Will cane grill cloth block highs?

[Greg Roberts]

I made new grills for my L100 and 4311 refurbishing project. Then I had a thought. What if this fairly heavy grill cloth blocks the highs from coming out of the dome tweeter?

www.dcchomes.com/JBL.html (http://www.dcchomes.com/JBL.html)

This type of grill cloth is used on all of the Klipsch Heritage line, but those all have the K-77 horn tweeter. Is there a difference with a dome tweeter? Should I only be using the more transparent plain grill cloth?

Thanks in advance for any help.

Greg

[Mr. Widget]

First to answer your question. Yes it will adversely affect the HF response of your speakers. The sound waves coming from a tweeter do not know what type of device created them and will all be affected by the grille material in the same manor regardless of tweeter type. The more sheer the material the better. When critically listening I always remove the grilles. There is no grille material that is truly sonically transparent.

Beyond that your question piqued my interest. The other day there was an article in AudioXpress describing what was entailed in replacing the T35A (K-77) that was standard in the Klipschorn and other Klipsch speakers for decades. Here is an anechoic plot of the T35A from EV that was featured in that article. I knew the little buggers were bad... but good grief this is terrible.

Widget

.

[Mr. Widget]

This is a plot of one of my L100s. It was taken on the woofer's axis with the speaker in the middle of the room raised about 1m from the floor. The response was better than I expected. The grille was removed and you will see a much better HF response than that little T35A can produce. The controls were both placed at the "Laboratory Standard" position... it did indeed produce the most linear response. I found measuring the speaker on the tweeter's axis the response was more uneven as there are significant cancellations between the mid and tweeter due to the overlapping nature of the design of the crossover.

Don't mind the lack of bass. If you use the L100 in a small room or near room boundaries the bass increases significantly.

Widget

[boputnam]

The response was better than I expected. :hmm: Me too! All this time I thought it was the waterbed I liked... :rotfl:

Well, it's 22C here in Johannesburg, and I'm going poolside with some fine Chardonnay. No-one's got a stereo here worth a dam - all teeny bullshit with crappy response but innocuous asthetics. Went to a disco last night - rager. Babes were dressed to the nines, and dancing amongst themselves. Wasteful, that... These babes are amongst the worlds most amazing eye candy - trust me. Anyway, the system was some near look-alikes to L100's - three-way coners, although with 15-in LF's, no horns, no subs. :barf: DJ was good, but after two-hours of the same throbbing un-changing and never-ending beat, :blink: I was done.

[4313B]

This is a plot of one of my L100s. It was taken on the woofer's axis with the speaker in the middle of the room raised about 1m from the floor. The response was better than I expected.Yet another reason to listen with your hears instead of your microphone. :p

In any case, nice graph! :)

When are you going to drag your gear over to Bo's house and have a plotting party? There should be a whole plethora of neato systems to measure over there! :)

[Maron Horonzakz]

Widget....The graph of the EV T35 is mine made many many years ago, At the Instatute for the Deaf. In St Louis. It was tested in a anechoic chamber. Along with many other drivers that day. John Warren borrowed the graph for his article. Can you imagine what it would look like with grill cloth in front of that tweeter?

[Zilch]

Should I only be using the more transparent plain grill cloth? You can somewhat assess the acoustic transparency of your grille material by holding it up to the light and comparing its net free (open) area to standard grilles. Also, if the obscuration by the "canes" is 1/8" or more, I'd anticipate problems.

It's easy to do a test: Run just the tweeters (on crossover, of course,) and from your listening position, have someone place and remove your grille material from in front of one of them. Your problem, if any, will be readily apparent.

[Hmmmm. No subs or waterbeds in South Africa? Gonna make a note of that....]

[Greg Roberts]

I wonder if anyone has a graph showing the level of modulation distortion of the L100 with 75 watts input? ;)


Greg

[Mr. Widget]

I wonder if anyone has a graph showing the level of modulation distortion of the L100 with 75 watts input? ;)


Greg


Sounds like Paul is still with us. ;)

Here are second and third harmonic distortion plots raised 20dB with input power at 5 watts. It was plenty loud.

Widget

[johnaec]

Widget - do you know the "percentage" translation for distortion from -dB? For instance, if 3rd harmonic distortion is -40 db, do you know what percentage distortion that translates to? (I used to know the relationship, but it's buried away somewhere in my gray cells right now...)

John

[Mr. Widget]

No. I'd have to research that, myself. Maybe someone has it at their finger tips.

Widget

[johnaec]

Well, I just did a quick interpretation from the 2012H spec sheet where they have both graphs and percentages listed for distortion, and it looks like 1% equates to about -35 dB and 3% equates to about -45 dB, at least as far as 2nd harmonic goes. 'Anyone know the technical conversion factors/procedure?

