AMPS: High Power Vs High Current?

[mtrycrafts]

...
I never thought about this before, but both my brother and brother-in-law are electrical engineers, and neither one of them care about Home Theater electronics at all.

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No money in that field. Doesn't solve world needs and problems.

 

[mtrycrafts]

Regardless of what HCA means, that amp can be considered literally a high current amp.

Well, the toroidal is 1.6kVA and rated 45A peak per channel(per the specs) which is hard to accept. That would be 225A peak total.
It would need a peak 180V on the rail for 4 Ohms? Or, that may be p-p.
Still, 90Vx45A peak would mean 4kW peak per channel into 4 Ohms?
Or, you need a 1 Ohm load on a channel to get this.

 

[Hetfield]

Well, the toroidal is 1.6kVA and rated 45A peak per channel which is hard to accept. That would be 225A peak total.
It would need a peak 180V on the rail? Or, that may be p-p.
Still, 90Vx45A peak would mean 4kW peak per channel?

I think Parasound knows what's it's doing and doesn't fudge numbers.

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[speakerman39]

The impedance overall means nothing. It is the impedance in the power range that matters especially below BSC.

It really is not difficult. Lets take a 20 volt rail voltage. If the impedance is 10 ohms then the maximum current that could be delivered is 2 amps. In practice it would be a little less, but lets ignore that. So the power delivered would be 40 watts. Now lets assume we have a good linear SS amp. Now lets make the speaker impedance 5 ohms. So the current will up to 4 amps and the power to 80 watts. If it is a really linear amp dropping the impedance to 2.5 ohms will be 8 amps, and the power 160 watts. If it can't deliver the current for the power required by the input then there will be clipping. In practice an real world amps are not that linear, and the power into 2.5 ohms will probably be closer to 120 watts.

Now lets make the impedance 20 ohms. In an SS amp it can't deliver a higher voltage than the rail. So voltage clipping will occur at above 20 watts.

Now lets take a tube amp. We can get any voltage we want, by selecting an appropriate secondary tap on the output transformer. So we can match power to any impedance and have the power constant through any range of impedance as long as it is constant with frequency

However here is the rub. Few loudspeakers have constant impedance. So if we match a tube amp to the mean impedance of say 8 ohms, and say it delivers 20 watts max into the load. Lets see what happens in a real world load. If the impedance is 4 ohms at 200 Hz it will deliver 10 watts at that frequency. Now say the impedance is 6 ohms at 900 Hz, it will deliver 15 watts at that frequency. So this is how at max power at the clipping point a tube amps response starts to follow the impedance curve. So if you have a tube amp speaker selection has a huge impact on the sound you get. The reason being is that tubes can not increase current as load impedance is reduced, like SS amps can.

Now you can see why highly sensitive speakers with very simple, and especially no crossovers, are so popular in the tube community. Back in the tube days I used pretty much exclusively full range drivers with no crossover.

Lastly your quest to look at high current versus high power is just nonsensical. The two are the same side of the coin. A high powered amp is high current. A high current amp is high powered.

A low current amp that was high powered would need a high output voltage and a very high impedance load. That situation is not encountered in real world loudspeakers.

You see power is Voltage X Current, always, no exceptions. So at a given voltage then you can only increase power by dropping load impedance so current can rise.

This is really simple very basic stuff about which there can be no argument. Don't get confused by the ignorant pig dribblers wasting ink in the Audiophool press. These people are unfortunately too numerous to count, and make the Internet full of error, which is inexcusable since this matter is so simple.

I understand this a bit better after reading a few times....LOL!!! But, what is BSC? Not quite clear on that. Thanks once again to TLS for taking the time to write this up. It is both very informative and quite helpful. Just some terms that I am not too familiar with. Thanks!


Cheers,

Phil

 

[Swerd]

But, what is BSC? Not quite clear on that.

BSC stands for Baffle Step Compensation.

Imagine a 6½" woofer in a rectangular 9" wide cabinet. Sound with wavelengths longer than than 9" tends to wrap around the edges of the cabinet. And sound with wavelengths shorter than 9" tend to reflect off of the front baffle. As a result, the longer wavelengths will be quieter than the shorter wavelengths.

Unless there is compensation for this, the sound will be noticeably louder in a region of the mid range. It can make voices and instruments sound a bit forward, nasal, 'shouty', or 'honky'. This louder frequency range is called the Baffle Step – because frequency response curves often show a range where the loudness is stepped up.

In speakers with passive crossovers, the baffle step should be compensated, or equalized, to level out the frequency response across the baffle step region. It's done by reducing the loudness across the baffle step region until it's about the same level as the bass below it. You cannot raise loudness in a passive crossover, you can only lower it. These circuits are called BSC circuits, and they reduce a speaker's sensitivity, requiring more power and more current across the affected frequencies.

Here is an example recently posted by rojo. See the region labeled 'Forward Image'. The baffle step starts above 1 kHz and continues to nearly 3 kHz. That's caused by a speaker without enough Baffle Step Compensation.

