So get these...
Chanzon 2pcs Wirewound Aluminum Shell Resistor 8 Ω ohm 100W ±5% Tolerance 8R Rohs Certified https://a.co/d/8YNxrA3
...and an inexpensive "analog" AC multimeter that shows millivolts AC, and play a 20hz, 1khz, and 20khz tones at a level of 2.83v from the amp's outputs and note any deviations, which there shouldn't be?
It's an old 80's carver amp.
If you want to look a lot deeper and with more precision, take a look at @IVX 's cosmos ADC for audio measurements. For amplifiers there is an extra breakoutboard that makes the input go all the way to 43V AC.
A perfect unit to use with REW...
https://www.aliexpress.com/item/1005003391728199.html
Cheers, Hans.
A perfect unit to use with REW...
https://www.aliexpress.com/item/1005003391728199.html
Cheers, Hans.
For frequency response testing at 1W, you only need a small load resistor, around 2 or 3W.
Those "certified" resistors need a big external heat sink to make 100W, which you don't need anyway.
Also, running an amp at full power for testing is a good way to blow it.
You won't find an inexpensive AC meter that will work, so just use the scope.
Those "certified" resistors need a big external heat sink to make 100W, which you don't need anyway.
Also, running an amp at full power for testing is a good way to blow it.
You won't find an inexpensive AC meter that will work, so just use the scope.
For frequency response testing at 1W, you only need a small load resistor, of around 2 or 3W.
Those "certified" resistors need a very big external heat sink to make 100W, which you don't need anyway.
Also, running an amp at full power for testing is a good way to blow it.
You won't find an inexpensive AC meter that will be accurate enough to work, so just use the scope.
Thanks again. So many opposing views on this. Use this meter. Don't use this meter. Use a sweep. Use a single tone. Using the dummy load wasn't even mentioned before your comment (unless I missed it). It's confusing. Lol.
Not sure how many other amps I might "test" in the future, but testing this old 80's amp is really all I have on my agenda right now. So the dummy load resistors I linked to would work, even though they're overkill at this point?
Not sure how many other amps I might "test" in the future, but testing this old 80's amp is really all I have on my agenda right now. So the dummy load resistors I linked to would work, even though they're overkill at this point?
Those resistors would work, but are not really needed for your purposes.
Again, remember that those are not even close to actually being 100W resistors,
unless you add large, expensive, external heat sinks.
I would not waste the money for a one time use like this.
Again, remember that those are not even close to actually being 100W resistors,
unless you add large, expensive, external heat sinks.
I would not waste the money for a one time use like this.
All my resistors are 1/2 watt and below. Those dummy load resistors cost about the same as some 5 watt resistor packs I looked at. About the cost of a #1 meal. Lol. Even if they're only actual 50 watt, I think I'll feel better about using them versus a "regular" lower wattage resistor.
Sure, but don't try to use them above a few watts, without a significant heat sink.
Also, at more than a few watts, those resistors will get very hot, and could burn whatever they touch,
Actually, the board you mentioned is a load-board for portable DACs measurements(usually <1/2W). Power-amps need nothing just Cosmos ADC+ 2.5mm TRRS plug.
Please do not quote the entire post just above yours. That is not the format of this forum and we have made it hard to do so. Don't kluge a work around. Quotes have been cleaned up.
One would think, if you really wanted to use a DMM, you could use a full wave bridge rectifier, followed by a RC low pass filter and have it measure DC instead. The diodes wont care about 20 kHz, nor will the RC filter.
Those come into play if you do the whole thing with pc audio gear. REW will do all sorts but you may be better of with ARTA as it has it's manual but the site also offers some tutorials which are enough to get you going*. The posh way needs a little interface box constructing with not much in it or the resistors can just be jury rigged, 😉 The details on one factor are scant if sound gear protection is added - how many jolts can be sent to your gear. 😉 Whoops replace jolts with volts. Jolts is not a bad way of thinking about them. Too many on semiconductors or amps cause them to let the smoke out or even explode.
Load resistors. There is a better type to use if suitable values can be found. Enamelled ceramic tube types. They don't mind getting extremely hot and dissipate more effectively than the types your interested in.
* No tutorials on testing amps. Seems to be lack of detailed ones on that. The signal from the mic used to test loudspeakers has to be replaced with a signal from the amp's load resistor. That may well need a divider. Either way that will need calibrating as a signal from a mic via an amplifier does. The sound gear also needs calibrating - you scope can be used to do that and the software can also check it's frequency response in the same way a multimeter can be. The tutorial on this is very verbose but the key points are given. Same could be done with REW,
Indeed the AC range on cheap multimeters will be designed to work for AC mains frequencies, which means at least 50 to 400Hz, but there's no requirement for any accuracy outside this range, though you may be lucky. 400Hz ac is used on some mobile equipment.