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    BiAmp Experiment

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    LeGrace

    Posts : 237
    Join date : 2016-08-07
    Location : Ontario, Canada

    BiAmp Experiment

    Post by LeGrace on Wed Dec 28, 2016 9:05 pm

    Decided to try biamping. Speakers are Tannoy D700's, dual 10" drivers. Decided to try driving the top dual concentric 10's with the M125's in triode mode, and the lower bass 10's with my SS Marantz PM11S1. Love it! Wish i had investigated  this sooner! Normally biamping is non productive, but I'm learning there are exceptions...

    Dogstar

    Posts : 292
    Join date : 2014-06-23

    Re: BiAmp Experiment

    Post by Dogstar on Wed Dec 28, 2016 10:39 pm

    Did you use any type of a crossover, active or passive, to control the power going to speakers since your two types of amps are not similar? I'm asking because I currently building a Tubelab Simple Single Ended amp and I was think of trying something like what you've done though I figured I'd need to use some type of crossover. The SSE amp puts out about 8 watts and I I know it's a little low but I was building the amp as an experiment.

    Tubelab also offers a board to build to build a push pull amp using EL84 power tubes. That amp puts out 18 wpc. Similar to an ST-35. That amp might work nicely as well.
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    LeGrace

    Posts : 237
    Join date : 2016-08-07
    Location : Ontario, Canada

    Re: BiAmp Experiment

    Post by LeGrace on Thu Dec 29, 2016 11:47 am

    Not in the classical sense of fully external with nothing internal to the speakers. But do have something rudimentary. M125's are connected through an external high pass crossover set at 160 hz.  

    Main interest in trying this was as a way to augment anemic triode mode. The extra 100w/ch out from the SS unit certainly amps up the bass! The M-125's still deliver the warmness of triode into the mids and highs, but now without worry of starving the bass as volumes increase. In UL mode the M-125's were more then up to the job, but I simply prefer the triode sound.  The associated power penalty is where things were going a bit pear shaped.

    This in turn has allowed me to convert the M-125's back over to dual tube format w/o sacrificing anything this time around. Quite pleased with how it all sounds now, a really nice full bodied presentation overall.

    Your 8w SSE could be fine if all it will be driving is the upper end. Anyway pays to experiment!
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    tajanes

    Posts : 19
    Join date : 2015-02-07
    Location : Chicago

    passive high pass filters

    Post by tajanes on Sun Oct 22, 2017 11:00 am

    I've calculated and ran (based upon input resistance of 270,000 of ST-120) two .01 caps in series (net .005) and placed btwn preamp and tube amp - it does attenuate the lows +/- 117Hz but only 1st order. Goal is to limit the range that the st-120 needs to work with - as I'm biamping, using the tube amp for mid and tw, keeping the speakers crossovers - and want to put in a high-pass that while reducing freq range of tube amp stays below the speaker's crossover range.

    Couple of questions:

    a) Are there advantage(s) to pulling out the lows pre-tube amp in this situation (i.e. not implementing a true active crossover, just trying to filter out the lows) or is a tube amp that generates a full range benefitted by not having connection to the low pass section (and hence the woofer) of a speaker's crossover anyway?
    b) Tried to do some math on a 2nd order pre-tube high pass filter, with input resistance of amp seems the inductor’s value would be basically a non-starter?

    Suggestions welcome- thanks

    Andy
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    deepee99

    Posts : 1774
    Join date : 2012-05-23
    Location : Wallace, Idaho

    This might be helpful

    Post by deepee99 on Wed Oct 25, 2017 11:05 am

    This is a typical review of the Vandersteen 5A series speakers, but beginning on Page 5 is a pretty helpful description of his use of hi-by pass filters between the pre- and power amps, and how same is recovered in the powered subwoofs.
    http://vandersteen.com/media/files/Reprints/5areviewaudioperfectionist.pdf
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    tajanes

    Posts : 19
    Join date : 2015-02-07
    Location : Chicago

    deepee99 - thx

    Post by tajanes on Wed Oct 25, 2017 1:26 pm

    Appreciate the link.

    Interestingly, the Vandies roll-off the low bass pre-amp (battery biased cap), then at the speaker’s sub/woofer amp compensate for the 1st order attenuation of these frequencies from the main signal…

    ...actually somewhat doable… using a dsp amp with your bass woofer…

    q remains is does the 6db pre-amp low bass signal attenuation (via the cap) protect a tube amp sufficiently from an unloaded low frequency work load ? guessing more than likely, or at least better than no attenuation



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    4MarkNY

    Posts : 21
    Join date : 2009-10-13

    Re: BiAmp Experiment

    Post by 4MarkNY on Sat Nov 04, 2017 8:38 am

    I have a set of Vandersteen 2ce that came to me recently that I have connected to my Dynaco VTA ST-70, and various preamps (PAS 3, ADcom, McIntosh). I just received a set of Y rca plugs last night, so I'm going to experiment with Bi-amping the Vandersteens to try this myself-likely with a SAE amp sitting on a self unused-
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    deepee99

    Posts : 1774
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: BiAmp Experiment

    Post by deepee99 on Sat Nov 04, 2017 11:49 am

    4MarkNY wrote:I have a set of Vandersteen 2ce that came to me recently that I have connected to my Dynaco VTA ST-70, and various preamps  (PAS 3, ADcom, McIntosh). I just received a set of Y rca plugs last night, so I'm going to experiment with Bi-amping the Vandersteens to try this myself-likely with a SAE amp sitting on a self unused-

    The Vandy 2ce's (I've owned a pair) are about as wimpy in the bass frequencies as Maggies are at sane SPLs. If you really want to get the most out of them, you'll need a subwoofer of some sorts. The SAE I am sure has enough juice to power a decent-sized Dayton or somesuch, which can be had without a lot of cabbage. Without a high-bypass filter, the output tubes will still be pumping at those lower frequencies, but you will most likely get the "full spectrum" at much lower volume levels. Good luck and keep us posted on your results.
    Cheers,
    deepee

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