Zilch's AK Design Collaborative - Econowave Speaker

[jackgiff]

I looked at that, Jack, and I believe there's an issue of the L-Pad increasingly pulling the cap to common, and ultimately shorting it to there, when set to max attenuation.

The effective capacitance of a 1 microfarad in series with a 4.7 microfarad is roughly .82 microfarads. The capacitive reactance of .82 microfards at the low end is very large. It isn't til frequency gets to about 50 KHz that the reactance gets less than 4 Ohms. I can't see that would cause any problems, but adding a 2 or 4 Ohm resistor in series with the cap, or in the pin 1 to common connection would protect virtually any high powered amp that can pump out enough power at 50 KHz to be bothered. How many amps that powerful are likely to be in someones home stereo systems? It still would be much better than correcting the sum of the tweet and the L-Pad.

Plus, at minimum attenuation, the HF output is zero. Who will be setting their L-Pads at Minimum?

 

[jackgiff]

Couldn't add a pic to my last post.

I wanted to edit my last post, but it wouldn't let me edit it and add a pic.

This simple correction to the modded HF should make it short circuit proof, while still feeding all of the correction signal to the tweeter. Simply split the correction resistor and move part of it into the connection between pin 2 and the tweeter. The circuit will see all 15 Ohms plus the resistance of the L-Pad across the cap , as before, but now it will see 5 Ohms if the L-Pad is set to minimum. Won't that take care of the short at min problem?

Edited...Whoops: This configuration won't work, cause the 5 Ohm resistor does change the effective impedance seen by the HF correction capacitor. At min L-Pad setting, the cap sees the 5 Ohms in parallel with the tweeter, not zero Ohms. This leaves a whopping big rising response at min setting. Big mistake on my part. Don't build yours like this. We have corrected the circuit so that it is consistent, effective, and short circuit proof, but Zilch is working on setting the final values using Spice.

I shot from the hip. Sorry about that.

 

[Zilch]

Looks better now, Jack.

I'll wire it up and report the findings here.... :thmbsp:

 

[lredelfs]

Waveguide for 600 Hz crossover

Please advise if the JBL wavequide would be a good match for a crossover at 600 HZ with a JBL 2445J driver. Please suggest the appropriate waveguide if this is feasible.

Thanks, Larry

 

[Zilch]

Please advise if the JBL wavequide would be a good match for a crossover at 600 HZ with a JBL 2445J driver. Please suggest the appropriate waveguide if this is feasible.

The PT waveguides don't reach that low, in my experience. If you're wanting to do two-way, the larger JBL biradials will get you down there, 2380 and 2350 series.

I've never tried pushing 2445 for full VHF extension, so I don't know if it'll go there; mine are used three-way on 2380 @ 800 Hz, and have "SL" damped diaphragms.

In large format JBL drivers, I've moved on to 2452H-SL throatless for two-way. I don't know how low those'll play on 2381 (a largely unknown biradial) or 2352, though. Not my job....

 

[jackgiff]

The best I can do.

After playing with the EconoWave guys for the past week, this is as good as I can get them without going to active or inductive components, which will increase the costs by around $20 per pair, minimum.

I played with the split resistor crossover, and finally figured out it didn't do anything but add at least one resistor, and maybe two. Went back to the original x-over, and these are the values that work best for me. I like it with the 1.5 microfarad HF compensation capacitor, but took pix of the HF FR's with both 1.5 and 2 microfarads. The first FR is with the 1.5 microfarad. Also is an FR of the full range response. Note that most of the roller coaster stuff is caused by the woofer. Even so, these sound fantastic.

I hope Zilch can get some flatter response using Spice, but I cannot see how Spice can lower the difference between the highest output level of the tweet, and the bottom end of the dropoff at 20 KHz. We shall see.

Zilch, where are you?

 

[skywave-rider]

wow

Wow that looks pretty amazing!
To my eye the 2uF looks better.
They are so close, though.
Wonder if you hear any sibilance due to the slight rise at c. 6k?
How big is that bump, 2-3dB?
Not too much.
Virtually flat.
I'm impressed.
:thmbsp:

 

[Zilch]

Zilch, where are you?

