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Dynaco A25

 
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MGM
Intermediate Contributor 25+


Joined: 13 Nov 2014
Posts: 36
Location: Witney Oxon

PostPosted: Sun Nov 16, 2014 10:33 pm    Post subject: Dynaco A25 Reply with quote

I have just acquired a pair of these and cannot quite believe how good they sound.
I've discovered they have a direct coupled bass/mid. driver and a single capacitor for the tweeter.
Having owned speakers with complicated crossovers it surprises me that simplicity can give such good results.
Who is complaining ? If it works, I for one celebrate it...
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iso
Senior Contributor 200+


Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Wed Nov 19, 2014 4:40 pm    Post subject: Reply with quote

You may find this forum handy
http://www.classicspeakerpages.net/IP.Board/index.php?showforum=20

Forum is biased like all brand related forums... Tom Tyson like to say that AR3a was the least colored speaker from 60īs to mid 70īs like some of us think about certain Kef models of 70īs. But... biased information can be handy compared to no information.

I have 3 early 70īs AR original model rebuild to perform (AR2ax, AR5 and AR3aImproved). AR2ax rebuild is close to be completed and results are good, even 3 way crossover consists only 2 caps, 1 coil and 2 level matching pots. AR2ax is not perfect... but I suppose such speaker has not been developed yet.

Best Regards

Kimmo
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MGM
Intermediate Contributor 25+


Joined: 13 Nov 2014
Posts: 36
Location: Witney Oxon

PostPosted: Wed Nov 19, 2014 6:57 pm    Post subject: Reply with quote

Thank you, ISO.
The Forum you mentioned has been very useful as there is a great deal on all aspects of Dynaco A25s.

Re. ARs, I once owned a pair of AR7s which my son used. Unfortunately they didn't have the original bass/mid. drivers fitted. I still have the original chassis somewhere.
I wish I had got them re-foamed and put back in the '7s before they were sold.
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M G Miles
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iso
Senior Contributor 200+


Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Thu Nov 20, 2014 10:31 am    Post subject: Reply with quote

AR7īs were my first real hifi speakers. It is hard to know if they really were better than my previous Peerles speakers built from kit, as my amplifier was not too good in these days. AR7 design is typical american cost effective 2-way of this area. simple as you can get... but original drive units are hard to replace with modern ones.

Do I remember correctly... were Dynaco A25`s built in Denmark using Scan Speak or other local drive units?

Best Regards

Kimmo
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MGM
Intermediate Contributor 25+


Joined: 13 Nov 2014
Posts: 36
Location: Witney Oxon

PostPosted: Thu Nov 20, 2014 11:15 am    Post subject: Reply with quote

Hello Kimmo.
Yes the A25s were built in Denmark using SEAS drivers, later to become Scan-Dyna, who also built amplifiers and tuner-amplifiers.

I read somewhere that over 600,000 A25s were made. Amazing !
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M G Miles
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Garethwatkins
Junior Contributor 20+


Joined: 18 Nov 2011
Posts: 22
Location: Tring, UK

PostPosted: Thu Nov 20, 2014 9:00 pm    Post subject: Reply with quote

SEAS do a modern take on the A25 using current drivers.

https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-classic-a25/
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MGM
Intermediate Contributor 25+


Joined: 13 Nov 2014
Posts: 36
Location: Witney Oxon

PostPosted: Thu Nov 20, 2014 11:30 pm    Post subject: Reply with quote

Thank you for the info. This modern design/update is very interesting, especially the way it follows the A25s cabinet loading technique and crossover.
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M G Miles
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MGM
Intermediate Contributor 25+


Joined: 13 Nov 2014
Posts: 36
Location: Witney Oxon

PostPosted: Wed Dec 03, 2014 10:04 pm    Post subject: Reply with quote

I have done some work on these loudspeakers, with the help of a friend who is involved in speaker design. The former owner had removed the tweeter control, and there was just a 5uf capacitor in series with the tweeter feed.
Nothing else.
I looked up 'Dynaco A25 crossover schematic' , which shows the original set up along with another circuit. My friend provided me with two 10 ohm resistors, as shown on the original circuit.
Also, the fibreglass normally fitted in the ports/vents was missing, so I acquired some.
After the resistors and the port material were fitted I gave them an extended listen.
They are surprisingly good. I didn't (a) expect so much detail to be present and (b) the bass end to be as extended.
My friend has suggested some changes could, perhaps, be made to the simple crossover, but for now I am really happy how they sound.
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M G Miles
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