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ZLH-20 speakers

BmWr75

BmWr75

Top octave? pfffffftttttt
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Finished up a pair of Zilch designed speakers today. See the design details at this thread:

http://www.audiokarma.org/forums/showthread.php?p=2188360#post2188360

Much thanks to both Zilch and Paratima for help and advice on this build. Here's a picture of the converted KLH-20s (same cabinet size as KLH-17s) running on my tube system. The "stands" they are sitting on are custom Tyler Acoustics subwoofers (turned off).

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kfa888 said:
You forgot to tell us one important thing, how do they sound!!!!

K
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I've got a bunch of very nice sounding speakers.......and these are right at the top of the list. Need to do an A/B comparison with a set of refurbished KLH-17s, plan to do that soon. Can say the bass on the ZLH-20s probably is far better than the stock drivers. Used the more expensive Selenium tweeter model and they sound amazing.
 
von.ah said:
What are yer other Ewaves? [on left] How do they compare?
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Those are Zilch designed eWaves using Heath AS-10 cabinets from the 1960s. You can read all about them at this thread.

http://www.audiokarma.org/forums/showthread.php?p=1805070#post1805070

The AS-10s sound amazing. It's not a fair comparison to the ZLH-20s because the AS-10s use much more expensive drivers (e.g., BMS compression driver, JBL woofer, JBL waveguide), an active crossover and bi-amplification.
 
Two very good Ewave threads, sir. My Ewave Journey has started, and hopefully I'll start my own thread in a few weeks.
 
Hey Zilch,

How long you think these ZLH-20s need to burn in before they start sounding their best???? :scratch2:

ROTFLOL,
BmWr75
 
Here's an REQW frequency response comparison between a ZLH-20 eWave and refurbished KLH-17 using the stock drivers. From 50 - 130 Hz, the ZLH-20 is approximately +5-8 dB. Much flatter response above 10k Hz also.

Green = ZLH-20, Blue = KLH-17

Measurements taken using REQW software, RadioShack SPL meter and boom mike stand approximately 3 feet away from tweeter and on axis with tweeter. Levels between the two speakers were matched prior to taking measurements.

The stock KLH-17 is ~4 dB more efficient than the ZLH-20 eWave.

Question for Zilch -- does the tweeter Lpad on the ZLH-20 look to be set at about the correct level?
 
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BmWr75 said:
The stock KLH-17 is ~4 dB more efficient than the ZLH-20 eWave.
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KLH promoted the 17 as having high efficiency AND providing good low-frequency response. The brochure stating that is posted elsewhere in this forum. It was only half true, by contemporary standards, as is confirmed by your measurements.

BmWr75 said:
Question for Zilch -- does the tweeter Lpad on the ZLH-20 look to be set at about the correct level?
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From the extended response at both ends of the spectrum, I'm assuming green is the ZLH-20.

How "hot" you play the HF is primarily a matter of personal preference, how you like it to sound. Try different settings to make that determination.

We know the R/S SPL meter mic typically exaggerates the HF response, with a peak around 7 kHz, so we don't know in absolute terms how the curve actually looks. I do recall you play your AS-10s like that also, as measured, presumably, by the same method. We may be looking at how you like it in your listening environment.... :yes:

Edit: Compare to my stock KLH-17 measurements here:

http://www.audiokarma.org/forums/showthread.php?p=2229845#post2229845

ZLH-17: http://www.audiokarma.org/forums/showthread.php?p=2304690#post2304690

L-Pad Adjustments: http://www.audiokarma.org/forums/showthread.php?p=2304672#post2304672

Answer: I designed around 12:00 as the flat L-Pad setting.... :thmbsp:
 
Zilch said:
From the extended response at both ends of the spectrum, I'm assuming green is the ZLH-20.

We know the R/S SPL meter mic typically exaggerates the HF response, with a peak around 7 kHz, so we don't know in absolute terms how the curve actually looks. I:yes:
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Yes, the green is the ZLH-20, updated my post to reflect that.

REQW uses a R/S SPL meter uses a calibration correction file that is supposed to make is read flat (who knows though, I don't have any way to verify that).
 
BmWr75, glad to hear you got 'em going! :thmbsp: I'm loving my ZLH-17's. Hearing notes I never heard before. I may hook one up to my guitar amp just for grins.

