Biamp, yea or nay?

One option I have yet to investigate is vertical biamping. I have dual posts so I could connect the woofers to my solid state amp, and place the mid bass and higher on the M125's. My only reservation is the manual for my Polk speakers indicates that any amps used in a biamping configuration should feature identical gain characteristics, which seems unlikely. I've developed a clear preference for Triode mode, and the power output hit is why I'm considering this option. Speakers are only 88 db efficiency. Yea or nay?

What will you be using for a cross over?

Tube Nube wrote:What will you be using for a cross over?

There are two sets of binding posts on the speakers, and the manual says I can use these to either biwire or biamp. Crossover is internal.

LeGrace wrote:One option I have yet to investigate is vertical biamping. I have dual posts so I could connect the woofers to my solid state amp, and place the mid bass and higher on the M125's. My only reservation is the manual for my Polk speakers indicates that any amps used in a biamping configuration should feature identical gain characteristics, which seems unlikely. I've developed a clear preference for Triode mode, and the power output hit is why I'm considering this option. Speakers are only 88 db efficiency. Yea or nay?

I vote nay for simplicity. Do you feel like something is missing?

YIKES!

Why ask at all? Try it, if you like it, stick with it. If not, try something else. At the very least, you will learn something.

That is the nice thing about this hobby - you get to experiment with various options and configurations to see what you really like.

Enjoy!

Traditionally (and that has little force here), bi-amping is for two more-or-less identical amps. But, you have the option of ignoring tradition and perhaps learning something.

Is there anyone familiar with bi-amping to the point they could give an un-bias opinion as to what gain in performance can be attributed to this wiring?
I am not trying to burst anyone's bubble. If bi-amping is in the blood then do what you like and as mentioned in your own words "try it". Using SS for the woofers would take the work off the m125's concentrating on the mids and high's.
Vertical compared to horizontal seems to be the most logical.
Experiment...that's part of the hobby. If it's a small investment and you know what you are doing...why not...you can always go back.
Just don't blow your speakers!!


Example of bi-amping
https://goo.gl/photos/rgEvZnCLnAuU5pXV6

bluemeanies wrote:Is there anyone familiar with bi-amping to the point they could give an un-bias opinion as to what gain in performance can be attributed to this wiring?
I am not trying to burst anyone's bubble. If bi-amping is in the blood then do what you like and as mentioned in your own words "try it". Using SS for the woofers would take the work off the m125's concentrating on the mids and high's.
Vertical compared to horizontal seems to be the most logical.
Experiment...that's part of the hobby. If it's a small investment and you know what you are doing...why not...you can always go back.
Just don't blow your speakers!!

In my *Opinion, Bi-Amping does nothing more than increase the power available to the speaker (AKA: Headroom). Headroom is almost never a bad thing, and almost always a good thing.

I am skeptical about systems that create vast power differences between sections. Keeping in mind what it takes to have a violin compete with an organ, energy levels (again, in my opinion) should be largely equally available to all drivers as needed. NOTE ALSO: good speaker manufacturers recognize this - woofers are seldom liquid cooled, whereas mids and tweets are often so. This is so that they might absorb and survive this energy.

Wild speculation here: As tube amps tend to clip softly, this has given some credence to such power differences, and as it seems to be a 'thing' to have disproportionate bass, that the music may be wildly unbalanced is not perceived as a bad thing. Unless one is positing a sub/sat system, powered sub-woofers are an abomination on this earth whose sole justification is the gradual shrinking of drivers to the point that even 200Hz is a stretch for them. So, let's cram a 15" woofer in a box and call it good. YIKES! I keep two sub/sat  systems, one Revox Piccolo and one AR Athena. They are fine systems when space is a premium, and they were designed from the git-go for the purpose. But a separate sub-woofer to compensate for an otherwise pitifully inadequate so-called "Full Range" speaker is just plain nuts.

Theres lots written about bi amping on the net. It really isnt worth it, according to most, without an active cross over that precedes the power amps. When this is done, the real advantages show--the amps directly control the individual speaker drivers, the amps have to work less hard because they arent dealing with the full frequency spectrum, intermodulation distortion is reduced, blah blah blah.

The speakers internal cross over needs to be diabled for this, by the way.
The trouble is, well, two problems... 1. A good cross over is expensive, 2. Setting it up is fiddly.

Interim solution-- Behringer makes a very affordable cross over that is said to be definitely not hi fi, but it is good enough to let you hear the benefits of active bi amping. I recommend trying it this way, and if you like the effect, consider down the road if a better cross over is woth the money.

