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Input sensitivity control and horizontal bi-amplification

post #1 of 31
Thread Starter 

Hi everybody!

 

I'm planning to test horizontal bi-amplification using different amplifiers. One of them have an attenuator intended for input sensitivity control.

 

Do you think this control may help to cope with issues regarding different amplifier gain factors? I think so, but I'm not sure.

 

Thanks to all.

post #2 of 31
What is "horizontal" bi-amplification?

Since you're using an electronic crossover, it should have its own level controls. If not, you'll use the volume controls on the amplifiers. This is pretty simple, or am I missing something?

--Ethan
post #3 of 31
Thread Starter 
Quote:
Originally Posted by Ethan Winer View Post

What is "horizontal" bi-amplification?

Since you're using an electronic crossover, it should have its own level controls. If not, you'll use the volume controls on the amplifiers. This is pretty simple, or am I missing something?

--Ethan

 

Hi Ethan. Thanks for your response.

 

Well, horizontal or conventional biamplification uses one amp to drive the mid-high frequencies and one more for the bass frecuencies. The amps do not need to be exactly the same but it is recommended both amps have the same gain.

 

Vertical biamplification uses two identical amps. One of them drives the left speaker and the second amps drives the right speaker.

 

I am not using an electronic crossover, BTW.

post #4 of 31
It will only help if the amp with the attenuator has equal or more gain than the other amp. When I last did that, with a tube upper amp and hybrid bass amp, I had to tweak the levels in my (homebrew) crossover. If you are doing "passive" bi-amplification from an AVR you are probably wasting your time, however... Or are you using a passive vs. active electronic crossover?
post #5 of 31
Thread Starter 
Quote:
Originally Posted by DonH50 View Post

It will only help if the amp with the attenuator has equal or more gain than the other amp. When I last did that, with a tube upper amp and hybrid bass amp, I had to tweak the levels in my (homebrew) crossover. If you are doing "passive" bi-amplification from an AVR you are probably wasting your time, however... Or are you using a passive vs. active electronic crossover?

Thanks DonH50.

 

I'm planning to use passive bi-amplification with two different amps. One is a tube amp and the other a SS amp. But I'm not sure about the gain of both amps.

 

The maximun gain of the100Watts per channel SS amp is 890mV when the attenuator is set at the MAX position. Its input impedance is 50kOhm. The gain is not mentioned in the owners manual

 

The tube amp is only 42Watts per channel. At this power output its sensitivity is 880mV and has a gain equal to 26dB @ 8ohm or 23dB @ 4Ohm. The input impedance is 100kOhm.

post #6 of 31
Quote:
Originally Posted by DonH50 View Post

If you are doing "passive" bi-amplification you are wasting your time
Fixed.
post #7 of 31
Roughly the same input level will output 100 W from the SS amp and 42 W from the tube amp. You will probably have to attenuate the SS amp's input.

You do not want full-range signals going to the tube amp; the bass frequencies will eat up dynamic range for no good reason. I would build or buy a simple second-order passive crossover if you don't want active. Marchand makes good ones, or you can DIY, or get an inexpensive (active) pro crossover for about $200.
post #8 of 31
Quote:
Originally Posted by A9X-308 View Post

Quote:
Originally Posted by DonH50 View Post

If you are doing "passive" bi-amplification you are wasting your time
Fixed.

smile.gif I still get messed up by marketing terminology. Passive bi-amping to me implies a passive (RLC) line-level crossover; active implies active circuitry (opamps, tubes, or transistors) in the line-level crossover.
post #9 of 31
Passive biamping is using the biwiring terminals on a speaker with the jumper removed and supplying full bandwidth signal to each channel of an amplifier each of which then drives a single stage of HP/LP pasive filter and associated driver.



Any line level, pre power amplifier xover is still an active set up irrespective of whether it uses only passives (RC, Ls are not practical here) or in combination with some active components (BJT, FET, opamp, DSP, toobs)
post #10 of 31
Quote:
Originally Posted by A9X-308 View Post

Passive biamping is using the biwiring terminals on a speaker with the jumper removed and supplying full bandwidth signal to each channel of an amplifier each of which then drives a single stage of HP/LP pasive filter and associated driver.



