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Matrix STR3000H in Dub Clash Scandal

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cilla.scope View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cilla.scope Quote  Post ReplyReply Direct Link To This Post Posted: 24 November 2009 at 1:13pm
I suspect certain people would be less quick to judge if you said "would an amp sound the same at lower levels with less output devices? I suspect it might, but I  might be wrong ..."  instead of stating it as a fact, and arguing the toss with experienced amp designers. 

At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times. The silicon in a quality  amp designed for use with large sub/bass drivers is capable of more power (in terms of thermal capacity of the devices) than it is rated for (or has PSU for) by a factor of 2 or 3 times .... its not there for output power, its there to provide  significant current capability into low impedances, with significant reactive content.  Go look at an impedance plot (both magnitue and phase angle) for a 18" driver on sub bass duty ... the impedance will dip from a nominal 4 ohms to less than 1 ohm at certain frequncies ... and this is where having large amounts of silicon pays off.

Damping factor and back EMF off the driver are significant issues in driving low frequency large speakers with a high  mms.   The damping factor would increase significantly, reducing cone control even at low powers. Damping factor is not solely dependant on voltage gain in the feedback loop. Current transfer capability plays a significant part too.

The cororally of this is that I have seen far too many attempts to adapt a hi-fi amplifier design to PA use, simply by bolting on more output devices, in the forlorn hope that it will scale up to a 1000W + capability. It doesn't work that way, which is why good sounding PA amps are not as common as you might have hoped.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote mk2_ginger_biscuit69 Quote  Post ReplyReply Direct Link To This Post Posted: 24 November 2009 at 2:56pm
it may be good, but its still bloody ugly/blank!! the facade looks very budget :(
''Remember that the object of a subwoofer is to enhance the output of your main speakers, not overpower it''

''Dubstep - an elongated electronic fart''
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SamV Quote  Post ReplyReply Direct Link To This Post Posted: 24 November 2009 at 3:08pm
I kinda like the look, simple, understated and here to do a job. At worst you could probably call it plain.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ArthurG Quote  Post ReplyReply Direct Link To This Post Posted: 24 November 2009 at 4:43pm
Originally posted by mk2_ginger_biscuit69 mk2_ginger_biscuit69 wrote:

it may be good, but its still bloody ugly/blank!! the facade looks very budget :(
yeah that's right, it looks the same to me. But you must consider the fact that a good face plate costs a lot of money in Europe. 
From what I see, with Matrix amps you pay for performance, not fancy looking. For some people it's the most important, for other well you have better choices around. but its more (much more) expensive...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cravings Quote  Post ReplyReply Direct Link To This Post Posted: 24 November 2009 at 5:16pm
i quite like the "plain" front. you can put it in a rack with anything else and it doesn't look out of place.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote teslaman Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2009 at 11:46am
Originally posted by cilla.scope cilla.scope wrote:

I suspect certain people would be less quick to judge if you said "would an amp sound the same at lower levels with less output devices? I suspect it might, but I  might be wrong ..."  instead of stating it as a fact, and arguing the toss with experienced amp designers. 
 
A fair point; If my post came across as curt then I apologise to everyone. In the spirit of what you are saying I open the floor for that very question:  Would an amp sound the same at lower levels with less output devices? I suspect it will, but I might be wrong.
I have proved to myself, using simulations, that it is true for follower type output stages but I suspect it is not true for for common-emitter (or common-source) type output stages due to the transfer function being heavily dependant on Hfe (or admittance).
 
At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times.
 
Is there any literature to support this "fact"? I understand an amp needs to deliver the required current but provided the 1000W amp in your scenario is not clipping and is able to deliver the necessary current then I fail to see why it would definitely sound worse then the 5kW one. Is it not possible that the 1kW amp may have a better design, with higher open loop gain and a lower output impedance (better damping factor) and thus could quite possibly sound better? I think its quite possible.
 
The silicon in a quality  amp designed for use with large sub/bass drivers is capable of more power (in terms of thermal capacity of the devices) than it is rated for (or has PSU for) by a factor of 2 or 3 times .... its not there for output power, its there to provide  significant current capability into low impedances, with significant reactive content. 
 
And no doubt to be more reliable under the more abusive conditions bass amps have to deal with? I believe bass amps have to deliver more average power than any other part of the spectrum and are generally designed to be able to provide approx. 1/3rd rated power continuously?
 
Go look at an impedance plot (both magnitue and phase angle) for a 18" driver on sub bass duty ... the impedance will dip from a nominal 4 ohms to less than 1 ohm at certain frequncies ... and this is where having large amounts of silicon pays off.
 
The term "nominal impedance" is an abused one by manufacturers. I prefer to know the DCR of the driver since it is a fact that the impedance cannot fall below the DCR value regardless of the type of enclosure used. Typically a "nominal" 4 ohm cab might have a DCR of 3 ohms so i'd be surprised to see any 4 ohm cab drop to 1 ohm! Do you have an example??
 
Having said that, I know that its not sufficient for an amplifier to only be able to deliver the peak current that an equivalent pure resistor load would need. Because of the stored energy in the moving mass the current peaks of a driver can approach double that of a pure resistor. I suspect thats where a good bass amp comes into its own - the massive amounts of current that are needed, as you say.

Damping factor and back EMF off the driver are significant issues in driving low frequency large speakers with a high  mms.   The damping factor would increase significantly, reducing cone control even at low powers.
 
I'm not sure what you mean here, high damping factor implies strong cone control so did you mean "decrease significantly"?
 
Damping factor is not solely dependant on voltage gain in the feedback loop. Current transfer capability plays a significant part too.
 