Here's my $0.02.

I use my VTA st-70 for the highs.  I have a dbx crossover set at about 300 Hz.  The highs go to the ST70 which drives a pair of horns from the Horn Shoppe.  The lows go to a solid state NAD amp which drives a pair of homemade subwoofers.  

(The rest of the system:  NAD CD player, NAD preamp, Linn Sondek LP12, Schiit Mani phono preamp with Swagman power supply)

I like the resulting sound.  Transients are very clear and distinct, nice soundstage. Have I done an A/B test of biamping vs not biamping?  No, but I trust my ears.

I balanced the outputs to each side by leaving the preamp balance at 12 o'clock and then fiddling with the gain on the crossover.  I didn't use a measuring mike and software, but I did a quick & dirty guesstimation by downloading the Keuwlsoft SPL Meter app for my smartphone.  I put in a CD of pink noise in the CD player and got the speaker outputs to match within one dB.  Maybe someday I'll get more precise, but that got them pretty good for the $ spent  (the app is free, and I don't think I paid much for the pink noise CD-- and anyway, you can now download pink noise samples for free).  

My next upgrade will probably be a tube crossover.  The dbx is okay, but it's really designed for PA systems--but I got it cheap and it's working okay.  I'm lusting after the VTA crossover;  maybe I'll get one for Christmas.

Active crossovers do put a different spin on things as long as the internal crossover is disabled. However, the OP is using the internal crossover. I suspect that in his case, it would require physical modification to the speaker to use an external unit.

Crossovers are (or at least should be) generally passive devices using a series of chokes (AKA inductors) and capacitors to achieve their goals. I would be concerned over an active crossover as there are many additional opportunities to cause distortion - and more concerned over a tube device as tubes are so much more variable than transistors. I guess it gets down to how many "things" are in the signal path.

De gustibus non est disputandum.

Thanks for the insights. This community is both helpful and knowledgeable!

The Polks are on the power hungry side. This would not be the first time biamping them. When I did this before it did help, especially bass performance. Although before I was using identical SS amps. I've come across a few references about mixing SS and tubes in a biamp arrangement. Just not wanting to blow anything up so proceeding cautiously asking questions first!  

Presently I'm using the pre outs on my Marantz integrated, so if I connect its speaker outs to the bass drivers then I'll still be regulating each amp section from a common volume control. Is this adequate to address the gain question? Leaving the crossover question. By not having an external crossover upstream of the amps do I run a risk of over stressing the M125's? Power ratings in this case are not hugely adrift, the Marantz is rated 100w/ch.

Please note the interpolations.

LeGrace wrote:Thanks for the insights. This community is both helpful and knowledgeable!

The Polks are on the power hungry side. This would not be the first time biamping them. When I did this before it did help, especially bass performance. Although before I was using identical SS amps. I've come across a few references about mixing SS and tubes in a biamp arrangement. Just not wanting to blow anything up so proceeding cautiously asking questions first!  

If you use SS for the bass and tube for the mid/treble, you should be fine. As previously noted, tube amps tend to clip softly.

Presently I'm using the pre outs on my Marantz integrated, so if I connect its speaker outs to the bass drivers then I'll still be regulating each amp section from a common volume control. Is this adequate to address the gain question?

Not really. A solid-state amp will respond differently than a tube amp. If either of the amps has an on-board attenuator (volume control), you may need to tweak that somewhat to get to the correct balance, especially as you may have a vastly different power-output one amp to the other. But, try and see if you like the result. The 'worst' that might happen is that you are a bit heavy on the bass. You always have the option of using the tone-controls on the pre-amp to do a bit of tweaking for balance between the mid/tweet and bass.

 Leaving the crossover question. By not having an external crossover upstream of the amps do I run a risk of over stressing the M125's? Power ratings in this case are not hugely adrift, the Marantz is rated 100w/ch.

Tube amps "stress" differently than solid-state amps. By clipping softly, the stress is reduced both to the amp and to the speaker. My best advice is to keep an eye on your OPT temperature until you are sure that they are OK. Put another way, it is unlikely that you will be stressing the tube amp, but that proverbial ounce of prevention is in order.  ONE MORE CAVEAT:  Make absolutely sure that you do not by accident or stray strand of wire connect the outputs of one amp to the outputs of the other. *POOF*.

For bi-amping, I would check out some of the new Class D amps that have built-in xovers. They're dirt-cheap and will run the bass quite well, easing the load on the tubes. Madisound
https://www.madisoundspeakerstore.com/welcome.php
has a good selection and they answer the phone.
Bi-wiring is a conundrum. It makes no sense electrically, but it certainly improved the performance of my Vandersteens and is recommended by him (at least on the 5As) while making no difference on other speakers I have owned.

