IV = current*voltage detection and action.
The output devices ( and what precedes) are generally damaged by sustained POWER dissipation.
50W across a hot power device might be the limit that can be maintained continuously. Increase that to 60W and eventually the device blows up.
but it may be able to pass a short term 200W if the transient lasts a very short time and does not repeat too often.
A detection strategy that calculates the POWER (I*V) and limits the dissipation can "protect" output stages form damage.
Many amplifiers have I detection and some have I*V (or IV) detection and all only allow for sustained or continuous levels of power dissipation.
transients are limited to the same levels as continuous.
Very few amplifiers have a strategy that differentiates between long signals and short signals and very short signals. These will often allow audio type transients to pass and yet for sustained overloads initiate protections.
A simple IV that does not differentiate very short from the longer duration peaks is very likely to limit valid audio signals into valid audio loads.
That will be audible.
For this reason simple IV is castigated by many and as a result very few Members and almost all audiophiles will not accept any protection systems.
My definition of a good IV system is:
All valid audio signals must pass to all valid audio loadings.
All damaging signals that exceed the allowed valid signals should be limited so that the equipment protects itself.
As you can probably gather, this amplifier protection has virtually nothing to do with protecting the speakers.
That is a quite different issue and there are many speaker protections strategies discussed on this Forum and just as many devices that can be added to any amplifier.
The output devices ( and what precedes) are generally damaged by sustained POWER dissipation.
50W across a hot power device might be the limit that can be maintained continuously. Increase that to 60W and eventually the device blows up.
but it may be able to pass a short term 200W if the transient lasts a very short time and does not repeat too often.
A detection strategy that calculates the POWER (I*V) and limits the dissipation can "protect" output stages form damage.
Many amplifiers have I detection and some have I*V (or IV) detection and all only allow for sustained or continuous levels of power dissipation.
transients are limited to the same levels as continuous.
Very few amplifiers have a strategy that differentiates between long signals and short signals and very short signals. These will often allow audio type transients to pass and yet for sustained overloads initiate protections.
A simple IV that does not differentiate very short from the longer duration peaks is very likely to limit valid audio signals into valid audio loads.
That will be audible.
For this reason simple IV is castigated by many and as a result very few Members and almost all audiophiles will not accept any protection systems.
My definition of a good IV system is:
All valid audio signals must pass to all valid audio loadings.
All damaging signals that exceed the allowed valid signals should be limited so that the equipment protects itself.
As you can probably gather, this amplifier protection has virtually nothing to do with protecting the speakers.
That is a quite different issue and there are many speaker protections strategies discussed on this Forum and just as many devices that can be added to any amplifier.
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Andrew,
Thanks! That's enlightening. I was thinking exactly along these lines ("a strategy that differentiates between long signals and short signals and very short signals. These will often allow audio type transients to pass and yet for sustained overloads initiate protections") but couldn't think of a right way of formulating it.
This looks like the kind of protection you find in active cross-overs/limiters, like those used in PA-systems. But those are usually dsp-based and employed BEFORE the power amp.
So, basically, the best and cheapest way of protecting your power amp, is by using it sensibly and using your ears. Am I right?
Thanks! That's enlightening. I was thinking exactly along these lines ("a strategy that differentiates between long signals and short signals and very short signals. These will often allow audio type transients to pass and yet for sustained overloads initiate protections") but couldn't think of a right way of formulating it.
This looks like the kind of protection you find in active cross-overs/limiters, like those used in PA-systems. But those are usually dsp-based and employed BEFORE the power amp.
So, basically, the best and cheapest way of protecting your power amp, is by using it sensibly and using your ears. Am I right?
I already have a limited capability to set through scripting (ATmega328) how
many milliseconds a V/I fault condition exists to finally trigger protection.
The next logical step is to actually use the analog inputs on the ATmega to monitor
V/I through an A-D convertor . Here you could get real "fancy" , and have
another ATmega analog I/O actually limit the output stage in response ... and/or
totally shut down.
