AudioCircle
Audio/Video Gear and Systems => Enclosures => Topic started by: mresseguie on 20 Feb 2020, 07:45 pm
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I've got a pair of A25 speakers that I bought from a guy on Craigslist about a year ago. I bought them because I wanted to hear what they sound like. After all, they're famous and practically everyone has heard a pair, right? Well, I hadn't. Now I've heard them.
The guy who sold them had monkeyed with the front baffle <which didn't worry me at the time>. It wasn't until after I had paid him my $200 and he was driving off that I removed the woofer in order to see just how screwed up the speakers were. It turned out that the front baffle portion that held the driver's screws in place had rotted out, so this guy had used caulk/liquid nails/black goopy gunk to 'seal' the woofers to the baffle. Of course, this throws the sound off.
Anyway, the speakers have sat in my office for a year now. I'm not going to listen to them. I've considered offering them up for sale; selling just the drivers (all 4 work) and keeping the cabinets for a future project, or just tossing them in the garbage when no one is looking. I could even offer them as a KARMA (recipient would have to pay for shipping!).
Anyone have suggestions? How should I handle this?
Michael
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Start a museum. :lol:
As with so many classics, I haven't heard them myself. I doubt it would be worth your time to do a restore. Episodes like this have taught me to quell curiosity and impulse. :D
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Pictures please. They have gunk to seal them from the factory (it's not glue though). I'm not sure anything sounds off about them yet. I like them personally buy recognize they aren't perfect and maybe not for use in ones primary stereo.
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Cell phone quality:
I think you can make out that the baffle is still intact, but the seller must have thought the screws were no longer capable <alone> of securing the woofer drivers. My original idea was to hire a guy locally to make me new front baffles. However, I'm not so enamored of their sound that I want to go to the expense or trouble of reconditioning this old pair.
(https://www.audiocircle.com/image.php?id=204940)
(https://www.audiocircle.com/image.php?id=204941)
(https://www.audiocircle.com/image.php?id=204942)
(https://www.audiocircle.com/image.php?id=204943)
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The woofer sealant on my Dynaco A25's is one that does not dry. Had to carefully peel the woofer out of its mounting hole.
Got lucky and found an A25 and A25XL that had tweeters mounted as mirror image pair. Sound very good for their age. Replacing the tweeter series connected electrolytic cap with a Solen PP film made a big difference in sound quality as did cleaning the attenuator switch contacts.
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Those are bone stock, probably never opened before. Totally factory and just fine. They aren't exactly meant to be played without the grilles...
They need a new capacitor if the tweeter isn't blown, and some fresh goo, that's it.
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The cabinets are worth burning.
The drivers can be used to build a decent speaker (i suggest removing the tweeter grill, use plywood and mirror image the boxes.and rebuilding the XO). The A35 cabinet is probably a better place to put them. Scott and i also did a modern classic TL for the SEAS current similar woofer and should work fine.
You will also find the parts are worth more than the drivers & the box together (and a lot easier to ship).
Drawings for A10/A25/A35/40 here:
https://www.t-linespeakers.org/classics/dynaco.html
The big TL; http://p10hifi.net/tlinespeakers/FAL/box-plans/classicTL-revisited-WD.pdf
dave
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Picture me slightly slack jawed in wonder that the goopy stuff on my baffles is supposed to be there!?!?! Huh.... :scratch:
I had considered replacing the cap, but I think I'm better off handing them over to someone in greater need than myself. I anticipate the need to sell gear in order to be able to downsize. [No, my Apollos are not for sale.]
Thanks, guys.
Michael
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Hi Hal,
That's no problem. Very carefully take a 1 inch putty knife and some rags and scrape up that gorpy glue. You want to be careful to not bring up any of the particle board. Fill the old holes with some silicone caulking and scrape them flat with your putty knife once the black gorpy stuff is cleaned up.
Get a roll of Mortite at the hardware store.It's like modeling clay on a string. It comes in a big roll and is used to fill cracks in old wooden windows and can be pulled out for the summer. It's the easiest way to make a uniform woofer gasket that does not harden and does not get goopy. When you put your woofer back in note where the old holes were and move the woofer over 1/2 an inch....remember to make new pilot holes smaller than the screws diameter. Protect that woofer from any slips of your hand! I know from experience.
I noticed that little point of crumbled particle board. One pair I fixed looked exactly like yours I put a Mortite gasket in an just kept it abutted against the woofers edge around the routed edge of the woofer cabinet hole.When your screws are in place it will be air tight I did the same with the tweeter. Don't over tighten the screws,the gasket does a job of holding too. The Mortite doesn't even squeeze out,it was made for Dyna it seems.
I saved 2 different Dynaco woofer gaskets. They were a cheap way out,foam, and are as thin as a piece of paper. I forgot wipe the black crap off the woofer frame too. When your done you will have a better Dynaco A-25 than before,,,,,Mark.