[quote="LeGrace"]Thanks for the insights. This community is both helpful and knowledgeable!

The Polks are on the power hungry side.

Afterthought:

Yes, Polks are power-pigs. And I have found over the years, the best response to power-pigs is more power, not bi-amping - well more on this in a bit.

I learned that power is power when I had two very, very heavily modified Dynaco ST120s, which I then set up one-each per AR3a speaker. Made a huge difference over only one (1) in the system. However, when I switched to a Citation 19, that difference went away. 120 wpc from one amp vs. 2x60wpc from two amps.

They did even better with the Citation 16.

Then, I tried it with two ST70s. Not so much. Then one each on Mono mode. Not so much.

I appreciate all the help! I'm going to hang tight for now. The old adage if it aint broke don't fix it comes to mind. Besides tube power I'm finding is not the same as SS power. Its sort of like having a 2x barlow lens!

The DIY experience of building the amps was so enjoyable I'm now investigating speaker kits. Along with an external active crossover I'll reserve the biamp opportunity for another day. Thanks again!

LeGrace wrote:I appreciate all the help! I'm going to hang tight for now. The old adage if it aint broke don't fix it comes to mind. Besides tube power I'm finding is not the same as SS power. Its sort of like having a 2x barlow lens!

The DIY experience of building the amps was so enjoyable I'm now investigating speaker kits. Along with an external active crossover I'll reserve the biamp opportunity for another day. Thanks again!  

Toob watts are much bigger than transistor watts, and longer and fatter, too.

LeGrace wrote:I appreciate all the help! I'm going to hang tight for now. The old adage if it aint broke don't fix it comes to mind. Besides tube power I'm finding is not the same as SS power. Its sort of like having a 2x barlow lens!

The DIY experience of building the amps was so enjoyable I'm now investigating speaker kits. Along with an external active crossover I'll reserve the biamp opportunity for another day. Thanks again!  

Wise man.

Within their comfortable operating parameters, watts is watts, whether tube or transistor.

Outside of those parameters, tube amps typically clip far more softly, and so tend to sound better at the margins.

Mostly why brute-force amps tend to be solid-state - as they need to be.

Peter W. wrote:

LeGrace wrote:I appreciate all the help! I'm going to hang tight for now. The old adage if it aint broke don't fix it comes to mind. Besides tube power I'm finding is not the same as SS power. Its sort of like having a 2x barlow lens!

The DIY experience of building the amps was so enjoyable I'm now investigating speaker kits. Along with an external active crossover I'll reserve the biamp opportunity for another day. Thanks again!  

Wise man.

Within their comfortable operating parameters, watts is watts, whether tube or transistor.

Outside of those parameters, tube amps typically clip far more softly, and so tend to sound better at the margins.

Mostly why brute-force amps tend to be solid-state - as they need to be.

Yes Peter, but remember, as regards high-powered amps: the fuses in a tube amp are there to protect the tubes; the fuses in a solid-state amp are there to keep the house from burning down.

deepee99 wrote:
Yes Peter, but remember, as regards high-powered amps: the fuses in a tube amp are there to protect the tubes; the fuses in a solid-state amp are there to keep the house from burning down.

RANT WARNING!!

You have hit on a pet-peeve of mine - fusing.


a) The typical fuse (even on a tube amp) as typically configured is there to protect real-estate, not the equipment.
b) Fuses are wearing parts, with a definite service-life. The closer they are to "ideal" the shorter their relative life.
c) Unless one is dealing with quite primitive and very unusual equipment, very nearly ideal fusing may be achieved - albeit at a cost.

How it is done:
a) This requires an ammeter of sufficient fineness as to be able to measure fractions of an amp, or only a few watts accurately.
b) For amplifiers, ideally, a dummy load will be available for calculation purposes - OR, speakers are separately fused (I detect many recoiling in horror at the concept of fused speakers).

Now, turn on the amplifier and let it warm up to full operating temperature. Note the quiescent current draw in amps.
Into a dummy load, drive it very nearly to clipping. Note the peak current draw in amps.
IF THE SPEAKERS are fused, use the peak current draw moving forward.
IF THE SPEAKERS are NOT fused, go midway to 2/3 the way between the quiescent and peak currents moving forward.

Look for quality US-made DUAL ELEMENT Time Delay fuses rated at the currents as noted above + perhaps 10%. Or not. I typically go "not".

