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How to get the most out of 105.2?
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speakerguru
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PostPosted: Mon Jun 18, 2007 8:34 am    Post subject: Re: Oi, oi, oi... Reply with quote

proffski wrote:
Surely dummy loads will not exhibit drive unit characteristics anyway?


The thermal modelling is voltage/time based and so it does not matter whether the units are connected or not.

The dummy loads are only needed during the test to terminate the x-overs and thereby keep the load to the amplifier within reasonable limits.
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proffski
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PostPosted: Tue Jun 19, 2007 8:25 am    Post subject: Reply with quote

Ah, I understand now, cheers.
Probably not the way I'd have done it but it worked...
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speakerguru
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PostPosted: Tue Jun 19, 2007 11:14 am    Post subject: Reply with quote

proffski wrote:
Probably not the way I'd have done it but it worked...

It’s very important for the protection mechanism to closely take into account the voice thermal time constant as well as the maximum permissible temperature. Otherwise it will either over or under protect. Finding other devices like fuses or polyswitches with the same time constant as each unit is pretty unlikely and these devices will have relatively wide tolerances. To avoid complaints, they would most likely have to be set up to over protect Crying or Very sad .

Idea It is perfectly possible to measure the voice coil temperature, while the speaker is in use, by applying a small constant DC current and low pass filtering. You then get a DC voltage which is proportional to the VC temperature. This can be used to switch in the protection device of your choosing just before the maximum temperature is reached. This requires setting up for the DC resistance of the particular drive unit at the initial room temperature. If any unit is replaced, this setting up will have to be repeated Exclamation . This scheme was used in prototype KM1s but abandoned in favour of the S-Stop type modelling (which required no end-of line setting up Mr. Green ).
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proffski
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PostPosted: Tue Jun 19, 2007 11:41 am    Post subject: Reply with quote

My present answer is very high efficiency loudspeakers and amplifiers that will not clip until the tiles on my roof begin to slide off…

No disco type music in my household and no tone controls for visitors to play with.
Also no room for currently fashionable highly compressed junk that is the growing trend…

Not blown a unit in moiré than 20 years!
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andrelly
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PostPosted: Sun Jun 24, 2007 4:08 pm    Post subject: Reply with quote

Hello everyone, I have got the crossover parts already. Now just need to find time to install them.
I am wondering if 105.2 is the grand daddy of designs such as Wilson Watt/Puppy? Cool ie. a woofer module at the bottom and mid/tweeter on top?
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proffski
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PostPosted: Sun Jun 24, 2007 4:15 pm    Post subject: Reply with quote

What about the Wilson Grand Slam II?
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Parts
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PostPosted: Thu Jun 28, 2007 10:52 pm    Post subject: Reply with quote

Going back to S-TOP protection circuits, I had a couple of probs with this when using my 105.4 (various amps caused it to trip, and I still suffered a blown tweeter due to clipping), it also posed a couple of problems when I wanted to attempt re-wiring and I did not have great faith in its connection method.

I removed the S-TOP circuit completely from my 105.4, and it completely improved the sound for the better, much clearer and transparent, with better weight and punch. I never suffered from any blown or damaged drivers after the removal, and these poor 105.4 suffered plenty of abuse being passed around family and friends. If only the veneer and heads had not got so scuffed or received a coat of black gloss Embarassed

Funnily enough the amp that clipped didn't seem to clip either, at least I cannot remember any clipping after removal of the S-TOP circuit ?, to be honest I thought the speakers seemed easier to drive ? Though the S-TOP was removed at the same time as Audioquest Midnight and Jade was re-wired into them, with concrete added to the hollow at the base of the main cabinet, with a spiked 1" b/bb grade birch ply bottom sealing the concrete.
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proffski
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PostPosted: Thu Jun 28, 2007 11:51 pm    Post subject: Reply with quote

Yup!

If you cannot hear a speaker or amplifier under severe stress then too much booze has been consumed.

Speaking from experience, I have been present when fine offerings like 104aB have had tweeters catch fire, B&W DM70s ditto on the panels, and all versions of Quads except for the originals and the very latest.
W.A.R. Deconing their 12" Bass drivers, burnt out coils on B110s, and many makes of tweeters going O/C.
In most cases too much wine and spirits were the main cause.

Could give a new meaning to S.T.O.P. I guess, but that would be no fun...
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andrelly
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PostPosted: Thu Jul 12, 2007 9:40 am    Post subject: Reply with quote

While attempting to fit the oversize caps on the board, another enthusiast recommended the replacement of ferrite-cored inductors. He claimed that ferrite is prone to changes in magnetic field and sound different with locations.... Shocked
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proffski
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PostPosted: Thu Jul 12, 2007 11:07 am    Post subject: Reply with quote

With care and knowledge!
Ferrite can saturate, the effect are em, interesting. You could go for laminated Iron cores or Air Cored Inductors.

Remember that the designers will have calculated the actual resistance of the wire as well as the inductance and Q will have been icorporated into the complete crossover design. Altering an iductors value can alter all the parameters.

One small change could have a massive effect on crossover performance.

So yes it may alter the sound, but will be beter or more accurate?
The better the loudspeaker, the more important the component values.
With a fairly complicated crossover as in the 105 tread with caution.

Kings new clothes and all that!
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speakerguru
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PostPosted: Thu Jul 12, 2007 3:15 pm    Post subject: Reply with quote

andrelly wrote:
While attempting to fit the oversize caps on the board, another enthusiast recommended the replacement of ferrite-cored inductors.

Exclamation 105 crossover inductors had iron dust cores NOT ferrite. See my other post http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=513


andrelly wrote:
He claimed that ferrite is prone to changes in magnetic field and sound different with locations.... Shocked

Rolling Eyes Pure B***S***
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andrelly
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PostPosted: Tue Jul 17, 2007 11:18 am    Post subject: Reply with quote

I did see some designs such as VonSchweikert that placed the inductors outside of the cabinet.....
I was told that better inductors would improve the musical 'swings' of the speaker.

So speakerguru, do you think that it is best to leave the original inductors alone? I know that I need to replace with the same spec'd inductors (not only in micro henries), but in other aspects as well.

This guy wo told me about inductors is an experienced automotive audio installator and had heard the difference from different placements of the x-over.. Rolling Eyes

Cheers...
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speakerguru
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PostPosted: Wed Jul 18, 2007 9:35 pm    Post subject: Reply with quote

andrelly wrote:

This guy wo told me about inductors is an experienced automotive audio installator and had heard the difference from different placements of the x-over.. Rolling Eyes
Cheers...


He may well be right. If the inductor is close to any steel car bodywork it will change the inductance.
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andrelly
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PostPosted: Thu Jul 19, 2007 10:29 am    Post subject: Reply with quote

My flooring is granite. Does it have any measurable magnetic properties?
Cheers...

Andy, should have followed your advise....sit-back-and-enjoy... Sad
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proffski
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PostPosted: Fri Jul 20, 2007 8:19 am    Post subject: Reply with quote

Oh yes! Sit back and enjoy indeed!
Two helpings of the Kings Singers "L'Arpeggiata” with Los Impossibles last night.

A stupendous performance!

Anyway, granite can have some minor magnetic properties; it is also naturally radio-active and produces Radon gas…
(Google Radon).

Of course the variations in the earths magnetic field must be taken into account as well as the massive solar cycle which is approaching, could cause some modulation of the magnetic field with interesting results… Wink
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