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Wow, please don't butcher them. Despite being the number one made speaker in the world there isn't a pile of them around for us to pick them up for nothing and enjoy.
The aperiodic vent at the bottom is special tuned, and for the tuning to work it needs to be very well sealed.
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Hi Hal,
That's no problem. Very carefully take a 1 inch putty knife and some rags and scrape up that gorpy glue. You want to be careful to not bring up any of the particle board. Fill the old holes with some silicone caulking and scrape them flat with your putty knife once the black gorpy stuff is cleaned up.
Get a roll of Mortite at the hardware store.It's like modeling clay on a string. It comes in a big roll and is used to fill cracks in old wooden windows and can be pulled out for the summer. It's the easiest way to make a uniform woofer gasket that does not harden and does not get goopy. When you put your woofer back in note where the old holes were and move the woofer over 1/2 an inch....remember to make new pilot holes smaller than the screws diameter. Protect that woofer from any slips of your hand! I know from experience.
I noticed that little point of crumbled particle board. One pair I fixed looked exactly like yours I put a Mortite gasket in an just kept it abutted against the woofers edge around the routed edge of the woofer cabinet hole.When your screws are in place it will be air tight I did the same with the tweeter. Don't over tighten the screws,the gasket does a job of holding too. The Mortite doesn't even squeeze out,it was made for Dyna it seems.
I saved 2 different Dynaco woofer gaskets. They were a cheap way out,foam, and are as thin as a piece of paper. I forgot wipe the black crap off the woofer frame too. When your done you will have a better Dynaco A-25 than before,,,,,Mark.
Hi Mark,
Those are mresseguie's A25's in the pictures.
Mine are in very good shape and sealed back up after the cap replacement.
Best,
HAL
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Over a million Dyna A25s were shipped, built by at least 2, maybe 3 OEMs. I expect that ove rthe entire popullation there are many variations.
dave
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IIRC there's only one minor difference between some of the models. The only thing you need to check is the uf value of the cap that needs replaced in all of them. Then you need some fresh goo from parts express, and a little deoxit to clean the switch. And I recommend some gloves for handling the mineral wool, not because it's nasty like fiberglass, but because it feels funny and leaves little bits of minerals on your hand you wash off. The soldering is slightly tricky because it's through the woofer hole.
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What I know about the A25:
I enjoyed mine very much for the ~9-10 years I used them.
The A25 had the simplest crossover imaginable (a single capacitor in series with the tweeter to keep the low frequencies out), probably one reason it was renowned for its transient response. Crossover was a relatively low 1500 Hz. The aperiodic tuning gave it very tight,articulate bass and a smooth impedance curve that made it an easy load for an amp. The bass tuning was accomplished by feeding it a low frequency square wave and adjusting the amount of stuffing in the port while observing the woofer output on an oscilloscope.
The later A25XL had a slightly more complex crosseover, a slightly smaller tweeter and about 3dB higher sensitivity.
I don't know where Wayner is but he is also a good resource for A25 know-how. He built beautiful replacement cabs for his. That's who I'd reacjh out to for advice. His A25 pictures are gone (below are a couple I saved) and maybe he is too but Frank Van Alstine might know how to reach him.
(https://www.audiocircle.com/image.php?id=204974)
(https://www.audiocircle.com/image.php?id=204975)
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Nice new boxes, but the tweeter will never be pretty!
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Hi you guys,
I looked again at the pictures and would like to add a little. Some earlier A-25's used a ScanSpeak woofer, not the more common Seas.The ScanSpeak has little bumps around the screw holes on the woofer frame while the Seas does not. So you might not be able to use new pilot holes.Once you de-gorp ,clean up the woofer hole and put a dab of caulking in the existing screw holes.The Mortite gasket you will have made does 90 percent of keeping the woofer in there anyway, like Blu-tack poster putty.
Folsum, I don't want to be mean but I couldn't even unfurl my roll of Parts Express speaker gasket material. It became a mess and I had to give it the heave ho.My roll of Mortite,and you get enough to do 100 speakers is still just as pliable as it was new 25 years ago.In my old apartment windows in Maine it dried out after a few years but that was Mortite exposed to mother nature not your listening room.I'm a big Parts Express fan though,there great.
Why put gorpy gunk back in when it shouldn't of been there to begin with. I will get some pictures including the sheer thin gasket Dyna used.When you make your Mortite gasket it's so easy it's like going back to kindergarten and playing with modeling clay. Scrinch in some little pieces around those screw holes...take care Mark Korda
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Some earlier A-25's used a ScanSpeak woofer,
In the A25s built by SanSpeak?
dave
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What I know about the A25:
I enjoyed mine very much for the ~9-10 years I used them.