This fuse will now accept a pretty massive turn-on surge, and very brief surges during operation. BUT IT WILL fail as a fast blow if the average current exceeds its rating for other than that very brief period.

http://www.onlinecomponents.com/datasheet/mdq2.aspx?p=10812576   One example given. Note that these fuses come in fractional values from 0.10A to 20A or more.

Now, you have a fuse that will protect the amp as well as the real-estate. And, by the way, these fuses do not like being short-cycled. Give them a few *minutes* rest between turn-on cycles.

END RANT.... again, not directed at anyone - but a manifestation of one of my many peeves when it comes to audio stuff. Too many years in the hobby witnessing far too many needless disasters.

Peter W. wrote:

deepee99 wrote:
Yes Peter, but remember, as regards high-powered amps: the fuses in a tube amp are there to protect the tubes; the fuses in a solid-state amp are there to keep the house from burning down.

RANT WARNING!!

You have hit on a pet-peeve of mine - fusing.


a) The typical fuse (even on a tube amp) as typically configured is there to protect real-estate, not the equipment.
b) Fuses are wearing parts, with a definite service-life. The closer they are to "ideal" the shorter their relative life.
c) Unless one is dealing with quite primitive and very unusual equipment, very nearly ideal fusing may be achieved - albeit at a cost.

How it is done:
a) This requires an ammeter of sufficient fineness as to be able to measure fractions of an amp, or only a few watts accurately.
b) For amplifiers, ideally, a dummy load will be available for calculation purposes - OR, speakers are separately fused (I detect many recoiling in horror at the concept of fused speakers).

Now, turn on the amplifier and let it warm up to full operating temperature. Note the quiescent current draw in amps.
Into a dummy load, drive it very nearly to clipping. Note the peak current draw in amps.
IF THE SPEAKERS are fused, use the peak current draw moving forward.
IF THE SPEAKERS are NOT fused, go midway to 2/3 the way between the quiescent and peak currents moving forward.

Look for quality US-made DUAL ELEMENT Time Delay fuses rated at the currents as noted above + perhaps 10%. Or not. I typically go "not".

This fuse will now accept a pretty massive turn-on surge, and very brief surges during operation. BUT IT WILL fail as a fast blow if the average current exceeds its rating for other than that very brief period.

http://www.onlinecomponents.com/datasheet/mdq2.aspx?p=10812576   One example given. Note that these fuses come in fractional values from 0.10A to 20A or more.

Now, you have a fuse that will protect the amp as well as the real-estate. And, by the way, these fuses do not like being short-cycled. Give them a few *minutes* rest between turn-on cycles.

END RANT.... again, not directed at anyone - but a manifestation of one of my many peeves when it comes to audio stuff. Too many years in the hobby witnessing far too many needless disasters.

Peter, good rant!
You neglected one worry: a fuse, when flashed, can become a direct conductor if the stuff inside vaporises then settles back in just the right order. On a boring Sunday, take apart your John Fluke meter. Buried deep inside is a 50-amp fuse which will catch such happenstance should the front-end fuse go south and result in a short. Odds of that are probably one in a million but ol' Fluke thought of most everything.

The whole idea in biamping is control over the bass and highs. Without an external xover it is a waste of time in my experience. YOU DO NOT NEED MATCHING AMPS!!!!!!!!!!!!!!!!!!!! In fact matching amps is counterproductive. Bass needs current the SS amps do better in current that's why expieranced biamped use them there, highs and mids sound so good on tubes. amps differ on bass and highs and you can choose the type of sound you want and have better control thro an external xover set to the design and a specs of your speakers. And yes you can use the internal xovers to a point. In my ADS L810'S We cut the traces between the low xover and the mids/highs install another pair of binding posts at the rear of speakers for bass drivers sending (in my system) 550 htz to the lows out of the external xover and 550 and up the the original binding posts that have been "separated (by cutting the traces) and jumping that input over the bass drivers and sending signal directly to the mid and high driver. The internal will split the highs and mids according to the internal xover to each mid and high driver. I like the charicteristics of the bass on my Krell so it handles the bass, a dynaco st 70 handles the mids and highs. Absolute bliss ,best of both worlds. As far as balancing the two amps go it's no issue as the external xover has output gain control so the amps are balanced in volume without issue.easy peezy. The result are amazing not subtle in any way.

I've always been a purist/minimalist. I stick with good 2-way speakers - double Advents for my solid state rig and Dynaco A-25s for the tube rig. I've only ever used biamping in car systems. The reason for this is the space constraints imposed by the car. In home systems, I've never used subwoofers - mainly because I always had a pair of well-designed cabinets with woofers that supplied the right amount of bass.

