Guest David Goncalves Posted March 30, 2009 Report Share Posted March 30, 2009 I've purchased a pair of nice looking Model 24s this weekend. The grill cloth was musty and ripped, so I replaced it with a fine burlap from Jo-Ann (attached with hot glue).The crossover has been replaced, and I'd like to check it against the original schematic. Anybody have that wiring diagram, or at least the component values? Link to comment Share on other sites More sharing options...
Guest David Goncalves Posted April 14, 2009 Report Share Posted April 14, 2009 I've purchased a pair of nice looking Model 24s this weekend. The grill cloth was musty and ripped, so I replaced it with a fine burlap from Jo-Ann (attached with hot glue).The crossover has been replaced, and I'd like to check it against the original schematic. Anybody have that wiring diagram, or at least the component values?Fine - I'll figure it out myself! To me, the speaker sounded off - weak midrange and a bit muffled. Surrounds of the speakers were refreshed with Permatex, checked by shining light at the surround and looking for light leaks. New gasketing material, but a little hole in the back was left for pressure equalization and to allow the wires out for my measurements.Crossover is parallel type. Tweeter is a first order, 8uF in series with a 3ohm resistor. Woofer is second order, 1.5 mH laminated iron I core, shunted by a 16uF cap. This agrees with findings of a fellow owner over on AudioKarma.Woofer in the box, sealed as in use, has a Fs of about 100 Hz, DC resistance of 4.4 Ohms, corner point where impedance begins to monotonically increase is 460 Hz. Max impedance is 35.5 Ohms at 20 kHz. Tweeter in the can (then in the box) sealed as in use with gasketing material, has an Fs of 527 Hz, DC resistance of 4.6 Ohms, Q yet to be determined, max impedance of a shade under 14 Ohms at 20 Khz.I've had a friend use his gear to measure the frequency response of the KLH 24 Series II. Response drops at about 50 Hz and 15 KHz, with a pronounced 5-7 dB peak at 11 to 15 KHz and a bit of a lake around 1-3 KHz.I'm rigging up the speaker for him to measure the response of the woofer and tweeter seperately. Link to comment Share on other sites More sharing options...
Guest David Goncalves Posted April 14, 2009 Report Share Posted April 14, 2009 Oh, and:1. I'm going back and refining the measurements around the resonances.2. I am aware that impedance and resistance are not the same thing. I'll correct that in the next pass.3. Permatex was applied in one coat, after a light cleaning of the old surround with solvent. I took care to not gob on more than was needed to do the job.4. Mortite was the gasket sealant used, I added a bead around the cardboard gasket just in case (can't hurt...).5. Driver measurements were made by running each pair of terminal leads out the back. The driver not under test was open circuit; the driver under test was driven in series with a 15 Ohm resistor by an amplifier, and measurements of AC voltage across that resistor and speaker were made. Resistance was calculated from this.Besides learning a little about speakers...Is that depression in the midrange area what I'm hearing? Or am I crazy?What's with the dramatic peak in the high end? (I wasn't able to hear anything up there)?And, lastly, is there anything I can do to improve the performance without gutting it? Link to comment Share on other sites More sharing options...
Guest David Goncalves Posted April 14, 2009 Report Share Posted April 14, 2009 and 6. Fs should be Fc. Link to comment Share on other sites More sharing options...
Guest David Goncalves Posted April 15, 2009 Report Share Posted April 15, 2009 ... Link to comment Share on other sites More sharing options...
JKent Posted January 12, 2010 Report Share Posted January 12, 2010 To me, the speaker sounded off - weak midrange and a bit muffled. Crossover is parallel type. Tweeter is a first order, 8uF in series with a 3ohm resistor. Woofer is second order, 1.5 mH laminated iron I core, shunted by a 16uF cap. This agrees with findings of a fellow owner over on AudioKarma.Hi DavidI agree--the 24s are a bit disappointing . I bought the system--TT/tuner/amp and speakers. Mine are marked Twenty-Four Series II and have RCA jacks. The xo is as you describe. I replaced the 2-part 8/16 cap with Carli 8uF and Carli 15uF + Dayton 1uF. Left the resistor. When I hooked it up to my big Sylvania receiver the sound level was a lot lower than my AR 2ax's and they sounded pretty anemic. I thought maybe I made a mistake on the xo, but fortunately had only updated one so I could compare the two. The old one sounded as weak as the new one.There does seem to be a LOT of fiberglass stuffing in these. I wonder if they are over damped?Kent Link to comment Share on other sites More sharing options...
JKent Posted January 13, 2010 Report Share Posted January 13, 2010 On second thought.... Now that both are recapped I've been listening to Jazz at the Pawnshop on CD and it sounds pretty darn good. I think the previous comparison was unfair--the AR2ax is a bigger, 3-way system and I was listening to rock on FM. The high quality live jazz shows off the 24's best features. A fairer comparison would have been with the AR4x. Right now they are in a different room so that will have to wait. May try comparing the 24s to some KLH 17s I just recapped. Another thought: Maybe the caps need to burn in a while before listening critically.After I work on the TT/amp it will be interesting to see how these sound with vinyl and the original system. I "assume" the amp was EQ'd to match these speakers. Stay tuned Kent Link to comment Share on other sites More sharing options...
JKent Posted January 20, 2010 Report Share Posted January 20, 2010 OK--I was wrong. The 24 system sounds great! After recapping the speakers I replaced all of the electrolytics on the amp board. Also replaced the wire-wound resistors because they looked corroded but that was probably unnecessary. One channel was going in & out but after cleaning the volume pot with DeOxit I think it's fine. The Garrard TT works on manual but not automatic- Not sure how to fix that. I have both spindles, so will just use the short one. The plastic TT cover is missing and replacements are too expensive.When I bought this there was an old Mamas and Papas LP on the TT. Not my favorite these days but boy--it really sounds good on this system. I'm sure the amp EQ was tweeked to match the speakers. Nice. Will try some LPs from my collection and see how they sound compared to playing them on my "modern" system. The FM is great too. It is the Waller tuner used in later Model Twenty-One table radios.This system sold for $300 at the beginning of its run and $350 at the end. Using the inflation calculator on the web, 350 in 1965 dollars would be $2,422 today! Pretty high end for a $45 CL find, maybe $15 worth of caps and a little work. Will put some Watco Oil on them today, then probably haul the system down to the local electronics parts store to sell (so I can buy more stuff!! )Kent Link to comment Share on other sites More sharing options...
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