Sealed three way monitor - anyone spot any probs before I start?

[bushmeister]

Hi,

I went for 1mm in the end, for a total of 5cm thickness. I routed out the back of the new oak baffle and also routed out the original baffle to prevent any cavitation problems with the overall thickness.

The difference between the epoxy and TMG was not discernible with my stethoscope and 'tap test' - both producing a completely inert sounding baffle with no obvious ringing even with a very hard 'tap'. I do believe the epoxy works well with this combination/thickness/stiffness to also provide good damping.

But I felt given the advice from Earle Geddes was to use TMG for CLD, this would give me more 'peace of mind'! It also provided a firm fixture after a few days drying time.

I am very happy with the changes, but I think the most obvious audible differences from the listening position still relate to the sorbothane gaskets, (which really improved the imaging and appeared to change the upper register tone), and the diffraction changes from the angled baffles.

The diffraction changes are quite measurable - maybe only a Db or two from my previous measurements, but even flatter around the 1.8khz crossover points. I had already optimised driver location on the baffle with the 'Edge' program, but the angled baffles produce even smoother power response.

Short of doing a full CLD enclosure from scratch I think I have reached the end of the journey with this project now. The crossover is optimised, the MC2 amps are excellent, and the cabinet is now as quiet as I can make it with good diffraction and power response. The drivers are obviously very low distortion from the off.

So I think I am going to have to think of another reason to get the router out.....this DIY bug is totally addictive isn't it?!? Perhaps I need a dedicated centre channel........

 

[xrk971]

This is a perfect place to try 3 way Harsch quasi transient perfect.

http://www.diyaudio.com/forums/multi-way/277691-s-harsch-xo.html

Woofer BW4 LPF: BES2 HPF mid BW4 LPF : BES2 HPF tweeter.

All acoustic target filter functions.

Set tweeter delay relative to mid by making equal to half a period of XO frequency. Including acoustic center offset. The. Set delay of mid/tweet group relative to woofer the same way.

All polarities are positive.

Properly set phase is flat throughout entire bandwidth except for 55 deg bump at XO points then back to zero.

Sounds very snappy and realistic with drums piano guitar bass when correctly set up. Until you hear it you think your system is great. Now it's even better. You can't go back.

Same topology should be applied to to bookshelf point source horn.

 

[eriksquires]

Thanks. One of the reasons for going from my current two way reflex monitors to a three way rather than another two way, was that I like to listen at pretty loud levels sometimes. My current monitors manage about 108 SPL at 1m, but going sealed obviously makes it a less efficient design, so the woofer and mid needed decent sensitivity, and I couldn't seem to find a sealed two way concept that could manage high SPL levels. The scan speak classic seemed ideal as it has a relatively high sensitivity for such a low fs and excellent extension in a sealed alignment, whilst the mid is also pretty sensitive for such a small driver and has excellent linear x-max. My reasoning might be faulty on this though of course!

I get the loud volume, but in what size of a room, and what room treatment do you plan on using? Having a speaker that plays loud and deep in an untreated and small room can be a nightmare.

The sensitivity of a speaker depends on the driver, not the cabinet. The ported cabinet for the same driver will be larger, and have a lower -3db point however if done reasonably well, with a faster cut off. At -10 db, sealed cabinets can beat ported.

 

[bushmeister]

Lol, thanks guys. These speakers were finished years ago.
I use them with distributed subs and are part of my 7.2 setup for HT too.

I built an active analogue crossover for them because I also use a turntable with them so wanted to stay analogue. However having used a minidsp 4x10 in another project, I am considering going digital.

 

[bushmeister]

This is a perfect place to try 3 way Harsch quasi transient perfect.

Xrk,
You are absolutely correct!
You can see at present these speakers use LR24 crossover slopes (all via analogue crossover), but given all three drivers (esp the 12MU mid) have a large usable pass-band, if I went with a digital crossover, a Harsch would be very easy to achieve.

Perhaps I should think about getting another 4x10hd......