JBL D-130s & Altec 511b horns...

[Tom Brennan]

RB---The large hole in the baffle may be intended for a JBL "potato masher" lens and horn. Or perhaps there is such a hole behind the plate.

Check the link for the potato masher. The unit is quite compact.

http://www.lansingheritage.org/html/jbl/specs/home-comp/175dlh.htm

 

[Redboy]

The round hole in the upper left of the picture is where the port tube is supposed to go - when I opened the other cabinet, it was in there. Behind the rectangular plate in the upper right is a rectangular hole.

Anyway, I'm not comitted to the D-130's and as RC's noted, "they may be worth more dead than alive" to me. Maybe I'll feel around to see if anyone local has a pair of Altec or JBL 15's that would be more appropriate. I don't have to have "punch you in the gut" bass, but I do appreciate good extension and it seems that the big cabinets could offer that, as Zilch noted earlier.

I'm excited to try the 511b's though, so I'm going to keep them for now.

I'm not a speaker guru and I won't pretend to be one. I'm just trying to figure out where to start. My goal as I see it is to build a two way system that will offer really excellent sound quality, not necessarily quantity. I listen at fairly low levels 99% of the time.

I'd also like to make sure the end product is as sensitive as possible, since I'm experimenting with fairly low-powered tube amps and really liking them these days. The sensitivity of the D-130's made them quite appealing to me, on the surface anyway.

I appreciate everyone's thoughts, opinions and comments so far - this is helpful. :thmbsp:

 

[Zilch]

Here's the inside view:

Yes, I saw that in your other thread. Is the hole in the upper left open through the front? If so, that's behaving as your port right now.

Pretty sure I couldn't sneak the 511b's in there.

Well, I need the dimension, please. How much room. 8"? 6"?

I have something in mind, and if you've been clicking my links, you've already seen it....

 

[Zilch]

RB---The large hole in the baffle may be intended for a JBL "potato masher" lens and horn. Or perhaps there is such a hole behind the plate.

Check the link for the potato masher. The unit is quite compact.

http://www.lansingheritage.org/html/jbl/specs/home-comp/175dlh.htm

Redboy wants quality sound. Potato masher rather sucks. 511b's only going to deliver with the right compression driver and compensation filter. Even then, it will be compromised. Hook it up. Get a baseline handle on what's happening. What driver's on the 511bs? Which diaphragm is in them? This all matters....

 

[Redboy]

Well, I need the dimension, please. How much room. 8"? 6"?

I have something in mind, and if you've been clicking my links, you've already seen it....

Oooh! :scratch2:

I'm going to have to click those links again - kept getting lost in all the numbers and mysterious jargon - but I'm headin' out with tape in hand...

 

[macaltec]

Redboy want quality sound. Potato masher sucks. 511b's only going to deliver with the right compression driver and compensation filter. Even then, it will be compromised....

Please elaborate. I am undergoing a similar project with some complications.

 

[Zilch]

Please elaborate. I am undergoing a similar project with some complications.

I'm a JBL guy, not Altec, but some Altec fans have asked me to "Fix" Valencia two-ways. The problems are well known. Here's the thread; start at this page to ignore the preceeding personality conflict there (not me):

http://audioheritage.org/vbulletin/showthread.php?t=14690&page=6

I'm about two weeks away from completing the measurements for a recommended solution. They're playing in the background right now. You can glean where it's headed near the end there....

 

[Redboy]

Okay, here are the dimensions inside the cabinet:

• 22.5 " wide
• 24 " high
• 15.5 inches deep
• round hole is 5" diameter
• other hole is 10" X 4"
• Driver is 7" down from top bracing strip
• Driver is 6" from far side

 

[Tom Brennan]

"Potato masher sucks."

Oh I dunno, they sound pretty good to me. There are better things, sure.

 

[Zilch]

Okay, here are the dimensions inside the cabinet:

Cool. I'm pleased to see your diligence here. Try to understand the jargon and get past it. This stuff is technology, not merely throwing random drivers in a box.

Hell, Rick (Tapehead47) is now measuring SPL differentials in another thread here, and my guess is that he was a diehard technophobe before this. :thmbsp:

Answer: The $10 JBL Progressive Transition waveguide for 1" thread-on compression drivers will fit. AK member Alexkerhead has a pair he's working with in another project. That's it in the Viscount boxes I linked to above.

Don't be put off by the fact that it's cheap. It's among the best of currently available JBL Pro horns for two-ways:

http://audioheritage.org/vbulletin/showthread.php?p=57029#post57029

 

[Redboy]

Yes, I saw that in your other thread. Is the hole in the upper left open through the front? If so, that's behaving as your port right now.

Sorry - missed that first time around. Yes, the upper left hole is open through the front.

 

[Zilch]

Sorry - missed that first time around. Yes, the upper left hole is open through the front.

The round hole in the upper left of the picture is where the port tube is supposed to go - when I opened the other cabinet, it was in there. Behind the rectangular plate in the upper right is a rectangular hole.

So, the tube in the pic is just sitting there, NOT going through the baffle? Doucanoe is certainly right, then. The tuning is not optimum for the D130s, and there's some improvement to be achieved, if you want to retain them. The one with no duct is closer to the correct 40 Hz tuning, actually.

If you'll tell me the ID of the duct, I'll be able to give you the proper length for tuning D130 in that box. OR, you can download WinISD, figure it out yourself, and learn stuff. D130 is in there.

You need to determine unequivocally whether the baffles are removeable. If so, that establishes a majorly different context for your ultimate design option considerations....

 

[Redboy]

So, the tube in the pic is just sitting there, NOT going through the baffle? Doucanoe is right, then. The tuning is not optimum for the D130s, and there's some improvement to be achieved, if you want to retain them. The one with no duct is closer to the correct 40 Hz tuning, actually.