Interruped by some AR2s in dire need of demolition here. :

[I'm trying them with the EconoWave crossover tonight.... :yes: ]

Back on it with CLIO and SPICE this weekend, but you've certainly set the bar mighty high now, Jack.... :thmbsp:

 

[Zilch]

Most Excellent:

Confirming Jack's EconoWave HF filter design, my Behringer RTA reads it the same as his, flat as Nebraska. I used 25 Ohms in lieu of 24, as that value is not available from PE. Driver #1 shown here:

CLIO shows the difference between 1.5 uF and 2 uF compensation capacitors in expanded vertical scale. I'm voting for 1.5 uF as the UHF is a bit hotter with some of my sample drivers.

Speaking of which, here's the four drivers using 1.5 uF compensation:

And finally, the adjustment range of the L-Pad using driver #2. Small variations in impedance at various levels do not appreciably alter the curve. Top to bottom, 5, 3, 1, 11, 9, and 7 o'clock:

Patricia Barber's sounding mighty silky on these right now, thank you Jack.... :thmbsp:

 

[skywave-rider]

And finally, the adjustment range of the L-Pad using driver #2. Small variations in impedance at various levels do not appreciably alter the curve. Top to bottom, 5, 3, 1, 11, 9, and 7 o'clock:

Patricia Barber's sounding mighty silky on these right now, thank you Jack.... :thmbsp:

I would think the slight rise at the very high end on minimum attenuation to be beneficial, actually. If you had to have it, that's not a bad place. Think?

 

[Zilch]

I would think the slight rise at the very high end on minimum attenuation to be beneficial, actually. If you had to have it, that's not a bad place. Think?

With JBL titaniums, I'd be tilting the response downward 5 dB over that range, but the Selenium "Tree of Life" embossing of the diaphragm as opposed to JBL's diamond surround as the source of the HF extension seems less harsh, and can tolerate flat. Same with BMS mylar; flat works.

This is where subjectivity comes in. Both Jack and I are liking the sound of the Selenium D220Ti on the PT waveguide compensated flat, but neither of us can hear the VHF; Myrna's the final arbiter at JackLab. Wiredbecker, who hears keenly up to 18 kHz, will listen to this combo here today to verify. Duff's friend Coy hears out past 20 kHz, and Mxlews, too. If they say it's good up there, it's good.

You have "Room Correction" on your AutoEQ, so it's an easy comparision for you to make. Get it flat, either actively or passively, then kick in the tilted response EQ for A/B comparison. I'm about to try that on EconoWave here.

We'll be doing another iteration of this once the waveguides are mounted in cabinets. I'll be interesting to see how much difference that makes, now that we have a baseline.... :yes:

 

[jackgiff]

Before these go into the cabinets, I plan to try the HF end with Altec 416Z's in Valencia cabinets (With its 806A disconnected), and with Trusonic 150FR's in homemade EV Baronet clones. Both woofers are 16 Ohms, and the Trusonic is very efficient, so that may give us a clue as to whether we have the proper range in the L-Pads so that "one size fits all."

I will need to patch up the values by connecting inductors and capacitors in series/parallel to get the desired values for these trials. Zilch, if you have any other brand woofers, maybe you could try a couple of them, just to be sure the lowpass output merges properly with the HF output of the EconoWave.

I hope there is enough room on the baffle for the Santana's to get the two three inch ports in, since these will become my garage speakers, and will be backed up against a wall. No place for ports on the back.

 

[Zilch]

Here's the PE list for the parts I'm using in the HF filter:

027-552 Solen 4.7 uF - $3.67
027-528 Solen 1.5 uF - $2.41
255-234 Jantzen 0.6 mH - $5.98
004-25 Dayton 25 Ohms - $1.25
004-15 Dayton 15 Ohms - $1.25
260-262 Dayton L-Pad - $9.25

Total - $23.81

Using Dayton caps, 20 Ga inductor, and 15W L-Pad knocks $8.94 off that, $14.87 total.

Dayton caps will sound a bit mellower; 20 Ga inductors, I'll have to order a pair to try unless that's what you're using, Jack, and the 15W L-Pads will likely work fine, but are lower quality.

I anticipate a fixed L-Pad ahead of the adjustable one to have the variety of common woofers balance in the control midrange. That's just two additional resistors, $2.50.

Either way, we're certainly in the "Econo" range for crossover cost so far.... :thmbsp:

I hope there is enough room on the baffle for the Santana's to get the two three inch ports in, since these will become my garage speakers, and will be backed up against a wall. No place for ports on the back.

Bottom works too, of course.

