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Multi-Way Conventional loudspeakers with crossovers

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Old 27th April 2007, 07:12 AM   #31
Grahame is offline Grahame  United States
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Look what the nice UPS man delivered!

Crossover Photo's

Below is the topology as best I could recover it from the board, and the first free layout program I could find on the web.

If anyone knows of something better I could use, let me know (if there is something that will simulate the XO and plot outputs even better!)

Crossover Topology

The numbers for the (inductors? wire wound resistors?) are the numbers printed on the tape on their edge. The R value is the resistance reading on my digital multi meter (0-200 Ohm range)

The values for the capacitors is whats printed on the red ended black ones , or read / guessed from the printing on the green ones ( since not all printing visible, went by size)

Click the image to open in full size.

The MD500 has been swapped out for the new one. When fault finding the buzz followed the speaker between cabinets - so I'm thinking the existing XO's are good for now.

Sounds a lot "cleaner"/"clearer" - no breakup / sibilance where there was before - uh -uhm goood. Matches the other "good" one.
Test tones / signals don't buzz like they did before, sounds nice + clean.

So I'm one happy camper for now, but I'm not letting it to go to my head. Female vocals - acoustic stuff - moderate volumes (I'm in an apartment/flat - so can't rock out) Nice + clean.

Its good to have both the 66's sounding like they should again.
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Old 27th April 2007, 01:59 PM   #32
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Hi Grahame,

I'm happy for you that the parts arrived OK and that you've got some good sound going again.

Unfortunately the "Crossover Topology" box is not opening - at least not with this computer I'm at - does it open with yours ?

regards,
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Old 27th April 2007, 02:24 PM   #33
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These may be of interest to someone on this thread. They use the Celestion MF500, which I believe is identical to the MD500 except for 50W power handling rather than 80W.

Free to whoever wants them.

Cheers

Greg
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Old 27th April 2007, 02:55 PM   #34
Grahame is offline Grahame  United States
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Quote:
Originally posted by Greg3333
These may be of interest to someone on this thread. They use the Celestion MF500, which I believe is identical to the MD500 except for 50W power handling rather than 80W.

Free to whoever wants them.

Cheers

Greg
Greg, they do look like the '66s but in a different layout.

Alan , the topology is also the last image in the Crossover Photos

Does this work ?




Click the image to open in full size.
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Old 27th April 2007, 02:57 PM   #35
Grahame is offline Grahame  United States
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I'm attaching the topology pic - see if that works
Attached Images
File Type: gif crossover.gif (24.4 KB, 610 views)
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Old 28th April 2007, 04:30 PM   #36
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Do we know what year those xovers are? Mine were built 1979 and the crossovers look different.....don't have them out right now to retreive the details...

Nice score ;-)

Anybody try replacing the tweetrs yet?

ToneDef2
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Old 28th April 2007, 05:10 PM   #37
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Just read the other posts...not sure where to post anymore, I confuse easly ;-)

Hello, i've been busy with getting the boat ready for fun/sun.
Looks like you guys are well underway......

I did do an A/B comparison with the MD500's after I finished the one that was buzzing, I would say faster, more accurate, articulate, cleaner mids with no breakup at the speakers weak spot....hope that makes sense?

But when I finished the second one....then I was very happy, my wife that loves music but knows not what makes it, noticed right away the difference, I sum it up to > as these adhesives fail they absorb more and more of the energy, hence altering it in different ways, generally reducing it too, the only part that was hard for me was replicating the amount of dampening applied, this took several reinstalls/listenings to get right, and I error-ed on the side of less…..

Put your 66’s on stands or spikes, you will love what it does for your bass... I installed spikes…I also am trying those baffle deflection cancellation rings on the tweeters AND I believed it was a positive move, as you know back then didn’t address this problem, just my subjective 2 cents…

Anyway great to see you guys are all over this………im very interested in your findings, just can’t get here to often, I will post this email if anyone needs a quick rout to me…. mailtoetebug@verizon.net


Cheers,
ToneDef2
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Old 5th May 2007, 05:57 PM   #38
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Default Cross-overs ; Tweeters ; Cabinet top problem .

Grahame,
it looks to me that the x-over schematic you posted was printed on the back of the x-over board - yes ?
If so, then your other x-overs in you 66s may have schematics printed on their backs also.

From the photos it seems the Inductors and the Black tubular capacitors are likely the same in both vintages of x-overs, but in the later vintage photo I see different green caps.
Now Celestion may have simply used the lesser number of new caps -{in suitable capacitance values}- in parallel to give the same total Capacitance as for the earlier vintage, or they may have changed capacitance value for some reason, thus when you have time do check what the caps or schematic are in your 66s.

tonedef2,
do I understand correctly that you have the later vintage x-overs - as Grahame posted in his original photos - the x-overs with the olive green 2 caps each in 2 unequal size pairs ?

__________________________________________________ __

One Critical capacitor :-
those black tubular caps have the word ELCAP printed on them - stands for "Electrolytic".
LL is "Low Leakage" ; N.P. is "Non-Polar" .

Well, low leakage when new, but after all these years there will have been internal deterioration and now some electrical leakage, even though there is no visible external evidence.

The 24uF cap -{MFD = uF}- is in series with your valuable MD500 in each speaker. Any leakage of the lower frequencies' part of the music, which this 24uF cap is supposed to prevent reaching the MD500, which now gets through as the old cap becomes more and more leaky over time -{as all Electrolytic caps do}- will cause the MD500s to be overdriven below the x-over frequency and eventually damaged.
I strongly recommend you both - Grahame and tonedef2 - replace the two 24MFD ELCAPs with new Polypropylene caps.
24uF is not a Standard value, but 12uF is, thus connect two 12uF caps in Parallel in the position for each 24uF old cap.

Are you buying Mail-Order, or from local shops ?

Got to go - will post more later.

tonedef2, you are on the right track with trying the difraction rings - I'll post more about this as soon as time to. This should be fully tried before you consider replacing tweeters.

regards,
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Old 5th May 2007, 06:52 PM   #39
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Hello,
Alan you are for sure a master at this interst, i will post a pic of my crossovers soon, yes mine are newer style board but still use ELCAPS, i will try and get values as well, conversly the tweeter can be affected by this and blown too.....

If i can't get the pics to post just email me at petebug@verizon.net will send some high rez pics....

Thanks and good hearing from you both....

ToneDef2
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Old 6th May 2007, 09:56 PM   #40
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Sorry for the quality, it's all i had time for....have some good pics now so use this email petebug@verizon.net

ToneDef2

Sorry cant post pics.........email ,me....I have all caps etc values off mine now...
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