muddy sounding bass bin

[AndyGrandy]

1977 LaScalas. Sidewalls have been strengthened with 3/4" MDF. New Eminence Kappa 15C drivers. New Cardas internal wiring. I'm bi-amping using a Marchand XM-44 in a hybrid configuration, so Actively crossing at 400Hz, 24db slope Linkwitz Riley type. So everything above 400hz is going through the re-capped AA passive to the original K55 attached to an EV SM120A horn and Beyma CP 25 tweeters. That's the set-up. When I mute the top end, i.e. everything above 400 Hz, the sound coming from the bass bins is, well, very muddy, boomy and basically horrible sounding. Like the drivers are in a closed, padded  box... I've tried two other active crossovers (Behringer and ART both two way stereo), as well as two different ss amps (Sony and Audio Source). Not that it matters but I'm driving the mid/hi combo with a Decware Zen amp, and I'm using two PSB subs on the low end. Sonic Frontiers Line 3 preamp and Cambridge CD transport and DAC. I've done a lot of reading on the Klipsch site but have not encountered any one discussing this "problem". Is it normal? No, can't be! Is their a fix? Something I've missed, something I can explore?

Help! Please...

AndyGrandy

[Khornukopia]

14 hours ago, AndyGrandy said:

When I mute the top end, i.e. everything above 400 Hz, the sound coming from the bass bins is, well, very muddy, boomy and basically horrible sounding... Is it normal?

 

@AndyGrandy, When low pass filtered at 400Hz, it is normal for a speaker to sound very un-natural. As far as examining your specific conditions, using an audio spectrum analyzer (free app on a smart phone or laptop?) can show you if you need some EQ. The main question is, how does it sound when playing full range music?

[billybob]

Would double check polarity.

[mark1101]

Probably nothing wrong.  When you listen to individual drivers it's hard to imagine they can sound like they do alone, yet magical when all played together.  You should measure the FR using REW or TRU TRA and verify the bass cabinets are working correctly.  My bet is nothing is wrong.

 

How does the speaker sound when you play all the drivers?

[LTusler]

My Jubes do the same thing.

[OO1]

what  ?

[AndyGrandy]

Thanks for the responses. I'll try to answer your questions... full range music sounds pretty good - except that I know that underneath that sound something is wrong, and when I mute the top end - there it is. I don't believe it goes away when the top is back, and it's affecting my enjoyment. Polarity has been checked and double checked. All OK.  The original woofers had been sold before I bought the LS; don't think I didn't ask! The caps are Sonicaps from Bob Crites. Tonight I thought I'd try a pair of SET amps (left and right) on the woofs just to see if it made a difference from the SS amps I've tried. BTW, all these amps have their own attenuators. No difference. I'm afraid I don't own any of the test equipment you mention Mark 1101, but what can go wrong with the bass cabinets? I haven't opened them up, nor did I do any of the resto work on them. Besides, it appears that others who've responded have similar experiences... One thing I can (and will do), is revert to the full passive system, and try the bass (alone) that way.

What opinions are there on crossover frequencies between bass and mid? Keep in mind I have Eminence 15C and EV SM120A horns (using the original K55V drivers). Also, would there be any improvement with new diaphragms in the K55s? The tweeters are time aligned physically with the mids...

And to think I bought LS and a 1.3 watt SET amp to keep things simple...

[the real Duke Spinner]

1 watt amp. ??

Best of luck pushing Bass thru the woofer

[geoff.]

Andy, any bass bin will sound awful without ALL of the other drivers playing nicely with each other. It’s remarkably lame on it’s own. As are each of the other drivers.

 

The Kappa 15C woofer is an excellent bass bin choice for a La Scala sized box, the Peavey FH-1 bins in the picture below have them, and I have tried them in La Scalas. The K-43 is stock in the bass bins for the LSI tops in the picture below and it is very comparable to the Kappa 15C. I prefer either the K-43 or the Kappa 15C over the K-33 in THESE bins, without a doubt. They both have more to give on the hand off to the squawker. A Klipschorn would favour the K-33, without a doubt, as BOTH it’s low frequency, and high frequency cutoff is significantly lower.

Having said that, you could try crossing at 425 or 450hz to the squawkers, maybe a 12db slope?
 

As an aside, at the moment I am playing with different crossovers in/on the top tophats. The bottom tophats are my reference with polyester re-capped AA crossovers. They have become the crossover all others are compared too. The tweeters look different but both have the same DE-120 drivers behind the lenses.

 

*** The suggestion to go full passive is sound, no pun intended. You will know right away if something is amiss with your active settings.

 

There are some caveats regarding the Kappa 15Cs though, MINE (two pairs over five years, still have both pairs) took about 50 hours to break in. AND the gaskets are made with a pool noodle type foam that makes it difficult to compress the woofer tightly to the doghouse. Many have replaced that gasket with a paper gasket.