Once the analog I/O buffers are perfected ... all the rest is "scripted" .
V3.4 might go this way.
OS
I have no idea what you just said...I already have a limited capability to set through scripting (ATmega328) how
many milliseconds a V/I fault condition exists to finally trigger protection.
The next logical step is to actually use the analog inputs on the ATmega to monitor
V/I through an A-D convertor . Here you could get real "fancy" , and have
another ATmega analog I/O actually limit the output stage in response ... and/or
totally shut down.
Once the analog I/O buffers are perfected ... all the rest is "scripted" .
V3.4 might go this way.
OS
When looking for capacitors for this amp (most are film capacitors), does it matter which brand/type you use? Does the "recommended application" from the data-sheet matter at all? What, if any, would be the effect of using the cheapest capacitors versus the more expensive ones, on the final sound quality?
Thanks!
Capacitor price has almost nothing to do with sound quality, nor with amplifier performance.
Correct capacitor TYPE to suit the duty at each location is very much to do with amplifier performance.
Choosing the wrong TYPE of capacitor can completely ruin the sound quality.
Note I said "price" in my first comment. That was very deliberate. Many assume high price = high quality.
Correct capacitor TYPE to suit the duty at each location is very much to do with amplifier performance.
Choosing the wrong TYPE of capacitor can completely ruin the sound quality.
Note I said "price" in my first comment. That was very deliberate. Many assume high price = high quality.
Thanks, Andrew.
So much is clear to me.
With regards to capacitor types, is seems there are several types of film capacitors: plastic film, polyester film, oil film, mica, etc. Is there any difference in application between these? In other words: is there a certain preference to one or the other specific to locations/functions in this amp? I don't know the difference, except that they look different (Vishay versus Panasonic, for example) and the quoted price tag. There are many options and I'd like to choose the right ones.
Nippon Chemi-Con , nichicon , even some of the surplus (Apex jr.)
.....or panasonic for electrolytic' s .
CORNELL DUBILIER silver mica for 100/470 pF compensation caps ...
This guy sell em' at a real good price - Tube Radio Capacitor Shopping Cart
Mouser/Digikey wants 1.50$ - $3.00USD each for silver mica .
Standard fare poly 100-250V from any authorized distributor is adequate
for all the .1 - .68u stuff. (wima ??)
You don't need to spend any more than 15-20$ on caps for a badger
channel and get the full quality and 20 years life (MTBF).
"audiophile caps" ... bahhhh ! - knock yourself out 
.
The only other "picky" sourcing is 1% resistors for Q1/2 emitter resistors and
buy some extra cheap (.23c) 1845/992's so you can find a few close in Hfe (DMM)
for the LTP/current mirrors.
Edit- the BOM has the lead spacing for all the caps - some pads
on the badger are multi pitch (this is also specified).
OS
.....or panasonic for electrolytic' s .
CORNELL DUBILIER silver mica for 100/470 pF compensation caps ...
This guy sell em' at a real good price - Tube Radio Capacitor Shopping Cart
Mouser/Digikey wants 1.50$ - $3.00USD each for silver mica
.Standard fare poly 100-250V from any authorized distributor is adequate
for all the .1 - .68u stuff. (wima ??)
You don't need to spend any more than 15-20$ on caps for a badger
channel and get the full quality and 20 years life (MTBF).
"audiophile caps" ... bahhhh ! - knock yourself out
.The only other "picky" sourcing is 1% resistors for Q1/2 emitter resistors and
buy some extra cheap (.23c) 1845/992's so you can find a few close in Hfe (DMM)
for the LTP/current mirrors.
Edit- the BOM has the lead spacing for all the caps - some pads
on the badger are multi pitch (this is also specified).
OS
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You don't have to repeat anything unless you want to be helpful. A1200 post thread is a lot for someone to read through who has only recently joined the frey.
just because you recommend something, doesn't mean that is LAW...
i will use whatever works for me, i have thousands and thousands of caps in my parts bin.....
go build yourself some amps and then show us how you did it, in pictures and not in words....