Calling all tube heads!!

Frank Z
Frank Z Posts: 5,860
edited February 2024 in Clubhouse Archives
I'm not well versed in tube-ology so I need some expert advice/opinions. What do you guys think of this.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3051846867&category=39783&rd=1

Enough juice to power a pair of SDA-2b's?
9/11 - WE WILL NEVER FORGET!! (<---<<click)
2005-06 Club Polk Football Pool Champion!! :D
Post edited by RyanC_Masimo on
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  • RuSsMaN
    RuSsMaN Posts: 17,986
    edited October 2003
    I've been watching that one too.

    Enough for the 2b's? No. I'd go a minimum of 20-25 continuous.

    I've heard the 2b's on 25 watts of class A power and it was PLENTY.

    Cheers,
    Russ
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
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  • organ
    organ Posts: 4,969
    edited October 2003
    What's the efficiency rating fo the SDA? 10 watts doesn't seem much but with tubes, you never know until you try. If you get it and it can't power the SDA, you can always hook them up on a different system with a pair of efficient speakers. My Dyna is 35w/ch but I hear a lot of people saying it's more like 25w and it powers the 4-ohms/88db/w/m LSi9 with ease.

    Try asking the forums on www.audioasylum.com and the tube forum on www.audiokarma.org. I bet you'll find someone there who owns the same amp. Try doing a search on their forums too.

    Maurice
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  • Frank Z
    Frank Z Posts: 5,860
    edited October 2003
    Originally posted by organ
    What's the efficiency rating fo the SDA?

    Good question, I wish I knew!
    9/11 - WE WILL NEVER FORGET!! (<---<<click)
    2005-06 Club Polk Football Pool Champion!! :D
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  • RuSsMaN
    RuSsMaN Posts: 17,986
    edited October 2003
    one 1 inch dome tweeter
    two 6.5" drivers
    one 12" passive
    39 5/8" H x 16 9/16" W x 11 1/2" D
    overall frequency responce 20Hz - 26kHz
    within - 3 db limits 38Hz - 20kHz
    Rec. amplifier 30-350 watts
    Normal Impedance 6 Ohms
    Efficiency 89.7db
    80 lbs. each
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
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  • Frank Z
    Frank Z Posts: 5,860
    edited October 2003
    Originally posted by RuSsMaN

    Efficiency 89.7db

    HMMMMM, I would have expected a higher efficiency rating.

    I was supposed to get my 2b's yesterday, but the UPS guy never showed up. Must have been all liquored up on near beer!!:mad:

    My wife was, and still is pissed!!
    9/11 - WE WILL NEVER FORGET!! (<---<<click)
    2005-06 Club Polk Football Pool Champion!! :D
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  • organ
    organ Posts: 4,969
    edited October 2003
    Ouch, that's going to be tough. I don't think the 10w/ch will provide enough juice especially with those passive 12 inchers. You can try saving a little bit more cash and look for a Dynaco stereo 70. At the moment their price is not going as high as they used to on ebay. It's a 35w/ch push-pull amp.

    Maurice
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  • HBombToo
    HBombToo Posts: 5,256
    edited October 2003
    Originally posted by organ
    I don't think the 10w/ch will provide enough juice especially with those passive 12 inchers.

    Maurice

    Interesting point. If the passive speakers are removed and the hole sealed would the efficiency increase?

    Twin
    ***WAREMTAE***
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  • Frank Z
    Frank Z Posts: 5,860
    edited October 2003
    That's why I asked the question guys, thanks for the assist. Not being familiar with tubes could get me into trouble. I'm not clear on how a tube amp thats only rated at 10, 20, or 30 watts can drive a mid efficiency speaker to even a moderatly high volume.
    9/11 - WE WILL NEVER FORGET!! (<---<<click)
    2005-06 Club Polk Football Pool Champion!! :D
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  • Frank Z
    Frank Z Posts: 5,860
    edited October 2003
    Any thoughts on these mono blocks?

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3053481905&category=39783&rd=1
    9/11 - WE WILL NEVER FORGET!! (<---<<click)
    2005-06 Club Polk Football Pool Champion!! :D
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  • madmax
    madmax Posts: 12,434
    edited October 2003
    Frank Z,
    Those are the real deal! VTL eventually turned into Manley which is now run by David Manleys' ex-wife. The company will no longer service them according to their website but I don't think that matters. A lot of people still service tube amps. I would expect that pair to be worth about $1200 to $1500. I'm sure it would be worth every cent of it too. They are VERY close cousins to my Manleys and should do a wonderful job with SDA's or better.
    madmax
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
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  • burdette
    burdette Posts: 1,194
    edited October 2003
    Originally posted by HBombToo
    If the passive speakers are removed and the hole sealed would the efficiency increase?
    Twin

    I don't know the formulas well enough offhand to answer that for sure... but you'd CERTAINLY be messing up the design. A passive radiator system is a type of bass reflex system, and the overall performance is an integration of the active drivers, the internal volume, and the size and weight of the PR. To simply remove the PR and seal the hole would be akin to taking the port out of a ported system and just sealing it up.

    To do that with any chance of success, you'd have to go back to the beginning and redesign the overall system and recalculate the internal volume... all the while hoping that the active drivers in question would perform well in an acoustic suspension enclosure - all that assuming you could get the T/S parameters from Polk (and they didn't give any to me when I asked) or have the equipment to measure the parameters yourself. I don't think Polk uses its 6.5inchers in AS alignments much.. do they? Aren't even the small bookshelfs ported?

    In short.. sure, you could do it.. but you'd be fundamentally changing the design, and the result would be a crapshoot.
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