Seas a 26 kit. Devore 093/096 style

Discussion in 'Audio Hardware' started by murphythecat, Nov 28, 2018.

  1. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    I've looked into these before and agree the cabinet in the kit does not get the best out of the woofer.
    The Madisound "aperiodic" port enclosure shows an F3 frequency (-3db) of ~80Hz (not so good IMHO).
    In the spec for the Seas woofer a sealed cab of 1.5 cuft volume has an F3 or 48Hz- much better ! You can probably go lower with even more volume.
     
  2. head_unit

    head_unit Senior Member

    Location:
    Los Angeles CA USA
  3. head_unit

    head_unit Senior Member

    Location:
    Los Angeles CA USA
    This DeVore Fidelity Orangutan O/93 loudspeaker Measurements
    measures 90.1 vs 93.
    So do we add DeVore to the Klipsch Memorial Altar of Sensitivity Liars? Or did DeVore ever reply about that?
    (I'd note that while Stereophile is driving at 8 ohms and the O/96 and O/93 are really 10+ ohms, that's only 1/2 dB difference).
     
  4. murphythecat

    murphythecat https://www.last.fm/user/murphythecat Thread Starter

    Location:
    Canada
    as far as i understand, the madisound graph is not accurate in the bass section measurements. In the madisound cab, the F3: is around 50hz. and in my room, both speaker are about -6db at 30-35hz. They are not bass monsters but far from being f3:80hz.

    the Seas a26 measurments over to Seas is more represetative of what i hear with the speakers
    SEAS A26 Kit

    so yeah about -6db at 35hz.
     
  5. Folsom

    Folsom Forum Resident

    Location:
    Eastern WA
    Yes, you're getting room gain.
     
  6. Folsom

    Folsom Forum Resident

    Location:
    Eastern WA
    I'm not sure anyone would, but I'm super curious if someone pulled the back lining out and gave it a listen... but leave it on the sides.
     
  7. murphythecat

    murphythecat https://www.last.fm/user/murphythecat Thread Starter

    Location:
    Canada
    the back wall panel is the most important place to treat, as the back wave from the woofer will directly reflect off the back wall panel and go back toward the woofer.
     
  8. Folsom

    Folsom Forum Resident

    Location:
    Eastern WA
    So? Can you explain to me why that is actually a bad thing? I would refer you to Altec speakers that have nothing inside of them and are highly prized.

    If one's goal was to actually just eliminate the backwave from causing as much compression then you'd use an IB or a very long cone to make it disappear. The Q of the box is more so what it's about. The wavelengths are mostly too long to be absorbed a lot by anything you can fit in it. In my experience Q of a box isn't as simple as the given number because aperiodic vents tend to sound good regardless of the rest of the box's Q. I also think it's possible the speaker is a little overdamped - one reason it seems to respond well to less damped tube amps.
     
  9. murphythecat

    murphythecat https://www.last.fm/user/murphythecat Thread Starter

    Location:
    Canada
    @avanti1960
    Since we are both fans and owned many Harbeths model, Id compare the bass performance of the Seas A26 between the Shl5plus (best) and the C7es3(worst).

    I had the Seas A26 and Shl5plus in my room for a month and the Shl5plus went audibly and measureably lower in the subhz territory with authority and did have more control of the bass from 20hz to 60hz. The A26 bass sounded clearer from 60 to 130ish hz. Also, i could feel in my body more the bass on the A26, better tactility and feeling in the guts, this gave the bass a more exciting experience bass wise.

    Id say the A26 bass is much better then C7es3, and worst then Shl5plus overall.
     
    Last edited: Apr 4, 2020
    Jacob29, Salectric and Seafinch like this.
  10. Xaborus

    Xaborus Active Member

    Location:
    USA
    Hey waterclocker! New member here! I've been looking for someone who can compare the Seas A26 kit to the 8008 Corner kit. I was thinking about building one or the other. Could you post your comparison? Thanks!
     
    waterclocker and murphythecat like this.
  11. murphythecat

    murphythecat https://www.last.fm/user/murphythecat Thread Starter

    Location:
    Canada
    on the back wall of my cab, ive installed 5 inch thick roxul. the idea is that it wont absorb bass due to their wavelenght being way too long, but to absorb unwanted mid or lower treble that could be reflected back on the back wall cab and back "thrue" the cone. that's why you see most speakers with extensive damping in the cabs.
    not sure why refer to internal cab dampin as Q. the Q of the aperiodic cab is determined by the density of the foam in the port, not the damping material inside the cab...
     
