Carver Preamp and the Toshiba 2SC2878 transistor - Page 4

K-amps · 8th May 2005, 02:06 PM

Guys, If Krell chooses to have no input coupling cap, let them. They thought at the time that it introduces distortion... maybe it does.

I would not like to use the argument that a DC on the preamp will destroy speakers... thats the preamp's fault not the power amp's fault. The power amp is faithfully passing the signal sent by the pre-amp and thats what it should do.

anatech · 8th May 2005, 02:39 PM

Okay, I'll buy that argument. But since DC on the output is not only an abnormal situation, but a dangerous situation, shouldn't the amp have detected this removed the output from the load in some manner? BTW, this is the same response that Bryston gave me after one of their amps went DC, except they refused to accept it was their amp, "our amps don't fail". But there it sat, unconnected to anything with full supply across the output terminals of one channel. A burn out in the vas section - not outputs or drivers

Give me a break. The DC condition did cause a fire that had to be extinguished. It was a pro gig, sound re-enforcement for a meeting indoors (not an abusive situation). A professional company did the setup and ran the board. Now, Bryston recommended leaving the amps on 24/7. Do you want this amp in your house while you are sleeping - or at work?

I think it is next to criminal to not include an effective method of protecting the speaker load. (Bryston suggested installing fuses in the speaker leads).

It is a fact of life that sometimes things fail on their own, or with encouragement. It is our responsibility that the damage goes no further. Is there argreement on that point? If so, why not?

-Chris

K-amps · 8th May 2005, 04:32 PM

I am not saying that protection should not be accorded. Only that it does not have to be done via an input coupling cap.

The amp should switch off or disconnect the speakers if DC is sensed on the outputs.

PS: Are you telling me I cannot use the Krell as a DC current control source?

anatech · 8th May 2005, 05:14 PM

Hi K-amps,
Understood. For the fanatical who don't like switches, provide a cap coupled input and a direct input. That will satisfy most for this I think.

Might work as a voltage source. Methinks you just insulted the fine folks at Krell.

Oh well, better send them an apology quick before they hunt you down!

-Chris

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8th May 2005, 02:06 PM	#31
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Guys, If Krell chooses to have no input coupling cap, let them. They thought at the time that it introduces distortion... maybe it does. I would not like to use the argument that a DC on the preamp will destroy speakers... thats the preamp's fault not the power amp's fault. The power amp is faithfully passing the signal sent by the pre-amp and thats what it should do.

8th May 2005, 02:39 PM	#32
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Okay, I'll buy that argument. But since DC on the output is not only an abnormal situation, but a dangerous situation, shouldn't the amp have detected this removed the output from the load in some manner? BTW, this is the same response that Bryston gave me after one of their amps went DC, except they refused to accept it was their amp, "our amps don't fail". But there it sat, unconnected to anything with full supply across the output terminals of one channel. A burn out in the vas section - not outputs or drivers Give me a break. The DC condition did cause a fire that had to be extinguished. It was a pro gig, sound re-enforcement for a meeting indoors (not an abusive situation). A professional company did the setup and ran the board. Now, Bryston recommended leaving the amps on 24/7. Do you want this amp in your house while you are sleeping - or at work? I think it is next to criminal to not include an effective method of protecting the speaker load. (Bryston suggested installing fuses in the speaker leads). It is a fact of life that sometimes things fail on their own, or with encouragement. It is our responsibility that the damage goes no further. Is there argreement on that point? If so, why not? -Chris

8th May 2005, 04:32 PM	#33
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	I am not saying that protection should not be accorded. Only that it does not have to be done via an input coupling cap. The amp should switch off or disconnect the speakers if DC is sensed on the outputs. PS: Are you telling me I cannot use the Krell as a DC current control source?

8th May 2005, 05:14 PM	#34
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi K-amps, Understood. For the fanatical who don't like switches, provide a cap coupled input and a direct input. That will satisfy most for this I think. Might work as a voltage source. Methinks you just insulted the fine folks at Krell. Oh well, better send them an apology quick before they hunt you down! -Chris

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