I just finished fixing up a pair of JVC kabuki POS speakers for my uncle. He had somehow managed to blow out both woofers, but the tweets were fine. :headscrat Anyway, they got my KLH-17 woofers and new crossovers. The old crossovers consisted of a 3.3 uf cap in series w/the tweets, period. Now has Butterworth on the woofs and 2nd-order L-R on the tweets, both crossing @ 2500, with an L-pad to more or less equalize the output. They are, as they say, good enough. And it makes room for more speakers around here. :D

Now, hopefully, I can get back and finish my documentation thread and get some more stuff done here. I, too, am finding the RS SPL meter to be a bit limiting. OK for quick comparisons and setting levels, but not so hot if you want fine measurements. Thinking about a better mic + preamp, but waiting a bit till the bank card cools off from the holidays.
 
A buddy of mine asked today how the ZLH-20s might stack up against the popular Dynaco A-25. I have a pair of A-25XLs, so here is the comparison.

All measurments taken using REQW software, R/S SPL meter and boom mike stand. SPL meter ~3 feet from tweeter and on axis with the tweeter. This measurement technique is probably far from perfect for accuracy, but is good for comparisons of different speakers.

Legend
Light green = ZLH-20
Blue = recapped KLH-17
Dark green = recapped Dynaco A-25XL
 
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Like you, I'm using the R-S SPL more for relative measurements. I don't think we can really do absolute charts with it. I'm looking into getting a good Behringer mike and pre-amp. Then I should be able to see how close the SPL actually comes.

As long as you're making comparisons between systems within the same test parameters, you should be OK. I was trying to figure out what made a big 60Hz or thereabout "hump" on one of my test runs. Tried just about everything. Then the air conditioner fan switched off. Oops! :o

I definitely think some of your chart lumps are environmental.

How much smoothing did you use on that last set of charts?
 
Paratima said:
Like you, I'm using the R-S SPL more for relative measurements. I don't think we can really do absolute charts with it. I'm looking into getting a good Behringer mike and pre-amp. Then I should be able to see how close the SPL actually comes.

As long as you're making comparisons between systems within the same test parameters, you should be OK. I was trying to figure out what made a big 60Hz or thereabout "hump" on one of my test runs. Tried just about everything. Then the air conditioner fan switched off. Oops! :o

I definitely think some of your chart lumps are environmental.

How much smoothing did you use on that last set of charts?
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1/3 octave smoothing.

No doubt my listening room, measurement technique, and R/S meter are not ideal. I too have to wait for the HVAC to not be running to take any measurements. Let me know if you get the new Behringer mike and how that goes for you. I've been thinking about a measurement equipment upgrade myself.

What I've learned from all this freq. response measurement is your listening room is the biggest factor above all else. Am thinking about getting a Behringer DEQ2496 so I can somewhat reduce room effects.
 
Will let you know soon as it happens. As I hinted at before, I have to wait till my bank card cools down from the holidays or (Heaven forbid!) one of my beloved customers actually places an order for my services.
banghead.gif
 
Color me confused. Got a set of KLH 20's. 4 Ohms nom; the 17's I've read about say 8 Ohms nom.

Would the graph look totally different then...

Also, my set have no ports or holes. My Sevens don't either. The pic there seems to have 2 ports. Is that part of the W'G-ification?

thx
 
I think I can answer that, well, those.

There will always be differences even between different instances of the same model speaker. However, the response differences should be minor between the 4 and 8 ohm models.

No ports in the original 17's or 20's. We put 'em there as part of the E'Wave thing. Zilch's box calculations called for 2 ports, each 1.5 inches diameter, each 8.5 inches in total length. Here's what mine looked like before and after installation. They point North, past the Selenium tweeter, ie, away from the woofers. It's kinda cozy in there, once everything's in place.

zlh14.jpg

zlh16.jpg
 
Susurus said:
Color me confused. Got a set of KLH 20's. 4 Ohms nom; the 17's I've read about say 8 Ohms nom.
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4-Ohm woofer's how they cranked up the bass in the 20. Tweeter's the same, allegedly.

Yes, there would be "implications," but, other factors being equal, the native response would be the same with respect to LF extension, for example.

No matter. We dumped the stock woofs in favor of more modern drivers in a vented alignment.... :yes:
 
Thx for clarifying.

Never seen 17s IRL so I didn't know how different they are. Tweeter pics look exactly the same as my Model 20's tweets.

By switching woofers you answer my other concern too. Woofers designed for Acoustic Suspension require less stiff mechanical suspension, relying on contained air instead. Maybe no suspension at all--or just barely enough to tenuously center the former/gap position...
 
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