Klh 17

[Zilch]

Quest for Bass:

4-Ohm Seas F25-EWR from BeoVox (Dynaco A-25 driver, lower impedance) bumps up the bass of stock closed KLH-17. WAY forward, it needs a lowpass filter for sure; it's running full range on the 17 crossover, substantially outpacing the tweeter, even set on "Increase:"

That's one heck of a step at 500 Hz!

 

[Pete B]

4-Ohm Seas F25-EWR from BeoVox (Dynaco A-25 driver, lower impedance) bumps up the bass of stock closed KLH-17. WAY forward, it needs a lowpass filter for sure; it's running full range on the 17 crossover, substantially outpacing the tweeter, even set on "Increase:"

That's one heck of a step at 500 Hz!

That dip looks odd, might be an in box cavity resonance, did you use some damping? Lower curve I'm looking at there.
Edit: that is not a nearfield measurement, is it?

These drivers have low cone mass, and high Vas - it will be difficult to get low bass in a small box.

 

[Zilch]

Hi, Pete,

Box damping is stock; I've never disturbed it in this pair; the black scrim is still in place, even.

Red and Violet are nearfield LF measurements, Cyan in both cases is ~44", on tweeter axis. :yes:

It's odd that the rolloff slope is different, also. The JBL 116H-1 shown on Page 1 gives the best closed-box LF response thus far, playing a full 15 hz lower. I may do more testing with those:

 

[RoyC]

The JBL 116H-1 shown on Page 1 gives the best closed-box LF response thus far, playing a full 15 hz lower. I may do more testing with those:

Interesting...
I have found the 8 inch JBL 116H and the 10 inch JBL 125A replacement foam surrounds to be the best replacements for the old AR 8 and 10 inch "sealed cabinet" woofers. They have a large roll, are very thin/extremely compliant, and are non-porous. Highly recommended.

Roy

 

[spkrdtr]

If there are any KLH 17 owners who have E-waved them and are willing to have a guest for a brief listening session and live in the NYC +100 mile vicinity, please PM me.
Thanks,

 

[spkrdtr]

Zilch has yet to bless this, but I think it's a complete bill o' materials. I've gone over it a couple of times, but one pair of eyes can always miss stuff. ara:

Here's the linky: Bill of Materials

I ran into a couple of problems: The 60 ohm resistor at C2 is not a production item, so I substituted two 30 ohms in series. Not sure how that will fit on the PCB's that are available, but it shouldn't be too tough. I'll find out when my order arrives and I actually start assembly.

The 3.5 mH iron-core coil at L2 is on backorder at both PE and Madisound. I don't know a lot of suppliers, but I guess there must be some around. A pricey option at PE is THIS COIL. Impressive specs, though.

Also, if you're looking for high precision in the crossover, you could upgrade the caps to the 1% types for a few dollars more. Also, the bypass cap at C3 can be upgraded at PE to a type specifically made for bypass.

The prices were all pulled today, so they're real. If anyone finds an error, sing out!

Okay, I may have missed something here or in another post, but I couldn't find the crossover board on your bill O' materials. P/N? source? price?

 

[Zilch]

Okay, I may have missed something here or in another post, but I couldn't find the crossover board on your bill O' materials. P/N? source? price?

It's the EconoWave PC board, documented in that thread and Jackgiff's "Etch your own" tutorial.

I'll PM you the details.... :yes:

 

[vinylisfinal]

i only have one comment..... and this remark comes from a friend of mine whom designed amplifiers for innersound..." measurements lie, what looks good on a scope can sound like complete garbage in reality" don't always trust readings and measurements..... imho, ya should have built cabinets, i did..... it is a lot of fun and very rewarding.

 

[Zilch]

i only have one comment..... and this remark comes from a friend of mine whom designed amplifiers for innersound..." measurements lie, what looks good on a scope can sound like complete garbage in reality" don't always trust readings and measurements..... imho, ya should have built cabinets, i did..... it is a lot of fun and very rewarding.

We do that, too, of course, but for some without the skills and equipment to build quality boxes, vintage cabs are a rational option available at thrift stores, garage sales, and curbside for far less cost.

