• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Lambda driver-based sub build.

Question:

I have a variety of round stock out in the barn; lengths of closet rod and handrail, plus a bunch of 3/4 dowels.

Should I select the least resonant ones to use? Or is that a non-issue in this application. Some of the thicker diameter/hardwood ones have quite a pleasant tone when struck, but it's pretty high pitched. Should I go with the smaller, deader/softwood ones?

:scratch2:
 
I dont think it would matter brett. As long as it keeps the walls stiff. mayhap try the hand rails. though i have read many accounts of people using dowels. use what you think is right. What you use will be on your concios(how ever its spelled). use what eases your mind...:D
 
At what frequency are you crossing over to your mains at? What is the slope of your crossover?
 
Gibsonian said:
At what frequency are you crossing over to your mains at? What is the slope of your crossover?
Click to expand...

I am running the crossover setting at its lowest (40Hz). Right now, I have it hooked up in parallel to the mains; the mains are still getting the full range signal from the amp.

I've tried running the plate amp in the signal path between the pre out/main in which I assume sends only the signal above the X-over out to the mains. I have not verified that, I'm still just listening, enjoying and tweaking.

The slope of the crossover is unknown to me. Although I did some subjective evaluating with test tones and found the sub is still active up past 200hz when set at 40hz.
 
Brett a said:
I am running the crossover setting at its lowest (40Hz). Right now, I have it hooked up in parallel to the mains; the mains are still getting the full range signal from the amp.

I've tried running the plate amp in the signal path between the pre out/main in which I assume sends only the signal above the X-over out to the mains. I have not verified that, I'm still just listening, enjoying and tweaking.

The slope of the crossover is unknown to me. Although I did some subjective evaluating with test tones and found the sub is still active up past 200hz when set at 40hz.
Click to expand...

There is no highpass filter on your plate amp. It's only has a low pass filter that is for connection to your sub to slope the response above the xover point you select. So the plate amp should not be connected to mains at all. PE site or Jung documents had no explanation of the slope of the included crossover, but if you can hear output at >200Hz, I'd say it is likely a6 or 12 dB slope. With setting at 40Hz you should see around a -30dB sound level attenuation at 200 Hz with a 12 dB slope or -15dB with 6 dB slope. You could easily hear output with a -15 dB reduction.

Would be nice if you had a buddy nearby with an RTA and mike so you could run pink noise through your speaks and see your room frequency response to help you adjust first by measurement tool, final by ear.
 
Gibsonian said:
There is no highpass filter on your plate amp. It's only has a low pass filter that is for connection to your sub to slope the response above the xover point you select. So the plate amp should not be connected to mains at all.
Click to expand...
So why the RCA outs then? Other plate amps I've see do have a highpass filter for the outputs. How did you determine this one does not? The lack of information/documentation on this amp is notable.

Gibsonian said:
Would be nice if you had a buddy nearby with an RTA and mike so you could run pink noise through your speaks and see your room frequency response to help you adjust first by measurement tool, final by ear.
Click to expand...
I have pink noise on a Stereophile Test CD (vol2). And have an RTA on my smartphone, but not sure of its validity as a measuring instrument in this situation.
 
I added more bracing yesterday including 4 heavy-duty shelf brackets. The blue tape remnants are from my DIYing a gasket using silicone calking covered with blue tape before mounting the back panel. I let it dry overnight and now I have a gasket of sorts built onto the back lip.

More Braces.jpg



795_More%20Braces
 
Last edited:
Brett a said:
So why the RCA outs then? Other plate amps I've see do have a highpass filter for the outputs. How did you determine this one does not? The lack of information/documentation on this amp is notable.

Just reviewed the (your are most correct, limited) information on PE site. It has no highpass filter, which is what you would need for your mains to be connected to this. The line out appears to be the lowpassed signal out, the same signal that goes to the poweramp section of your subamp. Would be easy to confirm.

I have pink noise on a Stereophile Test CD (vol2). And have an RTA on my smartphone, but not sure of its validity as a measuring instrument in this situation.
Click to expand...

Wouldn't trust the RTA on the phone, and not enough octaves of measurement I'm guessing, more of a toy or a very rough sketch of frequency range.
 
I use the RCA line level outputs on the Yung plate amp to daisy chain the signal to another Yung plate amp's line level inputs.
 
Poultrygeist said:
I use the RCA line level outputs on the Yung plate amp to daisy chain the signal to another Yung plate amp's line level inputs.
Click to expand...

hadn't thought of that.

on a related note; when I have the pre-outs "Y"'d with one set of cables to the sub and one set to the amp; am I affecting the performace of the preamp by giving it a different load?
 
Brett a said:
hadn't thought of that.

on a related note; when I have the pre-outs "Y"'d with one set of cables to the sub and one set to the amp; am I affecting the performace of the preamp by giving it a different load?
Click to expand...

It's possible. One of my preamps has two outputs and when I use only one the signal is stronger than it is when I use both.

But splitting a source like a CDP with a Y cable has little effect on the signal.
 
I know some believe you have to use really low crossover points to have subs blend with the mains, but I run my mains wide open, no high pass, and my three subs to 100hz, and I doubt anyone can locate them or even tell I have any subs in there...at least I can't. I use the subs bass to my advantage, not just the very deepest bass.
 
Forgot to mention, super job on the wood cuts and the bracing. That is one solid and resonance minimized box.
 
89grand said:
I know some believe you have to use really low crossover points to have subs blend with the mains, but I run my mains wide open, no high pass, and my three subs to 100hz, and I doubt anyone can locate them or even tell I have any subs in there...at least I can't. I use the subs bass to my advantage, not just the very deepest bass.
Click to expand...

+1. Overlap is good.
 
dumptruck said:
Might as well drill a hole in that vertical one for the pole piece vent on the woofer there.
Click to expand...
I just saw this post from back-a-ways. I had missed it earlier.

I was wondering what to do with/make of the hole in the center of the magnet. I did vent the second one. But the first one is still covered. How much of a priority should I make of opening it up and drilling it out? Is it something that can wait? a week? a month? a year?

Picture here:
http://www.audiokarma.org/forums/attachment.php?attachmentid=420102&d=1364487318

Please advise.
 
Brett a said:
I have pink noise on a Stereophile Test CD (vol2). And have an RTA on my smartphone, but not sure of its validity as a measuring instrument in this situation.
Click to expand...
Phone mics don't do bass, but the track 16 warble tones may be helpful to figure out what's happening by ear. If you can find a test CD/mp3/etc. with smaller intervals than 1/3 octave that would be better, though. Bass signals can be (data) compressed very effectively without loss, so even very low bitrate mp3s work just fine if that's what you find. With the 2nd order sub crossover at 40Hz, you've probably got a 2nd order parabola-like shape of sub response, then probably something resembling a 4th order 50Hz rolloff on the mains, AND the influence of the room + locations added to both. It's a bit of a crapshoot, but at least you've got more than one sub.
 
You must log in or register to reply here.
Back
Top Bottom