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frequency check on both channels


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Hi there,

well I still don't find my peace with my Scalas ;-) It seems to me that one speaker is slightly louder than the other one. So I changed the loudspeakercable (left/right speaker) and the result is that primarily female voices change from one speaker to the other one. This indicates to me that there is a fault in the chain of components before the speakers.

So I started to experiement with a test CD by Denon, measuring pink noise frequencies of 125 Hz, 1 kHz und 8 kHz for each channel (= 3 signals), using a noise level meter. The results are as follows:

left channel/right channel
62 / 66
65 / 65
70 / 73

This shows indeed to me that one channel is louder than the other one. So I changed the loudspeakercable (left / right) and expected to find the values changed from one speaker to the other one. But the result is different:

left channel/right channel
64 / 63
67 / 63
72 / 71

Does anyone have an explanation for that? Could it be that there is something wrong with the crossover of one of the speakers???

Thanks for your feedback and greetings from good old Germany,

Bernd


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Work backwards through the chain...

1] Is one side of the room consistently louder when changes are made?

2] Is one speaker louder?

3] Power amp channel?

4] Preamp channel?

5] Source channel (Phono EQ / CD player)?

Even if everything was measured balanced up to and including the speakers, once you sit down to listen their still might be some asymmetric aspects to the way your room takes the sound. What I would do is make the tests and measurements to be sure nothing is broken or misbehaving, then set the listening position where the balance sounds best.

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Try switching the actual speakers. Relative to the listening position, are the speakers toed in or pointing at your eyes EXACTLY the same. Look to see the same amount of inside cabinet on both. Is the Spl meter where your head is at the listening position, when you run it? Could be speaker placement, listening position, room acustics or all of them?

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Interesting.

There is a lot of information on your set up which we do not have and so I must ask some questions.

1) Can you tell us whether these are fairly well matched LS in theory. Do they use the same crossover (it will be marked as A or AA, or AL). Also, do they have the same drivers? I would be interested to know whether the midrange driver in the units are both K-55 . . . M or V. I suspect a midrange problem because of the female vocalist issue.

2) Are these something you just purchased (presumably used if they are plain old LS rather than LS II) or something you've been happy with in the past. That is to say, was there no problem in the past? I suspect there is a problem with wiring. We don't know from your description whether these could have been miswired by a previous owner.

3) I'm sure you are very careful about the polarity of connections feeding the speakers. But it is always worth a double check. In my experience, when there is an out of polarity (phase) problem, the phantom center image is a problem. It is not steady and moving one's head a bit left and right makes it a little better but not quite correct. If you can set the receiver/amp to mono, try this.

Also, make sure the internal wiring is correct. The crossover output has some plus and minus (red and black) where the drivers are being sent the signal. This could be the source of a problem, particularly if you bought them second hand.

4) If there is an electrical problem, the use of noise and a sound pressure meter are not very good test tools. I'm sure you've found that the meter read-out bounces around quite a bit.

5) To check electrical problems you really need a multimeter which will measure below 1 volt a.c. Here in the U.S. Tandy - Radio Shack has low cost units will do that. The major reason for low voltage measurements is that even 1 volt a.c. will be way too loud to tolerate.

6) You also need a source of a continuous a.c. tones (signal generator). Eric Winer's website has some software to use on a personal computer. There are others and you can Google around.

7) You will have to use a signal generator and drive your amp and then measure the voltage at the amp output. Be careful. Keep the volume level down.

These are nominal watts (in name, into a theoretical 8 ohm load).

1 watt results from 2.828 volts or 104 dB on the LS (this will kill your ears - don't do it).

0.1 watt results from 0.89 volts or 94 dB (way too loud).

0.01 watt result from 0.282 volts or 84 dB (still loud).

0.001 watt result form 0.089 volts or 74 dB (loud in a small room but maybe okay).

8) What you will have to do is use a signal generator to drive your amp to an output of say, 0.089 volts in both channels. Use the balance control until both channels are near that level of a.c. Use 1000 Hz as the frequency. for a start.

9) 1000 Hz is in the range where the mid is working well but you may try 3000 Hz. Then test the voltage where the crossover feeds the midrange driver.

The two drivers should be seeing about equal voltage. But because of the auto transformer in the crossover, it should be about 0.7 of the input to the crossover (I'll let you do the math.)

At least by the above, you can test whether the mids are getting equal voltage.

