Hi there. I've been reading about bi-amping and I thought it sounded like a good way to ensure whichever chipamp configuration I decide to build can provide good bass at high volumes, which is the only problem I foresee with going down the chipamp route.
So can people tell me their views on this?
I would have thought a LM3886 based (possibly in parallel - in which case I'll look at LM4780s instead) pair of monoblocs for the bass, and a pair of straight-forward non-inverted LM3875s for the high frequencies.
Does this sound like a reasonable set-up? What changes would you make?
Also, is there an advantage to running each monobloc from a separate power supply? That'll make a lot of transformers... Any other ideas for this? I've read about SMPS and I'm not sure whether this is the way forward.
Finally, how do you go about separating bass and treble?
Thanks for any answers.
So can people tell me their views on this?
I would have thought a LM3886 based (possibly in parallel - in which case I'll look at LM4780s instead) pair of monoblocs for the bass, and a pair of straight-forward non-inverted LM3875s for the high frequencies.
Does this sound like a reasonable set-up? What changes would you make?
Also, is there an advantage to running each monobloc from a separate power supply? That'll make a lot of transformers... Any other ideas for this? I've read about SMPS and I'm not sure whether this is the way forward.
Finally, how do you go about separating bass and treble?
Thanks for any answers.
Separating the bass and treble can be achieved with an active crossover ( http://sound.westhost.com/project09.htm ).
I'm going to build myself a pair of small 2-way speakers, bi-amped with a pair of LM3886 each (Mauro Penasa's MyRef RevC)
I'm going to build myself a pair of small 2-way speakers, bi-amped with a pair of LM3886 each (Mauro Penasa's MyRef RevC)
I'm doing the same. Costs soon build up the more enclosures you have.
An economical solution is 1 box per channel, containing PS, crossover, and hi and Lo amplification.
A more flexible approach if you might be into experimenting in future, is to have a separate crossover ( in with the selector/ pre-amp if you are building one) Then your amps can be built as simple stereo power amps.
You've arrived at the right time > the active filter group buy is underway, see group buys.
An economical solution is 1 box per channel, containing PS, crossover, and hi and Lo amplification.
A more flexible approach if you might be into experimenting in future, is to have a separate crossover ( in with the selector/ pre-amp if you are building one) Then your amps can be built as simple stereo power amps.
You've arrived at the right time > the active filter group buy is underway, see group buys.
I'm looking into this too.
I couldn't find princeton technology.
Jimbo1968 - I saw that group buy - would that do the job. How many do I need? I think I will build a preamp. It seems like a good move
I couldn't find princeton technology.
Jimbo1968 - I saw that group buy - would that do the job. How many do I need? I think I will build a preamp. It seems like a good move
Yup, a good time to be asking this question. The buy is still open I believe:
http://www.diyaudio.com/forums/showthread.php?s=&postid=870245#post870245
http://www.diyaudio.com/forums/showthread.php?s=&postid=870245#post870245
Hi,
for passive bi-amping, I would recommend you build two stereo amplifiers.
As a passive set up you do not need to split the signal into two frequency ranges. Each stereo amp will drive one treble unit and one mid-bass unit. Try to keep the amp right behind the speaker with VERY short cables (low capacitance, low inductance and cheap and has least effect on the amps ability to drive the speaker load).
You can, at a later date, easily adapt your passive bi-amping equipment into fully active by adding active crossovers before your power amps and removing the passive crossovers from inside your speakers. The only part that becomes redundant is the passive crossover.
Build you stereo power amps as near full monoblock as you can afford.
Each stereo amp will require:-
1 case,
1 transformer,
2 rectifiers,
4 banks of smoothing capacitors,
2 power amplifiers,
1 set of hardware, fuses, switch, terminal strip, terminals, interference suppression, soft start, DC block and any other ancilliaries you decide to add.
Each amp sees only the part load of half the crossover with a speaker hanging on the other end. This raises the effective impedance seen by the amplifier and reduces the work done by the amp, thus easing the load seen by the transformer and PSUs.
This provides much of the gain heard from bi-amping.
If you decide to go fully active you will need to dedicate a serious amount of time tailoring the crossover to include equalisation of various Qs and frequencies as well as some shelving of response. All this is already included in the manufacturer's standard passive crossover. They may also have included some time delay to improve time allignment.
Hope this gets you thinking and good luck.
BTW I have been bi-amped for a couple of decades and would NEVER go back, brief periods of single amping have proved bi-amping's (passive) worth.
for passive bi-amping, I would recommend you build two stereo amplifiers.
As a passive set up you do not need to split the signal into two frequency ranges. Each stereo amp will drive one treble unit and one mid-bass unit. Try to keep the amp right behind the speaker with VERY short cables (low capacitance, low inductance and cheap and has least effect on the amps ability to drive the speaker load).
You can, at a later date, easily adapt your passive bi-amping equipment into fully active by adding active crossovers before your power amps and removing the passive crossovers from inside your speakers. The only part that becomes redundant is the passive crossover.
Build you stereo power amps as near full monoblock as you can afford.
Each stereo amp will require:-
1 case,
1 transformer,
2 rectifiers,
4 banks of smoothing capacitors,
2 power amplifiers,
1 set of hardware, fuses, switch, terminal strip, terminals, interference suppression, soft start, DC block and any other ancilliaries you decide to add.
Each amp sees only the part load of half the crossover with a speaker hanging on the other end. This raises the effective impedance seen by the amplifier and reduces the work done by the amp, thus easing the load seen by the transformer and PSUs.
This provides much of the gain heard from bi-amping.
If you decide to go fully active you will need to dedicate a serious amount of time tailoring the crossover to include equalisation of various Qs and frequencies as well as some shelving of response. All this is already included in the manufacturer's standard passive crossover. They may also have included some time delay to improve time allignment.
Hope this gets you thinking and good luck.
BTW I have been bi-amped for a couple of decades and would NEVER go back, brief periods of single amping have proved bi-amping's (passive) worth.
Hi. Thanks for the replies everyone.
I think active filters may be a bit too complex for me. I don't like the idea of opening up my speakers just yet.
So far I see it like this:
Active (or Horizontal) Bi-amping
Splits the signal into high and low frequencies before amplification. One amp boosts bass and a channel goes to the bass unit in each speaker, while the other amp does the same for the tweeters.
Pros:
Can tailor different amps: one to specialise in bass and one to do the highs.
Reported to give a more dynamic sound
Cons:
Need to open up the speakers and remove the crossovers.
Need to make up specific Active crossovers tailored to speakers to insert before power amps. This involves some fairly complex calculations and the risk of damage to the speakers if wrong.
Passive (or Vertical) Bi-amping:
Two stereo amps each power one speaker across the whole of the signal range, with one channel powering bass and one powering highs.
Pros.
Can work with speakers' original internal crossovers.
Current is shared between bass and highs in each channel so the bass can hog the current when needed to produce a fuller sound.
Halves the load seen by the amp, taking away half the strain, and meaning each amp runs at half the level required to produce the same volume.
Cons.
Need two identical amps.
Amps should ideally be very close to the speakers. (AndrewT, thanks for all that information, could you have banana plugs fixed to the amps so they actually fit into the speaker bindings?)
Is that about the gist of it. Have I missed anything? I read about the vertical amping and wasn't sure how the signal is split inside each stereo amp so that one channel does bass and the other does high frequencies.
I think active filters may be a bit too complex for me. I don't like the idea of opening up my speakers just yet.
So far I see it like this:
Active (or Horizontal) Bi-amping
Splits the signal into high and low frequencies before amplification. One amp boosts bass and a channel goes to the bass unit in each speaker, while the other amp does the same for the tweeters.
Pros:
Can tailor different amps: one to specialise in bass and one to do the highs.
Reported to give a more dynamic sound
Cons:
Need to open up the speakers and remove the crossovers.
Need to make up specific Active crossovers tailored to speakers to insert before power amps. This involves some fairly complex calculations and the risk of damage to the speakers if wrong.
Passive (or Vertical) Bi-amping:
Two stereo amps each power one speaker across the whole of the signal range, with one channel powering bass and one powering highs.
Pros.
Can work with speakers' original internal crossovers.
Current is shared between bass and highs in each channel so the bass can hog the current when needed to produce a fuller sound.
Halves the load seen by the amp, taking away half the strain, and meaning each amp runs at half the level required to produce the same volume.
Cons.
Need two identical amps.
Amps should ideally be very close to the speakers. (AndrewT, thanks for all that information, could you have banana plugs fixed to the amps so they actually fit into the speaker bindings?)
Is that about the gist of it. Have I missed anything? I read about the vertical amping and wasn't sure how the signal is split inside each stereo amp so that one channel does bass and the other does high frequencies.
I don't know anything about passive bi-amping and just assumed that you were going to be building speakers.
Does passive bi-amping need identical amps? If not, it is extremely simple to try the concept before you start building your own amps.
Does passive bi-amping need identical amps? If not, it is extremely simple to try the concept before you start building your own amps.
Does using the passive crossover in the speaker with 2 amps really split the load on the amps? I heard that it didn't.
I guess the question is "What does a passive speaker crossover do with power that is "chopped off" by the filter?
There is a third option and that is a passive filter before the amp, but apparentely that requires some custom tuning to get right and doesn't work well in all cases) (hmmm like all crossovers?)
I guess the question is "What does a passive speaker crossover do with power that is "chopped off" by the filter?
There is a third option and that is a passive filter before the amp, but apparentely that requires some custom tuning to get right and doesn't work well in all cases) (hmmm like all crossovers?)
Hi,
neither passive bi-amping nor active speakers demand identical amplifiers for all the drivers.
In both cases there may be an advantage in choosing different amps with characteristics that particularly suit either the bass/mid or the treble. But the big down side to this is either needing four monoblocks or long cables from centrally placed stereo amps.
If the chip amps and PSU is light enough direct plug in would be an option. Nice idea.
As part of a test, I have a pair Sugdens driving the left channel and a Cyrus stereo driving the right at the moment. The only things they have in common are the gain, they're British and they are black. They sound just dandy, not identical but pretty good. eg. 180W+180W mono mosFET Sugdens vs 60W + 60W stereo BJT Cyrus, that's pretty unmatched.
neither passive bi-amping nor active speakers demand identical amplifiers for all the drivers.
In both cases there may be an advantage in choosing different amps with characteristics that particularly suit either the bass/mid or the treble. But the big down side to this is either needing four monoblocks or long cables from centrally placed stereo amps.
If the chip amps and PSU is light enough direct plug in would be an option. Nice idea.
As part of a test, I have a pair Sugdens driving the left channel and a Cyrus stereo driving the right at the moment. The only things they have in common are the gain, they're British and they are black. They sound just dandy, not identical but pretty good. eg. 180W+180W mono mosFET Sugdens vs 60W + 60W stereo BJT Cyrus, that's pretty unmatched.
Hi,
re full range signal into poweramp connected to half a crossover.
The crossover when used conventionally has the two halves in parallel and the overall impedance is the nominal impedance of the whole speaker.
To allow the two halves to combine to give a total impedance it must follow that each half has an impedance that is higher than the whole speaker impedance.
Each half will have an impedance that when in band will be similar to the nominal impedance of the whole speaker.
We have already seen that when half the crossover is in band it has a matching impedance then it also must follow that out of band it has a substantially higher impedance.
As an example take an 8ohm treble unit with a single pole high pass crossover of just a capacitor of value about 6u8F.
In band ie over 3kHz the amp sees the 8ohm driver as a load.
Out of band i.e. below 3kHz it sees the increasing impedance of the cap + driver in parallel and at 100Hz is equivalent to 8r + 234reactive ohms. The bass unit with an inductor in series will also have a rising impedance.
It is the rising impedance out of band that each passive amp sees as an easier load needing less current to be supplied to each half load.
re full range signal into poweramp connected to half a crossover.
The crossover when used conventionally has the two halves in parallel and the overall impedance is the nominal impedance of the whole speaker.
To allow the two halves to combine to give a total impedance it must follow that each half has an impedance that is higher than the whole speaker impedance.
Each half will have an impedance that when in band will be similar to the nominal impedance of the whole speaker.
We have already seen that when half the crossover is in band it has a matching impedance then it also must follow that out of band it has a substantially higher impedance.
As an example take an 8ohm treble unit with a single pole high pass crossover of just a capacitor of value about 6u8F.
In band ie over 3kHz the amp sees the 8ohm driver as a load.
Out of band i.e. below 3kHz it sees the increasing impedance of the cap + driver in parallel and at 100Hz is equivalent to 8r + 234reactive ohms. The bass unit with an inductor in series will also have a rising impedance.
It is the rising impedance out of band that each passive amp sees as an easier load needing less current to be supplied to each half load.
Hi Variac,
I sure glad at least you understood it.
As I was writing it I kept wanting to put values in but I know that can frighten off some readers.
I posted it anyway waiting for someone to ask a question on how to make something incomprehensible but starting from one hypothesis that's so simple.
I sure glad at least you understood it.
As I was writing it I kept wanting to put values in but I know that can frighten off some readers.
I posted it anyway waiting for someone to ask a question on how to make something incomprehensible but starting from one hypothesis that's so simple.
are you saying the top and bottom halves each needs to see 16 ohms for the crossover to behave asif its driving 8 ohms?
blottojon said:
I have the same question and what is the beter way for the signal split for passive bi-amp? 😕
The problem with what BlottoJon calls vertical biamping with his goal of sharing the power load is that the crossover point determines the power share.
Read Rod Elliot's biamping article and you'll see that if you choose to biamp with a crossover of 3KHz, the tweeter amp will need to produce very little power and the power required of the bass amp will be virtually unchanged.
To achieve the stated goal of significantly reducing the amplifier power requirements, the crossover point needs to be in the neighborhood of 300 Hz.
So, unless you are building a three way (or ahve a pair of subs that can reach that high), you should look at a more powerful amp if you are concerned about clipping a chip amp. Bridge-parallel isn't a bad choice and can be done with a pair of LM4780s per channel.
Nordic - no, it is not quite that way. Another way to look at it is below crossover, the woofer is effectively the only driver connected, above crossover it's only the tweeter. At crossover, the crossover impedance is about the same as the drivers'. In the woofer section, an 8 ohm woofer is in series with an 8 ohm crossover (to attenuate the signal by 3 dB), resulting in a 16 ohm load. The same for the tweeter. So, the two 16 ohm loads in parallel produce an 8 ohm load for the amp. In reality it isn't quite that simple, but the basic concept is there.
Read Rod Elliot's biamping article and you'll see that if you choose to biamp with a crossover of 3KHz, the tweeter amp will need to produce very little power and the power required of the bass amp will be virtually unchanged.
To achieve the stated goal of significantly reducing the amplifier power requirements, the crossover point needs to be in the neighborhood of 300 Hz.
So, unless you are building a three way (or ahve a pair of subs that can reach that high), you should look at a more powerful amp if you are concerned about clipping a chip amp. Bridge-parallel isn't a bad choice and can be done with a pair of LM4780s per channel.
Nordic - no, it is not quite that way. Another way to look at it is below crossover, the woofer is effectively the only driver connected, above crossover it's only the tweeter. At crossover, the crossover impedance is about the same as the drivers'. In the woofer section, an 8 ohm woofer is in series with an 8 ohm crossover (to attenuate the signal by 3 dB), resulting in a 16 ohm load. The same for the tweeter. So, the two 16 ohm loads in parallel produce an 8 ohm load for the amp. In reality it isn't quite that simple, but the basic concept is there.
Assume that we are talking about one channel. What if I take the output of my preamp and split it with a pair of y connector cables Then hook each branch of the y connector to the input of a power amp. Then hook one amp output to the mid/ treble crossovers, and the other amp's output to the bass crossover. One of the power amps has a volume control to get the balance right.
This seems to work, in my current setup. One possible problem is that the input impedence the pre-amp sees is probably half. What will this affect- freq response? Probably not too much if the amps have reasonably high input impedence?
This is useful to me because my woofers are less efficient than the other drivers and this way I can crank them up...without an l-pad on the mids and tweets, which sounds worse..
This seems to work, in my current setup. One possible problem is that the input impedence the pre-amp sees is probably half. What will this affect- freq response? Probably not too much if the amps have reasonably high input impedence?
This is useful to me because my woofers are less efficient than the other drivers and this way I can crank them up...without an l-pad on the mids and tweets, which sounds worse..
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