John

[grumpy]

If we're comparing power levels, (watts, not volts) I believe it goes 10log(ratio):

-10dB = 10%
-20dB = 1%
-30dB = .1%
-40dB = .01%
...

or 3dB per x2 difference.

I don't know the definition for THD (assuming it's summed non-fundamental
power within some bandwidth). Of course I could be full of superbowl leftovers...
http://audioheritage.csdco.com/vbulletin/images/smilies/puke.gif

[4313B]

Of course I could be full of superbowl leftovers...http://audioheritage.csdco.com/vbulletin/images/smilies/puke.gif:rotfl:

[johnaec]

If we're comparing power levels, (watts, not volts) I believe it goes 10log(ratio):

-10dB = 10%
-20dB = 1%
-30dB = .1%
-40dB = .01%
...

or 3dB per x2 difference.I'm aware of the power ratios you stated, and I think I've got a book or some documentation somewhere that goes over harmonic distortion, but I'll have to dig them out...

Also, I believe that every doubling in distance from the speaker results in -6 dB, correct?

John

[Mr. Widget]

Also, I believe that every doubling in distance from the speaker results in -6 dB, correct?

John

Yes... in a lossless perfect world. :)


Widget

[johnaec]

Yes... in a lossless perfect world. :)What - doesn't everyone set their rooms up anechoic?? :p

John

[Mr. Widget]

Greg,

This one is for you. I remembered that I had a pair of Klipsch Heresy IIs in storage. Here are the effects of the Klipsch Grille material on and off the newer horn tweeter. It certainly has much better HF extension than the old EV units.

Red Plot= no grille
Blue Plot= with grille

[Mr. Widget]

Now the bad news... not only is the bass super weak for a twelve incher, here are the 2nd and 3rd harmonic distortion plots of the Klipsch Heresy IIs. The input power was about 2 watts and I was worried about the woofers... I didn't have them frequency limited and the bass goes down to 10Hz.

The L100 had significantly less distortion and at a higher power level.

Blue= 2nd Harmonic raised 20dB
Green= 3rd Harmonic raised 20dB

[Mr. Widget]

Here is the L100 again for easy comparison. :)

[Steve Schell]

Y'know, that old plot of the T35 actually doesn't look that bad to me. If you consider 107dB as the average response, it is only about 6dB down at 15kHz. Not stellar performance, but not bad and certainly correctable with some mild EQ. The phenolic linen dome is well into mass rolloff above 10kHz., but is exhibiting good piston response and little if any breakup. These old EVs and the somewhat similar Jensen RP-302s sound very accurate and clean to me. I certainly prefer them to more recent designs that resonate the suspension to gain added response on top, and sound "tsss tsss" as a result. It really takes a ribbon design to move the mass break point high enough to achieve flat piston response to beyond 20kHz., but their overall sensitivity is quite a bit lower.

[sonofagun]

We built a pair of Klipschorns many years ago equipped with OEM E-V tweets. Found that a standard 2nd order x-over worked best rather than a first order (Harsh!). Guy who ended up with them said they sounded better than factory K'horns! :applaud:

Mr. Gidget...just wondering if you would have tested the raffle L100s with and without my foam grilles in place?

If I send you some foam, would you like to run tests on it to post here?

[Mr. Widget]

If I send you some foam, would you like to run tests on it to post here?

I'd be happy to. It might be interesting to see if there is a difference between the "Quadrex" and plain foam. To me it looked like the heavy weave pattern of the Klipsch grille created a diffraction gradient... you can see how the response got bumpy, it wasn't simply rolled off.

Widget

[Mr. Widget]

Grumpy has sharp eyes. The Klipsch Heresy II is not as bad as it seems compared to the L100 as far as harmonic distortion is concerned. Between measuring the L100 and the Klipsch, I was measuring some speakers with much lower distortion and so I had raised the level even further... I forgot to reset it to 20dB.:banghead: The JBL is still a bit better over much of the spectrum, but they are much closer in their distortion levels.

Widget

[tom57]

This is a plot of one of my L100s. .....The controls were both placed at the "Laboratory Standard" position... it did indeed produce the most linear response. ....

Widget

Hi, I found this interesting frequency plot from the L100. I am too using a pair of them.
Can you tell me what you mean with the "Laboratory Standard" position of the controls? Is it 5 on the scale (0..10)?

BR Tom

[Zilch]

"Search" knows the answer:

http://audioheritage.org/vbulletin/showthread.php?t=4541&highlight=laboratory+standard

[tom57]

Great - thanks a lot - will use search next time first ;-)