Quicksilver?

lpd · 28th December 2003, 10:41 PM

I recently acquired a pair of KT88 monoblocks. When operating the trannies hum a little (no hum from speakers, just trannies). Both amps have same amount of hum, is this normal? Otherwise great sounding amps.

SHiFTY · 29th December 2003, 07:05 AM

A lot of transformers hum in normal conditions. If they don't get hot and the hum isn't too loud, they are probably fine.

You could try tightening the bolts on them, or putting rubber dampers underneath them, but if its not too loud then just sit back and enjoy the music!

Original Burnedfingers · 29th December 2003, 12:19 PM

I have three sets and all have a very slight hum when you put your ear next to them. Exercise caution when doing this as a hot tube can result in burned ear.

J

lpd · 29th December 2003, 03:16 PM

The transformers don't get hot at all, slightly warm thats it. I ran them all day and as they warmed up a little the hum lessened. So after they cooled down I tightened them down and the hum has decreased quite a bit.

Burned what bias do you run yours?

The fellow I traded these from indicated 50ma, but I find 55ma sounds better and the company suggests 60ma per tube. He also installed a choke under the deck to save tube life. Only mod done and they operate 100%.

Original Burnedfingers · 29th December 2003, 09:35 PM

On the actual KT88 versions they recommend 120mA. I run about 110mA in hope of prolonging the output tubes. On my 8417 conversions that I use either 6550's or KT 88's in I run 100mA. In actual distortion tests the higher bias will lower the distortion somewhat.

J

lpd · 30th December 2003, 01:53 AM

What type of rectifier do you use ie. brand? The fellow I acquired the amps from stated that they were hard on rectifiers and didn't know what brand worked best. One blew a fuse on initial startup, but hasn't since. He recommended a variac to ramp up voltage?

Original Burnedfingers · 31st December 2003, 12:07 PM

lpd

My quicksilvers use either NOS GE 5AR4's or Sovtek brand. Mine have a slight modification in the power supply which involves adding some 1N4007 diodes. These diodes take the brunt of the load and the rectifiers smooth out the peaks. The result is nice bass without the worries of arcing of the rectifiers. If you do a search here you will find several topics on Quicksilvers and there will be a power supply schematic of the modification there. Hope this helps!

J

lpd · 31st December 2003, 09:07 PM

Hey what size and type of fuses does your KT88 amps use? Mine has 3 amp fast blows and one blows out from time to time if I turn on the amp too quickly. Would a slow blow fuse be appropriate?

Thanks

Peter

fdegrove · 31st December 2003, 09:41 PM

Hi,

Quote:

Mine has 3 amp fast blows and one blows out from time to time if I turn on the amp too quickly. Would a slow blow fuse be appropriate?

If the fuse is on the primary side of the powerxformer it should be a slow blow type.

Cheers,

battradio · 31st December 2003, 10:50 PM

If you have a good digital volt meter ,check your ac mains to make sure that the dc level is 1 volt or less . Hi dc levels will make the core laminations buzz .
Mark

28th December 2003, 10:41 PM	#1
lpd diyAudio Member Join Date: Nov 2003 Location: BC	Quicksilver? I recently acquired a pair of KT88 monoblocks. When operating the trannies hum a little (no hum from speakers, just trannies). Both amps have same amount of hum, is this normal? Otherwise great sounding amps.

31st December 2003, 10:50 PM	#10
battradio diyAudio Member Join Date: Dec 2003 Location: near ST. Louis MO.	If you have a good digital volt meter ,check your ac mains to make sure that the dc level is 1 volt or less . Hi dc levels will make the core laminations buzz . Mark __________________ To be better one must be different ,but to be different is not necessarily better .

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29th December 2003, 07:05 AM	#2
SHiFTY diyAudio Member Join Date: Jul 2002 Location: New Zealand	A lot of transformers hum in normal conditions. If they don't get hot and the hum isn't too loud, they are probably fine. You could try tightening the bolts on them, or putting rubber dampers underneath them, but if its not too loud then just sit back and enjoy the music!

29th December 2003, 12:19 PM	#3
Original Burnedfingers diyAudio Member Join Date: Nov 2002	I have three sets and all have a very slight hum when you put your ear next to them. Exercise caution when doing this as a hot tube can result in burned ear. J

29th December 2003, 03:16 PM	#4
lpd diyAudio Member Join Date: Nov 2003 Location: BC	The transformers don't get hot at all, slightly warm thats it. I ran them all day and as they warmed up a little the hum lessened. So after they cooled down I tightened them down and the hum has decreased quite a bit. Burned what bias do you run yours? The fellow I traded these from indicated 50ma, but I find 55ma sounds better and the company suggests 60ma per tube. He also installed a choke under the deck to save tube life. Only mod done and they operate 100%.

29th December 2003, 09:35 PM	#5
Original Burnedfingers diyAudio Member Join Date: Nov 2002	On the actual KT88 versions they recommend 120mA. I run about 110mA in hope of prolonging the output tubes. On my 8417 conversions that I use either 6550's or KT 88's in I run 100mA. In actual distortion tests the higher bias will lower the distortion somewhat. J

30th December 2003, 01:53 AM	#6
lpd diyAudio Member Join Date: Nov 2003 Location: BC	What type of rectifier do you use ie. brand? The fellow I acquired the amps from stated that they were hard on rectifiers and didn't know what brand worked best. One blew a fuse on initial startup, but hasn't since. He recommended a variac to ramp up voltage?

31st December 2003, 12:07 PM	#7
Original Burnedfingers diyAudio Member Join Date: Nov 2002	lpd My quicksilvers use either NOS GE 5AR4's or Sovtek brand. Mine have a slight modification in the power supply which involves adding some 1N4007 diodes. These diodes take the brunt of the load and the rectifiers smooth out the peaks. The result is nice bass without the worries of arcing of the rectifiers. If you do a search here you will find several topics on Quicksilvers and there will be a power supply schematic of the modification there. Hope this helps! J

31st December 2003, 09:07 PM	#8
lpd diyAudio Member Join Date: Nov 2003 Location: BC	Hey what size and type of fuses does your KT88 amps use? Mine has 3 amp fast blows and one blows out from time to time if I turn on the amp too quickly. Would a slow blow fuse be appropriate? Thanks Peter

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