Vertical or Horizontal Bi-Amping for MWM/402?

[Ziggurat]

I have a pair of K402 / 691's on their way to me, as well as a Xilica 8080.  I'm going to build SMWM's a-la DaveA.

 

Currently I have a Prima Luna Dialogue HP Premium integrated that has inputs allowing me to bypass the pre-amp section of this amp.  My thoughts were that I could grab a decent SS power amp to drive the bass section, and use the EL34-based Prima Luna for mid/highs, in a horizontal biamp system.

 

How does this plan stack up?

 

I see that many of you are operate vertical bi-amp systems using Crown amps and similar. Having had no opportunity to listen to any of this gear, I'm basically taking a leap of faith based on your experiences written out on this forum, so I am interested in your opinions. 

 

Am I wasting time considering horizontal bi-amping? Should I factor in a two-amp purchase and go straight to a vertical system?

 

Maybe I am suffering from audiophile snobbery, but I am struggling to shake the belief that a PA-grade amp will do an equal or better job than a good EL34 amp up top, even if vertical bi-amping is a "better" way to do things. I am more than happy to be schooled on this though!

 

Appreciate your thoughts.

[MenloBob]

Personally this is an ideal setup if you're into the tube sound. A few will say that having identical amps for the low/high on each side make the gain alignment easier. But no one running anything active should be doing so without REW and a calibrated measurement mic. It only takes a few passes with REW to get your gains perfectly aligned between top and bottom no matter what the amp combo. The horizontal config will give you the tube tone you're looking for without dropping a mint on an amp for the bottom end. 

 

There's a number of members here who would be happy to help you get this dialed in.

[Chris A]

I use horizontal bi-amping exclusively, if for no other reason that the stereo pair of loudspeakers will see the same amplifier characteristics on the left channel as the right.  I find that this is much more important to lock in the stereo imaging than to do vertical bi-amping and wonder if your left channel amplifier has the same characteristics as the right.  I've experienced wandering stereo images with frequency in a pair of co-axial full-range drivers before as a kid.  I don't want to ever have to deal with that again...because it really negates any phantom center imaging effect.

 

Chris

[babadono]

1 hour ago, Ziggurat said:

How does this plan stack up?

Stacks well. I never knew the horizontal vs vertical terminology but to me it only makes sense if you have two different stereo amps to do stereo biamping you would want to match the 2 bass bins with one amp and the HF horns with the other. Vertical only makes sense to me if you have 4 identical amp channels.

[AHall]

I use a vta70 with el34 tubes on the 402 and anthem mca20 on the jube bass bin. When I was first learning rew/xconsole and having Chris do all my peq via email I used 4ch on my anthem mca50 amp to simplifies things. Now that I’m more familiar with things I found the gain matching portion very easy. I’m much happier with tubes up top. Best of both worlds. 

[Ziggurat]

This is all very very good news. Thanks heaps!

[Ziggurat]

1 hour ago, babadono said:

Stacks well. I never knew the horizontal vs vertical terminology but to me it only makes sense if you have two different stereo amps to do stereo biamping you would want to match the 2 bass bins with one amp and the HF horns with the other. Vertical only makes sense to me if you have 4 identical amp channels.

 

Totally. I would only consider vertical bi-amping if i had four identical channels of amplification, hence the question.

 

I could go out and buy two identical high quality stereo amps at this point for vertical, or buy just the one stereo solid-state amp and use it for the low freq in a horizontal bi-amp system, retaining my EL34s for the high-freq. This looks like it is the way forward. 

[Coytee]

2 hours ago, Ziggurat said:

 Having had no opportunity to listen to any of this gear, I'm basically taking a leap of faith based on your experiences written out on this forum, so I am interested in your opinions. 

 

Boy are you in for a surprise!

 

 

For me, it's vertical but if you want to use the tube amp then I'd go horizontal and give that a whirl.

[babadono]

5 minutes ago, Coytee said:

 

Boy are you in for a surprise!

 

 

For me, it's vertical but if you want to use the tube amp then I'd go horizontal and give that a whirl.

