Questions about Krell CAST technology (obscure...)

[Boomzilla]

KeithL

Krell introduced a current-variable transmission method called CAST (Current Audio Signal Transmission). I have at least two components (DAC & Preamp) that have the capacity to use CAST connections between them. The preamp also has CAST outputs, but none of my power amps are CAST-compatible.

Is there any advantage to CAST? If so, is it worth buying CAST cables when the CAST chain stops at the preamp? In other words, must ALL components be CAST-compatible, from the source to the power amplifier, to gain the claimed advantages? And finally, are the "benefits" of CAST worth the expense of implementing it?

Thanks - Boomzilla

[routlaw]

I wouldn’t waste anytime thinking about it. I was at a dog and pony show for Krell some 17 or 18 years ago when D’agostino introduced this technology to the audio world with his LAT 1 & LAT 2 speakers. Which btw were the worst speakers I have ever listened to, complete with a $19.00 Vifa tweeter that sold for a cool $26K and $12K respectively. Anyway matched with CAST system would run any sensible audiophile out of the room. Grossly overpriced under engineered audio gear would be my description. Hifi spectacular with little to no musical listening pleasure.

[DYohn]

Nov 5, 2019 9:35:50 GMT -5 routlaw said:

I wouldn’t waste anytime thinking about it. I was at a dog and pony show for Krell some 17 or 18 years ago when D’agostino introduced this technology to the audio world with his LAT 1 & LAT 2 speakers. Which btw were the worst speakers I have ever listened to, complete with a $19.00 Vifa tweeter that sold for a cool $26K and $12K respectively. Anyway matched with CAST system would run any sensible audiophile out of the room. Grossly overpriced under engineered audio gear would be my description. Hifi spectacular with little to no musical listening pleasure.

As a former owner of a set of LAT-1 loudspeakers, I can confirm that they were beautiful to look at, but not so beautiful to listen to.

[routlaw]

So sorry for your misfortune of owning those speakers DYohn 😜

[DYohn]

Nov 5, 2019 9:55:40 GMT -5 routlaw said:

So sorry for your misfortune of owning those speakers DYohn 😜

I sold them for more than I paid, so it ended up being a win.

[pedrocols]

Some reviewers described those speakers as a "real value and a bargain" in the HiFi world...🤦

[DYohn]

Nov 5, 2019 10:01:29 GMT -5 pedrocols said:

Some reviewers described those speakers as a "real value and a bargain" in the HiFi world...🤦

The same reviewers who gush over anything from D'Agostino I'm sure.

[routlaw]

This conversation reminds me of a favorite philosophy. People believe what they want to believe. Choose what ever discipline you want, and certainly audio is no exception, prove to them scientifically or otherwise the futility of their believe and people will just dig their heels in that much more rejecting anything they don’t want to hear or believe.

At the risk of beating a dead horse, once again rarely if ever does price ever into the equation of how well an audio product performs or sounds like.

[mgbpuff]

I would think that there is an advantage to CAST connections, but just as XLR balanced input circuits have increased noise rejection over standard RCA unbalanced input connectors, if there is little noise in the environment, there will be little difference in the results. CAST utilizes high output impedance in the source component working into low input impedance in the receiving component (just the opposite of standard voltage signal designed components). The CAST signal path has a supply conductor and a return conductor just as an XLR circuit, so it has the same noise cancelation property as an XLR but because the input impedance is very low, noise has even less chance of affecting the input signal. Whether CAST is worth using or not depends on the particular environment (in my opinion, unlikely to be discernable in a typical home environment). To use CAST cables to a non CAST amplifier, I would think one would have to add a shunt resister across the amp terminals (I would not bother with such clap trap).

[KeithL]

From what I understand, CAST transmits audio signals using "current drive", as compared to normal audio signals, which are "voltage drive".

In theory, under some very specific conditions, current drive could be more resistant to certain types of noise and distortion than voltage drive.

Unfortunately, as is usually the case with different ways of doing things, it could also be more sensitive to other types of noise and distortion.

(There's nothing inherently wondrous about doing it that way.)

Current and voltage are sort of different aspects of the same thing.

However, at various points inside a typical amplifier, the audio signal may be thought of as "a current signal" or "a voltage signal"...

Krell seems to be claiming some specific benefit of having the signal appear as a current signal at the point where you send it between components.

(They also imply that they use a relatively high-current signal... which would be the equivalent of a low impedance voltage signal... which makes sense.)

However, as far as I can see, its main benefit is commercial rather than technical.

(CAST outputs can only be connected to CAST inputs; much as Nikon lenses work best with Nikon cameras; this tends to provide one more reason to buy more Krell gear to connect to your current Krell gear.)

It looks to me like you have to use those special "CAST cables" for CAST connections - because they use some sort of proprietary connectors.

(There may or may not be something special about the cables themselves... depending on some details they neglect to mention... but it looks like you would have to buy them from Krell anyway.)

Assuming that CAST offered some sort of benefits, then those benefits would be true for every connection where it was used, and would still be true even if it was only used in one or two spots.

However, since you asked, as a technology, I don't personally see any particular technical virtues of doing it that way, and can't imagine why it would make a significant difference.

Of course, as with any specific piece of gear, all things are never exactly equal.

(So it's possible that, on specific pieces of Krell gear that offer multiple inputs and outputs, the CAST inputs and outputs may sound better than the others... or not.)

(It's also possible that Bosch dishwashers really do work especially well with Finish Quantum  dishwasher detergent.)

I have a sneaky suspicion that their special CAST cables are probably expensive....

And, no, I personally wouldn't bother...

Nov 5, 2019 3:44:11 GMT -5 Boomzilla said:

KeithL

Krell introduced a current-variable transmission method called CAST (Current Audio Signal Transmission). I have at least two components (DAC & Preamp) that have the capacity to use CAST connections between them. The preamp also has CAST outputs, but none of my power amps are CAST-compatible.

Is there any advantage to CAST? If so, is it worth buying CAST cables when the CAST chain stops at the preamp? In other words, must ALL components be CAST-compatible, from the source to the power amplifier, to gain the claimed advantages? And finally, are the "benefits" of CAST worth the expense of implementing it?

Thanks - Boomzilla

[Boomzilla]

Thanks kindly, KeithL - EXACTLY what I needed to know. I appreciate it.

Boom

[tropicallutefisk]

Nov 5, 2019 10:01:29 GMT -5 pedrocols said:

Some reviewers described those speakers as a "real value and a bargain" in the HiFi world...🤦

At $37,500? That's the MSRP I found in an old Stereophile review. Yikes! What should they have cost if not a value or a bargain? 

[DYohn]

Nov 5, 2019 11:05:11 GMT -5 tropicallutefisk said:

Nov 5, 2019 10:01:29 GMT -5 pedrocols said:

Some reviewers described those speakers as a "real value and a bargain" in the HiFi world...🤦

At $37,500? That's the MSRP I found in an old Stereophile review. Yikes! What should they have cost if not a value or a bargain? 

$38K is reasonable in the high-end world. Indeed, it's sort of at the low-end price-wise for loudspeakers.

[routlaw]

Allow me to add a few more comments on this. During that dog and pony show D'Agostino did almost a couple of decades ago he used the analogy of audio circuits historically as trying to push water uphill, while his current driven CAST invention was the equivalent of allowing water to flow with gravity. I heard this straight from the horses mouth that evening. I don't know how much those CAST cables cost but he went on to explain that at the time they were nothing more than telephone wiring with a different connector much like what VPI turntables use with their tone arm wire to output connects. Sorry can't recall the name of the connector.

So a few months later while discussing this with another audiophile who had bought into the CAST system, he like me could barely stand to listen to it. This was a fellow who had huge sums invested in his hifi system, more than most people would spend on high end home in a life time.

Apparently those Lat speakers went up in price from when I was familiar with them. Oh well, such a bargain.

[KeithL]

As I understand it the CAST cable is also balanced - it simply uses "current signals" rather than "voltage signals".

(Krell describes the CAST cable as a "four pin connector" for each channel.)

In a standard "voltage source" signal, the source impedance is low, while the load impedance is high.

In a "current source" signal like CAST, the source impedance is very high, while the load impedance is low.

Therefore, in both systems, you have a low impedance at one end, and a high impedance at the other.

Whether either works better than the other will therefore not be at all certain.

It will depend on whether the dominant noise sources act more like "voltage noise" or "current noise".

And, to be quite honest, assuming the balanced portion of both is properly implemented, noise should not be a problem for either.

Nov 5, 2019 10:37:15 GMT -5 mgbpuff said:

I would think that there is an advantage to CAST connections, but just as XLR balanced input circuits have increased noise rejection over standard RCA unbalanced input connectors, if there is little noise in the environment, there will be little difference in the results. CAST utilizes high output impedance in the source component working into low input impedance in the receiving component (just the opposite of standard voltage signal designed components). The CAST signal path has a supply conductor and a return conductor just as an XLR circuit, so it has the same noise cancelation property as an XLR but because the input impedance is very low, noise has even less chance of affecting the input signal. Whether CAST is worth using or not depends on the particular environment (in my opinion, unlikely to be discernable in a typical home environment). To use CAST cables to a non CAST amplifier, I would think one would have to add a shunt resister across the amp terminals (I would not bother with such clap trap).

[vcautokid]

making this nice and simple. I sold Krell for almost 10 years and the CAST thing is a thorough waste of time as far as any net advantages. If you think they are cool sure. But in my sound room where I worked we sold other cable solutions and never bothered with CAST. It was interesting but that is as far as I would go. Loved the Krell stuff. CAST? I could leave it and not be too upset at all.

[macan15]

I understand that the Krell CAST technology is proprietary but are there other non-Krell preamps that have the CAST capability. Do realize that I can use balanced interconnects as alternative OR get a Krell preamp.

Newbie who happened to stumble onto this forum and must say I DO own a number of Emotiva products.

Thanks.

[KeithL]

I'm sure the term "CAST" is trademarked... and Krell may even hold patents on very specific details about how they go about it.

But there's nothing proprietary about using a "current based" rather than a "voltage based" audio signal...

Therefore, I suspect that other manufacturers cannot legally use the term "CAST" with their equipment...

However, it wouldn't be especially difficult to include an input or output on another device that was "functionally compatible" with CAST.

For example, Audio G*D offers a connection they call "ACSS", which they say is compatible with CAST, on some of their products. ( www.audio-gd.com/Master/Master19/Master19EN.htm )

They even tell you how to wire the adapter cables.

(NOTE: CAST uses a different sort of audio signal - so you CANNOT connect a CAST input or output to a standard balanced input or output simply by using an adapter cable.)

Mar 6, 2020 10:00:55 GMT -5 macan15 said:

I understand that the Krell CAST technology is proprietary but are there other non-Krell preamps that have the CAST capability. Do realize that I can use balanced interconnects as alternative OR get a Krell preamp.

Newbie who happened to stumble onto this forum and must say I DO own a number of Emotiva products.

Thanks.

[vcautokid]

If this means anything to anyone CAST is not even used on current Krell gear. Though you can find Krell audio in cars which is bigger news.