deepmukherjee Posted March 30, 2004 Share Posted March 30, 2004 Hi ! I have heard that in order to get the best of a HT system based on the RF-7, you must use a "High Current Amp". What is a high current amp? How do you know if the amp you are going for is high current or not? Does it make a difference in the clarity of the sound from the speaker?? Quote Link to comment Share on other sites More sharing options...
D-MAN Posted March 30, 2004 Share Posted March 30, 2004 I believe they are referring to a HIGH WATTAGE amp. Same thing, really. DM Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted March 30, 2004 Share Posted March 30, 2004 No, they are not the same thing. My understanding of it is this, Current (amperage) is the real power behind the scenes, HK amplifiers and receivers use the high current design which means they can supply more amperage per watt than your average receiver. For example they may have a 70W X 5 rating on their receiver but because of the high current design the power could be equivalent to receiver that touts a 100W X 5 rating due to the amperage being supplied. This also generally means that they have stout power supply transformers and capacitors which is a good thing since they will be more capable of handling transients with ease. Quote Link to comment Share on other sites More sharing options...
ygmn Posted March 30, 2004 Share Posted March 30, 2004 amps = watts/(volts) Volts = amps x ohms therefore amps = Sq root(watts/ohms) Therefore to increase amps you have to increase watts (power) or decrease the Ohms (speaker impedance). So normally; high current amps can handle low impedance speakers and remain stable....and not burn up with the higher amp delivered Quote Link to comment Share on other sites More sharing options...
D-MAN Posted March 30, 2004 Share Posted March 30, 2004 Beg to differ: P = ie which is watts (power dissapated = current x voltage) High current = high wattage. DM Quote Link to comment Share on other sites More sharing options...
jdm56 Posted March 30, 2004 Share Posted March 30, 2004 As the load (impedence) decreases, more current (amperage) is needed to deliver a given amount power (watts). So basically, high-current amps are amps that can deliver high amounts of power into low-impedence loads. For example, typical receivers are rated only into 8 ohms, and indeed most cannot deliver enough current into lower impedences to make their rated 8 ohm power. But a true high-current amp design (Krell comes to mind) will be able to double it's power output, with each halving of impedence; 100W into 8 ohms, 200W into 4 ohms, and 400W into 2 ohms. In the real world, few high-current amps can do this clear down to the 2 ohm range, because this usually involves huge power supplies, heat sinks and price tags. As for your RF7's, their high efficiency somewhat mitigates any current demand. They are an 8 ohm speaker anyway, and as such would not be a difficult load for any decent receiver/amplifier. Quote Link to comment Share on other sites More sharing options...
Champagne taste beer budget Posted March 30, 2004 Share Posted March 30, 2004 Amps = Volts/Ohms Volts = Amps x Ohms Ohms = Volts/Amps Watts = Volts x Amps Amps = Watts/Volts I always wondered about the claims of high current amps, since the current flow is based on the voltage applied. More volts would naturally also create more wattage, as shown above. I don't see how you could take amp "X" with 100 watts into a theroetical 8 ohm load and increase it's amperage output without also increasing it's wattage output. It's pretty much been my assumption that so called high current amps simply have a higher watt rating, but they needed some new fangled jargon to help sales, so they started touting the current flow aspect instead of the wattage increase. Maybe someone here can enlighten me as to the error of my thinking? Maybe they've decreased the voltage output, which would mean to obtain the same wattage output, it would create higher amperage? Quote Link to comment Share on other sites More sharing options...
Trooper Posted March 30, 2004 Share Posted March 30, 2004 IMO, Most of the people recommending a high current amplifier don't really know what they're talking about. But it's a long running audiophile necessity. As you can see from all of the equations presented by others above every amplifier that outputs 100W into 8 ohms is putting the same amount of current into that 8 ohm load (I=sqrt(100W/8 ohms) = 3.53A). This of course assumes amplifiers output the power that the manufacturer claims which is another story. What people typically mean by "high-current" is one of 2 things: 1. The amp can maintain it's output power into multiple channels simultaneously. For example to do 2 channels @ 100W requires 7.06A from the power supply. For 5 channels; 17.65A, etc. Some amps do 1 or 2 channels just fine then fall on their face - meaning maybe 70W into 5 channels (I think this is where HK gets there ratings and where people like Sony lie). The reason the power output drops is because the power supply can't supply enough current. 2. The amp can double its power into 4 ohms. An amp with sufficient current available will double (or nearly double) power into 4 ohms vs. its 8 ohm rating. This is beacuse the VOLTAGE required to make 100W @ 8 ohms and 200W @ 4 ohms is the same. The CURRENT required doubles. (Remember Voltage * Current = Power) Engineering-wise a "high-current" amp has 2 main characteristics: Low output impedence (which all modern solid state amps have) and a power supply capable of supplying the necessary current. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted March 30, 2004 Share Posted March 30, 2004 An amplifier that can put out high current will more easily handle a speaker's impedance swings. A large woofer in a ported enclosure ie: cornwall driven to high levels, will require more current than a bookshelf ie: rb 75. Quote Link to comment Share on other sites More sharing options...
J.4knee Posted March 30, 2004 Share Posted March 30, 2004 Beg to differ: P = ie which is watts (power dissapated = current x voltage) High current = high wattage. DM DM - Now divide each side by e and you get right back to YGMN's comment Quote Link to comment Share on other sites More sharing options...
