finally got them up & running. My xover is fairly minimalist zero BSC, .68uF & Mark's filter on the woofer, single resistor & 2nd order LR on the tweeter.
I was going to do a rave about how they have a much more forward sound than the Peerless drivers they're sitting on, 'till I realised I'd put the tweeter inductor BEFORE the cap... oops, luck I didn't fry my amp... That sorted they sound pretty damn good, better lower mids than the Peerless, & they integrate very well with my 10" Peerless woofers. I haven't tuned the port yet (currently ~ 37Hz), I think they need a bit more running in, but as stand alones they'll need more BSC, bass is there, just needs a bit more level. But I suspect I'm going to stick with using them as part of a 3 way...
I was going to do a rave about how they have a much more forward sound than the Peerless drivers they're sitting on, 'till I realised I'd put the tweeter inductor BEFORE the cap... oops, luck I didn't fry my amp... That sorted they sound pretty damn good, better lower mids than the Peerless, & they integrate very well with my 10" Peerless woofers. I haven't tuned the port yet (currently ~ 37Hz), I think they need a bit more running in, but as stand alones they'll need more BSC, bass is there, just needs a bit more level. But I suspect I'm going to stick with using them as part of a 3 way...
Attachments
I guess the rise in 5HD for the ER18RNX isn't audible?
http://www.zaphaudio.com/6.5test/ER18RNX-HD.gif
Starts around 200 Hz and peaks around 950 Hz. This definitely gets into the most sensitive region, no? The B&C 6ND430 and the Usher 8945P both show better midrange performance at the expense of slightly more distorted bass.
http://www.zaphaudio.com/6.5test/ER18RNX-HD.gif
Starts around 200 Hz and peaks around 950 Hz. This definitely gets into the most sensitive region, no? The B&C 6ND430 and the Usher 8945P both show better midrange performance at the expense of slightly more distorted bass.
not audible; this driver is smooth if correctly filtered. I used it in a MTM 2nd order electrical low-pass, -1.5dB @ 900Hz on woofers.
I just built the Zaph SR71 ported, as per design, and I'm now looking at Mark K's ER18DXT as a second build, same woofer and a highly regarded tweeter and design, by consensus a step up. (Mark's opening Lord Kelvin quote makes it clear I wouldn't be leaving the objectivist school. I'm in the middle; as any student of the history of science knows, some things we can't measure yet.)
Zaph didn't recommend sealing the SR71, while Mark K suggests this as an option for the ER18DXT. Discussing this for my SR71s in a different thread elicited some pretty strong views that the Seas ER18RNX woofer isn't well-suited for sealed use.
I'm enjoying the SR71's as they break in, and I need to play with stuffing variations, but if there are tradeoff liabilities to the port, I'm not enjoying the bass response enough to be sure I wanted to make those tradeoffs. I'm most sensitive to midrange voices and instruments, not the greatest recording but I often use Joni Mitchell's voice in "Blue" as an audio test, she sounds different on every system. (Or Norah Jones, but better recorded and she makes any system sound its best. Sales people use her.) So building the ER18DXT sealed is tempting.
Along those lines, I find better equipment well worth the trouble, and I believe that I can hear significance differences, but I'm 56, and my hearing no longer extends above 14 Khz. (Still 20/10 vision, win some, lose some...) I suspect that I hear less of a difference than other people report using audio software like Amarra or Pure Music because their improvements are mainly above my audible range.
So I wonder if my tweeters are distorting in my audible range because of higher frequency work they're doing that I can't hear. Would it make sense for me to modify the ER18DXT crossover with a low pass filter that rejects above 15 Khz? Or would that introduce more distortion than just leaving the tweeters to do work I can't hear?
thanks peter,
the 0.5 qubic feet corresponds with 15L. i don't mind that it needs to be bigger.
so you made the netto intern volume 24 L ?
1)what did you do with the front plate ? (or is the box just deeper ? )
2)did you change the crossover ?
what are the differences in sound, and why did you like it more ?
thanks a lot
the 0.5 qubic feet corresponds with 15L. i don't mind that it needs to be bigger.
so you made the netto intern volume 24 L ?
1)what did you do with the front plate ? (or is the box just deeper ? )
2)did you change the crossover ?
what are the differences in sound, and why did you like it more ?
thanks a lot
I've finished putting together just one of my speakers for this project so far, and the bass seems to be severely lacking. I've turned up the bass on my receiver and it's still kinda missing... maybe I am expecting too much, but I get more bass from my clock radio - PDX-13 - iPod Series - Yamaha - Australia
tandata, you are right! Most speakers, especially clock radios on a table have a huge up to 20dB boost at 80-200Hz. The ER18DXT doesn't.