The A25 had the simplest crossover imaginable (a single capacitor in series with the tweeter to keep the low frequencies out), probably one reason it was renowned for its transient response. Crossover was a relatively low 1500 Hz. The aperiodic tuning gave it very tight,articulate bass and a smooth impedance curve that made it an easy load for an amp. The bass tuning was accomplished by feeding it a low frequency square wave and adjusting the amount of stuffing in the port while observing the woofer output on an oscilloscope.
The later A25XL had a slightly more complex crosseover, a slightly smaller tweeter and about 3dB higher sensitivity.
I don't know where Wayner is but he is also a good resource for A25 know-how. He built beautiful replacement cabs for his. That's who I'd reacjh out to for advice. His A25 pictures are gone (below are a couple I saved) and maybe he is too but Frank Van Alstine might know how to reach him.
(https://www.audiocircle.com/image.php?id=204974)
(https://www.audiocircle.com/image.php?id=204975)
Hey!
Man! Those are pretty. I don't mind the look of those tweeters.
I've never heard them. But I think the key of these speakers is that those woofers are running full range and naturally rolled off just a right point and steep enough for the tweeters to come in, so no need for the crossover for the woofer. I love the design of these speaker.
Anyway, here's a modern day A25, the Seas A26 kit.
https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-classic-a25/ (https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-classic-a25/)
Buddy
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The tweeters in the gorgeous rebuild look like the newer ones from the A25XL.
Seas A26 10" 2-way Kit
That’s the kit we designed the big TL for.
(http://p10hifi.net/TLS/projects/VTL-images/classicTL-3D.gif)
Link to plans posted earlier.
dave
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Hey!
Man! Those are pretty. I don't mind the look of those tweeters.
I've never heard them. But I think the key of these speakers is that those woofers are running full range and naturally rolled off just a right point and steep enough for the tweeters to come in, so no need for the crossover for the woofer. I love the design of these speaker.
Anyway, here's a modern day A25, the Seas A26 kit.
https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-classic-a25/ (https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-classic-a25/)
Buddy
The woofer is not run full range. The inductance of the woofer (according to contemporary reviews) rolls the woofer at 1500 Hz and the cap on the tweeter acts as a high-pass. I'm guessing the slopes are gentle. The XL had a slightly more complex x-over.
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I haven't decided what to do yet. They're just sitting around doing nothing. There's now a high probability that I will try to sell them on Craigslist first. There are something like 30,000 university students in our town. [Can you say 'overrun'?] Surely, one of them would like a pair.
Thank you for all the input. I do appreciate it.
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Lucky students. I'll still be sitting around with $ in hand for shipping but I doubt it'll be a hard sell.
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I haven't decided what to do yet. They're just sitting around doing nothing. There's now a high probability that I will try to sell them on Craigslist first. There are something like 30,000 university students in our town. [Can you say 'overrun'?] Surely, one of them would like a pair.
Thank you for all the input. I do appreciate it.
Toss in a lava lamp and a blacklight Jimi Hendrix poster and it should be an easy item to move.
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Toss in a lava lamp and a blacklight Jimi Hendrix poster and it should be an easy item to move.
Heck, if you gonna do a Karma with the blacklight Hendrix poster thrown in then I’m all in with #43 please.
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I'm afraid I haven't owned a blacklight poster of anyone for decades. Blacklight bulbs are cheap. The buyer can pick one up at Fred Meyer/Kroger. :lol:
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The idea of having a poster on my wall makes me cringe now. :?
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I haven't decided what to do yet. They're just sitting around doing nothing. There's now a high probability that I will try to sell them on Craigslist first. There are something like 30,000 university students in our town. [Can you say 'overrun'?] Surely, one of them would like a pair.
Thank you for all the input. I do appreciate it.
Most college students these days don't want bulky stuff...and why would they when tiny ear buds connected to a phone that fits in a pocket are entirely sufficient to them? Just get those classics over to Folsom and buy yourself a pair of EPI 100's. :D
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Most college students these days don't want bulky stuff...and why would they when tiny ear buds connected to a phone that fits in a pocket are entirely sufficient to them? Just get those classics over to Folsom and buy yourself a pair of EPI 100's. :D
Valid point. However, I seem to recall a few of my son's college college buddies had simple audio or HT setups. There's a guy on our local Craigslist who has sold 2nd hand audio for years.
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I'm not far out of college, if that counts :lol:
I hope that's true about your son's friends, I want more people in the hobby.
