Fixed L-Pads

[Zilch]

1) I can tell you, not much here sounds sweeter than this system.

2) Citation 7.4 is 3.48 cuft. tuned to 29 Hz.

Mark, you may want to try your box tuned down to ~30 Hz, too.

I think I'll build per John W's uber-cool implementation.

Just picked up a pair of LE14H-1s and had 'em rehabbed.

Gotta do SOMETHING with them.

Thank you for this opportunity to play LE85s and LE14s two-way again.

[Gonna go listen more, now.... ]

More: As the time stamps indicate, I was up pretty late listening, and did a couple of additional measurements:

3) The MF adjustment control range, HF constant at "Normal."

So, if the MF is at Max to balance with LF, is there still enough HF to go with? Yup, if flat is boost enough:

4) Range of adjustability, both controls Min and Max in comparison to "Normal."

[Earl K]

Nice Work Zilch !

1) I can tell you, not much here sounds sweeter than this system.

- Now,,, I hope you realize that you've tricked yourself into wiring up ( and enjoying, you say ) a 2344 horn playing below it's "accepted-best practises", LF cutoff.
- Some around here may start to panic, if you use this as an example to challenge their current paradigm .
( You better unwire it and forget about it. )

- Of course, this is all due to the power of "bump filters" / not that I'm an advocate of them you understand .

- A question ; Why didn't you place the HF(s)' variable pot at the beginning of the circuit making it a true Drive Control ( a la , the 3134/5 network) ?
( The way it's now arranged, it also adjusts the F3 points for the preceding LC parts. )

[Zilch]

Some around here may start to panic, if you use this as an example to challenge their current paradigm.

POO on 'em, and the JON-BOAT they rid in on, too!!

http://www.jblpro.com/pub/obsolete/2344A.pdf

If we moved it to 1 kHz, they'd just be sayin' that's too high for LE14, instead....

A question: Why didn't you place the HF(s)' variable pot at the beginning of the circuit making it a true Drive Control ( a la , the 3134/5 network) ?

The way it's now arranged, it also adjusts the F3 points for the preceding LC parts.

Well, I don't think it matters, but I'm not above proving myself wrong in the interest of a better design.

You mean F3 of the bypass loop, or F3 of the basic highpass? I need to know where to look.

[Easily remedied using these fancy spring breadboarding thingies, if so.... ]

[Earl K]

Hi Zilch

You mean F3 of the bypass loop, or F3 of the basic highpass? I need to know where to look.

[Easily remedied with these fancy spring breadboarding thingies, if so.... ]

- I'm referring to the position of "LP-2" in the bypass loop .

- I'm not saying, that it's in the wrong postion . I am saying that at that position, with it offering variable resistance ( in parallel with the midrange loop below it ), in a small way it also changes the working impedance that the 1uF cap ( and .08mH coil ) "sees" . No biggy

[Zilch]

- I'm referring to the position of "LP-2" in the bypass loop .

As luck would have it, it's actually wired as you suggest would be optimum. Here's the measurements, both ways:

1) LP2 "in front"
2) LP2 "behind"
3) Highpass knee
4) HF response

If F3 shifts, it's negligable, apparently.

I've just ordered parts to build a pair.

$225.98 for two.

[Zilch]

Lest any doubt their VHF capabilities:

Six red-sealed LE85s of varied vintage and indeterminate usage histories, below.

4712 - Red, 7429 - Grn
15567- Cyn, 16881 - Vio
18172 - Blu, 22222 - Org

The signature of the 2344A horn is apparent (bottom). [Notches, anyone?]

The filter "bump," too.

I was using the red one for this work.

[Gonna switch to the cyan 'cause it's better lookin'.... ]

[Zilch]

Work in progress:

[hjames]

Missed the original discusion a few days ago about
no easy source of graph paper, then I found this yesterday online (from work!)

The answer: you can print your own!

http://www.pdfpad.com/graphpaper/

[dmtp]

No, I didn't drop off the end of the earth. It is just that work and other obligations keep getting in the way!
Anyway, I finally got a reasonable test set-up going and found some good weather (if COLD) to take everything outside for a semi-anechoic measurements.
First my gear: an old PIII computer with TrueRTA, an old (vintage) Marantz amp, Beheringer EM8000 mike with UB802 preamp. Now, some pics:
1. LE14A with XO

2. LE85 with XO showing L-pad @ min, mid, max

3. Expanded HF

4. Effect of HF boost

[dmtp]

I tried to upload more files, but for some reason I can't????
I'll try again later.

[dmtp]

Here are some measurements of the full system:
1. On blocks measured @ 3' (note difference in LF/HF levels and big notch @ 300)

2. Measured with speaker flat and mike 3' above (sort of 1 pi without digging a hole)

3. Ground plane measurement (speaker and mike both on ground)

This certainly looks the best. Not sure how it or others relate to real world. Now I have to finish of the speakers, put in foam, FG, etc. Seal all the leaks and then test them in the living room.
Stay tuned!

[Zilch]

Our LE14A nearfield results are certainly similar.

Looks like you need to attenuate the HF by an additional 10 dB or so. Try doing that with a fixed L-Pad just before the driver. I can't imagine your horn is that much more efficient; something else is up, maybe.

The VHF appears to be dropping off above 12 kHz. Measure something else to see if you're getting accurate results up there. If so, either your horn is killing it, or your driver isn't generating it like it should. Do you have any 2344(A) to try?

Waiting on some 24 uF caps for my crossovers. Once they're done and tested, I could send them to you for a week or so to compare with yours, maybe....

[dmtp]

No other compression drivers around. I'll hook up the other LE85 and see what is does. I did test my current system in the living room (the one in my avatar) and it is pretty much flat out to 20k.
What are you using for a schematic for your XO? Any changes from what I origianally posted? I am using Solen caps bypassed with AudioCap Theta's.

[Zilch]

What are you using for a schematic for your XO? Any changes from what I origianally posted? I am using Solen caps bypassed with AudioCap Theta's.

http://audioheritage.org/vbulletin/s...6&postcount=76

Put R4 (8 Ohms) in there, at least....

[dmtp]

Are you using an 8 ohm LE85? In addition to the 8 ohm R4, I notice you have L3=0.08 mH vs my 0.15. C6 is the same @ 1 uF. I also do not have R5 (20 ohm).
Or do R4/R5 form another L-pad that is further attenuating the LE85? And how does the HF bypass feeding into the 'knee' of the L-pad effect that? Hmmm, with R5 parellel LE85, the HF bypass would be 'seeing' about 8 ohms anyway, wouldn't it?
I'm sure I have 20 & 8 ohm reisitors. I'll see if I have a 0.15 mH or another 0.08 mH coil to try out your circuit. ( I was following the 16 ohm version posted elsewhere - not sure I still have the thread reference) I also want to try the other LE85 as all my testing to date has been done with the same unit.