[martyo]

I just had a birthday and my daughter gave me a couple new (to me) Keith Jarrett Trio Cd's, so for the last week and a half, that's about all that has been on the big set.

I'll just make the same point you made in your "Double" thread. Smoother and more full, fuller tone, all with more resolving. Sometimes when smoother is put out there it might mean at a loss of resolution and definition, but not here.  aa

[Big Red Machine]

How many amps of current would the Double 550 produce?

[avahifi]

Well each output device, six per channel, is rated at 16 amps of current, 250 watts power dissipation, and 250V DC across them (not all at once of course).

However, the amp as we supply it is limited to 6 amps by the provided speaker protection fuses.  Note that a 5 amp fuse will supply 200 watts into 8 ohms and that is enough to burn up most voice coils on a sustained basis.  If you put in a lot bigger speaker fuses, then then internal 8 amp B+ fuses will blow first, and you will have to pull the cover to replace them.

How big the fuses can be before you start damaging internal circuits, your speakers, your windows, or your ears?  We have not tested that. 

I suspect that there are very few speakers available that will not blow first if the amplifier is overfused.  The Double 550 is making over 300 watts per channel into 8 ohms, both channels driven.

The purpose of the amplifier was not just for absolute power, it was for the "ease" at which it delivers the power RIGHT NOW!  It is very fast, 3 dB down at about 100KHZ and slew rate limiting can never occur short of output clipping, and it clips softly.

Just for fun, at the upcoming AudioKarma show, we will probably run a pair of them bridged mono on Jim Salk's speakers in a pretty big room.  With over 1KW per channel to play with, we should have enough power.

Best regards,

Frank Van Alstine

[zybar]

Well each output device, six per channel, is rated at 16 amps of current, 250 watts power dissipation, and 250V DC across them (not all at once of course).

However, the amp as we supply it is limited to 6 amps by the provided speaker protection fuses.  Note that a 5 amp fuse will supply 200 watts into 8 ohms and that is enough to burn up most voice coils on a sustained basis.  If you put in a lot bigger speaker fuses, then then internal 8 amp B+ fuses will blow first, and you will have to pull the cover to replace them.

How big the fuses can be before you start damaging internal circuits, your speakers, your windows, or your ears?  We have not tested that. 

I suspect that there are very few speakers available that will not blow first if the amplifier is overfused.  The Double 550 is making over 300 watts per channel into 8 ohms, both channels driven.

The purpose of the amplifier was not just for absolute power, it was for the "ease" at which it delivers the power RIGHT NOW!  It is very fast, 3 dB down at about 100KHZ and slew rate limiting can never occur short of output clipping, and it clips softly.

Just for fun, at the upcoming AudioKarma show, we will probably run a pair of them bridged mono on Jim Salk's speakers in a pretty big room.  With over 1KW per channel to play with, we should have enough power.

Best regards,

Frank Van Alstine

Frank,

I hope the hotel electricity is up to the task of feeding your amps.   

Thanks for the additional info.

George

[boycephoto]

Frank,

I am looking forward to your display at AKFest. 

Dave

[Big Red Machine]

Frank,

I hope the hotel electricity is up to the task of feeding your amps.   

Thanks for the additional info.

George
[/quote]

I am too as hotels typically have minimal power reserves, especially during shows!

Frank, I see specs like this one often, and was wondering what Current Capacity really meant when it came to an amp's ability to drive a speaker.  Here is a quick copy of a Halo amp spec:

        Current capacity:
        135 amperes peak

        Power bandwidth:
        2 Hz - 120 kHz, +0/-3 dB at 1 watt

        Total harmonic distortion:
        < 0.15 % at full power

Any insight as to how important Current Capacity is?

[avahifi]

I don't know how Halo presents their data, but I have seen this "current capacity number" arrived at simply by adding up the max current spec on all the output devices, which would allow, with the Ultra Double 550, to come up with current numbers of 96 amps, 192 amps, or 384 amps, depending upon whether you totaled the number of plus drivers on one channel, all the drivers from one channel, or all the ouput drivers in total.

I would suggest that numbers that put the typical arc welder to shame are a bit suspect.

Regards,

Frank

[Panelman]

Frank,

what do the watts look like for a steady 4 ohm load?

Thank you