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I know there's a reason Dave chose 333hz.

333 Hz was Tysen. Not quite sure where the XO is on the MTM (because series XOs are slippery in that respect), somewhere between 300-400, closer to the former i'd guess. To keep XO simple it was targeted to be around the baffle-step frequency.

If you are going active and 200 is as high as you can go, then well worth a try.



Paid Member
2011-02-04 11:35 am
Thanks Dave - my top mounting idea was for a 2nd alpair6. The more I think about it, the single el166 MTM would probably suit better for my small room. One el166 and two alpair6m would give a pretty close efficiency match if I decided to go passive at some point.


Have you started building this yet? You know I can't build all of 'em. :D
I did not find any information about that here. But if i decide to build these with a slot port i could calculate the vent length to be the same tuning frequency as a round port version.

I'm not sure if i'll build the dual or single driver version...

More headroom
More cone area
The EL70 is at a better height, more on-axis

More expensive
Slightly larger
Less good-looking

If i decide to build those i'd need recommendations on filters too. I have an active crossover named Reckhorn S-1.

That is the filter options for that one.

I would actually prefer a passive filter since i wouldn't have to buy another amplifier and struggle with that sort of stuff. But i have no experiences of designing/building filters.

I'd like to keep this build as cheap as possible.
The EL70 is at a better height, more on-axis[


any passive XO below ~200 Hz, is gonna start approaching the cost of another amp (unless you use really cheap parts)

Well, i sit in a computer chair when listening. Not a sofa. So if the speaker shall be on-axis it as to be around 120cm above the floor. My current speaker stands are almost 1m tall.

Where do you recommend crossing it over?
Both the single & double driver versions are the same height, and avaerage driver Zd is the same. Since EL70 is in separate enclosure you can do all sorts of creative things to get it at the right height.

Given a suggested XO of 80-150 Hz the woofer boxes could be folded, put a cusion on top and you can have extra seating (or glass or a slab of rock & it becomes a couple tables to pile junk on.

When i look at the drawings you posted they are not the same height.

I don't know what you are talking about, regarding the EL70 being in a separate enclosure.

I don't want to fold them since that makes it even worse. All i'd need is some way to raise them a little more off the floor (i do have some stone plates 4cm tall) so the EL70 gets to ear-height.