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Dynaco A-25 mods

U

Urizen

Lunatic Member
This past weekend, I installed a pair of Morel MDT-20 tweeters and a pair of Dayton 5.1 uF 250v 1% caps, both from Parts Express (great fast service, as usual). Total cost: $74.60. (almost three times what I paid for the speakers:sigh: )

I did an A/B comparison between the modded and unmodded A-25s, and it sounds as if a blanket were lifted off the speakers after the mods. Much more extended highs, still on the East Coast side of sound, and with that, better imaging and a deeper stage. There is no grain and they roll off very smoothly, snare drums have more snap, and cymbals sound more realistic in sizzle and decay. The lack of sibilance is excellent.

One nice thing about the Morels; they are an exact drop in replacement. Absolutely no mods are needed to the cabs, other than installing new speaker caulk from PE. They leaked air badly without fresh caulk. The screw holes lined up perfectly.

I also treated the switch contacts with DeOxit and FaderLube.

Highly recommended, and I look forward to even better sound as the new components break in.

I had mentioned in an earlier thread that I preferred the A-25 to similar sized speakers from the 70's, such as the KLH Model Seventeens and EPI 100's, not that those are bad speakers. This mod sets them even further apart.

Next up...grill replacement. These aren't beauties with the grills removed.

Pics below show the different tweets, caps, and the finished speaker.

Regards,

Ken

dynatweet1.jpg


dynatweet2.jpg


dynatweet3.jpg


dynatweet4.jpg


PS: Thanks, EchoWars, for the inspiration!

Regards,

Ken
 
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MarkAnderson said:
I'm experiencing deja-vu.
Click to expand...

I had posted this on an old A-25 thread of mine a few days ago, and simply moved it here to bump it.

Cheers, bro'! I wouldn't be listening to these right now, if it weren't for you.:rockon:
 
I've listened to the Morel many times, and it's a tweeter I like. But I went with the Seas 27TBFC/G simply because its slightly wider dispersion pattern, and to keep the speakers 100% Seas.
 
EchoWars said:
I've listened to the Morel many times, and it's a tweeter I like. But I went with the Seas 27TBFC/G simply because its slightly wider dispersion pattern, and to keep the speakers 100% Seas.
Click to expand...

I found that the original Seas tweeters sounded better with the perforated metal grills removed. It's the only reason I went for the Morel over the Seas.:yes:
 
The grill doesn't hamper the new tweeter, and is in fact why it has better dispersion than a similar tweeter without such a grill.

Many people have used the MD-20 for a replacement in the A-25. But, far be it from me to run with the pack - I wanted to choose my own tweeter based on what I felt were the most important parameters.

There are many possibilities for a good replacement for the stock Seas tweeter. Your solution and mine barely scratch the surface (but I do think these are likely two of the three best choices).
 
Urizen said:
There's a third?

The Seas and the Morel were the only tweets I could find info on.
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SEAS 27TFFC... the tweeter SEAS recommends as a direct-replacement for the Dynaco A25.

IMHO, they perform better than the Morel or any of the aluminum domes. The lack of a breakup mode/response peak just above 20KHz seems to make them sound significantly smoother than the metal domes, while being JUST AS DYNAMIC sounding. In fact, the most common comment I hear in regards to systems with the 27TFFC installed, is that the tweeter actually makes the BASS SOUND BETTER... as in better perceived midbass transients. Makes sense... get the leading-edge right, EVERYTHING sounds better!

Regards,
Gordon.
 
EchoWars said:
The grill doesn't hamper the new tweeter, and is in fact why it has better dispersion than a similar tweeter without such a grill.
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EW, would you please explain to this novice how a perforated grill could enhance dispersion?

Thanks,

Ken
 
GordonW said:
SEAS 27TFFC... the tweeter SEAS recommends as a direct-replacement for the Dynaco A25.

IMHO, they perform better than the Morel or any of the aluminum domes. The lack of a breakup mode/response peak just above 20KHz seems to make them sound significantly smoother than the metal domes, while being JUST AS DYNAMIC sounding. In fact, the most common comment I hear in regards to systems with the 27TFFC installed, is that the tweeter actually makes the BASS SOUND BETTER... as in better perceived midbass transients. Makes sense... get the leading-edge right, EVERYTHING sounds better!

Regards,
Gordon.
Click to expand...

Thanks Gordon! Does make sense and now I have to buy and give them a whirl!
 
Urizen said:
Thanks for the succinct answer.:rolleyes:
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Sorry...I'm no speaker guru. My very basic understanding is that it is there to disperse the acoustic energy, and removing it will result in a narrower horizontal and vertical dispersion pattern.

Ask me about something I know well...I'll ramble on for hours. :boring:
 
EchoWars said:
Sorry...I'm no speaker guru.
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Me either. Sorry if I came across as brash, but I am truly interested as to how a metal grate can help a tweeter sound better. Perhaps someone else will chime in, and thanks for all the cool information you posted on this thread.

You are correct, the Morel is a fine sounding tweeter.
 
wider dispersion = better off-axis performance

I'm no expert either, but the reflecting off metal grills could create a wider dispersion of the sound waves... this may not have any real effect on how they sound if you are sitting directly in front of the drivers, but it could improve off-axis performance.

Image it as a wider angle of coverage... tweeters tend to be much more directional than woofers.
 
hpsenicka said:
I'm no expert either, but the reflecting off metal grills could create a wider dispersion of the sound waves... this may not have any real effect on how they sound if you are sitting directly in front of the drivers, but it could improve off-axis performance.

Image it as a wider angle of coverage... tweeters tend to be much more directional than woofers.
Click to expand...

I get that part, thanks, but conversely, would that not hamper on-axis performance?
 
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