Note that this does not mean the mid drivers are indeed wired "in phase". You have to take a very close look at the wiring. You can do this without all the tests I've descibed above. You'll have to check the driver and find which terminal is "plus" on each (yes you have to unscrew it to get a look) and make sure that one is wired to the plus on the crossover output on each speaker.

On the woofer, there should be some color coding on the wires. Make sure they are correct.

- - - -

I know the above is fairly complicated. Still, I suspect it is a midrange problem. Also, we don't know whether your speakers are unchaged from the factory, or whether there could be changes by a previous owner.

Best,

Gil

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This is a very interesting topic......and I would bet that many people have exactly the same issue to some small degree (or more) and do not even realize it. I have had this issue with multiple sets of Heritage speakers. They almost NEVER match outputs exactly.

There are many variables as everyone has discussed. However, the plain fact is that there is a LOT of variability in the output of the squawker (K-55) and tweeter drivers (K-77). Their outputs vary all over the place. The drivers were not very consistent with regard to output and/or frequency response.

I have been through this issue with mismatched drivers over and over and over.....and Bob Crites knows very well. He has matched drivers for me time and time again.

I have found brand new drivers to have dips in the frquency response at odd spots. I have found pairs of K-77 tweeters that one plays louder or has slightly different timber (very common). Some of these issues can be corrected by replacing the diaphrams and some can not.

IMHO it is actually difficult to find a pair of older Heritage that each driver still matches its mate exactly. You need to work with them and definitely ask for matching when you buy a pair of drivers.

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Bernd,

Welcome to the forum. That should have been said in the first place.

There are a lot of good people here who make it a happy and informative "city" of diverse ideas.

Please let us all know what you find with your speakers and do to solve a problem. We all learn by the experience of others,

Always consider yourself welcome to join in the club.

It rains here in the U.S.A. too.

Best,

Gil

Gil

post-2552-13819338555118_thumb.jpg

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The results are as follows:

left channel/right channel

62 / 66

65 / 65

70 / 73

This shows indeed to me that one channel is louder than the other

one. So I changed the loudspeakercable (left / right) and expected to

find the values changed from one speaker to the other one. But the

result is different:

left channel/right channel

64 / 63

67 / 63

72 / 71

Does

anyone have an explanation for that? Could it be that there is

something wrong with the crossover of one of the speakers???

I didn't read the other replies...just skimmed and didn't see anyone mention this, but my apologies in case they did...

Anyways, your test indicates that your problem is happening upstream

from the speakers. Your listening impressions of female voices

indicates the same. What kind of source and upstream equipment are you

running? It seems to me like you've got an old school analog balance

knob, or two seperate volume knobs somewhere where the "0" points

aren't the same. You might also have tubes or caps going bad on you too.

So just to stress it again, your speakers or crossovers are not at fault.

To troubleshoot further, can you document the changes that happen when

you swap the LR inputs to your amp? Are you running a seperate preamp

and amp? If so, document what happens when you switch the LR wires

there too. Basically work your way backwards from the amp to the source

until you find a wire where no difference occurs. The offending piece

of equipment will be downstream from the first set of wires that don't

switch which side is louder.

Also, are you making sure that your SPL meter isn't move between

measurements? Sometimes moving the meter even an inch can result in

10dB differences (due to the nature of room acoustics). [:o]

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Hi guys,

thank you so much for your absolutely great feedback!

Well first about my equipment - I use a Yamaha AX1 surrond amplifier (switching to direct processing while testing and didn't touch the volume during the tests), I use a DVD 2800 MKI by Denon and an Acoustic Solid turntable with phonotools arm (made by jelco), using a pickup by Ortofon (Kontrapunkt a) and a Project tube phono-preamplifier. Furthermore I use my old speaker (three way with horn resonator) made by a small German company and headphones by Bang & Olufsen.
My reference recording: the song 'Brothers in Arms' by Dire Straits - on CD and on vinyl, which is probably the most well known song I use for testing. I furthermore use recordings by Torri Amos, Kate Bush and a band called 'Die Form' (CD called InHuman).

