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Old 3rd February 2013, 01:07 AM   #1
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Default SEAS A26 Speaker Kit

Is there anyone out there who has actually built a pair of cabinets to house the Seas A26 kit sold by Madisond Sound?

There are two drawings on the Madisond web site, and they give different dimensions. I would like to be certain before I cut wood. I know that I shouldn't cut the baffle/motor board before I have the actual drivers in hand, but even so, there should be some consistent plans.

Thanks in advance for your help!
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Old 3rd February 2013, 11:56 AM   #2
system7 is offline system7  United Kingdom
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This is quite an amazing speaker, IMO. In the tradition of the Wharfedale Melton and the DeVore Oragutan. Easy to listen to in a good room.

No, I haven't built one, but the design is flexible at 28 litres. You just need to keep the front layout and dimensions similar. Simple strong box required with aperiodic vent on front or back.

Click the image to open in full size.

The Madisound Speaker Store

A simple 3.3uF and 10 ohm resistor on the tweeter is all that is required. I'd guess the tweeter is offset at 1:1.618 Golden ratio. Valve amps will love it.
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Last edited by system7; 3rd February 2013 at 11:59 AM.
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Old 3rd February 2013, 12:18 PM   #3
balerit is offline balerit  South Africa
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Ah, following my idea of offsetting the tweeter.
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Old 3rd February 2013, 10:38 PM   #4
tsip is offline tsip  Greece
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I am in the process of planning to build this project. Which drawings are you referring too? I can only find the seas paper.
At the moment i am trying to decide on bracing...this will be my first speaker project
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Old 7th April 2013, 10:05 AM   #5
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Hi,
I am also planning to build a pair of speakers based on the Seas A26 kit. It will also be my first DIY project. I was looking at the Zaph SR71 first but I am looking for that vintage sound. I usually like closed enclosures and bass reflex so the Dynaco A25 reissue aperiodic design might be a good compromise.

Though, I find the T35 tweeter that Seas recommends in their factory kit is really expensive.
I was considering switching it for the 27TDFNC (somehow similar to the TDFC). This one has the advantage of being quite linear and much more affordable. Moreover, it has a grid to protect the dome against curious small fingers (as did the original A25 BTW).
The specs say: recommended frequency range 2500-30000Hz, but I wonder if it could match the A26RE4 below 2.5kHz -- while the T35 goes theoretically easily down to 1.5kHz.
I am planning to use the 3.3uF cap in series with an L-pad to adjust the tweeter level.
I have seen A25-replica designs based on the A26RE4 using the Millenium tweeter, the 29TFF/W (2200-25000Hz) or even the TDFC (2500$ the pair for these latter on Annandale!)
My question is then: Does the T35 worth the investment over the more affordable 27TDFNC, considering it is such an old school speaker? And would I need to change the crossover?
Thanks for your replies

Last edited by EaZy; 7th April 2013 at 10:11 AM.
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Old 7th April 2013, 12:48 PM   #6
system7 is offline system7  United Kingdom
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I thought Madisound were doing quite a keen price on the drive units bought together!

Firstly, this SEAS project is quite an old school idea, but it's not low tech AT ALL. To get big woofers like 8" and 10" working well needs a very special 1.5" tweeter and some tidy natural rolloff in the cone. The problem is the time-alignment distance with the deep bass unit, which drives you to shallow slopes and low crossover for a good result.

They really don't make 'em any more, since the whole two-way market has moved to the easier 6" bass, 1" tweeter idea. Morel make some very good polycones around 6" and less which need no more than a bafflestep coil, but these are best crossed as low as you can.

You always work at crossing over at the mean between the bass cone breakup and the Fs resonance of the tweeter assuming both are reasonably well-behaved. This space gets tight with big cones, but you get the nice bass and solid delivery. It's a pleasant sound and works particularly well with valve amps.

What I'm saying, is you are going to struggle with lesser tweeters. A 6"/180mm project like the SEAS Mimir or SEAS Idunn is going to roll in more affordable and better balanced than a modification.
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Old 7th April 2013, 02:11 PM   #7
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Quote:
Originally Posted by EaZy View Post
Hi,
I am also planning to build a pair of speakers based on the Seas A26 kit. It will also be my first DIY project. I was looking at the Zaph SR71 first but I am looking for that vintage sound. I usually like closed enclosures and bass reflex so the Dynaco A25 reissue aperiodic design might be a good compromise.

Though, I find the T35 tweeter that Seas recommends in their factory kit is really expensive.
I was considering switching it for the 27TDFNC (somehow similar to the TDFC). This one has the advantage of being quite linear and much more affordable. Moreover, it has a grid to protect the dome against curious small fingers (as did the original A25 BTW).
The specs say: recommended frequency range 2500-30000Hz, but I wonder if it could match the A26RE4 below 2.5kHz -- while the T35 goes theoretically easily down to 1.5kHz.
I am planning to use the 3.3uF cap in series with an L-pad to adjust the tweeter level.
I have seen A25-replica designs based on the A26RE4 using the Millenium tweeter, the 29TFF/W (2200-25000Hz) or even the TDFC (2500$ the pair for these latter on Annandale!)
My question is then: Does the T35 worth the investment over the more affordable 27TDFNC, considering it is such an old school speaker? And would I need to change the crossover?
Thanks for your replies
You mention seeing the A25 replica designs, which are probably the ones from World Hi-Fi. Their designs use either the T29CF001 or the 29TFF and seem well thought out and developed. It might be worthwhile to check out their designs as they had two alternate cabinet designs (one a floor stander), and crossovers for both tweeters
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Old 8th April 2013, 10:27 AM   #8
ODougbo is offline ODougbo  United States
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I'll drink to that

Quote:
Originally Posted by system7 View Post
I thought Madisound were doing quite a keen price on the drive units bought together!

They really don't make 'em any more, since the whole two-way market has moved to the easier 6" bass, 1" tweeter idea.
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Old 8th April 2013, 10:51 AM   #9
Bromle is offline Bromle  Norway
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Troels Gravesen has performed some measurements on the Seas T35C002 tweeter: Large domes
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Old 8th April 2013, 11:00 AM   #10
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Well, I am located in France so I cannot benefit of Madisound rebates.
I just ordered two A26re4 and two 27TDFC. These are 300$ less than a pair of T35. I'll give a first try with these tweeters, if they really do not do the job I can still mount two T35 afterwards instead. For the crossover I just ordered the 3.3uF cap, it will be mounted in series, as Seas recommends to filter the T35 tweeter at 2kHz. To me it makes no sense to have a 200$ 94dB/W tweeter like the T35 if it attenuated with a 10Ohm resistor. The sensitivity of the TDFC is still a little bit better than the A26re4, I ordered a few pairs of resistors and give a try using different values. The enclosure will be made out of birch multiply, with lamb wool damping.
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