Ed,
Actually, given that electrodynamic speakers rect to current, only current and nothing but, this may be a good thing...
And Tube Amp's where almost never designed for matched load, but usually a ratio of 3:1 (rare exceptions exist), for example the 2A3 with it's 800 Ohm Anode impedance was specified for 2.5K load SE and 5K Push-Pull, giving a 3.125 Ratio...
Ciao T
Yes modern vacuum tube amplifiers are designed for output impedances below the "Name" value and loudspeakers are rated for a nominal impedance twice the minimum.
I should not discuss in specific what is in not yet approved standards, but there are limits on test set up source impedance.
Then there are loudspeaker designers who use networks to get flat impedance so that the amplifier impedance variations have less effect.
Wave, you did understand I was using metaphors? Loudspeakers should be designed to run from a very low source impedance.
In my use there is a difference between the words driver meaning a part of a loudspeaker and loudspeaker meaning a complete unit even if it has only one full range driver.
So a driver responds to current a loudspeaker is intended to be driven by a voltage.
Now if you want to build a multiple driver integrated amplifier unit, you have an active loudspeaker and can do what you want. The issues then are basically input sensitivity, bandwidth and power -3db compression point.
Yes you want the proper cap in that place. Remember it should get a Hipot test before shipping and it is a destructive test.
Simon, do you understand I disagree on any extremism that inevitably throws out baby with dirty water?
I have low wattage zero feedback designs to drive effective full-range speakers. I have designs to drive speakers with complex crossovers that sometimes have close to zero impedance dips. I have some designs to drive subwoofers by a negative output impedance. All of them satisfy requirements to drive own speakers. But if to select amps by criterion how close their output resistance is to zero we gain nothing but satisfaction of own meaningless criterion. Thanks God there is no such standard, so we still have some freedom to explore different possibilities.
I have low wattage zero feedback designs to drive effective full-range speakers. I have designs to drive speakers with complex crossovers that sometimes have close to zero impedance dips. I have some designs to drive subwoofers by a negative output impedance. All of them satisfy requirements to drive own speakers. But if to select amps by criterion how close their output resistance is to zero we gain nothing but satisfaction of own meaningless criterion. Thanks God there is no such standard, so we still have some freedom to explore different possibilities.
I worked for quite a while as a service agent for Dranetz mains disturbance analysers, you would be amazed at how many KV the spikes can be on the mains in your socket.
Wrinkle
So, electro-mechanical inverter with heavy flywheel is probably a good thing to have in basement.
I know where to get one, cheap. Oh wait, it's 24V DC out. I once had a military surplus 120V 60Hz to 120/220 400Hz motor generator. Never could figure out what to do with it.
We have a 12KW generator here at the house that is connected to the city gas line. I've looked at the output on a scope, it's ugly.
We have a 12KW generator here at the house that is connected to the city gas line. I've looked at the output on a scope, it's ugly.
At the 2001 CES I was attached to a high dollar speaker manufacturer who was showing in two separate rooms, one with a New Zealand electronics manufacturer with their own motor generator outdoors and an inverter indoors. They spent almost the whole show trying to get the setup to work worth a hoot, but finally gave up and on Sunday just plugged into the wall. Bitter lessons...
Thanks,
Chris
Thanks,
Chris
Did they make also a Faraday cage in the listening room?
What's really surprising is that they were a serious, technical, non-tweaky outfit who made good serious amps. I think they just got caught up in the whole challenge-of-it-all thing and couldn't let go.
The other room we showed with VAC and everything ran like a dream. Durned tubes.
Thanks,
Chris
He likely would get better results by adding more filter capacitance to his amp.
Our old 15 amp AC line has no trouble powering our 1800 watt electric heaters.
Better yet, power amps should employ some kind of active regulation to lower impedance.
Another thought, what gauge wire is used in the transformer of a power amp? Much less than 6mm, I'm sure.
