Mark K's er18dxt

[DIYBras]

And one more good thing: this MarkK project is not bass-heavy (in fact in perhaps the most bass-honest 6"+1" speaker I've heard from a long time), so in bass department probably is perfectly OK about wall proximity.

 

[454Casull]

I'm thinking of possibly building a pair of these in the future. However, I'd be modifying the design to turn it into an on-wall monitor for near-field use with my PC.

As I don't currently have much knowledge of passive crossover networks, can someone please tell me what I would be removing or changing if I wanted to get rid of BSC in the crossover?

 

[voxxonline]

I have seen people making 24 l boxes for them. How do I tune my speaker for this?
I am making cabinets from the scratch and possibly increasing 15 to 24 l

 

[Dave Bullet]

I have seen people making 24 l boxes for them. How do I tune my speaker for this?
I am making cabinets from the scratch and possibly increasing 15 to 24 l

Download a copy of WinISD and enter the TS params of the ER18. Choose your box size of 24 L and see what port length you need for your desired slope.

If increasing volume - go backwards to maintain baffle geometry. You could probably get away with towering these as long as baffle width is the same and tweeter / woofer proximity to baffle top remains

 

[panndder]

Would it be advisable to build the ER18DXT with an active crossover, instead? I have a minidsp on hand, so I was thinking about building a designed based on this but using the DSP as the crossover. Is there any risk or downfall to doing this, provided I put a capacitor in series with the tweeter? Any other thoughts, etc.?

Furthermore, is this still the design to go with if you want a slightly more modern take on Zaph's SR-71? I know the design is about ten years old, so is there something else I should consider?

 

[Richidoo]

Is it still possible to get the crossover schematic for this design now that audioheuristics.com is gone?

I'd like to build these for my HT. I had them bookmarked for years, now finally ready to move ahead and the webpage is gone. oops!

I remember that it was a very simple crossover with relatively shallow slopes, which I prefer. Thanks!

 

[Sypher]

The Seas ER18DXT ported two way

 

[Richidoo]

That's it!
Thanks very much Sypher!

 

[invaderzim]

In the writeup it says that if you are going to use them with a subwoofer, build the sealed version.

Are the dimensions the same for the sealed version?

 

[critofur]

Build them with vents, and then see if you prefer the sound with the vents blocked - at least you have more flexibility that way.

 

[invaderzim]

good point.

 

[invaderzim]

With the waveguide tweeter is it still necessary to round over the front baffle?

 

[digitalthor]

With the waveguide tweeter is it still necessary to round over the front baffle?

It seems like it. Heissmann measured the DXT, and found out that it needs either a very narrow or very wide baffle for it to work its best. Or else it would widen around 3kHz:


Test report | Seas DXT 27TBCD / GB (H1499-06)


You can then make some big angle cuts to make the cabinet normal size and still keep the baffle narrow around the tweeter.

 

[invaderzim]

That was a great write-up on it, thanks for the link. The angle cuts are probably beyond what I can do with a hand-held circular saw. I was pretty thrilled that the panels I cut were within 1/32" of what I wanted. I'll do a round over though.

 

[invaderzim]

next question, how close is close enough on DCR for the 2.5 mH inductor? The schematic calls for 14G with .6 ohm and I have an 18G with .88 ohm Looking at it being nearly half again more I figure it isn't a good idea; but thought I'd check since it would save me about $70 on the build.

 

[invaderzim]

here's the schematic of the crossover.

 

[system7]

Which coil you use won't make a scrap of difference. 0.28R change is not something you will hear. Consider the driver is around 6R!

10% component tolerance is about the limit of what is audible.

You might find these articles interesting:

Starling-TBFC (Seas ER18RNX with Seas 27TBFC) – AmpsLab

I think I could do that one with a different waveguide tweeter too:

Finch (Morel CAT378 + Vifa PL18W0-09-08) – AmpsLab

Mike kindly sent me the Finch circuit. As long as the slopes match, you can swap tweeters.

H1499-06 27TBCD/GB-DXT

 

[invaderzim]

Holy cow, there is a lot of information at that site. This is making it more fun, knowing more of what is going on with the speakers.

I'm not locked into any design yet and, while I'd really like to try a waveguide I do realize that there are excellent designs without them.

looks like different efficiency between the tweeters. The off axis performance of the DXT (on the bottom) does show.