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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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    True Bi-Amping

    mazeeff
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    mazeeff


    Posts : 155
    Join date : 2014-01-06
    Age : 69
    Location : Grand Rapids, Michigan, USA
    • Post n°1

    True Bi-Amping Empty True Bi-Amping

    Post by mazeeff Fri Sep 26, 2014 6:27 am

    I am considering running two ST-70's in a true bi-amping mode. The crossover's in the speakers would be completely removed, and replaced with a "low" and "high" input. I would have the option of running the ST-70's vertically or horizontally. In vertical mode, each amp is driving a speaker, whereas in horizontal mode, each amp drives lows or highs. Between my stereo preamp and ST-70's, I would need to add a passive or active crossover. I really like the sound of the EL34's, and would like a little more power than one ST-70 provides. My questions are.

    1. Has anyone tried this? If so, did you like it? Pros or cons?

    2. Should I use vertical or horizontal bi-amping. Vertical results in both amps working in a similar fashion. Horizontal results in one amp being dedicated to lows (the other to highs). This would allow me to set up one amp specifically set up lows, with a set of tubes to complement that arrangement.

    3. What should I use for the crossover? Passive, active, computer driven dsp, etc.

    Thanks,

    Mike
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    Bob Latino
    Bob Latino
    Bob Latino
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    Posts : 3262
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    True Bi-Amping Empty Re: True Bi-Amping

    Post by Bob Latino Fri Sep 26, 2014 9:46 am

    Hi Mike,

    1. I have tried this and it works well with two Dynaco type amps.

    2. I have tried it both ways and with TWO Dynaco type tube amps I feel that vertical biamping is better than horizontal biamping. The two main reasons why I feel vertical biamping is better (when you use a single amp on each stereo channel) are (1) better soundstaging due to the fact that signal isolation is better because each amp is carrying just one audio signal and any bleed over of signal from one channel to the other (in this stereo amp) doesn't make any difference (2) Since the bass notes require more out of the amp's power supply than the treble notes, the bass is split between the power supplies of TWO amps when you vertically biamp.

    The only time I think that horizontal biamping will work better is if you have a hybrid amp situtation with one SS amp and one tube amp. In that case. you would put the SS amp on both bass sections of your system and the tube amp on both top end sections of the speakers.

    3.  I really cannot answer this one as I have never used an active crossover. Customers tell me that they work well. If you have the time and $$$, you might want to experiment with different ways to divide up the audio signal

    Bob

    Below ... Customer from Virginia using two VTA ST-70's to biamp ..

    True Bi-Amping BiampingwithtwoST-70s_zps683cbf7e

    Below ... I used to biamp with two VTA ST-120's on my Magnepan MG 3.6R's but now I have two VTA M-125's on this system.

    True Bi-Amping BiampingapairofMagnepan3_6_zpsc8ad039f

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    wildiowa
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    wildiowa


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    Join date : 2012-03-19
    • Post n°3

    True Bi-Amping Empty Re: True Bi-Amping

    Post by wildiowa Fri Sep 26, 2014 11:03 am

    Not sure I can explain this using the correct terms....but the only thing I can offer in bi-amping is to somehow protect your high end tweeters/horns etc. when you hook up, move or service the system as with no crossover there is no frequency split and an unintentional short or spike or other transient can fry your high end. I was switching inputs experimenting one time and the resulting spike took out the tweeters...forgot with no crossover the full frequency went through the high end. Some people put in a capacitor to offer some protection but not sure how that affects the bi-amping concept....my 2 cents worth.....it really is a drag when you take out your entire high end, and gets expensive too.
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    mazeeff
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    mazeeff


    Posts : 155
    Join date : 2014-01-06
    Age : 69
    Location : Grand Rapids, Michigan, USA
    • Post n°4

    True Bi-Amping Empty Re: True Bi-Amping

    Post by mazeeff Fri Sep 26, 2014 11:05 am

    Bob. Thanks for the most excellent response. I have a couple of questions.

    1. In your vertical bi-amping scenario, what did you feed the input of each amp with? Did you feed the same input to both L/R, or did you use some sort of crossover to split the high/low frequencies?

    2. Did you remove the passive crossovers from the speakers?

    Thanks,

    Mike
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    mazeeff
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    mazeeff


    Posts : 155
    Join date : 2014-01-06
    Age : 69
    Location : Grand Rapids, Michigan, USA
    • Post n°5

    True Bi-Amping Empty Re: True Bi-Amping

    Post by mazeeff Fri Sep 26, 2014 11:08 am

    wildiowa wrote:Not sure I can explain this using the correct terms....but the only thing I can offer in bi-amping is to somehow protect your high end tweeters/horns etc. when you hook up, move or service the system as with no crossover there is no frequency split and an unintentional short or spike or other transient can fry your high end. I was switching inputs experimenting one time and the resulting spike took out the tweeters...forgot with no crossover the full frequency went through the high end. Some people put in a capacitor to offer some protection but not sure how that affects the bi-amping concept....my 2 cents worth.....it really is a drag when you take out your entire high end, and gets expensive too.

    Very good point! I will look at ways to prevent this. Perhaps, I could leave the speaker crossover in for the high end, and drive the woofer directly.


    Last edited by mazeeff on Fri Sep 26, 2014 12:20 pm; edited 1 time in total
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    Bob Latino
    Bob Latino
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    • Post n°6

    True Bi-Amping Empty Re: True Bi-Amping

    Post by Bob Latino Fri Sep 26, 2014 12:06 pm

    mazeeff wrote:Bob. Thanks for the most excellent response. I have a couple of questions.

    1. In your vertical bi-amping scenario, what did you feed the input of each amp with? Did you feed the same input to both L/R, or did you use some sort of crossover to split the high/low frequencies?

    2. Did you remove the passive crossovers from the speakers?

    Thanks,

    Mike

    Hi Mike,

    1. Both VTA ST-120 amps were fed with a preamp that had dual outputs for each channel. If your preamp does not have dual RCA outputs, I am sure you could use a Y connector with a single male plugged into your preamp and then use two interconnects plugged into the two female sections of the Y connector.

    2. No - I used the passive crossovers in the speaker itself.

    Bob
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    • Post n°7

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