But I'm quite interested in biamping with my tube amps. Not, as audiofreak1954 suggests, for more control over the bass and highs. My reason is to take advantage of the what my amps have to offer.

I used to have an AVA-modded ST-70. I kept wondering why my solid state rig sounded better than my tube rig. I got ahold of an ST-35 and found that the ST-70 was my weak link. The ST-35 has the sweetest mids and highs I've ever heard, but it doesn't have enough power for much bass. I unloaded the ST-70 and got a pair of MK-IIIs - solid bass but not quite as sweet on the mids and highs.

Based on my best car audio systems (I was in the business for many years), I now want to try a biamped tube rig with my three amps. I guess it would technically be something like triangular triamping, since I'm already vertically biamping by virtue of the monoblocks. I've brought this up a few times here and don't find much interest in the community, except for a few people using electronic active crossovers, and I feel like it could be done better passively. So I'm glad you brought it up, LeGrace.

Here's a thread on another forum where there are a number of folks who seem to know a lot about this subject, and are able to explain their reasoning clearly, with less distortion and intermodulation difficulties than found in other discussions on the web. At least, that's how it stacks up through page two of the discussion. That might give all the perspective on the topic that's needed.

-Brenton

Edit - sorry, I forgot the link. Here it is:

http://www.whatsbestforum.com/showthread.php?9567-The-sonic-benefits-of-an-active-crossover-A-discussion

For my own sake, I am going to try and make sense of this. I invite input where I go astray.

a) Bi-Amping means using more than one amplifier to drive speakers.
b) This comes in (at least) two flavors: 1. using the speaker's on-board crossover. 2. using external crossovers.
c) Many OEM speakers have external jumpers on the crossovers to permit this option.
d) Those that do not, and also have internal crossovers, would require some sort of physical modification to the speaker to permit this option.
e) Those with internal crossovers would require some sort of physical modification to permit the use of external crossovers.
f) For these purposes, we will not differentiate between the many types and styles of external crossovers - just that they exist and are *NOT* OEM - I write this last as my Maggies have external crossovers but they are OEM and specific to that model. They can be bi-amped *and* also by their removal from the path, external crossovers may be used without modification to the speaker.
g) There are (at least) two schools of thought: 1. Bi-amping for headroom. Multiple lower-powered amplifiers to get more overall power. 2. Bi-amping to enhance a given frequency range, e.g. Tubes for mid/tweet, SS for bass.

So, without goring any oxen, delving into received wisdom or revealed religion, it would seem to me that those of us who have the desire, means and time to try these things, with some basic understanding of the safety and common-sense issues involved should do so. And report back. Sighted or not, blind-tested or not. I have the means - several sets of identical solid-state and tube amplifiers, three types of 'divisible' speakers, two of vastly different nature (planar and acoustic-suspension) and more. I have made a few tries along these lines and based on those tests, quite brief, I found no value in the concept other than more power = more headroom. More headroom = Good. Grunt, scratch, scratch. I have not mixed tube & SS.

Thoughts: Assume my AR3a speakers in excellent and fully maintained condition. These are known power-pigs. Solid-State options include: AR Amplifier, Dynaco ST120 & 80, Citation 19, Citation 16, Revox B251, Revox A722.

Tube Options: Dynaco ST70, Dynaco ST35, Scott LK150

If, from that array, you had to pick one (1) SS amp for the bass, and one (1) tube amp for the mid/tweet, which would they be? And thoughts as to why would be enlightening - at least to me.

Now, if you are willing, apply the same to the Magnepan MG-111. Warning: the Maggies are even more piggie than the ARs. The LK150 falls apart trying to drive them alone. The 19 is barely adequate, the 16 is quite wonderful.

I will have some 'free' time in a few weeks and may just try these suggestions.

Have since approached the problem from a somewhat different angle. Now have the M125s connected to my subwoofer. In this way I insert an external crossover into the mix, allowing me to pass only frequencies above the setting I select (up to 180 hz) to the M125's. Apparently that's what that knob on the back of the sub is for!!

Definitely has cleaned up the bass, no more muddiness. I attribute this to eliminating phase cancellation associated with 3 speakers generating the same frequencies in less then perfect phasing. The mids and highs now have more prominence coming from the main speakers, such that triode mode is sounding better then ever.

Interesting what a small wiring change can deliver, gotta love experimentation! Also beginning to appreciate what AF1954 was alluding to re the importance of segregating frequency bands when using multiple power sources!