 

*** If the woofer is not solidly coupled to the doghouse you will lose everything that is magic about a folded horn. Improper padding inside the doghouse will have a similar effect. The original La Scalas had ZERO padding, the new ones have one sheet laid on the woofer from what I could discern in a Klipsch production video. If the passive route shows no improvement you may want to open the doghouse and see what’s shakin’ inside.

 

Try the full AA passive with some decent solid state and let us know how it went, please.

 

 

 

 

 

[MEH Synergy]

If the woofers are corner loaded or close, with a 400 hz crossover or better, you may experience boomy bass without room equalization. May want to invest in an older AVR with "auto eq" of some sort or get something newer with DIRAC. Will make all as perfect as can be and very simple.  You can also use active XOVER, REW and PEQ to flatten things out a bit.   

[babadono]

6 hours ago, AndyGrandy said:

I'm afraid I don't own any of the test equipment you mention Mark 1101,

A calibrated UMIK sound measurement microphone and the free REW software app. will set you back about $100. And will allow you to measure and analyze your system to your hearts content or until you are sick and tired of analyzing it. Of course you need a platform to run the software on. Either a PC or laptop.

[Peter P.]

Here's a cheap experiment-even though you've checked polarity, deliberately wire ONE speaker with reverse polarity.

 

What if something else in the chain is not wired correctly (possibly internal where you can't see it).

 

This test is free and it won't hurt to try.

[Travis In Austin]

On 12/30/2022 at 8:26 PM, AndyGrandy said:

That's the set-up. When I mute the top end, i.e. everything above 400 Hz, the sound coming from the bass bins is, well, very muddy, boomy and basically horrible sounding.

 

You have a lot of variables going on here. 

New woofers, active XO, with an AA recapped, listening only to the bass bin. new wire, etc. 
 

The quickest and simplest way to figure out what is happening is take one speaker and return it to stock (I wouldn’t bother with putting the original caps or wire in, or removing the bracing, YET). But I would run the stock speaker with the AA only. You have got to have a good control speaker that you are able to judge from - first whether you can hear a difference, and if so, a preference.
 

A/B them enough to KNOW what you are hearing. We all have cognitive bias, so it will be difficult to judge at this point, but try as best you can to listen as neutral as you can several times, several songs. 

 

Things are complicated by trying to solve the problem by listening to LF only. As others have mentioned, very strange sounding bass is what you will hear when you turn off the top end. The same with Jubilees, Khorns, and even a full range Grandure system. (It does it with direct radiators also. The only way you can tell what’s going on now is with measurements. Listening to the bass bin only and trying to determine what is going on with your ears is futile. Imagine trying to see the if you preferred  different guitar strings and only put the top 3 strings on the guitar. It’s going to sound weird. 

 

 

[Travis In Austin]

On 12/31/2022 at 5:59 PM, OO1 said:

what  ?

He is probably referring to when you turn the MF/HF off from the active crossover and only hear the bass from the Jubilee bass bin it doesn’t sound very good by itself. 
 

The same the other way, no bass bin, just 402. Pretty horrible.
 

Hearing that for the first time is pretty unsettling because our brains don’t know how to process it. Full range music, or nearly so, but only 400 and below is coming through. It’s unnatural and so you can’t draw any conclusions from it (unless you have spent a lot of time listening to just bass bins, and then it would be pink noise).

[Travis In Austin]

On 12/31/2022 at 7:06 PM, AndyGrandy said:

The original woofers had been sold before I bought the LS; don't think

Just saw this, so that makes a control and A/B difficult.

 

I think others have covered it, what you hear out of only bass bin doesn’t sound good. Find some AES pink noise and play bass bin only, completely through passive networks and see if you hear a difference going from left to right (if you have a preamp that allows you to do that). If you hear a difference then there is probably a polarity issue. I think some rightly jumped on polarity when they saw “muddy”

because that is a common culprit and most have the mud with all three drivers going. 
 

 

[Travis In Austin]

Well here is a question, something I have never tried, does pink noise sound different through a speaker when you reverse the polarity? 

[AndyGrandy]

Problem solved... I decided to revert to a full range, passive setup, mute the top end, and listen to just the bass. Everything was as it should be; no muddiness etc. So, the bass bin not being the problem, nor the passive network - must be the active crossover... and then it struck me; the Marchand XM-44 is a four way xover: low, low/mid, high/mid and high. I had the 400 low pass modules in the "low" spot when they should have been in the "low/mid" one. I changed them, and voila! Thanks to everyone for the suggestions, I do appreciate that. I think I'll stick with the "hybrid" xover network (active on SS for the bass; passive SET on the top) but I'm wondering about the xover point for the active. The 15C is rated at 63 to 2800 Hz, however we all know that the response is all about the horn. In the LS, the passive (for the K-33) was set at 400 Hz (1977), however that is a bit low for the EV SM120A horn, which is stated to have a "useable" response down to 500 Hz, although in the literature it is given as 800 Hz... (the later Sentry was said to have crossed it at 400...). I'm thinking I need to cross at least at 500 but perhaps higher if the LS bass bin would allow that. Ideally I would go as high as 800 Hz but that's probably unrealistic. Anyone know how high the LS bass bin will go?