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  #1  
Old 02-14-2003, 10:40 PM
teddyedwards teddyedwards is offline
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analogue time alignment

what process can be used to time align different speakers (specifically subwoofer & main bass), i understand that to do it digitally would be easy, however i'm interested in an analogue solution.
the RLA crossovers have some form of delay for the full range output? (to align it with the subwoofer)....what about the tweeters hung in the dancefloor, do they get delayed?
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  #2  
Old 02-15-2003, 01:33 PM
clubman5 clubman5 is offline
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Analog delay

I know there is Linear phasing inside the RLA but how to do this in equipment that wasnt designed with it, I dont know!

I guess it would have to be built in to the circuit and I know its done with capacitors, but how to create it is beyond my scope! yes, there is actually something I dont know!
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  #3  
Old 02-21-2003, 04:16 PM
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daveg daveg is offline
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Analog Delay

To create delay you need to store audio information and then resend it at the selected period in time.

How could a capacitor store audio information?

Thats right it can't, if it could we wouldn't play records we would use well charged capacitors!

A digital delay can store audio and send it after a period of time, nothing new,we've had the technology to store digital sound for a long time. A anolog delay would have to use tape as in roland space echo or using a reel to reel on variable speed.

A capacitor can alter phase at a specific frequency up to 180 degrees and we can reverse the phase by swapping the polarity giving a 360 degree range. By moving the phase of a band in relation to another you are in effect moving the driver back and forth. The lower the frequency and longer the wave length the more greater this 'delay'.

The point in time of the wavelength can be shifted but it cannot be 'delayed' in a real sense. For this you need a way of storing audio info. Phase correction of the crossover point might be more audible than the actual delay of a long bass horn. Does anyone want to know more on this subject?
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  #4  
Old 02-21-2003, 04:28 PM
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daveg daveg is offline
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Analogue Delay

What the RLA gear and Shorty's and Scotts systems have probably got is a combination of gear which is suited to the phase compansation inside the RLA crossover. The recomended crossover points of yestaday will also give the right quality of bass/mid when using this set up. Also bear in mind that electrical crossover points are entirely different to the actual accoustic crossover point you will achieve. This is due to the vast gain of the bottom end compared to the mid. I find it is the transient quality of bass (the timing and speed) which defines a good alignment of bass to mid. I think this must be possible by a process of educated tweaking, but I don't go for horn bass or mid so it all comes easy for me!
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  #5  
Old 02-21-2003, 05:30 PM
frankddr frankddr is offline
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analog delay

You can delay the signal using analog devices and not tape or digital,I used to use the Acousticomputer (I think thats hwo it was spelled? )which did just that.It uses BBD chips (bucket brigade devices) that basically act like many caps in a row each one storing the audio for a very very short time but when you add them all up it can delay the signal as much as you want..The downside is the noise and distortion also add up and to boot it runs hot as hades. The Acousticomputer we had would keep burning out parts if left on too long.
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  #6  
Old 02-21-2003, 05:45 PM
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daveg daveg is offline
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Analog Delay

Would be nice to see one of these. Still not sure how it can be done. You mention noise, was this unit a effects tool or a accoustic allignment tool. I am not familliar with old effects units they also must use delays of a sort to create phazing and echoing sounds. To get capacitors to store and release audio info in a controled manner sounds somewhat problematic.
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  #7  
Old 02-21-2003, 06:08 PM
frankddr frankddr is offline
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Acousticomputer

It was a studio delay device,we are talking circa 1980-81 here..Complicated is not the word for it..If you have the Yamaha Sound Reinforcment Handbook there is a basic schematic of it in the delay section under analog delays.
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  #8  
Old 05-06-2003, 05:59 AM
recklessmax recklessmax is offline
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analog delay/ time alignment

The analog delay ure talking about is basically a BBD (bucket brigade delay) based on a set of chips called CCD(charge coupled device) In essence they each contain a chain of hundreds of series connected sample and hold analog memory cells or "buckets" (hence the BBD title) that are clocked via an external generator so that the decvic acts like an analog shift registor and are clocked out in time delayed form at the chains end. eact memory cell consists of a small CAPACITOR and a TETRODE mosfet and acts like a sample and hold stage.

"Heating" as i read in previous posts is a concern but not too much of, cause it depends on the clocking frequency and the (CCD) device used, simply put the higher the clocking frequency for any given number of stages (they range from 1024 to over 4096) the higher is the shifting/charge discharge process and hence the heating. Coming to the pioint at hand of using them for time aliging sub bass or mid bass, I dont see much of a problem at all either with the distorion or the heating as both the distortion and heating (specially the distortion) goes down as the upper frequencies are restricted!! they are cheap and simple to buld and are pretty forgiving as well though u need a specialist engineer to carefully align them internally, discussion of which is beyond the scope of this post here. If anyone is interested they can contact me on recklesmax@yahoo.com and i'll be pleased to offer my help.