D-MAN Posted March 30, 2004 Share Posted March 30, 2004 I was responding to Frzninvt... Sorry. DM Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted March 31, 2004 Share Posted March 31, 2004 Champagne taste beer budget, Yeah, to some extent it's a marketing ploy, but there is some basis in engineering if the company is honest. Let's say you and I both make amps. Both of our amps are designed to swing a maximum of +/- 30 volts in the output stage. Into a simple 8 ohm load, we'd be talking a maximum power of 112 watts (power equals voltage squared divided by resistance), and we'd be dumping 3.7 amps into that load. Let's say our amps are both rated at 100 watts into 8 ohms, which is a bit conservative. Now, let's connect our amps to a wickedly difficult speaker. An old Apogee Scintilla, to use an extreme example. Its impedence dips to 0.8 ohms at some frequencies. Turn up the volume. Theoretically, if we apply that 30 volt potential across that 0.8 ohm load, we'd be talking 1,125 watts (using the same Ohm's Law formula). However, our amp would need to be able to dump 37.5 amps of current into the load in order to reach that power output level. If *MY* amp can dump a lot more current into a load than *YOUR* amp can, my amp is going to do a much better job with those Scintillas. Let's say your amp is an output transformerless tube thingie, with a maximum current capacity of, uh, 5 amps. I build massively overengineered solid state boat anchors that can dump 50 amps of current. Both our amps are rated the same, 100 watts into 8 ohms, and they will both deliver that power. Hook them up to the Klipschorn, and yours'll probably sound better. Hook them up to the Scintilla, and mine will deliver 1,125 watts, producing a sound level of about 113dB (Scintilla was something like 83dB / watt / meter, if memory serves correctly.) Yours, limited by the 5 amp current capability, will probably break, and will produce at most 20 watts into that load, producing a sound level of about 95dB. *I* build *HIGH CURRENT AMPS*. I'm so proud... Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted March 31, 2004 Share Posted March 31, 2004 Just to add more fuel to the fire, in the 70s there was a rating that started to show its head (I dont know if it is still in use) and it was called MUSIC POWER. You could have two amps rated at say 100 watts, one was RMS the other was MUSIC POWER. The RMS amp would produce approximately TWICE the current as the MUSIC POWER amp. The difference was that the first amps rating in watts was for RMS (Root Mean Square) watts and the second amp MUSIC POWER was PEAK TO PEAK watts. RMS means the AVERAGE voltage in the sine wave, which is for the sake of argument approximately ½ that of peak volts. MUSIC POWER or PEAK TO PEAK is the measurement of the tops of the peaks of voltage thus throwing OHMS law a curve and gives a false reading of watts available in the amp. This was a marketing ploy to sell lower power amps in the AMP WARS of the 70s. I wonder if this is still in effect today with different names such as NORMAL and HIGH CURRENT ratings. Quote Link to comment Share on other sites More sharing options...
v3spitfire Posted April 1, 2004 Share Posted April 1, 2004 I think the big difference between watts and amps, according to any electrical engineer, is that Watts may give you a jolt, Amps kill you! Quote Link to comment Share on other sites More sharing options...
Colin Posted April 1, 2004 Share Posted April 1, 2004 Good example, professor Ray, I thought music power was the old IHF (?) rating before RMS took hold, the old IHF rating made the newer solid-state amplifiers look less powerful compared to the old tube varieties, BTW, we now know that a tube amplifier can deliver about 5 times more current (voltage?) than a solid-state amplifier, making low powered tube amplifiers sound better than their low wattage would indicate. Quote Link to comment Share on other sites More sharing options...
Trooper Posted April 1, 2004 Share Posted April 1, 2004 ---------------- ... BTW, we now know that a tube amplifier can deliver about 5 times more current (voltage?) than a solid-state amplifier, making low powered tube amplifiers sound better than their low wattage would indicate…. ---------------- Huh!?! The laws of physics prevent anything like that from happening. Now if you'd said 5 times more distortion I'd be with you. Quote Link to comment Share on other sites More sharing options...
hwatkins Posted April 1, 2004 Share Posted April 1, 2004 Hooray for Ray - Hit it on the head. He kept me from offering misstatements to try and say what high current meant. I discovered the differences when I was trying to power my Maggies (quite some time ago). There are specific needs for high current with reciprocal price tags. You have to ask if you gain a benefit to match the higher price. In my experience - high efficiency 8 ohms (nominal of course) setups don't benefit greatly from the high current (others will disagree). Now as to the old Maggies - quite a different story... Quote Link to comment Share on other sites More sharing options...
Petrol Posted September 7, 2006 Share Posted September 7, 2006 with all this new found 'knowledge' I am left wondering where does all this leave a silly sob like me when shopping for an 'affordable' reciever... by affordable, I'm talking about going as far below a 'street' price of $1k as anyone dare go while still being able to obtain a good amount of reliability, features, etc. btw, how do I compare, say HK's 'High-Current' watts vs., Yamaha's 'High-Current' watts vs. , etc., etc. etc. ? Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted September 7, 2006 Share Posted September 7, 2006 As the load (impedence) decreases, more current (amperage) is needed to deliver a given amount power (watts). So basically, high-current amps are amps that can deliver high amounts of power into low-impedence loads. For example, typical receivers are rated only into 8 ohms, and indeed most cannot deliver enough current into lower impedences to make their rated 8 ohm power. But a true high-current amp design (Krell comes to mind) will be able to double it's power output, with each halving of impedence; 100W into 8 ohms, 200W into 4 ohms, and 400W into 2 ohms. In the real world, few high-current amps can do this clear down to the 2 ohm range, because this usually involves huge power supplies, heat sinks and price tags. As for your RF7's, their high efficiency somewhat mitigates any current demand. They are an 8 ohm speaker anyway, and as such would not be a difficult load for any decent receiver/amplifier. this is a correct explanation ... Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted September 7, 2006 Share Posted September 7, 2006 what are you looking for??? 5.1, 7.1, stereo? I like HK and they have not clipped yet I have the HK3480 rated at 120 watts high current. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.