My experience with that was with a 10KVA UPS. This thing did 3 phase 220 with corrected phase rotation. The battery part was 1/5 of the slice and the "guts" weighed substantially more.
As a serious piece of hardware, the inverters were always on and supplying the output AC which was perfect sine-wave. Make-before-break switches and circuitry meant you could test it by flipping a 2" wide breaker.
At that point huge machines didn't know the difference between battery. They also did not know the outside world.
It was cool at the time.
P
With all the BS about cables, most people with serious power amps need to worry more about the power available at their outlets.
p
Please refer to Ohm's law concerning your old 15 amp AC. The wire in the transformer? GEEZ. It's the winding, not the gauge.
Real batteries
http://www.sbsbattery.com/UserFiles/File/STT 2 Volt Cells.pdf
A stack of the 4000AHr cells should do.
http://www.sbsbattery.com/UserFiles/File/STT 2 Volt Cells.pdf
A stack of the 4000AHr cells should do.
Dear Ed,
The 2A3 Datasheet I quoted was from the 1930's...
What we really have at issue is commercial reality and interchangeability. Voltage drive (Zsource ~ 0 Ohm) maximises several quite pernicious distortion sources in speakers, while Current drive (Zsource ~ oo Ohm) minimises them.
But Voltage source Amplifiers and Speakers with passive crossovers made for Voltage source drive are interchangeable, something seems of great value to many in many fields (though fully active speakers are making inroads and we may eventually see some using current drive, other than some obscure German Marques).
Yes, doesn't that seem odd and counter intutive?
I did that in the 80's. I used current drive for all drivers.
Among the benefits of Current drive, power compression is cancelled, eddy current distortion is cancelled. The effects sonically are not negligible.
Ciao T
The 2A3 Datasheet I quoted was from the 1930's...
What we really have at issue is commercial reality and interchangeability. Voltage drive (Zsource ~ 0 Ohm) maximises several quite pernicious distortion sources in speakers, while Current drive (Zsource ~ oo Ohm) minimises them.
But Voltage source Amplifiers and Speakers with passive crossovers made for Voltage source drive are interchangeable, something seems of great value to many in many fields (though fully active speakers are making inroads and we may eventually see some using current drive, other than some obscure German Marques).
Yes, doesn't that seem odd and counter intutive?
I did that in the 80's. I used current drive for all drivers.
Among the benefits of Current drive, power compression is cancelled, eddy current distortion is cancelled. The effects sonically are not negligible.
Ciao T
Chris,
Wherever we demo AMR as much as possible we bring own power cables (which are first and foremost TUV Germany tested for electrical safety and secondarily have suitable electrical parameters to minimise any issues that contribute to "mains cable sound". We also use quite high grade connectors (this makes a difference, especially if there are unbalanced impedances).
We also bring our own Power distribution boards, high quality, with a few small capacitors providing power factor correction (we do need to make them switchable one day), the snubbers are inside the gear, also connected with our power cables.
We always get excellent results plugging all this straight into the Wall, even at Chinese AV Expo's (The chinese market is very important now, only place where people still have money to spend), where the power is notoriously double plus ungood.
Sadly some dealers/distributors insist on making use some "audiophile" mains cables and power conditioners, which rarely work that well...
Ciao T
Wherever we demo AMR as much as possible we bring own power cables (which are first and foremost TUV Germany tested for electrical safety and secondarily have suitable electrical parameters to minimise any issues that contribute to "mains cable sound". We also use quite high grade connectors (this makes a difference, especially if there are unbalanced impedances).
We also bring our own Power distribution boards, high quality, with a few small capacitors providing power factor correction (we do need to make them switchable one day), the snubbers are inside the gear, also connected with our power cables.
We always get excellent results plugging all this straight into the Wall, even at Chinese AV Expo's (The chinese market is very important now, only place where people still have money to spend), where the power is notoriously double plus ungood.
Sadly some dealers/distributors insist on making use some "audiophile" mains cables and power conditioners, which rarely work that well...
Ciao T
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