Yes I  concur I think @Ziggurat is going to be mucho happy. The 402s are amazing horns.

Horn if you're honky

[Ziggurat]

Thanks for the encouragement!

 

I've had discussions with a few of you via email and the forum here.  By all accounts the new setup should be in a different league to my current Altec 19s - which I totally love.  Seems like I won't be able to go wrong. 

 

In fact... I am going to run the K691's in on top of the 19's when they arrive - temporarily using the Altec network to drive them instead of the 811b horn and driver. That in itself will be an interesting experience. I will put up some pics. 

 

The K402 setup is a month or so away, so I am chafing at the bit, and working through plans for their arrival.

 

Thanks again!

Edited May 17, 2019 by Ziggurat

[glens]

7 minutes ago, Ziggurat said:

In fact... I am going to run the K691's in on top of the 19's when they arrive - temporarily using the Altec network to drive them instead of the 811b horn and driver. That in itself will be an interesting experience. I will put up some pics. 

 

Interesting perhaps but I wouldn't reach any conclusions when doing that.  The Klipsch horn is going to need some frequency shaping not provided by that network.

[Ziggurat]

1 minute ago, glens said:

 

Interesting perhaps but I wouldn't reach any conclusions when doing that.  The Klipsch horn is going to need some frequency shaping not provided by that network.

 

Absolutely. It will only be for a bit of fun.  I will save the fine tuning for once I have built the bass horns. The Altec XOs have a little bit of adjustment available by the L-Pads, but I am sure you are right.

 

I also considered making some throat adapters for the K402s permitting me to bolt on the Altec drivers.... but it would be a wasted effort unless I could do it quickly. Even then, it would be a short term folly just for fun.

[glens]

Bolting on that driver might be worth the experimental effort, but you'd still need some frequency shaping for the horn.  Somewhere around here is a schematic for a passive network for that horn (and the specific driver that was used).  The LCR stuff (beyond the simple series capacitors and parallel inductors) in parallel with the driver does that shaping - the horn is more constant directivity (a good thing) at the expense of constant response.  Level matching should work well with the L-pad in that network if memory serves.

[Ziggurat]

16 hours ago, glens said:

Bolting on that driver might be worth the experimental effort.....

 

Well I suppose I could spin something up on the lathe.... will see what the K691 sounds like, in the first instance.

[Islander]

Going with horizontal bi-amping makes sense in a few ways.  Both woofers are powered by their amp, and both tweeters are powered by their amp.  This keeps things consistent from left to right, which is important for stereo imaging.

 

Many people think that since they like the sound of low power tube amps, those are a better choice to power the tweeters, but when the crossover point is really low, like the 480 Hz. or so of the Jubilees and presumably the Super MWMs, the load is divided fairly evenly between the bass and treble amps.  The bass amp covers roughly the 5 bottom octaves 20-480 Hz., while the treble amp covers roughly the top 5 octaves 480-20K Hz.  This is quite different from the typical 1800 Hz. crossover point of many smaller speakers.

 

Accordingly, it makes more sense to get either a matching pair of fairly powerful tube amps, or a matching pair of fairly powerful SS amps, whichever you prefer.  This way, the sound has tonal consistency from bottom to top, plus the gain matching is much simpler.

[mikebse2a3]

23 minutes ago, Islander said:

Many people think that since they like the sound of low power tube amps, those are a better choice to power the tweeters, but when the crossover point is really low, like the 480 Hz. or so of the Jubilees and presumably the Super MWMs, the load is divided fairly evenly between the bass and treble amps.  The bass amp covers roughly the 5 bottom octaves 20-480 Hz., while the treble amp covers roughly the top 5 octaves 480-20K Hz.  This is quite different from the typical 1800 Hz. crossover point of many smaller speakers.

 

Actually the K402/K69 and K402/TAD4002 are up to 10db more efficient than the Jubilee LF and this is reflected in the reduction in power requirements demanded of the HF amplifier. 

