Er18rnx/27dxt mtm

[Nuson]

Hello,
So im planning to build a pair of bookshelf MTMs, with good sound and a great kick. I was recomended these two speakers, and they really seem great, especially the ER18s have a lot of satisfied users, but so does the DXT.
It is also worth mentioning that i live in norway, and i have yet not found any resellers with the Dayton or Fountek tweeters used in Dennis Murphy and Paul Kittingers ER18 build.
Before replying to any of the questions below, please note that this is my first DIY project, and though ive tried to read up as good as possible (through loudspeaker cookbook etc.), not everything is explained as clear.

I have X-over 3 Pro, so i decided to try to set up the xo, and set it all up as 3rd-Order Butterworth, because if i am not mistaken, MTMs with odd-order Butterworth are good (due to a reason that dissapeared from my mind as i was typing it). The problem is that i get a peak at the LP xo frequency no matter what.
Second i was curious about driver sensitivity, x-over3 displays that the two woofers sum up to a sensitivity total of 94,5dB and the tweeter has 92dB would this be an issue?
Third i was curious if i have to worry about impedance differences when calculating the crossover values in x-over3.
Also, i have been told that its worth getting xo components that are decent, with a build like this, in this pricerange, what xo components would you pick?

Thanks for your time, correct me if ive said something weird! Im also open to suggestions if you have other speakers that would fit my description.

 

[Swerd]

Instead of using the SEAS 27TBCD/GB-DXT tweeter and trying to design your own crossover, you might want to try this design ER18RNX-27TDFC MTM. It includes cabinet drawings for both floor standing and bookshelf MTMs. That SEAS tweeter is probably available where you are in Norway. The crossover point is at 1650 Hz.

Although the woofers and tweeter are very good in this design, I haven't heard it so I can't say if it will sound as good as the Murphy/Kittinger design.

 

[Nuson]

Thanks, the TDFC build seems nice, but actually i found the Fountek NeoCD 3.0M RB at Europe-Audio, i might just order from them, the price including import fees are probably still below the price i would pay in norway, even for the woofers. But the problem is that they have no er18s in stock, and they are only expecting 2 in the next shipment, ill probably contact them.
It really looks like a great build, but i havent decided yet whether i have enough space for non-bookshelves.

 

[Swerd]

Thanks, the TDFC build seems nice, but actually i found the Fountek NeoCD 3.0M RB at Europe-Audio, i might just order from them, the price including import fees are probably still below the price i would pay in norway, even for the woofers. But the problem is that they have no er18s in stock, and they are only expecting 2 in the next shipment, ill probably contact them.
It really looks like a great build, but i havent decided yet whether i have enough space for non-bookshelves.

It's good that you could find the Fountek ribbon tweeter . You should be able to use it with Dennis Murphy's crossover in the bookshelf MTM cabinet designed for the ER18-27TDFC. I don't see any reason why this would not work.

The bookshelf MTM cabinet will be tuned to 38 Hz with a 2" diameter port tube that is 4" long. F3 will be 54 Hz and it is predicted to provide usable bass as low as 40 Hz. That won't be as low as you could get with Paul Kittinger's larger floorstanding cabinet, but it might better suit your needs.

 

[Nuson]

I appreciate the help, seems like ive found my build, now all i have to do is give Europe Audio a call and check how long it would take for them to order up another pair of ER18s, worst case i could order the tweeters from them, and get the woofers locally.

Thanks

 

[doors666]

the design mentioned was not voiced or tested, if you dont have the skills to do that, i suggest you refrain from using that. There is an er18 and dxt MT design from markk at The Seas ER18DXT ported two way. you might get better results from modifying that one.
My suggestion to you though is to pick a existing proven design and make that as it is. Its hard enough for a new comer to make a speaker, doing your own design is not a small task. The results might not be as pleasing as what you would get by following a design from a guy who's been designing speakers for some 20-30 years.

 

[cantonguy]

the design mentioned was not voiced or tested, if you dont have the skills to do that, i suggest you refrain from using that. There is an er18 and dxt MT design from markk at The Seas ER18DXT ported two way. you might get better results from modifying that one.
My suggestion to you though is to pick a existing proven design and make that as it is. Its hard enough for a new comer to make a speaker, doing your own design is not a small task. The results might not be as pleasing as what you would get by following a design from a guy who's been designing speakers for some 20-30 years.

Did you end up doing this? I am going to build this design shortly and finish it in rosewood(building own cabinet).