If you'll tell me the ID of the duct, I'll be able to give you the proper length for tuning D130 in that box. OR, you can download WinISD, figure it out yourself, and learn stuff. D130 is in there.

You need to determine unequivocally whether the baffles are removeable. If so, that establishes a majorly different context for your ultimate design option considerations....

Yeah the tube's just sitting there - fell out. I really should have popped that back in before taking pictures!

I'm going to have to wait a little to get any more measurements. And to check the "baffle removability."

And I think doucanoe's already crunching some numbers for the heck of it! But I can see that I need to get into this a little more. Right now I'm lost!

 

[Zilch]

But I can see that I need to get into this a little more. Right now I'm lost!

Well, trust the Zilchster on this part: it's really, really fun once you get a little deeper into it, and you've got a good resource with doucanoe helping you get there. Let me know if I can assist you guys further. I've tried to highlight some parameters I'd be looking at for your project; others might approach it differently, of course.... :thmbsp:

 

[Redboy]

I'm grateful for the thoughts and ideas presented here so far. This is good for me. Stretches my brain muscle a little. Reading those threads Zilch linked to is serious exercise! Like a fat man in a marathon - it ain't happenin'!

Hypothetically speaking, what can I expect to hear if I just go with the parts I've got cobbled together at the moment? I'm thinking it would almost be a shame to trade in the D-130s without ever really listening to them.

Keep in mind that I don't have a lot of experience or a lot of things to compare to aside from the Klipsch Forte's in my system that I really love.

Assuming I tune the cabinets properly to the D-130s liking, what would happen if I use the Eminence crossovers as suggested and the 511b's with 808-8a drivers behind them?

What's the "weakest link" in that idea?

Or am I going to have to just do this thing and find out for myself?

 

[Zilch]

Two weak links:

1) No extended bass. You know the answer to that one, now.

2) Rolled off highs. You'll either have to add a compensation network (what Model 19 was about) or a tweeter. I'm working up a solution for Valencias with 811b horns that should be applicable to 511b. It'll be a couple of weeks, yet.

Buy those crossovers and tune your boxes properly. Establish a baseline for their performance. I can't tell you comparatively, as I don't know Klipsch Forte from a hole in the ground....

Your gorgeous cabs with what I presume to be original bases and a different load, below.

 

[macaltec]

FWIW, I am having trouble getting the upper end of a woofer to mate well with the lower end of the horns, unless of course it was an Altec woofer. I've tried both JBL and Eminence. While they both work and I can get the ouput level of both to match up well there is just something about it that really grates on my nerves after a few minutes. That was with the Eminence passive XO's or bi-amping with an EV active XO. No equipment to measure response with but I am working on that.

 

[Zilch]

Should be textbook, unless there's something wonky about the compression drivers.

Swap the polarity on the HF, and listen again. There's certain to be time-alignment difficulties because of the depth of the horn moving the driver so far back.

You need an RTA, minimum, to see this stuff. With the polarity "wrong," you move the horn forward and back for the deepest notch at crossover, then re-invert the polarity to achieve correct alignment.

The balance may also be dubious if you're doing it by ear. Due to the rolled-off HF, you set the HF driver too high trying to bring the attenuated treble into balance, and end up with nasty boosted midrange....

800 Hz?

Which JBL?

What driver's on the 511b?

Stock diaphragm?

 

[macaltec]

Should be textbook, unless there's something wonky about the compression driver.

Swap the polarity on the HF, and listen again. There's certain to be time-alignment difficulties because of the depth of the horn moving the driver so far back.

You need an RTA, minimum, to see this stuff. With the polarity "wrong," you move the horn forward and back for the deepest notch at crossover, then re-invert the polarity to achieve correct alignment.

The balance may also be dubious if you're doing it by ear. Due to the rolled-off HF, you set the HF driver too high trying to get treble balanced, and end up with nasty boosted midrange....

800 Hz?

Which JBL?

What driver's on the 511b?

Stock diaphragm?

811B/808-8A with radian 1228 diaphragm passively crossed @ 800Hz. I tried it with an Eminence Delta 12LFA and now a JBL 12" cast aluminum frame woofer from a CF-120. I'll add that the horn drivers were on my 511's atop the A7's and the sound was superb. The 811's originally had an unmolested pair of 806A drivers and with an active XO (because of the impedance differences) the same "problems" were experienced. The 806's are now on the 511's and in use with the A7's (biamped/active XO as was with the 808) and the sound is quite fine. I have Visual Analyser 8 and can make the proper connection to at least moniter a signal being played. I undertsand the concept but have not practiced it yet.

Edit, I've done the polarity swap numerous times and really can't say definitively that it sounds any different either way ( both active or passive)

 

[Zilch]

Well, you saw my results with the Radian 1228 in 804A. Without compensation, that whole setup on 811B horns is "unlistenable," in my view, and unless the Radians behave better when measured in different Altec motors, they're likely to get the big :thumbsdn: here for the notches in the frequency response. Even compensated, I cannot fix those but with active EQ, and that's not in the "toolbox."

I'm running alternative (non-Altec) drivers on the 811B right now, and they're playing just fine, so it's not the horns, inherently. They retain their Altec "throaty" coloration, even; not my preference, but I'm not doing this for me. If you're willing to spend $250 for a pair of new compression drivers (I don't sell them,) send me a PM and I'll give you the "formula" to try. Otherwise, it'll be a couple of weeks before I finish this up and submit the complete report for consideration.

I am unfamiliar with either of the woofers you're using, alas. You may have to get the "right" woofer for it all to work to your satisfaction. I'm using LE14H-3 in those 2 cuft detritus L55 boxes, and they're blending well....