LaScala Bass loose booming; any thoughts

[Bubo]

Greetings,

Don't know if its the music I am listening to lately, Delerium Karma etc, but the bass on my 1979 LaScalas sounds loose and booming for lack of a better description. Speakers are stock origingal and currenly driven off of my old but loved Pioneer Elite VS 09-Tx vintage 5.1 AB receiver running in 2 ch.

Low res on you tube, still smokes on percussion

I have my Mac Stack C-32 and MC 2205 out of the Mac crates and am racking them as I type, well almost as I type.

I am running the Elite on direct so its direct from the 24bit DAC to the amp section bypassing all the tech. With good headphones detail surpasses what is comming out of the LaScalas

I recently listened to the same music on some Vintage Altec 820C dual 15" corner cabinits 50-16.5K. bass was far more detailed and complex and satisfying. The horns on the 803 drive down to 800Hz. The female voice resolution and quality sounds better on the LaScalas but that may just be the amp and CD player the owner had hooked up. He told me on tubes the sound was so much smoother.

I already posted all the pics and cut sheets on the Audio Karma pages if you scroll down.

http://www.audiokarma.org/forums/showthread.php?t=476108

Honestly, I might have swaped him for my LaScalas if not for the extra $14K that would have been required.

Any thoughs on booming LaScalas and mid bass resolution?

My thoughts are turning towards Selinium drivers and horns. This is the baskettball size driver, so I may have to go down a bit in size and power.

112 db 1WM

http://www.parts-express.com/pdf/264-230.pdf

http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-329

http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-230

And some kind of bass bins that are high res or a dual front firing 15 inch vented cab.

Open for discussion, my faith has been shaken or do the crossovers just need a recap?

[HDBRbuilder]

When was the last time you cleaned the bass bins out?

My first advice is to check the upstream components.

Second, check screw-down connections on the crossover network, both wires from the amp and wires to the drivers. Don't just tighten them, actually CHECK them, when the screw is removed, under it may look like old battery terminals, and need a cleaning with solvent then a reassembly...solvent and q-tips does the trick here.

Third check the connections at the drivers. (if you have to go this far, then you will have to pull the bass bin door to check the woofer connections)

When you check the woofer connections, you can also pull the woofer, remembering the orientation of it by making permanent marker marks on the basket edges by the mounting holes closest to you before you remove the screws.

Then take your vacuum cleaner hose and wand and suck out all the crap around the compression slot that was covered by the woofer, and then look at the front of the doghouse, and vacuum out all the crap back in the sides of the rear of the doghouse...

You will be surprised at all the crap that has accumulated there, trust me on this!

Let me know if you need to do more than this.

Andy

[Bubo]

Cleaning sounds like a good idea, certainly a low cost start.

Was thinking of pulling the crossovers and sending them to Crites for refirb and replacing the horn gaskets.

Hopefully no dead rats hiding in the vents, but I'll look.

thanks

PS the old Altec 820 had just been completely disassebmled, refirbed and reassembled.

[HDBRbuilder]

Is the issue DEFINITELY in the speaker?

Andy

[Bubo]

I'll hook up a Class A integrated amp to the speakers in the AM and see if the problem persists.

[Quiet_Hollow]

My first guess would be to ask if you've moved them recently. Maybe the new location isn't so hot acoustically.

If not that, then my second concern would be to check for air leaks, which are profoundly detrimental.

Using some aquarium tubing as a stethoscope, open the dog house, play some 25-30 Hz tones and probe around the edge of the driver and the seams of the interior cabinetry listening for air puffing out.

Then inspect the integrity of the seal on the bottom panel, and check that for leaks once it's fastened back in place. Won't cost a dime.

[Boomzilla]

Quick stupid question here, please: Having never upended a pair of La Scalas, is the bottom screwed on? Nailed on? Glued on? How hard is it to yank & get to that woofer? Also, once the bottom is open and the woofer removed, why not upend the woofer by 180 degrees when reinstalling? I've heard that those big 15" jobs have a tendency to sag over time causing eventual voice coil rubbing? Reversing the woofer's physical orientation during cleaning would help prevent this, yes? I suspect my cones have had gravity tugging on them for about about 30 years... Thanks.

[Marvel]

Quick stupid question here, please: Having never upended a pair of La Scalas, is the bottom screwed on? Nailed on? Glued on? How hard is it to yank & get to that woofer? Also, once the bottom is open and the woofer removed, why not upend the woofer by 180 degrees when reinstalling? I've heard that those big 15" jobs have a tendency to sag over time causing eventual voice coil rubbing? Reversing the woofer's physical orientation during cleaning would help prevent this, yes? I suspect my cones have had gravity tugging on them for about about 30 years... Thanks.

There are a bunch of screws! Plus a gasket that will make you think the bottoms are glued on! Yes, if you open them up, you could rotate the woofers 180 degrees. I'm not sure it's worth all the trouble to do that, but that's just my opinion.