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I'm not an old man myself, but college was many years ago. With that said, I guess there's a bit of a caveat to my overly generalized statement earlier. Vinyl's resurgence is clicking with some of the younger crowd, including college age folks. Along with vinyl, vintage hifi has caught on with that same crowd. Many record stores I've been in are often playing music on vintage gear and may also have vintage receivers and speakers for sale, reasonably priced. It's pretty cool to see. I find myself wanting an old receiver from time to time. I love the look and overall tactile qualities missing from a lot of modern gear. Old receivers can sound pretty darn good too. :D
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Valid point. However, I seem to recall a few of my son's college college buddies had simple audio or HT setups. There's a guy on our local Craigslist who has sold 2nd hand audio for years.
And a little older "young" people are getting into audio and HT. My oldest is a little north of thirty and is setting up an audio/2 channel HT rig. I gifted him a pair of Polk RTi6 speakers and I'm refurbing a Pioneer PL 550 turntable for him, so some of those college grads that stuck around town could be interested as well.
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This thread seemed to die without so much as a whimper, let alone a bang. Did they get fixed? Sold?
My first pair of speakers were A25s. I had them through college and took them with me when I joined the Navy. There's an old expression among Navy wives that, "three moves equals a fire," and somewhere along the way my Dynacos, a Sansui integrated amp, and some Craftsman tools didn't arrive at my next duty station. All were replaced by other things, but I still miss those A25s.
Madisound has an "A26" kit, but I'm not paying $800+ for the nostalgia of re-owning them.
Madisound Seas A26 (https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-classic-a25/)
(https://www.madisoundspeakerstore.com/images/products/preview/a26%20kit%20pair.jpg)
I'm guessing that my Canton Karat 40s are a step up from the A25s and I'm planning on relegating those to bedroom duty anyway. Maybe I'll keep an eye out on CL for a pair of A25s for garage speakers.
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A modern TL in the mold of the Radfords & IMFs that that kit drops into. From what people have said about this combo (all in Europe that i have seen) $800 would be reasonale value if popped into this box which will get much more out of the woofer.
http://p10hifi.net/tlinespeakers/FAL/box-plans/classicTL-revisited-WD.pdf
dave
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Dave,
Stock crossover or a proprietary design?
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Wow. It was just two months ago that I last posted on this thread, yet all hell broke loose in more than one way (I don’t mean in this thread). I still have the A25 speakers and I still have not decided what to do with them. If I had an inexpensive amp to power them, I guess I could put them in my work/garden shed.
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Dave,
Stock crossover or a proprietary design?
Stock,
dave
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Wow. It was just two months ago that I last posted on this thread, yet all hell broke loose in more than one way (I don’t mean in this thread). I still have the A25 speakers and I still have not decided what to do with them. If I had an inexpensive amp to power them, I guess I could put them in my work/garden shed.
Sell them to jcsperson so he can determine if they are as good as he remembers them to be.
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Sell them to jcsperson so he can determine if they are as good as he remembers them to be.
Thanks for the nudge. There are just too many distractions in my life lately....I sent him a PM just now. Shipping costs will be pretty high, so his buying locally is a much better deal.
Michael
Edit: Nostalgia lost to another choice. It seems they're destined for my shed or a local sale.
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Thanks for the nudge. There are just too many distractions in my life lately....I sent him a PM just now. Shipping costs will be pretty high, so his buying locally is a much better deal.
Michael
Edit: Nostalgia lost to another choice. It seems they're destined for my shed or a local sale.
The defining characteristics if the A25 were definition, tight bass, and a flat impedance curve. The last two resulted from the 'aperiodic' tuning. I question whether this can be replicated in the DIY remakes and 'aperiodic ports' out there. It wasn't as simple a just putting some fiberglass in a port. Dynaco tuned the port in each system by feeding a low frequency square wave into the system and observing the output on an oscilloscope. The amount of stuffing was adjusted to get the resistance in the port and thus the transient response just right. I'm guessing the average end user lacks the gear to do that. A labor intensive process that no speaker maker would invest in a moderately priced model today.
This loading also makes the impedance surve quite flat, so it's easy to drive.
An A25 in good condition should still be listenable assuming the 5uf non polarized electrolytic crossover cap is good. Bass tightness would still be first rate. It has probably been surpassed in other aspects. But if the price is right (not $800) then WTF.
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Location?
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Location?
97330
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One of the popular "urban legends" about the A25 is that its sensitivity (efficiency) is 90db/1W/1M.
This number comes from an old Stereophile review published in the 1970s. It did say they measured at 90db, but it was with a 10 watt signal at 6'. Which means they are actually around 83db/1W/1M.
There were two other published measurements on them back in the 1970s, one put them at 83db, the other at 84db.
I bet I've seen people post that they are 90db efficient a few hundred times.
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Those lower numbers sound about right- and in the ballpark for most similar speakers of the era. As the saying goes, though, numbers can be deceiving, and the flatter-than-usual impedance curve probably allowed most amps to deliver more usable power than some other speakers.
The later A25XL was about 3dB more sensitive.