Good luck to you all,

Max.
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  #9  
Old 05-06-2003, 06:03 AM
recklessmax recklessmax is offline
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analog delay/ time alignment

The analog delay ure talking about is basically a BBD (bucket brigade delay) based on a set of chips called CCD(charge coupled device) In essence they each contain a chain of hundreds of series connected sample and hold analog memory cells or "buckets" (hence the BBD title) that are clocked via an external generator so that the decvic acts like an analog shift registor and are clocked out in time delayed form at the chains end. eact memory cell consists of a small CAPACITOR and a TETRODE mosfet and acts like a sample and hold stage.

"Heating" as i read in previous posts is a concern but not too much of, cause it depends on the clocking frequency and the (CCD) device used, simply put the higher the clocking frequency for any given number of stages (they range from 1024 to over 4096) the higher is the shifting/charge discharge process and hence the heating. Coming to the pioint at hand of using them for time aliging sub bass or mid bass, I dont see much of a problem at all either with the distorion or the heating as both the distortion and heating (specially the distortion) goes down as the upper frequencies are restricted!! they are cheap and simple to buld and are pretty forgiving as well though u need a specialist engineer to carefully align them internally, discussion of which is beyond the scope of this post here. If anyone is interested they can contact me on recklesmax@yahoo.com and i'll be pleased to offer my help.

Good luck to you all,

Max.
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  #10  
Old 05-06-2003, 08:27 AM
samuel samuel is offline
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SME 30 12 R tone arm modification

Hi to all the people that post on this site, I have found it very inspiring.

Can anyone tell me how I can modify my Technics 1200 SL MK2's with the SME 30 12 R tone arm? Is it recommended? What are the pro's and con's? and where are they available?

I hear it is a straight tone arm as opposed the angled one that is stardard with the 1200's
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  #11  
Old 05-19-2003, 07:42 PM
teddyedwards teddyedwards is offline
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delay of a kind

when i put the initial post up on this topic, i wasn't suggesting an electronical solution to the analogue time alignment question - rather the relative positioning of the subs, full range, and tweeters. sorry for being vague - should have kept the RLA question seperate but i'm confused at the best of times.
Though Frank and Max thanks for all the info on the crazy old technology...never knew that kind of stuff had/could ever been implemented...did it sound ok or a little dodgy? not that its a feesible option, but interesting none the less.
Back to the positioning of subs & full range etc...
tweeters hung over the dance floor with no delay - i've only ever heard these on phazon sound systems, which i think are digital, but there can't have been a delay on analogue systems like the garage, but it still sounds ok eh? no tricks?
what kind of delay would you expect from a Levan sub -
Surely the delay due to the folded horn would be at least 10ms necessitating a distance of (.01*344)about 3.5metre. is it sufficient to stack the full range cabs on the back of the sub and leave it at that?
i don't understand how this all works together without a leap of faith - like i say the closest thing i've heard to a real quality system is phazon at Sankeys in manchester UK - never have i heard a similar setup with all analogue...someone put my mind at ease.

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  #12  
Old 12-04-2008, 11:58 AM
Mistick Krewe Mistick Krewe is offline
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acousticomputer

http://cgi.ebay.com.au/ws/eBayISAPI....m=110317268180

ends today...

5 hours...
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  #13  
Old 12-04-2008, 02:31 PM
der geile ami der geile ami is offline
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consider the tweeter arrays to be an effect. Keep in mind that they spray VHF in all directions, so there isn't really a way to align them with any other source. If you are in the middle of a square dancefloor, you could theoretically delay them to the nearest full range stack/hang, but as as soon as you travel between the tweeters and the stack/hang, that delay value is incorrect. I am not familiar with phazon/steve dash delaying tweeter arrays and am fairly sure they were/are (he plays around with different digital boxes these days) run straight off his analog isolator.

back in the day, 2 inch compression drivers had a hard time going over 6k, so bullet and slot tweeters were used to extend hf response in both concert and club systems alike. Modern compression drivers can reach high enough to make tweeter arrays redundant aside from the characteristic "sizzle" effect they offer. It has been almost 6 years since I've heard these things, but I've grown to prefer a more accurate or neutral sound. Others do not, which is why I call these an effect. Dave Rat, who has mixed the red hot chili peppers for basically their entire career, has also experimented with running live music through tweeters on an aux send, specifically choosing which instruments have any chance to go through them.

Recklessmax, you have things backwards concerning distortion on the bbd delay, as one typically needs to delay the higher frequencies, not the lower frequencies when aligning horns.
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