Bruce

[HDBRbuilder]

Before you rotate the woofers, be sure the leads to them will still reach the connections on the woofer If the woofers get enough regular exercise, they probably don't care if they are rotated or not. The real weight in the speaker is the magnet, whIch shouldn't be moving any in relation to the basket, and the surrounds of the cone are corrugated paper, so they should be able to take up any slack from any sagging possibilities anyway. So, if the length of the leads to the woofer negates your being able to rotate it without changing to longer leads, then it shouldn't make any difference for your remaining lifetime, but you may want to think about whoever you will the speakers to. You may want to replace the gasket material on the woofer door area, though. Lots of screws to deal with, so make sure you align the bottom properly when replacing it so that it goes on the way it came off. Also be sure to avoid over-tightening the screws when you replace it, because they may have their pointy tips come through the inside of the bottom of the doghouse if you do so. I advise not using a screw gun, but a regular screwdriver so you can "feel" the screws going in. Don't rely on the screws to pull the door down snugly, but instead, push down on it and let the screws just hold it in place to where you have pushed it...make sense? One of the main goals is NOT to strip the wood out of the holes when replacing the screws, so that the screw will actually hold the plywood on and keep the seal around the door. If you strip out a hole just take some wooden matches and glue and refill it, let it set up, and put the screw in again....a simple but effective time-proven fix.

Andy

[Bubo]

Thanks for the responses.

Already answered but I'll restate:

Bottoms are screwed on, lots of screws and yes install by hand or they will run through the wood.

Gasket on bottoms appeared good the one time I inspected them (2 years ago), woofers appeared to be in good shape looking at them aka no holes or deformations. The Cavity is tight, so taking the woofers in and out is probably a pain and presents an opportunity to damage them.

The cabinets are quite heavy, so this provides lots of pressure for the seal, but yes it could leak.

Trouble shooting:

I took the Pioneer Receiver out of the signal path and am now running the speakers off of my same year 1980 McIntosh equipment, I also connected a 1975 Dual turntable just back from refirb at the shop and tracking perfectly according to my spectrum analyzer EQ.

On LPs the booming is reduced substantially perhaps because no one was driving the Hz freq on LPs in the 1970s.

I took the RCA leads directly from the DVD player playing Delerium Karma track 1, the sound is flatter but less booming $3 DAC.

Later today I will take my Emotive XDA 1 DAC which has a top 4 chip set in it and place it in the signal path and retest for booming sound.

The Mac gear has been sitting in its boxes since it was factory refirbed a few years ago so it is definitely in spec and sounds like it on LPs, perfect. They did However not catch the Analog meter that is still not working on the 2205 amp, all switches and dials and sound are otherwise perfect.

Once all of the electronics have been replaced and the good DAC is in place I will test again.

The crossovers are due for a rebuild, so that may be the next step is to ship them to Crites for refirb and test, then go from there.

PS how do you post pictures on here, very not obvious.

[Bubo]

The Pioneer Elite VS 09-TX was making a noise on shut off that was audible on speakers, took it to shop. Power supply requires repairs, power relay shot etc... this may be the source of the problem.

Replaced it with my McIntosh MC-2205 amp, couple of weeks later noise at shut off, just got off the phone with the same shop, some caps leaking etc, DC leak etc.

Now onto 3rd amp, Yamaha MX-600 that I picked up cheap a year ago, also making some noise at shut off. I'm running out of amp that are not in the shop at this point.

However, booming bass not present on Mac or Yamaha

[derrickdj1]

Sorry to hear about all the amp problems. Hard to tell what is going on when you can't isolate the problem form other confounding varibles. I hope everything works out!!!

[drboar]

The vibrating sides of the La Scala does add to the boom. Something along the lines of

http://www.klipschupgrades.com/lascalabraces.shtml

Will reduce the problems a lot

[Quiet_Hollow]

Something along the lines of...

They need to be made more like the ones found in the Peavey FH-1 to fully resolve the issue..which is minor to begin with.

It's also worth mentioning that if you put any appreciable power (anything over a watt) into the bottoms in the bass / sub-bass region, the bottom panel of a typical (non-pro) La Scala will flex pretty good also. On the order of 1/32" to a 1/16" @ 9V with anything < 60 Hz. Four screws through the bottom panel, around the opening edge of the doghouse would prevent that.

[drboar]

There might be limitation due to looks with regard to braces, that is why I suggested those rather modest ones. Otherwise I am all for braces, to "much" of them hardly hurts does it?

[Bubo]

Update Dec 15, 2012

Picked up the Mac 2205 Amp and the Pioneer VSX TX-09 at the shop last night. Deltronics in Chicago, actually the nearby Woodridge location.

2205 went in the rack and works flawlessly, a bit edgy but that is the 2205.

This AM moved the speaker cables from the 2205 to VSX and ran the coax connection from the Sony cheapo CD player into the digital in on the Pioneer. This was a huge mistake, since all thoughts of selling this sweet sounding AB amp just went out the window. The worst part is I am going to have to back out on selling it to a neighbor for $350.

Looks like the 2 large caps on the power supply and the speaker relay were replaced. The construction quality is the same as the mac stuff with Faraday cages for the internal components, 4 of them and lots of copper on the rfi enclosure for the system. Why did I plug it in?

This makes it 6 receivers, 5 Yamaha mx amps, and a mac stack and a daughter who just fell in love with Vinyl records when I hooked up the old Dual 604 turntable, which according to the tech who tuned it up, my ears and the dual bank spectrum analyzer in my rack tracks dead on. Tech volunteered that the German unit tracks better that the $3000 TTs he gets in the shop "don't sell it ever".

I feel at least one more 6 foot equipment rack headed for the Living Room.

[derrickdj1]

Sounds like it was worth the wait! I am glad everything audio is going well.[<)][] I did pick up a Yamaha M 80 to drive my 7's and still have the two M 70's.