Any line level, pre power amplifier xover is still an active set up irrespective of whether it uses only passives (RC, Ls are not practical here) or in combination with some active components (BJT, FET, opamp, DSP, toobs)

That is not really what passive biamping means. At least that is not what it used to mean. That's what it has come to mean. It used to mean something more along the lines of what DonH50 aluded to. There was a time when we would use the term "fool's biamping" around here to describe what is in your diagram so as to distinguish it from what was once called passive biamping,
post #11 of 31
Quote:
Originally Posted by sivadselim View Post

That is not really what passive biamping means. At least that is not what it used to mean. That's what it has come to mean.
That's the way I have been using it for decades. I got my first active system 30 odd years ago and scratch built my first not long after that.
Use of the terms line level and speaker level xovers would clarify it better. I do agree with the term 'fools biamping' though.
post #12 of 31
Different strokes. I have been using the terms "my way" since weaned back in the early 70's doing pro installs and then later custom home audio systems (one of the Shure VP's had a dedicated Greek/Roman villa style outbuilding with an augmented/stacked HQD system and ML electronics that was the most expensive and best-sounding I had seen/heard). To me and all the folk I've worked with through the years the goal of bi/tri/whatever-amping was to eliminate the passive speaker crossovers (many pro cabs came without internal crossovers) and replace them with line-level crossovers (active or passive). That way we could use smaller mid and treble amps and big bass amps. "Your" scheme was new to me until getting back into the whole HT thing a couple of years ago; I had never heard of that type of "passive" bi-amping. Using all amps full-range like that wastes a bunch of (voltage) headroom and idle power.

To each his own - Don
post #13 of 31
Quote:
Originally Posted by JorgeLopez11 View Post

I am not using an electronic crossover

If you're going to all that trouble, you really should use an active crossover. They're not that expensive. This one is excellent, but others are very good and some cost half as much:

http://www.musiciansfriend.com/pro-audio/rane-ac-22s-active-crossover

The quote below is from my Audio Expert book.

--Ethan
Quote:
Originally Posted by The Audio Expert 
Another potential problem with crossovers is distortion added by the inductors and capacitors at high power levels. One solution is an active crossover. This splits the signal into different frequency ranges before the power amplifiers, rather than after using passive components inside the speaker cabinet. An active crossover requires separate power amplifiers for each frequency range, as well as the crossover itself, which is a separate electronic device. So an active crossover is more expensive to implement, but it offers many advantages.

An active crossover also lets you easily adjust the balance between woofer and tweeter to better integrate drivers that have different sensitivities. Adjusting the volume with a passive crossover requires placing a resistor in series with the more efficient driver, which wastes power. With an active crossover, you simply adjust a volume control on the power amplifier. Also, an active crossover doesn't lose power through passive components, especially inductors whose internal coil resistance is in series with the woofer. Avoiding this resistance also helps preserve an amplifier's high damping factor.
post #14 of 31
Quote:
Originally Posted by JorgeLopez11 View Post


I'm planning to use passive bi-amplification with two different amps. One is a tube amp and the other a SS amp. But I'm not sure about the gain of both amps.

Passive biamplification is a waste of time.

Using a tubed amp for one or both of the amps doesn't really change that. In fact it probably makes passive amplification an even bigger waste due to the excess output impedance that the tubed amp(s) is likely to have.
post #15 of 31
Jorge, take a look at this post and thread. The day I took those we were using a rig which seems similar to what you're attempting, using an ST-70, a SET, and various ss amps. We listened in various configurations of fools bi-amping and full range for each. It was mainly an excuse to get together for beers and music, but enlightening all the same. My takeaway was this: the tube/ss fools bi-amped setups all sounded kind of schizophrenic, with the lack of that tube 'body' on the woofs afforded by the harmonic embellishment. I guess to my brain, the "tube sound" sounded better when applied across the board, not just to specific frequency bands. Oh, and I found that I actually like the sound of SET amps, the horror!

Keep it real, the woo is deep down tube alley, but have fun on the journey.
post #16 of 31
Thread Starter 

Thanks to all for your kind responses.

 

In any case I'm going to try the passive bi-amplification setup while I check the links regarding active crossovers.

post #17 of 31
For active crossovers, also take a look at miniDSP.
Edited by Wayne Highwood - 6/24/13 at 9:10am
post #18 of 31
Any active crossover worth it's salt has gain controls for the output channels. Therefore you do not need (nor want IMO) matched amps. The gain controls on the crossover will not only allow you to match the gains, they can even be used to coarsely correct response bumps.

For me, the whole idea of bi-amping is to select the amps based on the frequencies they are passing. I use 6V6 PP tube amps for my tweeters. These put out 10 watts. I use KT88 PP tube amps for the mids. They output 70 watts. And my subs get 300w each from a SS amp. I use a Berhinger active crossover and a Berhinger bass equalizer in the subs.
post #19 of 31
Thread Starter 
Quote:
Originally Posted by Glimmie View Post

Any active crossover worth it's salt has gain controls for the output channels. Therefore you do not need (nor want IMO) matched amps. The gain controls on the crossover will not only allow you to match the gains, they can even be used to coarsely correct response bumps.

For me, the whole idea of bi-amping is to select the amps based on the frequencies they are passing. I use 6V6 PP tube amps for my tweeters. These put out 10 watts. I use KT88 PP tube amps for the mids. They output 70 watts. And my subs get 300w each from a SS amp. I use a Berhinger active crossover and a Berhinger bass equalizer in the subs.

Thanks Glimmie. That's what I learnt yesterday after a quick look at Marchand Electronics site. 

 

I think this active crossover will do the job:  http://www.marchandelec.com/xm66.html

post #20 of 31
Quote:
Originally Posted by JorgeLopez11 View Post

Thanks Glimmie. That's what I learnt yesterday after a quick look at Marchand Electronics site. 

I think this active crossover will do the job:  http://www.marchandelec.com/xm66.html

The Marchand gear is excellent. Well engineered. The XM66 is a new product and I'm sure it's performance is excellent too. But keep in mind while the variable frequency control is neat, the analog techniques to do that are often less than ideal audibly. If you know the crossover frequency needed, you could go with one of his fixed units. And they really aren't fixed, they just require some small boards be swapped out for different frequencies.

The other route is to go with a DSP based digital crossover. Here the crossover is mathematically perfect within the constraints of the data width. However now we have an analog to digital conversion and back. So that too can compromise the fidelity.
post #21 of 31
Had not seen the XM-66 before, neat! Looks like a L-R maybe using state variable filters?

Marchand also makes excellent passive (RLC, no active electronic) crossovers, but of course any such will be more dependent upon your line-level source and load impedances.
post #22 of 31
Quote:
Originally Posted by JorgeLopez11 View Post

 

I think this active crossover will do the job:  http://www.marchandelec.com/xm66.html

I can't believe the price of Marchand products. Rane makes a number of different 2 and 3 way active crossovers with continuously variable frequency controls. They perform well. They can often be obtained for reasonable prices on eBay and other used equipment sites.
post #23 of 31
Thread Starter 
Quote:
Originally Posted by Glimmie View Post


The Marchand gear is excellent. Well engineered. The XM66 is a new product and I'm sure it's performance is excellent too. But keep in mind while the variable frequency control is neat, the analog techniques to do that are often less than ideal audibly. If you know the crossover frequency needed, you could go with one of his fixed units. And they really aren't fixed, they just require some small boards be swapped out for different frequencies.

The other route is to go with a DSP based digital crossover. Here the crossover is mathematically perfect within the constraints of the data width. However now we have an analog to digital conversion and back. So that too can compromise the fidelity.

 

Glimmie,

 

Wayne Highwood recommended miniDSP but I actually prefer the XM66 solution. Regarding the crossover frequency, I'm not sure about it. That's why I may be choosing the variable frequency control capabilities of the XM66. 

 

In any case, my three way Revel crossovers are specified at 190Hz and 2900 Hz, so I'm thinking of playing with active crossover frequencies starting at 100Hz (active crossover for the lows and pasive for the mid-highs).

