I've tried learning how to calculate my power amps so I have perfect match power going to my cabinets but Bro this is over my head haaaaa

Best explanation I have seen of Old tech (AB, H etc) Amps vs New Class D etc. Would be interested to see if there are any newer amps that can sustain the long bass tones e.g. LabGruppen PLM models. The old Crest 7001, 8001s would just keep pumping...

Cheers Dave, i feel more validated for my sedimental purchase of an old Perreaux 9000B.

Fantastic as always

I feel so redeemed by the fact that someone as experienced as you is saying the same things I am saying. I experience a lot of resistance (pun intended) when trying to bring facts and science into audio discussion. I would love to hear how you feel about the mighty "watts rms" which I find to be a nonsensical unit in the context it's used.

Great video man, but now days everyone goes for the K watt sticker, dont even bother to look at frequency respond or weight. and power draw.. 👍👍

I wish amps would have ratings for the internal specs as energy storage/capacitance, rail voltage, and power supply wattage I assume would be better specs to pay attention to nowadays. I try to look at max power draw and efficiency numbers to get an idea of sustained output capacity even though that’s not the whole story for music.

Yes, I ear told me the same thing when class d amps came along, the old Bryston and Crest amps worked better. With class D I go for 50% more power to keep things safe.

Hi Dave how is your experience with Hypex based class d amps

so basically I sold all my passive speakers because I couldn't afford the amps I needed. I should just quit all together

👍

the average val of the absolute value of the sine function is .637 not .707, I'm a little confused on where that number is coming from

My subwoofer is very happy at the end of every video :)

can you get hold of a VOID Acoustics Infinite 8 V2, and do the test with that??? i own such an amp and i think it's a great amp but, i kinda got doubtful about amps now... great videos thanks for each and everyone of them. you really reignited my passion for audio and tech again.

What a great video series! I have just one consideration: when you divide Voltage^2 by R to compute the power you are supposing a purely resisitve load --> In case of a speaker, which is characterized by an impedance figure, it must be considered the frequency of the signal to compute the impedance. Nominal impedance is at 1 kHz. Lower frequencies (like the 225 Hz you had on the example) will lead to lower impedance since the inductance component will behave more more like a short circuit giving you the true resistive part and so, for the same voltage, higher currents (and power)

interesting video been trying to put together a small pa on battery running 50w a channel on 4 ohms with a 92db/1w speaker but curious if upgrading to a 99db/1w at 8 ohms would be worth the upgrade as it then gives 25w from the amp

I want to mention Georg Simon Ohm . Great guy.

If you don’t know who Dave Rat is, you should probably look him up…he’s been around for a bit!

"Old" tube amp at full power/overdrive may sound "awesome", the "new" digital amp may not ;-)

Thanks Dave.

11:32 4 times more power out 2kW = 8kW not 4kW ... or did I missed something?

Keen to see where this leads. Does this explain the difference we hear between different classes of bass guitar amps? For example, my Gallien-Krueger 700RB-II feels noticeably more alive, responsive, punchy and with more character than similar output digital amps, including GK and Fender. I understand speakers/cab makes a difference but I have played enough different rigs to feel the difference. The tones can be similar and both are great options, but in my experience those MOSFET solid-state amps like the old GK 400/700/800 and old Trace Elliot AH250/AH300 amps simply delivered more of everything. You can push and push them much harder than their digital cousins. Curious to know your thoughts and understand the factors at play.

Waw... sorry Dave , Im not an expert , but with all respect due , you are talking about Efficiency for something called Sensitivity express in dB/1W/1m, efficiency is the ratio of the average acoustical power (in W) radiated by the loud- speaker to the total electrical average power (in W as well) supplied to the loudspeaker its a number without dimension or expressed in % wich is very different things ...

I'm curious what the spec sheet rating would be for the new amp that you just showed us. I was hoping to learn if the peak was the rating that manufacturers use as "peak" and if RMS was fairly true to being actually true RMS even during dynamic loading. If the modern amp you tested showed a rated 350 watts at 4 ohm RMS or something similar, then it would appear you only benefit from the peaks creating a large burst of power to follow dynamics of music instead of a more compressed, flat signal. I look forward to seeing where this goes

thumbs down? really? congrats to "that guy"

Grate video as always. I look forward to your videos. You produce content that I really like.

Aww Dave! How could you miss that?? P=IE ; as, Watts=Amps x Volts; then returning to Ohms law and derivations. I forgot all this twenty years ago until now!

What would have been interesting to see is the recovery of the amp. I thought I saw a hint of it when you stopped the signal. This would give a good idea of how often you can hit it like that.

The SQRT(2) = 0.7071 factor works for sine waves only. This would be 1.0 for square waves, and much less for a typical music signal.

What if some amps use 30a/220 and break it down to a lower v does it still reduce the performance of the amp. Or 30a twist plug to a 110

Thanks dave...

So this test is with the amps set just a hair below clipping, correct? How do the amplifiers behave when you have more headroom to work with, if the amps are running at, say 75% of their maximum capacity?

Worth noting is that Ohm's Law is only for direct current. With alternating current you also have capacitive reactance and inductive reactance, and to calculate those successfully, you need some knowledge of vectors, phasors and imaginary numbers. Or you can cheat and eliminate all reactance (or close to it) from the circuit, leaving just the scalar resistance value that can work with Ohm's Law. As it turns out, testing with a purely resistive load also helps eliminate bias in testing by not favoring one kind of reactance over another, and not favoring one kind of load. In sound reinforcement, most loads will be inductive, so eliminating this bias is less critical than with hi-fi speakers, where one finds more capacitive reactance in drivers, and passive crossover elements. There's also test equipment that can hide all the calculus from you while testing real-world loads. But if you don't have access to fancy test equipment, you can still get accurate and precise measurements by using just a calibrated resistor, a good voltmeter and the DC power formula.

My guess is that 90% of music actually has a "loudness signature" simular to the power handling capabilyties of new amps.

Dave at 11:30 you say that it needs 4000W to get as loud, yet it is a 6dB difference, so it should be 8000W. Am I missing something?

Dave you can just skip an extra step by multiplying Peak to Peak times 1.14.

Thank you so much Dave! There are likely a lot of “sound guys by need” like me out here that didn’t get this info in school. This helps a lot!

Thanks for another great video Dave! I like the classic amps. For the most part today's products are BS compared to previous consumer goods from the 60s 70s and 80s. Too much engineered obsolescence now. Your tv's and automobiles forward all ambient sound to a 3rd party for possible future persecution. I drive cool old Fords and will never get rid of my fat stack of Adcom GFA 585's & 565's pushing those 15" and 18" Cerwin Vegas. Old school or no school!

I am so excited for this series in power amps!

Awesome video Dave; thanks!!

Wow, that was quite shocking, the rate at which the modern amp fell off surprised me, I have read about sagging but I hadn't imagined it would be that fast. Talk about cliff hanger, ... : )

Thank you for that video. Can't wait for next episodes. All best.

Was this made with my comment in mind?