SLO-100 Bias Adjustment

[qwintar]

How do you set the bias on the Soldano SLO-100 head? I've had one for 6 months (IT IS AWESOME) and I'm gonn retube with some Slvetna (BTW: Buy them from SRS WEBSTORE at EBAY for unbelievalble prices)

I've got a bias probe tool and was told by Soldano to set the bias at -56 to -58 volts, but WHERE? I used to set the bias on my Carvin legacy by measuring across the BYPASS switch.

ANYONE KNOW??

 

[qwintar]

Just got the answer:
if you use a bias probe, set the current at 25 to 35 milliamps. You can measure across the standby switch, or remove the 1 amp fuse amd measure across the fuse holder. In these cases you are measuring the total current for all tubes and when we have measured it this way it is about 100 milliamps. This works out to about 25 ma per power tube. The preamp tubes combined use about 10 ma.
The voltage (-58 volts) would be measured on pin5 of the power tube socket, or actually on the resistor which is soldered to that pin. and wrapped with heat shrink.

 

[MARCO]

I will NEVER buy from SRS Webstore again. Their Customer Service is horrible. I bought a supposed match quad of tubes from them back in December and they refuse to leave feedback for their customers. I have asked them numerous times why they could not leave feedback for me and their response was they were having trouble with their website. I finally asked them today and their response was "get lost, a-hole". I have the e-mails to prove it. I will never buy from them again and if I ever ran into the person who told me that, they would be left with no limbs. Just some Buyer Beware for those of you buying stuff over the net.

 

[Dave C]

Use your bias probe, determine which tube is drawing the most current and set bias from that tube to 25-35ma per previous post. Soldano's recomendation will most likely be too cold but very safe , as read from pin 5 noted in a previous post. Hope this helps , I've got 2 SLO-100's and they are very easy to bias.
Dave C

 

[qwintar]

Thanks. I checked the overall bias across the switch (4 tubes x 25ma = 100ma) per Bill Sundt at Soldano. Didn't have to adjust anything, it was very close. I'll do a re-check with the probe, though, now that I have a procedure.

TWO of the power tubes Svetna6l6's have a fuzzy blue glow around the plates from power up... only the 2 left tubes. The two power tubes on the right (looking from the front thru the grille) only glow from the white/yellow/heater? lights inside the tubes. The amp SOUNDS fine on both normal and OD settings. Any Idea what this is? Never noticed it before. The tubes are about 8 months old.... BTW, I bought them from SRS Webstore because they're prices are the lowest around... If you know of another vendor with GREAT PRICES, let me know!!!