Speakers

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Re: Speakers

Postby Shannon Parks » Tue Jul 19, 2005 12:14 pm

dbailey wrote:Hi Folks,

I'm in the process of building a ST-35 and I'm really excited about the project.

I have a pair of Energy C-3's that I will be using with the amp, but I'm wondering if there are speakers out there that are better suited to the ST-35.

Have any of you come across speakers that work exceptionally well with the ST-35?

Thanks,
Dave


Hi Dave,

I see that these are 92dB/w/m. They should definitely work well. I use some Infinity SM-82's (two-way large bookshelf) with my ST35 rig.

Shannon
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Postby MarkC » Tue Jul 19, 2005 1:04 pm

Hi Dave,

If you're into the whole DIY experience, you might take a look at the AR.com Ed Frias bookshelf speakers. They're pretty popular and have gotten rave reviews....I built a pair about 2 years ago and just haven't had a reason yet to replace them. They're not the final answer in speakers but for the $, you'd be hard-pressed to beat them. Go to Audioreview.com and click on 'learn'. Read the reviews and look at the plans.


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Postby erichayes » Tue Jul 19, 2005 10:55 pm

Hi All,

This is going against my own best interests, as this is the speaker Bud Wyatt and I have chosen for one of our reference systems, but the Dynaco A-25 is still one of the finest speaker systems ever made. I have a pair of Seas/D'Appolito Thors, and I consider them to be excellent reproducers. The A-25s (which also use Seas drivers) kicked the Thors' asses on everything except pipe organ, where the Thors' transmission line coupling gave that lower half octave of bass response.

The A-25s usually go for around $120~175 a pair, but MAKE SURE they are the original series. These can be identified in several ways. First, the terminal board will be stamped "Made in Denmark". Second, the grill, if it hasn't already been removed, is held on with some of the nastiest, possessive black adhesive I've ever encountered--it's still sticky after 35 years. If you slowly and patiently worry the grill off the cabinet, you should see a woofer held in with 6 screws and a 1.5" soft dome tweeter held in with 4 screws. The tweeter should be NNW of the woofer, not due north.

If you find any deviations from the above, don't buy them. This obviously makes buying on eBay risky (ask me how I know all this stuff...) but there were over 600,000 pairs sold in their time, and you can probably find a decent pair shopping locally, especially on the east coast and in the midwest.

The only mods Bud and I have made to them is to replace the 4.7µF electrolytic crossover cap (wear gloves!) with a Solen polyprop., and the woofer leads with 18 ga silver plated wire. Leaving the grill off and removing the lip in front of the baffle board will also reduce diffraction, but the latter shouldn't be tried unles you're a skilled woodworker.

Trust me; you will be rewarded with excellent sound if your amp is performing properly.
Eric in the Jefferson State
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speakers

Postby leadtower » Thu Jul 21, 2005 6:50 pm

Can you build simple boxes. If so allow me to make a recommendation. I use a pair of Pi Theater 4 speakers with my ST 35. Wonderfull combo. Take a look at the PiSpeakers website. They have a pair of two way 94 db eff. kits that sell for about 200$. My Theater 4's are about 94 db eff. so the 17 watts from the ST 35 drives them perfectly, filling a large room with sound without any strain or clipping even on Mahler and Led Zeppelin or the Count Basie Big Band. You would think they are in the room. Bass is tight deep and tunefull and the mids are smooth and full, lots of detail and air on the highs. Very lively and musical. Nice even response up and down.
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Postby WA4SWJ » Fri Sep 30, 2005 11:22 am

OK Eric,

Following your advice and searching the auction site, I got a fairly decent pair of Dynaco A-25's for a decent price. They do sound very good when driven by my eiclones. Low efficiency, especially when compared to my Klipsch's, but the more I listen to them the better I like them. I use a Denon DCD-1560 CD player direct into the eiclones.

Other than the crossover capacitor change and the wood work you mention (which I don't have the tools to accomplish), what other tweaks are known? I've read somewhere that taking the metal dome off the tweeter helps, which seems to be a very minor tweak. I haven't done that yet.

Any real improvement possible with new drivers like the Morel MDT 20 tweeters? Do they need any crossover work? Maybe I'll run a Spice simulation on the crossovers (again someday when I have time) and see if those can be tweaked.

Just curious if they can be further improved since these are used speakers that are a little banged up and I'm willing to tweak them and see what happens.

BTW - I am building two 6550 P-P amps based on the Norm Koren Local Hero design right now. I'm builidng them on some new copies of the Dynaco Mark II chassis also found on that auction site. Someday I'll post pictures. Can't wait to hear these speakers with those amps. Of course the eiclones are fabulous too. (Yes, I'm addicted.)

Thanks guys.

Regards,
Ed Long
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Postby erichayes » Fri Sep 30, 2005 9:55 pm

Hi All,

Ed, I've also heard of the tweeter cover mod but must confess I haven't performed it yet. My guess is that the result would be psychoacoustic more than anything, as the mesh of the cover, and the proximity of the cover to the dome, would cause little diffraction. But as you pointed out, it's a very simple, reversible mod.

The beauty of the A-25 is its simplicity. With a mechanical 6dB/octave crossover, the drivers are everything in this system. I haven't listened to any Morel mods, but I do have a pair of the Mk II A-25s which use a 1" soft dome tweeter. They are very polite sounding, but are no match to the originals. I haven't pulled the drivers to see what kind of crossover they have; I listened to them for about 10 minutes and put them on the shelf where they've been ever since.

What's almost frightening about the A-25s is their ability to reflect the quality of the amplifier and signal source. I thought, back in the 70's, that they were OK speakers, but nothing to get orgasmic over. Well, that's because all the electronics I'd heard driving them was OK BNTGOO. As the metamorphosis of the 100 watt monoblocks took place over the last four months, Bud and I could hear, with no ambiguity, the positive result of the changes we made in the circuitry. When we reached the point where we started hearing the shortcomings of the source, we knew these were speakers truly in a league of their own.

I'm glad you got a good pair, and I hope you'll start tweaking your signal train and allow the A-25s to be your guide.

73
Eric in the Jefferson State
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Postby WA4SWJ » Sun Nov 13, 2005 8:00 pm

OK Guys,

I'm listening right now to my Dynaco A-25's with my ST-35 clone and the A-25's are just fabulous. I did make a tweeter change this evening to Morel MDT-20's. The A-25's I got off the auction site did not have the original tweeters - or at least I don't think they did. The ones that were in there had orange cones (maybe I'll post a picture of them some day) and only 3 holes so I'm skeptical that they are original Dynaco. But, when I removed them to replace them with the Morel MDT-20's, I only found 3 holes in the wood to match the orange coned tweeter mounting holes. However, the holes were worried out a little so it's hard to tell. Someone obviously fooled around with them in the past. So it is probably not possible that these were the original tweeters from the factory. The rest of the speakers are otherwise original as described above (how to tell a real pair) and the enclosures are in reasonably good shape so I'm happy.

The Morel tweeters sound a lot better I think. I'm not good with all those audiophile words, but they sound much clearer to me than those orange ones (don't know who made those yet but I'm researching). The treble is more open now. Since the Morel's are a little less efficient they also sound more balanced - the old tweeters seemed a bit bright. The source is a Denon DCD-1560 CD player direct into the ST-35. Everything sounds really, really great.

But, the original thread was what kind of speakers to go with a new ST-35 clone being built. I can say the ST-35 drives these Dynaco A-25 speakers very nicely indeed. Man, do I love this stuff!

All the best to everyone and enjoy all those great amps you're either building or have built!

Regards,
Ed Long
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Postby erichayes » Mon Nov 14, 2005 2:28 am

Hi All,

Ed, I'm wondering if the tweeters you describe might be Advents that were modified to fit the A-25 cutout. You describe them as having cones, rather than domes, and with a little filing and fitting they could fit in the hole. The Advent tweeters also had an expanded metal grill, but were mounted on a masonite substrate. The original tweeters were green, and they all burned up. The replacements were red, and were fairly robust. They were used in the Advent Loudspeaker and the Smaller Advent Loudspeaker.

If the description doesn't match your tweeters, well...never mind.
Eric in the Jefferson State
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Postby WA4SWJ » Mon Nov 14, 2005 8:54 pm

Eric,

Well, I mis-spoke. They aren't cones - they're domes but they're an orange color. I've seen pictures of the Advents but not really detailed ones so they could be from an Advent speaker. The magnets are square on and they are marked MT-160-3 on the back. They also have dates from the 70's on them but I forgot the exact dates and I'm in Ohio on business right now so they're out of sight.

Anyway, I'll check them out again when I get back and maybe post a picture or two of them.

But, the bottom line is that the A25's sound really good and I'm very happy with them. Glad I got them.

More later once I get back!

Regards,
Ed Long
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Karlsons

Postby EWBrown » Tue Nov 15, 2005 6:25 am

THe aforementioned "Karlsons" with Pyle PYM-1298 12 inch woofers (manufactured by Eminence, basically a low-cost Kappa-12) and some 32 year old ALtec 811B horns, with 806-8A compression drivers and N801-8A "dividing networks" aka crossovers, sound great on the DIY35, and any other amp that I've tried them on. Crossover point is 800 Hz.

I may try some Selenium DT150 horn tweeters crossed over at 3K just for comparison, but I suspect the Altecs will be the final choice.

These are very efficient speakers, I'm getting close to 98-100 dB SPL efficiency, which is a vast improvement over the 84-86 dB that my smaller "bookshelf" test speakers deliver, and even more efficient than my nearly 40 year old Bozak B302As.

/ed B in NH
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Postby WA4SWJ » Mon Feb 27, 2006 9:17 am

Interesting new speaker - looks like the Dynaco A-25's with new drivers and crossover parts. Not sure if they are available in the US. Anyone tried these?

http://www.world-designs.co.uk/products.htm

Regards,
Ed Long
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Postby Kinacus » Fri Mar 03, 2006 10:06 pm

OK,
I have the recently built St 35 clone with CC Chongs Cap board. It is in the living room. It streams Dianne Reeves through a set of Klipsch Fortes.The bass makes the windows vibrate and the mids pierce my heart.The Dynaco 25s are in the dining room, and they sound good with their new Morel tweeters, but the Klipsch penetrate my middle age crab shell and make me feel the music in my SOUL. The ST 35 is the real monster, and I am reverential.
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Dynaco 25's

Postby leadtower » Sat Mar 04, 2006 5:31 pm

Dyna 25's. I have a pair I listen to occasionaly. Original tweeters and the woofers with the rubber surrounds. I like them; but they kinda roll-off a little low and the mids are not real well integrated to my ears. I thought there was a mod that evens out the frequency response a little. Doesn't the tweeter come in around 2k? The bass is nice; not quick or detailed but fairly musical. To be honest I am wondering If I am missing something? They are SEAS components. With the vented slot along the bottom.
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