 

[speakerman39]

BSC stands for Baffle Step Compensation.

Imagine a 6½" woofer in a rectangular 9" wide cabinet. Sound with wavelengths longer than than 9" tends to wrap around the edges of the cabinet. And sound with wavelengths shorter than 9" tend to reflect off of the front baffle. As a result, the longer wavelengths will be quieter than the shorter wavelengths.

Unless there is compensation for this, the sound will be noticeably louder in a region of the mid range. It can make voices and instruments sound a bit forward, nasal, 'shouty', or 'honky'. This louder frequency range is called the Baffle Step – because frequency response curves often show a range where the loudness is stepped up.

In speakers with passive crossovers, the baffle step should be compensated, or equalized, to level out the frequency response across the baffle step region. It's done by reducing the loudness across the baffle step region until it's about the same level as the bass below it. You cannot raise loudness in a passive crossover, you can only lower it. These circuits are called BSC circuits, and they reduce a speaker's sensitivity, requiring more power and more current across the affected frequencies.

Here is an example recently posted by rojo. See the region labeled 'Forward Image'. The baffle step starts above 1 kHz and continues to nearly 3 kHz. That's caused by a speaker without enough Baffle Step Compensation.

Thanks a bunch Richard as I had no clue. Have heard of this, just never really knew what it meant. I will be sure to read this carefully. Probably several times......LOL!!! Thanks for taking the time to post this. It is a BIG help to me, as well as, to others.


Cheers,

Phil

 

[PENG]

Well, the toroidal is 1.6kVA and rated 45A peak per channel(per the specs) which is hard to accept. That would be 225A peak total.
It would need a peak 180V on the rail for 4 Ohms? Or, that may be p-p.
Still, 90Vx45A peak would mean 4kW peak per channel into 4 Ohms?
Or, you need a 1 Ohm load on a channel to get this.

A couple points to consider:

- 45A peak typically means peak, not peak to peak, for sine wave you know that would be 31.8A. We can assume they did base the value on sine wave, but that's just a reasonably assumption, and we could be wrong. If you want to know exactly what they mean, then you are going to have to ask them.

- It says each channel, that does not imply all channel driven simultaneously. There is no way that 1.6kVA transformer can handle 5X31.8A rms, unless the load is 2 ohm or less. Otherwise even a 30A breaker would trip if it last any longer than a few seconds.

Such kind of specs is really more hype than practical. unless the load dips to 1 to 2 ohms, the 31.8A rms is not that useful. Even for a 4 ohm load, 4X31.8A = 127.2V. We both know that amp won't have rail voltage any where near that kind of voltage.

I consider it a truly high current amp mainly because of the 1.6 kVA transformer and 100,000 uf of capacitance, and the 5X200W into 4 ohm specs, not because of the practical value of the so called high current capability. Now that's assuming Parasound's specs for this particular amp is accurate. From what I know, there is no guarantee that their specs for every products are 100% accurate.

 

[mtrycrafts]

A couple points to consider:

- 45A peak typically means peak, not peak to peak, for sine wave you know that would be 31.8A. We can assume they did base the value on sine wave, but that's just a reasonably assumption, and we could be wrong. If you want to know exactly what they mean, then you are going to have to ask them.

- It says each channel, that does not imply all channel driven simultaneously. There is no way that 1.6kVA transformer can handle 5X31.8A rms, unless the load is 2 ohm or less. Otherwise even a 30A breaker would trip if it last any longer than a few seconds.

Such kind of specs is really more hype than practical. unless the load dips to 1 to 2 ohms, the 31.8A rms is not that useful. Even for a 4 ohm load, 4X31.8A = 127.2V. We both know that amp won't have rail voltage any where near that kind of voltage.

I consider it a truly high current amp mainly because of the 1.6 kVA transformer and 100,000 uf of capacitance, and the 5X200W into 4 ohm specs, not because of the practical value of the so called high current capability. Now that's assuming Parasound's specs for this particular amp is accurate. From what I know, there is no guarantee that their specs for every products are 100% accurate.

That 5x200W into $ Ohms is why my curiosity. And as you pointed out with your numbers, things just don't sound right. At 200 Watts, you are only talking about 7A per channel. So, yes, 5 of those would be 35A RMS
total. And, to me, 7A per ch is not high current but a good amp that is capable of full power with all channels driven.

 

[Hetfield]

I think John Curl knows this stuff just a wee bit better than us. He has been designing amps for 30 plus years. You should email Parasound with your concerns. I bet you get a thorough and lenghty explanation of the numbers.

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[lovinthehd]

I think John Curl knows this stuff just a wee bit better than us. He has been designing amps for 30 plus years. You should email Parasound with your concerns. I bet you get a thorough and lenghty explanation of the numbers.

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Why don't you instead of just being a fan of the brand? Post the answers up. Parasound is not beyond marketing....

 

[Hetfield]

Why don't you instead of just being a fan of the brand? Post the answers up. Parasound is not beyond marketing....

