- Dynaco A-25s - add tweeters - hifitommy 16:10:00 07/04/09
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- In Reply to: RE: Dynaco A-25s at ...Best Buy? posted by Kirk57 on July 02, 2009 at 15:55:10
i sat one on each a25 on the front edge, used a 0.5uF cap and a potentiometer, wired it in with bananas in parallel and POOF, extended highs AND lows (better transient waveform through the entire speaker). after about a month, i inverted phase on the tweeters and again POOF, even more extended highs.
it was so airy that i cant imagine not doing that if i ever own a25s again.
oyeah, they do well when stacked (2 pair in parallel) like advents.
...regards...tr
- RE: Dynaco A-25s - add tweeters - Ron Oehlert 21:44:50 07/04/09
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- In Reply to: RE: Dynaco A-25s - add tweeters posted by hifitommy on July 04, 2009 at 16:10:00
Who can hear any frequencies not blocked by such a small value capacitor? Certainly not Humans, perhaps Dogs can. The results obtained via phase reversal are indicative of a psycho-acoustic phenominia per any change.
- thanks for the kind words - hifitommy 22:06:27 07/04/09
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- In Reply to: RE: Dynaco A-25s - add tweeters posted by Ron Oehlert on July 04, 2009 at 21:44:50
you MUST be correct with that air of authority. conversely, i must be deaf and stupid as well.
just for fun, try using your spell check function.
...regards...tr
Edits: 07/04/09
- RE: thanks for the kind words - Ron Oehlert 09:39:42 07/05/09
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- In Reply to: RE: thanks for the kind words posted by hifitommy on July 04, 2009 at 22:06:27
The capacitive reactance of an 0.5uf capacitor @ 6 ohms is almost 40,000 Hz & well over 50,000 Hz @ 8 ohms. Isolation & measurement of the so-connected driver will show no significant output within the range of Human hearing (whose upper limit is one full Octave or more below 40,000 Hz).
- um, huh? - tubegarden@aol.com 14:45:11 07/10/09
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- In Reply to: RE: thanks for the kind words posted by Ron Oehlert on July 05, 2009 at 09:39:42
What am I missing? Drivers have output beyond the xover freq, unless you do bi- or tri-amp with digital xovers ... right or wrong?
Happy Ears!
Al
PS just asking, my own ears are not really interested ;)
- um, huh? - tubegarden@aol.com 14:45:11 07/10/09
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- RE: thanks for the kind words - Ron Oehlert 09:39:42 07/05/09
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- thanks for the kind words - hifitommy 22:06:27 07/04/09
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- RE: Dynaco A-25s - add tweeters - Ron Oehlert 21:44:50 07/04/09
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- They say anything is worth what you pay . . . - M3 lover 16:20:28 07/02/09
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- In Reply to: RE: Dynaco A-25s at ...Best Buy? posted by Kirk57 on July 02, 2009 at 15:55:10
but in this case, I'd say you got a way better deal! I found a pair of A-25s at a yard sale (original owner with boxes still), re-oiled the cabinets, upgraded the crossover cap, removed the metal screens from the tweeters, and now have a very musical source for the den. Good for you.
Growing old is hell related former youth.
- RE: They say anything is worth what you pay . . . - Ron Oehlert 20:15:21 07/02/09
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- In Reply to: RE: They say anything is worth what you pay . . . posted by M3 lover on July 02, 2009 at 16:20:28
Why did you remove the tweeter screen? Its' purpose was not to prevent you from stupidly poking your curious finger into the dome (the grill cloth does that), but rather to provide proper dispersion of high frequencies; with that screen removed the tweeter has un-even high frequency response. Any Seas (the mfg of that A-25 tweeter) catalog, then or current, will explain such dispersion screen purpose (Seas is on line, too). However, replacing an aged-out electro-chemical constructed capacitor is required maintenance.
Edits: 07/02/09
- tweeter grills - M3 lover 22:57:28 07/02/09
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- In Reply to: RE: They say anything is worth what you pay . . . posted by Ron Oehlert on July 02, 2009 at 20:15:21
Hi Ron:
A somewhat common complaint on the A-25 is the limited HF extension and definition. At least a few Inmates have reported improved performance by replacing the Seas tweeter. In my case, I found increased HF information by the simple, no cost solution of removing the metal screen from the fabric dome. I've offered this suggestion two or three times in past comments on the A-25 and no one yet raised your point on increasing un-even response.
So I took your advice and looked at Seas tweeters in Madisound and the Seas site on line. Only one textile dome tweeter includes a grill and the Madisound listing states only that it is "protected" by that grill. The remainder of the 27TDF series of fabric dome tweeters are shown without grills.
Now, is it possible you drew your conclusion from the following statements on the Seas web site?
"The relatively fragile aluminium diaphragms may be protected by wire mesh or perforated metal grilles, or by plastic diffusers. The diffusers also linearize the frequency response to an amazing degree."
I don't raise these points to be argumentative but in the hope of learning. If you can reference Seas information on the screens, that would be interesting. But since they offer so many fabric dome tweeters without screens I wonder how critical they can be to optimum performance?
Growing old is hell related former youth.
- RE: tweeter grills - Ron Oehlert 12:14:37 07/03/09
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- In Reply to: RE: tweeter grills posted by M3 lover on July 02, 2009 at 22:57:28
Yes, I drew my conclusion per such info from Seas, & the screen diffusers were much more widely used on their tweeters in the past. With no disrespect to you, I just wish someone would actually measure response before & after when redesigning the A-25.
- Agree regarding measuring changes. - M3 lover 12:21:40 07/04/09
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- In Reply to: RE: tweeter grills posted by Ron Oehlert on July 03, 2009 at 12:14:37
But then that applies to a majority of the suggestions posted on line.
In my case, the only measuring devices I have are attached to either side of my head and they are far from NOS -- just old stock!
Growing old is hell related former youth.
- Agree regarding measuring changes. - M3 lover 12:21:40 07/04/09
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- RE: tweeter grills - Ron Oehlert 12:14:37 07/03/09
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- tweeter grills - M3 lover 22:57:28 07/02/09
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- RE: They say anything is worth what you pay . . . - Ron Oehlert 20:15:21 07/02/09
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