As to the measurement thing, experience here on AK and elsewhere belies your friend's remark; as an audio hobbyist you owe it to yourself not to dismiss the many apparent successes documented here.... :thmbsp:

 

[spkrdtr]

MY KLH-17 e-waves

I started working on a pair late last fall and had to set them aside to do other things. During the interim period I orderd all the parts, including the standard e-wave PC board.
Now that I just finished assembling and testing one of two and wanted to share my results.
A picture is included and shows it's been built pretty much to Zilch's plan using the Dayton Classic DC250-8 woofer and the Selinium D220Ti horn and wave guide shown earlier in this thread.

I've included two sets of polars. One is with the speaker rotated cloclwise (CW) looking from above and the other is the opposite rotation. I ran another set of polars using HolmImpulse software and got similar results (see attached). Also included is a nearfield measurement on the woofer.
My polars were done using a home made set up incorporating an MCM tech turntable with a ball bearing lazy susan base that can hold up to 200 lbs. See the link below for a description of the set up.
http://www.audiokarma.org/forums/showthread.php?p=3873104#post3873104

On axis, the freq. range is from 65 hz to 19 kHz -3dB at ea. end.

After I finish the second speaker I'll conduct some listening tests and report my impressions in a subsequent post here.

 

[Zilch]

Compare:

 

[spkrdtr]

After I finish the second speaker I'll conduct some listening tests and report my impressions in a subsequent post here.

I've completed my listening impressions and found them as built per the KLH 17 thread to be too boomy at the low end for my tastes. I also sensed a 'hole' in the mid-bass response. As the NF woofer response I posted shows, it's response is rather limited from it's natural roll-off on the low end to just over 170 hz.

With the fine sounding Selinium DT220i compression driver rolling off with the HP filter at around 2 kHz, it would seem the output below 1 kHz down into the 200-300 hz range would be depressed and, it sounded like it.

I first tried plugging the vents and noticed less boominess. I then tried a few modifications to the LP filter to extend it's response upward with no audible success. I went back to Zilch's original LP but added some FG stuffing to the now-sealed box. That lowered the Fc 5 hz to 58 and box Q from 1.09 (high) to 0.81.

Both speakers were modded with the plugged ports and added FG. Another round of listening tests were conducted using acoustic music. There still seems to me to be some lacking of mid-bass. However, I feel Zilch's original e-wave design will make most listeners of contemporary and rock music happy. For those wanting better overall response thru the mid-bass range, perhaps a different woofer should be considered that doesn't have a nasty 2 kHz response peak. If I still had the original woofers, with their less than ideal bass extension I would probably re-install them.

Maybe, a 3-way design should be considered for larger e-wave designs (LA's and NLA's) where the edge breakup of most modern woofers presents a challenge of crossing them high enough to avoid the mid-bass hole or risk a respose hump in the 2 kHz range.

 

[Zilch]

Thank you for your review, Carl. I also found that closed-box, the DC250 played a little flatter at the low end. The biggest difference came with using them without boundary reinforcement, i.e., on stands out from the wall(s).

You can see in this thread that finding a flatter-low-frequency contemporary woofer that'll play extended bass in those small boxes is a challenge. From the curves I presented here, it looks like JBL LE10 might come closer to matching your preferences. You might try KLH-6 woofers, as well.

Time permitting, I'll give DC250 another try here using PCD; my lowpass incorporates a substantial amount of BSC to achieve "contemporary" voicing in the small KLH-17 alignment, which you are experiencing.... :yes:

 

[spkrdtr]

Note my edit to prior post to add box Q change with closing of vents and added stuffing.... much more to my liking.
Good luck with finding an appropriate woofer.....

Thank you for your review, Carl. I also found that closed-box, the DC250 played a little flatter at the low end. The biggest difference came with using them without boundary reinforcement, i.e., on stands out from the wall(s).

You can see in this thread that finding a flatter-low-frequency contemporary woofer that'll play extended bass in those small boxes is a challenge. From the curves I presented here, it looks like JBL LE10 might come closer to matching your preferences. You might try KLH-6 woofers, as well.

Time permitting, I'll give DC250 another try here using PCD; my lowpass incorporates a substantial amount of BSC to achieve "contemporary" voicing in the small KLH-17 alignment, which you are experiencing.... :yes: