Amplifier slew rate

I am getting close to publishing my memoir! It's called 99% True and it is chock full of adventures, debauchery, struggles, heartwarming stories, triumphs and failures, great belly laughs, and a peek inside the high-end audio industry you've never known before.

[dell]

When I was working at Analog Devices we built some high end opamps that were 2" sq brics with a few dozen FET's and transistors inside along with resistors and diodes. These were all discrete parts and I remember we used a ferrite bead on the output lead of this little brick to boost the slew rate to 200 v / us. That was hot stuff for 1970.

[stevenslusher]

Slew rate, rise time, TIM (transient intermodulation distortion) was a big thing in the late '70s, Sansui and their Diamond Differential circuit, Kenwood/Trio, Harman Kardon were competitors in the slew/TIM wars

[BlankBrain]

I have some '80s gear that I still love. Many improvements have been made to op-amps since then, and it's tempting to drop in some new silicon. The usual advantages are lower noise and much higher slew rates. The faster circuits come with the hope for better sound and the increased likelihood of high frequency oscillation. Sparkfun sells tiny circuit boards that allow you to put surface mount devices on through-hole boards. The trick is getting the right capacitors in the right places to keep things stable!

[terrywho]

It will be interesting to see how PS audio integrates their ribbon tweeter with their cone midwoofer. That's a common combination, but most examples sound like two transducers and a crossover rather than a seamless loudspeaker, especially in small enclosures. That said, even unloaded, their speaker looks pretty nice.

[Grassy_Gnoll]

What fun it is to ride and sing a slewing song tonight!

[bjorntheviking]

Paul, I just came across this video at random, but we met many years ago, and funnily enough there would be no Osten Audio Labs had it not been for you, we have not crossed paths again since so I will use this as an opportunity to say thank you.

[silicone]

Wow, now I understand why some amps sounded sluggish. Thanks Paul!

[doylewayne]

turn the top sprout speaker upside down so the ribbons match up and you will have the modern stacked Advent configuration that i fell in love with long ago...thanks Paul

[minutesago]

Wow, great story.
Who slew?!
Also now appreciate what analog audio emulators are attempting to do with slew rate controls.
Thanks, all the best in 2019

[ianyates]

Hi Paul pleas show us a completed pare of those speakers beautiful eye candy, and we know they are going to sound sublime I want some it is Christmas after all lol 😜

[brendanlawton]

Isn't it cool how some of the best things come about through mistakes? {Learn something new everyday} Cheers to mistakes and what we learn through them.

[janinapalmer]

Slew rate is ever important as Paul rightly explained... I remember the 741 and the LM301... the latter requires a compensation cap added to it to control its open loop gain ... we have come a long way since those little devices came on the market . My preamplifier is designed around NE5534AN devices the 'AN ' suffix denotes very low noise in nano volts per square root of the applied frequency. They have a slew rate of over 70v / us which ain't at all bad ..
You must be aware though .. too much high slew rate maintained throughout the amplifier chain can lead to oscillation effects

[eugenepohjola]

Howdy. Slew rate is important.
Slew rate determines how well the upper bands can ride upon the bass. The larger the slew rate the better upper band fidelity. Only measuring the bandwidth does not say anything about the slew rate. A poor slew rate degrades the clarity and resolution of the upper bands.
Regards.

[MsFireboy]

Thanks for posting. I’m now in the process of building Astable multivibrator oscillators. I have found that the uA741 op-amp when viewing on my scope looks like the leaning tower of pizza. CA3140 is a little better. But the LT1007 is the winner in slew rate straight vertical lines on my scope. Do you remember these chips?

[kozkoz]

Paul I'm a huge fan of yours your videos just make me want to spend more money on equipment WHAT A HOBBY? I go way back to things like acoustat ESL magnet plasmas Randell research cables etc. I'm writing to you about cables and something you said about shielded cables that are connected on one end as a qausi-balanced cable I believe you stated not to do this and if so why not ? I do make cables it's a recipe for me and enjoy it please explain or someone reading this join in thanks

[Peter_S_]

If I lived in Bakersfield, I would want a really excellent audio system. It would be essential for properly reproducing the Bakersfield Sound.

[ilikoldies]

Hi! Paul! .. I always enjoy your interesting, and informative videos. Thank you for sharing your knowledge, and experiences with us. ... I don't normally bother you with my comments, but I wanted to wish you, and your family, and friends at PS Audio a very Merry Christmas, and a Great, and Happy New Year. ... Mike

[markfischer]

Here's the short and skinny. Power amplifier frequency response is measured at one watt into a 4 or 8 ohm resistor. Solid state amplifiers invariably look ruler flat across the audio passband by this test. But at higher power levels the high end rolls off and while the power bandwidth may show it to be adequate with a steady state signal the amplifier may not respond fast enough to keep up with the waveform exactly. So amplifiers have to be able to deliver power into real world loads that can be reactive and even kick back with reverse EMF. Big well regulated power supplies with a lot of stored energy in capacitors able to muscle it's way controlling any speaker it's hooked up to keeping up with high frequency transient waveforms sound best. Matti Otala of Harman Karon discovered this back in the mid 1970s. He called the failure of the amplifier to keep up "transient intermodulation distortion." Intermodulation distortion is any distortion that doesn't fit into any of the neatly defined forms of distortion.

[realitykicksin]

Wonder how much this can be measured through the speaker impulse plot and the Speaker frequency damping waterfall plot. This stuff should be measurable in the last chain link? Maybe some speakers are too slow and this gets aliased? Did anyone compare these plots with different amps?

[josephlalock]

those woofers look pretty close to the ones in my b&w 601 series 1. surprised with that as paul dislikes b&w.