Agreed, the driver stages must be able to properly drive the output stage allowing high output currents at any instantaneous output voltage. This allows proper driving of highly reactive loads. It is also the reason I despise some amplifiers with SOA protection schemes - it's not the protection itself per se as this is necessary, its the skimping on numbers of transistors which means that the SOA activates with normal but highly reactive loads connected, yuck! MOSFET's have an advantage over BJT's for both these issues I think, do you agree?

The cororally of this is that I have seen far too many attempts to adapt a hi-fi amplifier design to PA use, simply by bolting on more output devices, in the forlorn hope that it will scale up to a 1000W + capability. It doesn't work that way, which is why good sounding PA amps are not as common as you might have hoped.
Agreed, a lot of PA amps seem unable to take abuse like I would expect. Domestic amps are designed to provide 1/8th their power rating continuously. I believe for PA amps 1/3rd rated power is more the minimum standard? I've certainly seen this recommended by key people in the industry. However I think there are a lot of PA amps out there that cannot do this and the new lightweight ones seem to be more guilty than the older toroidal powered ones....? I believe the 1/3rd power standard should be a priority, especially on amps for bass applications. What do people think?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote teslaman Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2009 at 11:57am
Originally posted by teslaman teslaman wrote:

Originally posted by cilla.scope cilla.scope wrote:

 
At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times.
 
Is there any literature to support this "fact"? I understand an amp needs to deliver the required current but provided the 1000W amp in your scenario is not clipping and is able to deliver the necessary current then I fail to see why it would definitely sound worse then the 5kW one. Is it not possible that the 1kW amp may have a better design, with higher open loop gain and a lower output impedance (better damping factor) and thus could quite possibly sound better? I think its quite possible.
 
Sorry, I missed the point here! Damn the lack of edit feature!!
The *same* topology 5Kw amp sounds better than its 1kW brother - I remain to be convinced on this, what is the reason? I can't simply accept more silicon = better performance. There must be a quantifyable reason and if both amps can deliver enough current and are running un-clipped then what can it be?? If you say it's down to damping factor then what would happen if this was made identical too?

 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dougies Music Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2010 at 1:00pm
why did this argument stop?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tallmike Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2010 at 1:15pm
Originally posted by Dougies Music Dougies Music wrote:

why did this argument stop?
 
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cilla.scope View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cilla.scope Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2010 at 6:37pm
no, I thought I won, and I haven't got the energy to convince fools of the errors of their ways ...  if he thinks he can get the same sound by ripping 80% of the output devices out of an amp, let him. its a well known and proven too many times fact that you need significantly more current capability than you might think to drive a bass bin well. that why amps with plenty of silicon in the output stages sound better than cheap ones with economies.

Speakers do not present a resistive load, they present a complex impedance, often dipping below the 'nominal' impedance of the speaker and to deliver 1000W of power you will often need more current than the calculation for a straight 8 ohms resistive would imply ...   which is why a 1000W amp attempting to run 1000W into a bin will not sound as good as a 5K amp of the same design doing the same job. And thats before we even start thinking about headroom.




Edited by cilla.scope - 03 January 2010 at 6:38pm
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cilla.scope View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cilla.scope Quote  Post ReplyReply Direct Link To This Post Posted: 03 January 2010 at 6:51pm
Originally posted by teslaman teslaman wrote:

Originally posted by teslaman teslaman wrote:

Originally posted by cilla.scope cilla.scope wrote:

 
At low frequencies, the peak current capability is what counts, and you would run into current limit problems a long long time before you got to overheat problems. You'll find that for driving large speakers (18", 21", with 4" voice coils) large quantities of silicon are what  count ... a 5kw amp running at 1000w sounds better than a identical topology 1000W amp at 1000W,  large quantites of silicon sound better. Fact. Proven more than enough times.
 
Is there any literature to support this "fact"? I understand an amp needs to deliver the required current but provided the 1000W amp in your scenario is not clipping and is able to deliver the necessary current then I fail to see why it would definitely sound worse then the 5kW one. Is it not possible that the 1kW amp may have a better design, with higher open loop gain and a lower output impedance (better damping factor) and thus could quite possibly sound better? I think its quite possible.
 
Sorry, I missed the point here! Damn the lack of edit feature!!
The *same* topology 5Kw amp sounds better than its 1kW brother - I remain to be convinced on this, what is the reason? I can't simply accept more silicon = better performance. There must be a quantifyable reason and if both amps can deliver enough current and are running un-clipped then what can it be?? If you say it's down to damping factor then what would happen if this was made identical too?

 


Oh, sure, theres no reason a different design  smaller amp wont sound better , better, smaller amp wont sound better than a poorer larger amp .. but  we where talking about identical desin topologies.

lets say we have a 1Kw amp rated into 4R resistive,  at 1000W  I^2 R = 1000,  so about 16A ... so lets say it has enough silicon to manage 16A and goes into current limit above that ...  whats it going to do when it tries to drive into 3R and deliver 100W of output into a load presenting a 60 degree phase angle?  cos phi will be 0.5 ... so you already need 32A .. and into 3R (quite possible at certain frequnecies in a nominal 4R driver) .. 40A?

This is why you need more current capability than the basic power equation would suggest ... the impedances are not pure resistive and not a nice constant 4R either.  If you measure up the actual output current capaility based on the silicon of any decent amp, you'll be suprised at how many times overrated it is. Its not done for fun. AMp makers dont typically use more silicon than they have to for no good reason ...

Anyway, you go ahead and rip 80% of the output devices out of an amp and see if it sounds the same.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2022 at 1:50pm
Guys,what about this Matrix STR3000:



Edited by EmPro - 20 June 2022 at 1:51pm
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