    waterclocker likes this.
  12. waterclocker

    waterclocker Forum Resident

    Location:
    NW Indiana
    I am still extremely happy with the 8008-Corner and I have not gone back to the A26. No doubt the A26 are excellent, but 8008 are closer to full range and perform much better with low power tube amps.
    My room is quite small, at 9.5' by 13' and the 8008 are a beautiful match. They dig deep with low power, like really deep compared to the A26. I think the A26 need more power behind them to be the best
    and a subwoofer wouldn't hurt either. Otherwise, the mids and highs are pretty comparable between the two, very clear and realistic sounding with great gear behind them. I would highly recommend using
    excellent quality caps on the tweeter circuit for both designs, I have Mundorf Supreme Gold/Silver on the A26 and Jantzen Alumen Z in the 8008. The only place the A26 wins out for me is slam from the larger
    woofer and only if you have a decent amount of power. For my taste, I have not found anything better than a low power SET or SEP amp on the 8008. I recently borrowed a 2A3 SET amp from a friend and I couldn't
    believe what 3.5 wpc can do with the 8008. My 11 wpc SEP amp digs a bit lower in the bass, but the transformers are also massive in comparison. Either can play louder than I can stand in that room and do
    well with all types of music. I'll often throw on some Daft Punk and crank it up while I work around the house. I probably wouldn't do the 8008 in a large room or without putting them near the corners. I tried
    the 8008 in my larger basement area, but they didn't really work there, not enough bass reinforcement. System synergy and the room are very important with the 8008. Tekton Perfect SET ended up working
    well in the basement, but I still like the 8008 more. The Tekton have better dynamics, but there is a certain richness, vibrance, and synergy the 8008 have with low power tube amps. I hope that helps! The 8008
    will soon be getting a walnut veneer, so A26 will be my backup while I work on them :)
     
    Xaborus likes this.
  13. Folsom

    Folsom Forum Resident

    Location:
    Eastern WA
    I would contest the "unwanted" part in many cases.

    Damping is measured in Q. There is no port. The aperiodic vent does not resonate with the woofer. But it does providing a type of damping by being a tuned "leaky" vent. When you model a speaker and add an aperiodic vent you lower the Q from the typical .707 box.
     
  14. Xaborus

    Xaborus Active Member

    Location:
    USA
    Thanks Waterclocker! I really appreciate the feedback!

    Oh man this is a hard decision... the 8008 Corner kit seems double the price... but may just be "end game" and save me from the expenses of adding a subwoofer.

    Unrelated, but It doesn't help that the Klipsch Heresy IV are getting treat reviews too lol.

    I appreciate you adding on info about the Perfect SET's! I actually was looking at those too!
     
    waterclocker likes this.
  15. Kaiser Soze

    Kaiser Soze Member

    Location:
    North Carolina
    Howdy folks. I have recently developed some interest in this speaker kit, and a web search led me here. I was happy to find a forum where people are discussing this speaker. I am interested in other people's opinions, and am glad to hear that the people who have bought this kit like it.

    One thought that I'll share right away concerns the enclosure, its size, and the bass rolloff. It is a complicated question, but often something that happened a lifetime ago was done out of necessity and over time the reason it was done has been forgotten. I'm trying to say that it may be that the aperiodic port wasn't so much part of the goal of the design but was something that was necessary because if the enclosure were sealed, it would have been very large. There is no way to know whether the new Seas' driver is a perfect match to the original, and most likely it is not, but in any case if you were to want to use this woofer in an acoustic suspension design, the enclosure would need to be about 2.7 cubic feet, for Qtc = .71. If you are amenable to a higher value of Qtc = .8, then it will be 2 cubic feet, about the same size as the Large Advent. This posits an interesting alternative: buy just the parts and buy an older but decent pair of big Advents off eBay, use the Advent enclosure and sell the Advent parts back on eBay. By the way, to know how much stuffing to use, you talk directly into the enclosure (with the driver removed) and listen to the reverberant sound you make, then add stuffing incrementally until the reverberant sound isn't noticeable.

    The aperiodic "vent" is really just an opening in the enclosure that serves the purpose of lowering the Q (Qtc) by weakening the pneumatic spring. That's all. Obviously this isn't free, or all speakers would use the trick. I don't think it is difficult to figure out that the back wave is going to escape through the opening and cancel with the front wave, thereby reducing the bass. In theory this will be a gradual effect occurring throughout the woofer's range. If it were a Linkwitz-style open baffle speaker the rolloff would be (if my memory is correct) -6 dB/octave. The new A26 isn't a completely open baffle so it won't be anywhere near that great, but regardless of how much it actually is, loss of bass will absolutely, positively be an overt, primary effect of that aperiodic "port". It isn't like a bass reflex speaker (don't like them BTW) because there is no Helmholtz radiator effect - this effect requires an air mass within a tube. There is no tube. Just a hole with some acoustic impedance added to it. I think it is also interesting that you can get the exact same effect by using a smaller hole without the added acoustic impedance. I don't know how much smaller the hole would need to be, but I know for a fact that there is a size such that the acoustic impedance will be the same as it is with the big conspicuous ugly hole with the damping material, and that the effect would be altogether the same.

