz. If you compare the graphs there is up to an 8db difference between them in frequency response in this range. When I bump up the EQ in this range enough to bring the M40 up to flat or just slightly bumped at around 3.5 khz the sound changes dramatically for the better. It sounds like taking a blanket off and becomes a much more involving and realistic listening experience. I would like to modify the cross overs to eliminate this 2-5 khz dip so EQ is not needed."

#327632 - 11/05/10 02:14 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: Wuchak]
danmagicman7 Offline

Registered: 12/16/05
Posts: 1467
The M3's do not have a crossover...think the M40's could be wired the same way because of the same woofer configuration?

M22s|VP100|QS4s|HSU STF2

#327635 - 11/05/10 02:52 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: danmagicman7]
Wuchak Offline

Registered: 12/18/09
Posts: 42
I was wondering about that. I thought since the M40's were in a larger cabinet they might have added a crossover. I just looked at the Sound Stage graph for the M3ti's and they have almost the same dip as the M40 does. Maybe it's just the way the 6.5" driver is voiced. Maybe I have to live with a touch of EQ. Running from the laptop that's easy since Foobar has an EQ. Running from other sources will require putting the Behringer Ultracurve DEQ2496 back in the setup. Since I went to the amp switching arrangement that I have now that's going to be tricky to do.

#327636 - 11/05/10 02:53 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: Wuchak]
ClubNeon Offline

Registered: 02/06/09
Posts: 3453
Loc: Western Maryland, USA
Passive electronics, like cross-over components, can't boost dips. They can only cut signal levels. Your use of the EQ is the most appropriate way to fill in the hole. A parametric EQ with fine grained controls for center, width, and slope would be idea. But if what you've done improves the sound, then it may be enough.
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#327638 - 11/05/10 03:11 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: ClubNeon]
Wuchak Offline

Registered: 12/18/09
Posts: 42
Thanks for the advice. It looks like I'm going to have to figure out how to get the EQ back in the loop. Most of my listening is from the PC these days so it's covered there but for the radio, cd player, and the new vintage tape deck that followed me home yesterday I'll need to hook it up.

#327639 - 11/05/10 03:21 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: ClubNeon]
tomtuttle Offline

Registered: 06/20/03
Posts: 8334
Loc: Tacoma
I'm not sure it's true that the M3 "has no crossover". There's certainly already at least a high-pass filter on the tweeter and the product page lists a 2.2k Hz crossover point for the M3v3. I don't think that the woofer - even if it is running full-range and rolling off mechanically above that point - is going to make much of a difference in your targeted area.

At any rate, if it was just a simple matter of changing the crossover to achieve better performance out of the system, why wouldn't Ian have done that in the first place?

To do this right, you would have to start from scratch, measure the drivers using appropriate methodology and equipment, and re-design the entire system. Might be an interesting exercise for an experienced speaker designer, but unlikely to yield a "better" system, IMO.
bibere usque ad hilaritatem

#327660 - 11/05/10 07:40 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: tomtuttle]
Wuchak Offline

Registered: 12/18/09
Posts: 42
Ian might not have done anything different because they probably had the voicing he was looking for. I can live with the EQ bump since most of the time now I listen to music from the laptop. It's more convenient than changing discs.

#327814 - 11/08/10 06:56 PM Re: Crossover mod for M40ti to remove upper mid dip? [Re: Wuchak]
2x6spds Offline

Registered: 03/16/02
Posts: 2726
Loc: CA, USA
The M3's 6.5" woofer has no cross-over. It rolls off mechanically at its limits. The tweeter has a cap and resistor to protect it from lower frequencies - coordinated with roll off characteristic of the woofer.
Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.


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