Um because I have sent them a zillon emails over the past 3 months and they have answered each and every one and don't feel like bothering them again. I'm not concerned about this stuff as you guys and honestly it's mumbo jumbo to me. I wouldn't even ask the question correctly. How's that for honestly? The only thing I know is the amp has serious power, built like a tank, and powers my Def Techs very well. It doesn't run hot which surprises me. It gets warm to very warm.

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[mtrycrafts]

... The only thing I know is the amp has serious power, built like a tank, and powers my Def Techs very well. It doesn't run hot which surprises me. It gets warm to very warm.

Yes, it has a very large transformer and lots of caps. It seems to deliver 200Watts into 4 Ohm load all channels driven. But the numbers just don't add up at their website that may have a misprint.
I am not that interested in sending an email.
As to John Curl, perhaps he was a good designer at one time, then he was drawn to the dark side of audio.
One only has to follow AA where is has posted for many years. So, no, I am not impressed by him one bit.

 

[lovinthehd]

Um because I have sent them a zillon emails over the past 3 months and they have answered each and every one and don't feel like bothering them again. I'm not concerned about this stuff as you guys and honestly it's mumbo jumbo to me. I wouldn't even ask the question correctly. How's that for honestly? The only thing I know is the amp has serious power, built like a tank, and powers my Def Techs very well. It doesn't run hot which surprises me. It gets warm to very warm.

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So in other words you don't have a clue?

 

[PENG]

I think John Curl knows this stuff just a wee bit better than us. He has been designing amps for 30 plus years. You should email Parasound with your concerns. I bet you get a thorough and lenghty explanation of the numbers.

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I emailed Parasound multiple times in the past and did get answers every time, that's why I also suggested mtry to email them about the 45A thing. HD also made a valid point, they are not beyond marketing, but I did get honest response from them, based on my own assessment.

I also emailed John Curl a few years ago. I highly doubt he would respond to email now and I don't think he is with Parasound any more.

This high current thing is by nature subjective, how high is high really? So when you and I consider our amps (we both own one) high current, others may not and that's fine, and expected.

 

[Hetfield]

Well as I said this way over my head and probably 90% of people reading this. To say your not impressed by a guy that has designed some great amps is a little strange to me but hey who am I to say you should be impressed by.
By the way I'm a fan of a lot of audio companies. They are all interesting in their own way. Outlaw audio, Emotiva, SVS, HSU, and a ton more the list would be too long to name. I'm not stuck on any one brand. I bet Emotiva makes great amps and products, as does Outlaw audio and a ton more. I find them all interesting. Parasound isn't the only audio company I am a fan of.

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[Hetfield]

So in other words you don't have a clue?

I don't have a clue because I'm not an audio engineer. All I know is they have been extremely honest and upfront with me but I don't so highly technical questions as this. That's why I say you guys that know about this stuff and are concerned should ask. I'm sure they'll give you a detailed answer. I don't really care to be honest.

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[lovinthehd]

I'm probably the least fan of Parasound as an old girlfriend of mine sold for them and she had absolutely no clue. Lots of good amps out there, often at better prices than theirs. It's not that big a deal, it's still just an amp.

 

[Hetfield]

I'm probably the least fan of Parasound as an old girlfriend of mine sold for them and she had absolutely no clue. Lots of good amps out there, often at better prices than theirs. It's not that big a deal, it's still just an amp.

I have seen this exact post by you before and I still don't understand it. You don't like them because a girlfriend used to sell them? She had no clue about what, Parasound amps? Seems like a strange reason to not like a companies products if you ask me. I had a girlfriend that sold ice cream and had no idea how it was made but I still eat Carvel ice cream. I don't get it.

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[lovinthehd]

I have seen this exact post by you before and I still don't understand it. You don't like them because a girlfriend used to sell them? She had no clue about what, Parasound amps? Seems like a strange reason to not like a companies products if you ask me. I had a girlfriend that sold ice cream and had no idea how it was made but I still eat Carvel ice cream. I don't get it.

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No, she had no clue about audio in general (her own system had crappy speakers and components but a Parasound amp). She was a pretty blond and that's why she had the position, she sold to guys at audio stores. I've just not found their gear exceptional. Lots of good amps out there. Why do you continue to put them on a pedestal without knowing why?

I make my own ice cream.

 

[Hetfield]

I emailed Parasound multiple times in the past and did get answers every time, that's why I also suggested mtry to email them about the 45A thing. HD also made a valid point, they are not beyond marketing, but I did get honest response from them, based on my own assessment.

I also emailed John Curl a few years ago. I highly doubt he would respond to email now and I don't think he is with Parasound any more.

This high current thing is by nature subjective, how high is high really? So when you and I consider our amps (we both own one) high current, others may not and that's fine, and expected.

Yeah I would email them but I really don't care. Only thing I know is the amp is a beast, ample power. I'm not allowed to say clean, dynamic power anymore because I'll be asked to explain how using trigonometry and ohms law. I'll just say it has plenty of power for my taste.

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