Help me Jim or Al, I don't know if my math is right, but isn't 6,000 watts equal to 50 amps on a 120 VAC line?
Amp and preamp on same outlet?
Just how much of a no-no is this? ARC goes as far to print in their manual to say to have the amp and preamp on their own circuit. I live in an apt. and I'm forced to have both plugged into the same outlet. Cords just don't reach....How much sound quality is lost by doing this? It sounds great as is, but is there a major detriment to this? I'm curious.
- ...
- 125 posts total
John, yes your math is of course correct. And the 700cx does indeed have a max power consumption spec of 6000 watts, which if anything seems a bit low in relation to its specified output power rating of 2800 watts/channel into a 2 ohm load (the 8 ohm and 4 ohm ratings being 700 and 1400 watts respectively). But it seems safe to assume that it would be an unusual occurrence for the amp to be used in a manner that would require it to draw more than 20 amps x 120 volts = 2400 watts for a long enough time to cause a 20 amp breaker to trip. Best regards, -- Al |
50 amps is correct. But we should keep in mind that the amp is likely never going to produce such power, as it would only be possible if the load were one ohm. I remember the Apogee Full-Range speaker approached that value, but the speaker cables used in such an installation would add to the load impedance and limit the possibility of such power. On most 4 ohm loads the output power is about 1500 watts. In addition if I recall correctly, its the power transformer in that amp that has that rating, not the amp itself. The transformer would current-limit the amp even if the output section was capable of delivering such power. Line voltage sag can cause some amps to heat up as the bias point can shift somewhat depending on the design so I can see that reducing the sag with a higher current breaker might have an effect. But installing such a breaker without upgrading the associated wiring would be foolhardy and would not meet code in any state in the country. |
Audiolabyrinth, IF, Krell is indeed telling customers the amp was designed to be connected to a 120V 30 amp branch circuit for use in the USA or Canada. Again IF!!! You are the one that that does not understand what Krell is actually up to. If Krell is having to connect the amp to a 120V 30 amp circuit for the amp to operate properly as designed as well as to achive the amps reported specs then Krell should be using a captive power cord and a NEMA 125V 30 amp plug on the end of the cord. The user, customer, would then be required, per NEC Code, to install a 120V 30 amp branch circuit with the correct NEMA 125V 30 amp receptacle for the Krell amp plug. Per NEC Code a 30 amp branch circuit requires #10AWG minimum wire and shall be connected to a 30 amp branch circuit breaker, period. The receptacle must be a NEMA rated 125V 30 amp receptacle, period. No exceptions. Instead Krell is apparently more interested in building a product that violates NEC code safety standards for the USA by using a 20 amp max rated IEC inlet connector on the amp where by the user can use a power cord that has a NEMA 5-15P or a NEMA 5-20P plug. Then Krell has the gull to tell a customer that bought the amp to change out the breaker at the electrical panel from a 20 amp to a 30 amp, which I believe the real reason is, because the Krell amp is nuisance tripping the 20 amp breaker on startup in rush current. So because Krell was too tight to design/incorporate a soft start circuit to limit inrush current to solve the customer's problem of the 20 amp breaker nuisance tripping they tell the customer to change out the 20 amp breaker to a 30 amp breaker. What they should be telling the customer is to change out the 20 amp breaker to a 20 amp HM, High Magnetic, breaker that has a longer delay time for startup inrush current. Problem solved. I wonder how many Krell users have followed the advice of krell? How many users who changed out the 20 amp breaker to a 30 amp on a 20 amp dedicated branch circuit that has #12AWG 20 amp rated wire? As I have pointed out earlier in this thread the current carrying contacts as well as the other current carrying metal parts of a 20 amp breaker are identical to that of a 30 amp breaker. Had an EE at Krell done his/her homework he/she would know this as well. They would also know as well a typical TM, thermal magnetic, breaker will easily pass short bursts of current of 120 amps all day long. More than enough for their amp but not enough apparently for startup inrush current. A 30 amp TM breaker will pass short bursts of 300 amps. Hell you can arc weld with 120V at 30 amps. And if the branch circuit wire is of any length and #12AWG copper once I get the #12 branch circuit wire cooking I won't have to worry about tripping the 30 amp breaker. I have looked at every article in NEC Code that pertains to the code violations and nowhere in the NEC Code book is an exception given for Krell inc. Audiolabyrinth , did you know? Krell recall I would bet that no owner of the Krell amp mentioned in this thread has anything in writing from a representative of Krell inc. stating Krell recommends changing the breaker on a 20 amp branch circuit from a 20 amp to a 30 amp breaker. All a user/customer has is a verbal conversation that is worthless in a court of law. So who is in violation of State, and local governing body safety electrical codes and electrical safety standards when a 20 amp breaker is changed out to a 30 amp breaker on a 20 amp branch circuit? . The person/home owner that changes it out of course. I suggest you call you insurance agent and ask him/her if you are covered by your home owners insurance policy in the event of an electrical fire if it is found a 30 amp breaker is installed on a 20 amp branch circuit. Then call the governing electrical inspection department in your city and ask them about changing the 20 amp breaker to a 30 amp breaker on a 20 amp branch circuit. NEC Code 210.21 (B)(3) Receptacle Rating. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacles ratings shall conform to the values listed in table 210.21(B)(3), ........... NEC Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits. Circuit Rating ..... Receptacle Rating (Amperes) .............. (Amperes) 15 ............................ 15 20 ....................... 15 or 20 30 ............................ 30 Minimum wire size #10awg. Breaker size 30 amp. *No exception given for Krell Inc. Circuit Breaker Myths Siemens Breakers Electrical-forensics . |
- 125 posts total