    If you calculate the theoretical -3 dB point for a sealed enclosure, it works out to about 45 Hz, which isn't bad at all. It will be essentially the same whether Qtc is .7 or .8.

    I'm actually contemplating going the route of using an old Advent cabinet. Those things are plentiful on eBay, USA Audio Mart, etc. Of course most of them are beat up, but there are some good ones. I haven't decided whether to do that, or whether to build some cabinets from scratch (ugh), or what exactly. What I'm actually pondering is a way to make the Seas cabinet larger by about 1.5 cubic feet, using a custom stand that will look like a stand but will actually be an addition to the speaker. I think this is a serious possibility, and I think there are ways to do it that shouldn't be terribly difficult. But it probably will mean cutting a big hole in the bottom of that lovely Madisound cabinet. The more I think about it, the more I think this is a feasibly option.

    The think I like least about this speaker is the cost of the tweeter. Most of the cost of the kit is to pay for the tweeters. The tweeter has a nice smooth rolloff without the sharp knee that is typical of most tweeters. This is a critical property given that the tweeter will contribute significantly to the midrange output. But even with this requirement, there's just about got to be other tweeters that are similar, even a bit larger, that can be made to work with a capacitor and resistor in series. Different values for the capacitor and resistor, most likely, but so what. There's just gotta be three or four hundred dollars to be saved by finding an alternative tweeter.

    I didn't intend to write this much, and I apologize for butting in here and being so free with my opinions. I hope I haven't offended anyone. I really, really like this kit, but I think that it is the woofer that makes it special, and the woofer isn't expensive enough to justify the cost of the kit. There's just got to be other tweeters that will work just as well.
     
    Gumboo likes this.
  16. Helom

    Helom Forum member

    Location:
    U.S.
    I finally took the plunge and ordered the A26 kit. Bought the cherry cabinets too since they're not that big an upcharge. If I like the sound of these drivers I can build better cabs in the future. I plan to line the insides of the Madisound cabs with No-Rez damping material from GR Research.

    For those interested in this kit, there is a cheaper tweeter option in the Seas Prestige 27TDFC. The only caveat is it has a different diameter so won't fit the baffle cut-outs of the Madisound cabs. I've heard variations of this tweeter and it's pretty darn good.
     
  17. murphythecat

    murphythecat https://www.last.fm/user/murphythecat Thread Starter

    Location:
    Canada
    ill be very curious what you think of them! yes, highly recommended to line the back panel with some absorption: ive used roxul.
    I settled with the 12 ohm resistor btw.
     
    Helom likes this.
  18. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    be careful subing that tweeter, it is truly unique for the job with a bigger diameter and able to cross over at a low frequency at the woofer’s comfortable hand off point. look at the madisound spec sheets and freq resp plots for the individual drivers.
    i looked at them as a possible DIY project and would not have subbed that tweeter.
     
    Helom likes this.
  19. Wayne Nielson

    Wayne Nielson Forum Resident

    Location:
    My House
    [​IMG]

    I designed these A25XL speakers years ago before the SEAS A26 ever existed. I eliminated the grill, removed the front baffle edge, made them mirror image and had the "teak" veneer on all sides, including the back. The aperodic vent was also inverted for cosmetic reasons.

    Only mod to the internals was a new 8.0uf cap and a complete cleaning of the 3 position level switch. These are called the A25XLCDB speakers. The cabinets were built by a fellow I know that makes cabinet displays for the U of M. He is a master craftsman. The seams are perfect. The teak is also on the inside of the cabinet, as he claims that having the veneer on both sides stabilizes the cabinet thru weather changes.

    Wayner
     
    Last edited: Aug 6, 2020
    33na3rd likes this.
  20. Helom

    Helom Forum member

    Location:
    U.S.
    The alternative tweeter I mentioned has the same recommended low-limit crossover point as the larger unit, but you're correct that it will behave differently in terms of dispersion. It is closer in sensitivity to the woofer however so requires less padding.
     
    avanti1960 likes this.
  21. Helom

    Helom Forum member

    Location:
    U.S.
    To post a pic here you have to use an image-hosting app like Imgur.

    https://forums.stevehoffman.tv/threads/can-someone-please-explain-how-to-upload-images.643380/
     
  22. Wayne Nielson

    Wayne Nielson Forum Resident

    Location:
    My House
  23. Helom

    Helom Forum member

    Location:
    U.S.
    It’s not visible on my end, just a broken-image icon.
     
    bajaed likes this.
  24. Wayne Nielson

    Wayne Nielson Forum Resident

    Location:
    My House
    Well, I guess that's the end of posting.
     
  25. bajaed

    bajaed Forum Resident

    Well we would love to see them!
     

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