Most bass-reflex speakers are tuned to give maximally flat response (or boost) to the low limit - the ER18DXT is not.
You can download some RTA or FFT widget to your smart phone and see how they measure! If you use the tone control in your amplifier you'll get more bass out of ER18DXT.
Most bass-reflex speakers are tuned to give maximally flat response (or boost) to the low limit - the ER18DXT is not.
You can download some RTA or FFT widget to your smart phone and see how they measure! If you use the tone control in your amplifier you'll get more bass out of ER18DXT.
A couple of thoughts
Tandata
It's unfortunate you are having bass output issues. Mark's design is an excellent one. I had the great pleasure of listening to it (original prototype I think) at the Northern CA DIY gathering in 2009. The speaker was demonstrated on a 24" stand about 18"- 24" or so from the rear wall in a large room. It exhibited a nice sense of tonal balance, clarity, power response while projecting a nice image field. Actually, the amount of bass output for the size of the box was surprising. IIRC, this system is essentially flat to 50 Hz (quasi half space) with an F3 around 47 Hz. Mark has engineered in baffle step compensation, so the F3 number is valid in most environments, again assuming stand mounting and 1'-2' distance from the baffle face to rear wall. Of course the Seas woofer is only a 7" class driver with an xmax of 6 mm peak, so it is not going to be a window rattler except in very small rooms where cabin gain becomes a significant factor.
With that said, one needs to check the usual stuff. Crossover errors, double check the woofers for correct phase marking with a 1.5 volt battery, proper box tuning, no box leakage and so on. Not a bad idea to check the tweeters also. Another good idea is to play them in a different room. Once in a while you can encounter a room where room dimensions and construction can have a significant absorptive effect on bass output. Had a friends house back in CA that just ate bass frequencies up! Where a 10" sub would normally work reasonably well, we had to go up to a very high output 15" get really get things moving. Good luck!
Tandata
It's unfortunate you are having bass output issues. Mark's design is an excellent one. I had the great pleasure of listening to it (original prototype I think) at the Northern CA DIY gathering in 2009. The speaker was demonstrated on a 24" stand about 18"- 24" or so from the rear wall in a large room. It exhibited a nice sense of tonal balance, clarity, power response while projecting a nice image field. Actually, the amount of bass output for the size of the box was surprising. IIRC, this system is essentially flat to 50 Hz (quasi half space) with an F3 around 47 Hz. Mark has engineered in baffle step compensation, so the F3 number is valid in most environments, again assuming stand mounting and 1'-2' distance from the baffle face to rear wall. Of course the Seas woofer is only a 7" class driver with an xmax of 6 mm peak, so it is not going to be a window rattler except in very small rooms where cabin gain becomes a significant factor.
With that said, one needs to check the usual stuff. Crossover errors, double check the woofers for correct phase marking with a 1.5 volt battery, proper box tuning, no box leakage and so on. Not a bad idea to check the tweeters also. Another good idea is to play them in a different room. Once in a while you can encounter a room where room dimensions and construction can have a significant absorptive effect on bass output. Had a friends house back in CA that just ate bass frequencies up! Where a 10" sub would normally work reasonably well, we had to go up to a very high output 15" get really get things moving. Good luck!
1) Get the cut sheets (dimensioned drawings) of the drivers.Gents, cannot find which screws to use for er18 and dxt drivers?
Could you please suggest
2) Determine the ID of the mounting holes.
3) Determine the style of screw you want to use (wood, socket head, pan, machine screw with tapped rear plate or nut, etc.)
4) Determine the right size.
5) Buy them.
Very simple.
Assembled er18dxt few days ago. It was lacking in bass, and I thought it is going to be like that. But today I have stuffed HEAVILY boxes with filler. I had nothing to loose but gained a lot more bass. Satisfied. Probably need to check how it will be with LESS stuffing, all in all need to find a balance. To me it is enough of lows ! Just want to check few things and report back.
Guys, how was your stuffing ? How much is too much ? Don't want to compromise transparency though.
P.S. : Can filling affect (hold) bass membrane movement ?
Guys, how was your stuffing ? How much is too much ? Don't want to compromise transparency though.
P.S. : Can filling affect (hold) bass membrane movement ?
Last edited: