Tri-amp output powers
 

What's the deal with choosing output powers when tri-amping? If my 3-way
speakers are rated at 50W, and I want to double the number of bass drivers,
what o/p power should I choose for each amp?

At the moment, I'm thinking of 100W low bass, and 50W each for bass/mid and
treble. Won't my T27s freak out if there's a 50W amp dedicated to them? In
the present 3-way setup, how would the power from a single 50W amp split up
in terms of which driver gets what power?

In spite of being unsure of this, I'm presently thinking that an easy way to
do this is a stack of three Cyrus Two amps. That way, I can adjust the
volumes to balance the level to each driver, with overall output determined
by the capability of the low bass section. I could also compensate for the
somewhat recessed mid that becomes apparent at times.

From what I've read, the Cyrus Two is very good at detail, but a little
light on bass. I like the idea of good detail. I'm after bass which is
tight, solid, and very low. It doesn't have to be mega-loud. Maybe the light
bass (be there such) can be compensated for by adjusting the volume of the
low bass amp, or using some sort of filter at the pre-amp.

Am I on a concievably-sensible track with this Cyrus Two idea?


--
Wally
www.artbywally.com
www.wally.myby.co.uk

Tri-amp output powers
 

Wally wrote:

What's the deal with choosing output powers when tri-amping?

Where's your crossover?
If you are still using the passive crossover from your speakers
then you will need the same power rating for all amps.

If you have an active crossover then the tweeter amp can be rather
lower powered. In theory you could get full power out of a CD at any
frequency but in practice the levels drop at higher frequencies.
An experiment on your favourite music with an audio editor such as
Goldwave will be helpful. Split it into three at your chosen
crossover frequencies and search for the maximum level in each file.
This will show the relative voltage and hence power required for each
amp, assuming all drivers have the same sensitivity.

Won't my T27s freak out if there's a 50W amp dedicated to them?

Only if it thumps on switch-on and you don't have the original
crossover.

Am I on a concievably-sensible track with this Cyrus Two idea?

Yes.

--
Eiron.

Tri-amp output powers
 

In article , Wally
wrote:
What's the deal with choosing output powers when tri-amping? If my 3-way
speakers are rated at 50W, and I want to double the number of bass
drivers, what o/p power should I choose for each amp?

Can you say how you intend to "double the number of bass drivers"? Any
anwer will depend upon how you are thinking of doing this. i.e. how are you
going to wire them up, mount them in the same or different cabinets,
crossover/filter arrangements, etc.

At the moment, I'm thinking of 100W low bass, and 50W each for bass/mid
and treble. Won't my T27s freak out if there's a 50W amp dedicated to
them? In the present 3-way setup, how would the power from a single 50W
amp split up in terms of which driver gets what power?

In spite of being unsure of this, I'm presently thinking that an easy
way to do this is a stack of three Cyrus Two amps. That way, I can
adjust the volumes to balance the level to each driver, with overall
output determined by the capability of the low bass section. I could
also compensate for the somewhat recessed mid that becomes apparent at
times.

The problem is that the power ratings for speakers are quoted on an
entirely different basis than that quoted for amplifiers. The speaker's
ability to handle a given power also depends upon other factors as well.

From what I've read, the Cyrus Two is very good at detail, but a little
light on bass. I like the idea of good detail. I'm after bass which is
tight, solid, and very low. It doesn't have to be mega-loud. Maybe the
light bass (be there such) can be compensated for by adjusting the
volume of the low bass amp, or using some sort of filter at the pre-amp.

Am I on a concievably-sensible track with this Cyrus Two idea?

In principle, it may well be OK. But you have not provided enough detail to
be sure.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Tri-amp output powers
 

"Wally" wrote in message


What's the deal with choosing output powers when tri-amping? If my
3-way speakers are rated at 50W, and I want to double the number of
bass drivers, what o/p power should I choose for each amp?


You might want to look at existing implementations of tri-amped speakers to
see how they pick power ratings.

At the moment, I'm thinking of 100W low bass, and 50W each for
bass/mid and treble. Won't my T27s freak out if there's a 50W amp
dedicated to them?

You might fry them.

In the present 3-way setup, how would the power
from a single 50W amp split up in terms of which driver gets what
power?

The power split depends on the frequency ranges split off for each driver,
and how much energy is in each band, for different kinds of music.

You can measure the voltage across the driver voice coils while the system
is in use. A 'scope or better yet a digital recorder are good tools for
this. You want to look at peak levels because that is the critical case for
undistorted operation.


In spite of being unsure of this, I'm presently thinking that an easy
way to do this is a stack of three Cyrus Two amps. That way, I can
adjust the volumes to balance the level to each driver, with overall
output determined by the capability of the low bass section. I could
also compensate for the somewhat recessed mid that becomes apparent
at times.

That's one of the nice things about active n-way systems. You can get the
balance you want regardless of the efficiency of the drivers.

From what I've read, the Cyrus Two is very good at detail, but a
little light on bass. I like the idea of good detail. I'm after bass
which is tight, solid, and very low. It doesn't have to be mega-loud.
Maybe the light bass (be there such) can be compensated for by
adjusting the volume of the low bass amp, or using some sort of
filter at the pre-amp.

Here's a low cost 3-way active crossover with a good reputation and lots of
flexibility:

"Behringer DCX2496 Ultra-Drive Pro Digital Crossover System"

http://www.behringer.com/DCX2496/index.cfm?lang=ENG



Am I on a conceivably-sensible track with this Cyrus Two idea?

Tri-amp output powers
 

Jim Lesurf wrote:

Can you say how you intend to "double the number of bass drivers"? Any
anwer will depend upon how you are thinking of doing this. i.e. how
are you going to wire them up, mount them in the same or different
cabinets, crossover/filter arrangements, etc.

Isobaric subs using B139s, wired in parallel, infinite baffle cab of 60-80
litres, active low-pass filter before the power amp.


The problem is that the power ratings for speakers are quoted on an
entirely different basis than that quoted for amplifiers. The
speaker's ability to handle a given power also depends upon other
factors as well.

Something to do with losses in the crossover of a conventional speaker, and
the fact that the speaker's rating is for the full three-driver setup with
crossover?


Am I on a concievably-sensible track with this Cyrus Two idea?

In principle, it may well be OK. But you have not provided enough
detail to be sure.

Subs as above, B110 bass/mid, T27 tweeter. I figure that, if a Cyrus Two can
drive the 4 ohm isobaric subs to a volume that I'm happy with, then the B110
and T27 should be fine. I'm looking into an active crossover for all
frequency bands, before the power amps.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

Tri-amp output powers
 

Eiron wrote:

Where's your crossover?
If you are still using the passive crossover from your speakers
then you will need the same power rating for all amps.

It doesn't exist at present, but the plan is to use an active crossover
before the power amps.


If you have an active crossover then the tweeter amp can be rather
lower powered. In theory you could get full power out of a CD at any
frequency but in practice the levels drop at higher frequencies.
An experiment on your favourite music with an audio editor such as
Goldwave will be helpful. Split it into three at your chosen
crossover frequencies and search for the maximum level in each file.
This will show the relative voltage and hence power required for each
amp, assuming all drivers have the same sensitivity.

Interesting. Is Goldwave a freebie?


Won't my T27s freak out if there's a 50W amp dedicated to them?

Only if it thumps on switch-on and you don't have the original
crossover.

Righto.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

Tri-amp output powers
 

Arny Krueger wrote:

You might want to look at existing implementations of tri-amped
speakers to see how they pick power ratings.

Thassa good idea - I'll do some troffing.


At the moment, I'm thinking of 100W low bass, and 50W each for
bass/mid and treble. Won't my T27s freak out if there's a 50W amp
dedicated to them?

You might fry them.

How about if I was disciplined with the Cyrus volume control?


The power split depends on the frequency ranges split off for each
driver, and how much energy is in each band, for different kinds of
music.

You can measure the voltage across the driver voice coils while the
system is in use. A 'scope or better yet a digital recorder are good
tools for this. You want to look at peak levels because that is the
critical case for undistorted operation.

Righto.


Here's a low cost 3-way active crossover with a good reputation and
lots of flexibility:

"Behringer DCX2496 Ultra-Drive Pro Digital Crossover System"

http://www.behringer.com/DCX2496/index.cfm?lang=ENG

Looks like a nice bit of kit, but a bit pricey for my budget, I'm afraid.
I'm considering something home-brew.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

Tri-amp output powers
 

Wally wrote:



If you have an active crossover then the tweeter amp can be rather
lower powered. In theory you could get full power out of a CD at any
frequency but in practice the levels drop at higher frequencies.
An experiment on your favourite music with an audio editor such as
Goldwave will be helpful. Split it into three at your chosen
crossover frequencies and search for the maximum level in each file.
This will show the relative voltage and hence power required for each
amp, assuming all drivers have the same sensitivity.


Interesting. Is Goldwave a freebie?

http://www.goldwave.com
You can download an evaluation version.

I tried splitting a track (Money, from the CD layer of the DSotM SACD)
at 300Hz and 3000Hz.
The peak voltages we
Low 0.96
Med 1.00
High 0.82 (surprisingly high)

So you could use a couple of Cyrus Twos and a Cyrus one for the treble
but it would be better to use three identical amps.


Won't my T27s freak out if there's a 50W amp dedicated to them?

You could use a capacitor in series with the T27, as long as you
factor it into the active crossover response.

--
Eiron.

Tri-amp output powers
 

"Eiron" wrote in message
...
Wally wrote:



If you have an active crossover then the tweeter amp can be rather
lower powered. In theory you could get full power out of a CD at
any
frequency but in practice the levels drop at higher frequencies.
An experiment on your favourite music with an audio editor such as
Goldwave will be helpful. Split it into three at your chosen
crossover frequencies and search for the maximum level in each
file.
This will show the relative voltage and hence power required for
each
amp, assuming all drivers have the same sensitivity.


Interesting. Is Goldwave a freebie?

http://www.goldwave.com
You can download an evaluation version.

I tried splitting a track (Money, from the CD layer of the DSotM
SACD)
at 300Hz and 3000Hz.
The peak voltages we
Low 0.96
Med 1.00
High 0.82 (surprisingly high)

So you could use a couple of Cyrus Twos and a Cyrus one for the
treble
but it would be better to use three identical amps.


Won't my T27s freak out if there's a 50W amp dedicated to them?

You could use a capacitor in series with the T27, as long as you
factor it into the active crossover response.

--
Eiron.

More to it than that - the passive crossover normally found in a
speaker is actually quite lossy.

From an article in Wireless World many years ago when bi and tr amping
were just starting, it suggested that against a 'normal' 30Wpc amp,
tri-amping needed about 20W for the bass or bass-mid, 10W for the mid
and 4-5W for the tweeter. Base that on the inefficiency of most modern
speaker systems and the equivalent of a 100Wpc amp would need 60, 30,
and 15, and that would still be far too much in most cases.

I remember one chap who did bi-amping with a 15W Class A for the bass
and 5W class A for the tweeter, and any DBT he did always gave
preference for the calss A kit.

So who needs power?


--
Woody

Tri-amp output powers
 

On Wed, 10 Nov 2004 07:56:40 GMT, "harrogate2"
wrote:


"Eiron" wrote in message
...
Wally wrote:



If you have an active crossover then the tweeter amp can be rather
lower powered. In theory you could get full power out of a CD at
any
frequency but in practice the levels drop at higher frequencies.
An experiment on your favourite music with an audio editor such as
Goldwave will be helpful. Split it into three at your chosen
crossover frequencies and search for the maximum level in each
file.
This will show the relative voltage and hence power required for
each
amp, assuming all drivers have the same sensitivity.


Interesting. Is Goldwave a freebie?

http://www.goldwave.com
You can download an evaluation version.

I tried splitting a track (Money, from the CD layer of the DSotM
SACD)
at 300Hz and 3000Hz.
The peak voltages we
Low 0.96
Med 1.00
High 0.82 (surprisingly high)

So you could use a couple of Cyrus Twos and a Cyrus one for the
treble
but it would be better to use three identical amps.


Won't my T27s freak out if there's a 50W amp dedicated to them?

You could use a capacitor in series with the T27, as long as you
factor it into the active crossover response.

--
Eiron.

More to it than that - the passive crossover normally found in a
speaker is actually quite lossy.

From an article in Wireless World many years ago when bi and tr amping
were just starting, it suggested that against a 'normal' 30Wpc amp,
tri-amping needed about 20W for the bass or bass-mid, 10W for the mid
and 4-5W for the tweeter. Base that on the inefficiency of most modern
speaker systems and the equivalent of a 100Wpc amp would need 60, 30,
and 15, and that would still be far too much in most cases.

I remember one chap who did bi-amping with a 15W Class A for the bass
and 5W class A for the tweeter, and any DBT he did always gave
preference for the calss A kit.

So who needs power?

Just had a look at some modern pop music (Avril Lavigne - so pretty
much mainstream) with Audition - and it was interesting. I high pass
filtered and low pass filtered the files to mimic the action of a
crossover and looked at peak levels in Statistics to see how much
smaller the tweeter amp could be. The answer was that peak levels were
no lower above 2200Hz than they are below.

So for modern pop, you need a tweeter amp as powerful as the woofer
amp.

d
Pearce Consulting
http://www.pearce.uk.com