 

Just FYI, the variable frequency Marchands unit XM9L costs a little bit less than the variable frequencies XM66, both using 24 step attenuators.

 

 

 

Quote:
I can't believe the price of Marchand products. Rane makes a number of different 2 and 3 way active crossovers with continuously variable frequency controls. They perform well. They can often be obtained for reasonable prices on eBay and other used equipment sites.

 

Well Arny, I've never used a RANE product but my preamp and my amps use single ended connections. RANE's are balanced.

post #24 of 31
Quote:
Originally Posted by arnyk View Post

I can't believe the price of Marchand products. Rane makes a number of different 2 and 3 way active crossovers with continuously variable frequency controls. They perform well. They can often be obtained for reasonable prices on eBay and other used equipment sites.

Marchand stuff is hand built and he uses good commercial grade components. Rane is good too but the component and build quality are a bit less.

You could say that Marchand is an honest no frills audiophile grade while Rane is mainly sound reinforcement grade.

Never mind that I personally use Berhinger corssovers and EQs rolleyes.gif
post #25 of 31
Quote:
Originally Posted by Glimmie View Post

Quote:
Originally Posted by arnyk View Post

I can't believe the price of Marchand products. Rane makes a number of different 2 and 3 way active crossovers with continuously variable frequency controls. They perform well. They can often be obtained for reasonable prices on eBay and other used equipment sites.

Marchand stuff is hand built and he uses good commercial grade components. Rane is good too but the component and build quality are a bit less.

I have a fair number of Rane crossovers and equalizers in play. They run 20-30 years old and they still meet spec on the test bench and sound good in use.
Quote:
You could say that Marchand is an honest no frills audiophile grade while Rane is mainly sound reinforcement grade.
{/quote]

Hmmm, "Audiophile grade" = manufactured using processes that were out of date 30 years ago?

{quote]
Never mind that I personally use Berhinger corssovers and EQs rolleyes.gif

I'm looking at the Ultra-Q Pro driving my Paradigm subwoofer.

Elsewhere, Rane SE-15s hold strong.
post #26 of 31
Quote:
Originally Posted by arnyk View Post

I have a fair number of Rane crossovers and equalizers in play. They run 20-30 years old and they still meet spec on the test bench and sound good in use.
I'm looking at the Ultra-Q Pro driving my Paradigm subwoofer.

Elsewhere, Rane SE-15s hold strong.

Yes, don't get me wrong. There is nothing wrong with the Rane gear. I have used many pieces myself over the years too.

The Behringer stuff also get's a bad rap from the "audiophiles" because of it's price. But I have a test bench on the level of yours too and did not find anything bad with the Behringer gear. I have seen countless articles online to replace the power supply which I considered. But when I measured the noise with the stock supply I could see no reason to replace it. I really love the hacks where they strip out the ADC and DAC analog filter circuits and drive the cables direct into the ADC and out from the DAC thorugh some magic transformer.

Talk about tweeter damage! eek.gif

Behringer and other commercial sound products are junk = yet more audiophile price driven voodoo.
Edited by Glimmie - 6/26/13 at 12:20pm
post #27 of 31
Quote:
Originally Posted by arnyk View Post

I have a fair number of Rane crossovers and equalizers in play. They run 20-30 years old and they still meet spec on the test bench and sound good in use.

Same here. My Rane crossover is just over 20 years old and it still works perfectly.

--Ethan
post #28 of 31
I use a dbx; Rane did not have one with the LF range I wanted in my price range. Rane has long had a reputation for quality pro gear at a reasonable price.

I have not used Behringer anything for a long, long time. 20+ years ago the components I tried felt cheap, the mixer sliders were not smooth, and they were noisy. I have no experience with their recent products. Many folk I respect have commented that they are decent these days, especially the amps and feedback control (DSP) units.
post #29 of 31
Thread Starter 

Just a quick update.

 

I finally pulled the trigger and bought the Marchand Electronics XM66-AA electronic crossover.

 

Mr Phil Marchand personally attended my request. Nice service!

post #30 of 31
I'm jealous. smile.gif
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