 

Example: This is typical of what I see with Vertical Bi-amping:

 

Left Meter is Jubilee LF ~.5 watts

Right Meter is K402/TAD4002 ~.05 watts

 

 

[mikebse2a3]

35 minutes ago, Islander said:

Going with horizontal bi-amping makes sense in a few ways.  Both woofers are powered by their amp, and both tweeters are powered by their amp.  This keeps things consistent from left to right, which is important for stereo imaging.

 

Vertical Bi-amping has the maximum db of channel separation which offers the best possibility for imaging also IMHO.

 

miketn

[Islander]

1 hour ago, mikebse2a3 said:

 

Vertical Bi-amping has the maximum db of channel separation which offers the best possibility for imaging also IMHO.

 

miketn

 

To respond to both of your posts, first, the big blue dials make a convincing case.  Is the sensitivity ratio between the 402/691 and the La Scala II LF pretty much the same as that between the 402/TAD4002 and the Jubilee LF?

 

As for which way to bi-amp, what you say makes sense, but it just seems odd to me to have one side of an amp handling bass, while the other channel handles treble, with the same situation driving the other speaker.  I know, that may sound a bit silly, but it offends my sense of symmetry, if that makes any sense.

 

As for channel separation, my MX-D1 power amps are dual-mono, rather than regular stereo, and each channel has its own power supply. The crosstalk is rated at 100 dB, and that number was confirmed in the Stereophile lab test.  Right now, I’m listening to All Blues (the weekend evening blues program) on KNKX on Net Radio, and those amps and speakers sound great to me.

[mikebse2a3]

1 hour ago, Islander said:

To respond to both of your posts, first, the big blue dials make a convincing case.  Is the sensitivity ratio between the 402/691 and the La Scala II LF pretty much the same as that between the 402/TAD4002 and the Jubilee LF?

 

Yes it should be very close.

 

1 hour ago, Islander said:

As for which way to bi-amp, what you say makes sense, but it just seems odd to me to have one side of an amp handling bass, while the other channel handles treble, with the same situation driving the other speaker.  I know, that may sound a bit silly, but it offends my sense of symmetry, if that makes any sense.

 

Don’t be offended my friend.. 😄

 

Curious why would you feel symmetry is better off when a stereo amplifier in Horizontal  Bi-amping is handling L and R signals that exhibit very little symmetry in a stereo recording?

 

1 hour ago, Islander said:

As for channel separation, my MX-D1 power amps are dual-mono, rather than regular stereo, and each channel has its own power supply. The crosstalk is rated at 100 dB, and that number was confirmed in the Stereophile lab test.  Right now, I’m listening to All Blues (the weekend evening blues program) on KNKX on Net Radio, and those amps and speakers sound great to me.

 

Vertical Bi-amping involves stereo amplifiers sharing a common power supply anytime I’ve seen it described.

 

If you have true mono amplifiers (regardless of if they share a common chassis) then I wouldn’t consider that as Vertical Bi-amping but does have the potential to technically out perform Vertical Bi-amping with stereo amplifiers.

 

 miketn 🙂

[Islander]

No, I’m not offended at all.  Sure, stereo signals do differ from left to right, but are more alike than when one side is powering the bass content and the other one is driving the treble content.  In my imagination, the amps would be carrying lopsided loads.  I did say it was a bit silly.

 

As for the dual-mono part, I’ve seen and posted pictures of the insides of the MX-D1 amp in the past.  There’s two of everything, except for the power lead in and the on-off switch.  It was a statement product for Yamaha, with minimal compromises, and able to power any kind of speaker, even down to 2 ohms.  That’s probably why MSRP was $5,000 when they came out in 2005.  Unfortunately, having a mid-fi name on a hi-fi product didn’t help sales, kind of like the first-gen Ford GT.  “Sure, it’s fast and all that, but it’s a Ford.  For that money I could buy a Ferrari.”

 

In regards to the horizontal/vertical thing, one amp doing bass and the other one doing treble is horizontal, right?  I can safely say that this kind of thing never ever comes up in any conversations with my non-audio fan friends, which is most of them.