12" woofers may get you the requisite baffle space for front ports in Santana, if necessary. There are several good extended-bass JBLs.... :yes:

 

[tubtub]

Jack & Zilch,

How do you like the sound of this project so far. Are the speakers and compression drivers 8 ohm or 16ohm. Are you done tweaking and finalized with the design. I am going to put in an order for the compression drivers and parts soon. Thanks for nice project.

 

[jackgiff]

A change in the low pass maybe?

I tried the EconoWave HF as presently configured with the bass end comprised of a Stephens Trusonic 150FR, housed in a homemade cabinet. The Trusonic 5KT tweeter was disconnected for this test. I sensed a little bit of a drop in the crossover region, due to the fact that the low pass frequency was selected to suit the JBL LE14A's that will be used as woofers in my own pair. The LE14A's had a bit of peaking at 1.6 KHz, which was eliminated by dropping the low pass to 900 Hz.

That doesn't suit the Trusonics as well, since their response at 1.6 KHz is not like the JBL's. Raising the low pass back to the targeted 1.2 KHz, improves the crossover response, and it doesn't seem that raising it any more will improve the crossover response due to the FR of the Trusonic 150FR. The Trusonic speaker is also a 16 Ohm driver, so different values of crossover components were necessary.

Pictures show the cabinet with the 150FR, and the mess of parts on the top of the cabinet. FR's are shown for the response of the 150FR wide open (no crossover) and with it operating at the 1200 HZ final crossover configuration. Also shown are the ideal settings for the overall system using the 900 Hz and the 1200 Hz crossovers.

I will now go try the same tricks with the Altec Valencia woofers.
__________________

 

[jackgiff]

Jack & Zilch,

How do you like the sound of this project so far. Are the speakers and compression drivers 8 ohm or 16ohm. Are you done tweaking and finalized with the design. I am going to put in an order for the compression drivers and parts soon. Thanks for nice project.

tubtub, don't go buy parts just yet, if you are planning to build this project. We need a few more days to complete the formula. The JBL woofers and the D220Ti's are all 8 Ohm parts, but the 2 woofers I will try to mate the HF end with are both 16 Ohm. When we are done, we should have a parts list for using 4, 8, or 16 Ohm woofers at the proper crossover frequency, and the drivers for the top end are 8 Ohms.

They sound spectacular, and I have built several pairs of two ways before. I will compare them to four of them when they are in the cabinets and can be moved easily. But I expect they will hold their own very well.

As Tony the Tiger would say, "They are GRREEAAAATTTTT!"

 

[wiredbecker]

Jack & Zilch,

How do you like the sound of this project so far. Are the speakers and compression drivers 8 ohm or 16ohm. Are you done tweaking and finalized with the design. I am going to put in an order for the compression drivers and parts soon. Thanks for nice project.

Hey Tub, I like the sound a lot. The Selenium compression driver installed on these horns with the crossover, sound excellent!

Some adjectives that I settled upon to describe this horn combo are: Crisp, clear, well balanced and accurate (especially in comparison to every speaker I own) I only have one pair that use horn drivers the Klipsch Heresy, and these waveguides best them with ease. Of course with a statement like that I'll have to bring the Heresy's over to Zilch's for proper measurement..

The Econo-Waveguide is great!

 

[skywave-rider]

I only have one pair that use horn drivers the Klipsch Heresy, and these waveguides best them with ease. Of course with a statement like that I'll have to bring the Heresy's over to Zilch's for proper measurement..

The Econo-Waveguide is great!

If you do that, make sure the Crites tweeter is installed on the Heresy.

 

[jackgiff]

Got the Altec test done late last night, so here are the results. The Altec needed a little higher crossover just like the Trusonic. 1.2 KHz is probably the best frequency to use in the low pass part of the EconoWave crossover, since it will fit more woofers than the 900 Hz the JBL likes. If you are using an LE14A, as I am, we can just live with the small peak at 1.6 KHz. It was measured, but it can't be heard, so we need to forget about it.

Pix show the Altec Valencia 416Z being used for bass, and xover parts on top of the cabinet. FR's are shown for the response at 900 and 1200 Hz. The last FR is for the 416Z woofer running full range (no crossover).

 

[Zilch]

1.2 KHz is probably the best frequency to use in the low pass part of the EconoWave crossover, since it will fit more woofers

So, 1.5 mH and 12 uF nominal, Jack, and tune with Zobel as required?

I'll try that with some 12" drivers here. :yes:

If you do that, make sure the Crites tweeter is installed on the Heresy.

Heh. Just happen to have a pair of those.... :