So the listening effect:

On the song Brothers in Arms Mark Knopfler sings primarily from one side - not very strong but definetly the voice isn't coming form the middle, on CD and on vinyl!
Torri Amos songs come mostly form the center but I have a live recording where the stage is not in the center.
Kate Bush 'The Kick inside' comes from the center.
Die Form - industrial, elektronic music whith high dynamics and one strong female voice - troubles me most, since it is my preferred music. The female voice doesn't come from the center, while the 'rest' is pretty fine. When I change the loutspreaker cables (left <-> right speaker) the voice changes from one speaker to the other. Of cause you hear the voice on both speakers but it is not in stereo. I checked the recording with my B&O headphones and the voice comes from the center. I will check especially this recording with my old speakers once again. When I change the balance so that the female voice comes from the center, the other sound doesn't.

This is why I started testing with the volume meter (I am a quality engineer so testing is my business...)

The Scalas:

Sold as the last in stock for Germany - they indeed smell a bit moldy, although they were in an orginial packing that wasn't opened before. Both are equiped with K-55X and K-77F drivers.

The sad thing is that there are even marks on the finish of the speakers and because of these I will have to return them anyway [:'(] Since these were the last in stock 'old' Scalas for Gemany the dealer will refund me...

It is really a sad story. I intended to buy great speakers after using my old ones for 15 years and now I have a lot of trouble with them. So I might be not in this community in a few weeks when I returned the speakers and the new edition of the Scalas is too expensive (I got the old ones for a very special price).

In German we have a saying - better an end with horror than endless horror... [:'(]

Newertheless thank you so much,

Bernd

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You are in Europe and got a special price on new versions of the latest model of the original La Scala and you are returning them because of some marks on the finish?

For the money you saved are these marks so deep and awful that they can't be repaired?

Do you think you can find anything as good as the La Scalas... ?


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Hi,

checking the polarity means not to connect plus with plus but plus with minus on one of the boxes right?

But I have the effect on both speakers - right connection: (female) voices with a tendency to the right -> changing the channels: (female) voices with a tendency to the left...?!

About the refunding - well the matter with the frequency and the resulting problem with voices is simply too much trouble. Of cause I can get a carpenter for the money saved on the speakers, but I can get not help here in Germany when I keep the Scalas and I might not be able to solve the frequency problem... The Scalas are quite exotic here and Germany is often know as a 'service desert'. Means that I might not get any support from the dealer nor the European headquarter of Klipsch. And I really have much more important things to care about - ask my girlfriend...;-)

If I had here people as described on this forum where experts are available to improve even the matching, the situation would be different but unfortunately this is not the case.

Speakers better than the Scalas? Means another long search....I've been searching for good speakers for around two years. And certainly more costly. But what is the alternative?

All the best,

Bernd

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Still sounds to me you have a fixable problem just takes time to fix.If you take the Scalas back you may be sorry later.Have you looked at new Heresys,or new Cornwalls.I say if you got room for Scalas figure out the problem the reason you dont hear the problem on your old speakers is the Scalas are probably more sensetive 104db at 1watt.So even a little problem with the source will show up.Good luck but try to fix it you wont be sorry later.Rick

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To check for one possible problem on polarity just move the connection at the power amp. Switch the speaker cables there. Move the cable connected to red to the black post and the other on to the red post. +>>>>to minus. and ->>>>to + See if the sound image centers between the speakers. If this makes no imorovement don't forget to move the cables back again like they were.

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Dear all,

yesterday I gave my Scalas a very last try.

My reference recordings were the song 'Brothers in Arms' by Dire Straits and a song by 'Die Form' - french SM/gothic/industrial music.

To rule out that there is a fault in the chain until the Scalas I checked everything with my old speakers. The center was all the time perfect - Mark Knopfler's voice was just in the middle of the two speakers. So I also checked if the sound meter would find a difference with the old speakers to rule out that there is a fault that is barely audible. The values on the fist take were equal on both speakers. Then I changed the speakercalbles between the speakers - still the same! Then I exchanged plus and minus still everything as expected.

I used another pair of speakers - center also fine.

Then I put the sound on the Scalas. Once again, voices, especially the female ones of Die Form pirmarly coming from one speaker. I exchanged the chanels - voice coming primarily from the onther side. Then I exchanged plus and minus - still no improvement. And exchanged the channels with the plus and minus still exchanged - again no improvement.

For a last check I took a look at the Scalas cables - everything fine.

So - the speakers will return to Klipsch. At least in my case the speakers aren't worth their money. What a pitty.

All the best,

Bernd

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Sounds like the problem follows one channel?? If thats true problem is not speakers. Klipsch speakers will show every problem you have up stream.I would bet its a dirty interconnect just try twisting all connections to make sure you have good contact.Rick

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