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SUB THREE (Stereo Pair) Implementation with BAT Tube Mono Blocks


Schuesmp
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I am considering adding two Vandersteen SUB THREE subwoofers to one of my two-channel audio systems. The system features JBL L300 Summit speakers (circa 1980) and two Balanced Audio Technology (BAT) VK-76SE vacuum tube power amplifiers configured “by wire” as mono blocks. The focus of this post is proper implementation of the Vandersteen M5 High-Pass Crossovers (specifically, model M5-HPB) with the aforementioned “by wire” configuration of the BAT mono block power amplifiers.

This configuration involves the following:

BAT VK-53SE preamplifier -> Pair of XLR analog interconnects -> Pair of Y cables (single XLR female to double XLR males) -> BAT VK-76SE power amplifiers (each of the Y cable XLR males connect to one input of each BAT power amplifier - four connections in total) - Jumper cables connect the left and right speaker outputs of each BAT power amplifier to fully achieve the “by wire”  mono block configuration -> Speaker cable from one pair of speaker outputs (binding posts) of the interconnected speaker outputs -> JBL L300 Summit Speakers

My sense is that I would simply insert each Vandersteen M5-HPB High-Pass Crossover between the applicable XLR analog interconnect cable from the preamplifier and the applicable Y cable, but I may be missing an important consideration or obstacle. For example, does the connection scheme impact selection of the appropriate input impedance rating within the M5-HPB? The manufacturer of the power amplifiers (BAT) identifies the input impedance of each phase as 100k ohms (200k ohms summed). Intuitively I would select 200k ohms in each M5-HPB but, again, I may be missing an important consideration.

Of course, in view of the benefits of potentially adding two Vandersteen SUB THREE subwoofers (e.g., relieving the power amplifier of low frequency output) and the relatively high sensitivity without substantial impedance dips of the JBL’s, I could simplify the setup significantly by running only a single BAT VK-76SE power amplifier in stereo mode, outputting a very beefy 75 watts per channel (150 in the current mono block configuration), but I would like to avoid this compromise if possible.

The forum’s guidance and views would be greatly appreciated!

        

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  • Schuesmp changed the title to SUB THREE (Stereo Pair) Implementation with BAT Tube Mono Blocks
20 minutes ago, TomicTime said:

I think RV should comment on the proper place and DIP switch setting for the M5 filter.  The hipass will certainly take load off the amp and L-300 and two Sub 3 will allow for fixing room modes. I have a sub 3 w Treo… love it.

Best

Jim

Thanks for the reply, TomicTime.

As an owner of Quatro Wood CT's, and especially because I recently successfully completed the task of resetting the EQ of their powered bass sections after relocating the speakers, I fully subscribe to the benefits of the combined high pass crossover and adjustable bass. Based on my in-room measurements of the JBL L300 Summit's, I feel I know exactly how I would mitigate a few dips and peaks below 100 Hz using the EQ's of the SUB THREE's.

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3 hours ago, Schuesmp said:

I am considering adding two Vandersteen SUB THREE subwoofers to one of my two-channel audio systems. The system features JBL L300 Summit speakers (circa 1980) and two Balanced Audio Technology (BAT) VK-76SE vacuum tube power amplifiers configured “by wire” as mono blocks. The focus of this post is proper implementation of the Vandersteen M5 High-Pass Crossovers (specifically, model M5-HPB) with the aforementioned “by wire” configuration of the BAT mono block power amplifiers.

This configuration involves the following:

BAT VK-53SE preamplifier -> Pair of XLR analog interconnects -> Pair of Y cables (single XLR female to double XLR males) -> BAT VK-76SE power amplifiers (each of the Y cable XLR males connect to one input of each BAT power amplifier - four connections in total) - Jumper cables connect the left and right speaker outputs of each BAT power amplifier to fully achieve the “by wire”  mono block configuration -> Speaker cable from one pair of speaker outputs (binding posts) of the interconnected speaker outputs -> JBL L300 Summit Speakers

My sense is that I would simply insert each Vandersteen M5-HPB High-Pass Crossover between the applicable XLR analog interconnect cable from the preamplifier and the applicable Y cable, but I may be missing an important consideration or obstacle. For example, does the connection scheme impact selection of the appropriate input impedance rating within the M5-HPB? The manufacturer of the power amplifiers (BAT) identifies the input impedance of each phase as 100k ohms (200k ohms summed). Intuitively I would select 200k ohms in each M5-HPB but, again, I may be missing an important consideration.

Of course, in view of the benefits of potentially adding two Vandersteen SUB THREE subwoofers (e.g., relieving the power amplifier of low frequency output) and the relatively high sensitivity without substantial impedance dips of the JBL’s, I could simplify the setup significantly by running only a single BAT VK-76SE power amplifier in stereo mode, outputting a very beefy 75 watts per channel (150 in the current mono block configuration), but I would like to avoid this compromise if possible.

The forum’s guidance and views would be greatly appreciated!

        

If I understand correctly you are trying to add a pair of SUB THREEs to the JBL's.  This will not work so well as the SUB THREEs are not sensitive enough and they are sealed 2nd order woofers.  This most likely will not blend well with the JBL's as they are a 4th order bass alignment.  This would require some finagling for sure, but I am not certain it will work with the adjustments available.  You would have to try it.  RV 

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Richard: You understood correctly. The 15-inch woofer of the JBL L300 crosses over to the midrange compression driver at 800 Hz, so I presumed a seamless blend with a SUB THREE would be possible. I appreciate your expert, cautionary view.

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15 hours ago, Schuesmp said:

I am considering adding two Vandersteen SUB THREE subwoofers to one of my two-channel audio systems. The system features JBL L300 Summit speakers (circa 1980) and two Balanced Audio Technology (BAT) VK-76SE vacuum tube power amplifiers configured “by wire” as mono blocks. The focus of this post is proper implementation of the Vandersteen M5 High-Pass Crossovers (specifically, model M5-HPB) with the aforementioned “by wire” configuration of the BAT mono block power amplifiers.

This configuration involves the following:

BAT VK-53SE preamplifier -> Pair of XLR analog interconnects -> Pair of Y cables (single XLR female to double XLR males) -> BAT VK-76SE power amplifiers (each of the Y cable XLR males connect to one input of each BAT power amplifier - four connections in total) - Jumper cables connect the left and right speaker outputs of each BAT power amplifier to fully achieve the “by wire”  mono block configuration -> Speaker cable from one pair of speaker outputs (binding posts) of the interconnected speaker outputs -> JBL L300 Summit Speakers

My sense is that I would simply insert each Vandersteen M5-HPB High-Pass Crossover between the applicable XLR analog interconnect cable from the preamplifier and the applicable Y cable, but I may be missing an important consideration or obstacle. For example, does the connection scheme impact selection of the appropriate input impedance rating within the M5-HPB? The manufacturer of the power amplifiers (BAT) identifies the input impedance of each phase as 100k ohms (200k ohms summed). Intuitively I would select 200k ohms in each M5-HPB but, again, I may be missing an important consideration.

Of course, in view of the benefits of potentially adding two Vandersteen SUB THREE subwoofers (e.g., relieving the power amplifier of low frequency output) and the relatively high sensitivity without substantial impedance dips of the JBL’s, I could simplify the setup significantly by running only a single BAT VK-76SE power amplifier in stereo mode, outputting a very beefy 75 watts per channel (150 in the current mono block configuration), but I would like to avoid this compromise if possible.

The forum’s guidance and views would be greatly appreciated!

        

The concern would be the integration between the JBL woofer and the SUB THREE as the phase angle of these two alignments will be a challenge to sum without a huge dip in frequency response which the adjustments available on the SUB THREE won't be able to correct.  RV

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2 hours ago, ctsooner said:

You could sell the JBL’s and get another set of Steens. Lol. 

I could do that, but I am more likely to keep the JBL's and add another pair of Vandersteen's. The vintage JBL's have significant sentimental value to me and sound extraordinary.

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