Plate voltage on B.A.D SLO 100?

CEG85

CEG85

Active member
Anyone have Info on what the plate voltage is on the new SLO100?
Wanna throw in some JAN 6L6WGB, but they are rated at 400v max.

Also curious to know what preamp tubes you guys are running in these amps.
 
I don't know about the new ones, but the older ones came with Sovtek Wafer Bottoms because they could handle 500 VDC or a little over that. I can't remember if I ever ran anything other than those in mine.
 
Not sure but the unofficial schematics show about 500v. Worth noting is some voltage ratings are more suggestive that hard limits like el84’s which most every manufacturer runs 25%+ over the suggested max plate voltage.
 
I’ve heard 500v as well.
When it’s time to throw the new tubes in there, I’ll probably make a post or thread in regards to the PV on the newer SLO100’s.
Any info on what the bias is usually set to on these amps?
I’ve heard they are usually biased cold, around 25-30ma depending on the plate voltage.
 
I would always do it based on dissipation % based on plate voltage first and tone second. Ah hell, if it sounded good and was within 50-75% dissipation, I'd go with that.
 
I don't know the answer to your question about plate voltage, but what I can tell is that I've tried them all with different power tubes in my 1989 SLO and those JAN Philips ECG 5881's AKA 6L6WGB's were my favorite sounding power tubes in it (though haven't tried yet any BAD era SLO's). I biased it around 28ma (not sure yet what's optimal). I definitely preferred 5881's in it to 6L6GC's. They just bring out more warmth, richness, growl, tonal complexity, better mids. They're not as tight or crisp as 6L6GC's, but SLO's aren't that way anyway by nature. I also really liked the 5881's by RCA, GE and US Tung-Sol, but JAN Philips were my overall favorites. I've not had any issues using those tubes in it. I actually thought my Sovtek 5881's were my least favorites in it of what I've tried despite being the "tubes for it". I even liked my JJ 6L6GC's more, but the older Sovtek 5881's sounded quite good in it. FWIW, the BAD SLO's might have different tube preferences vs my '89

For preamp tubes my 2 favorites (really for most compressed high gain amps in general) were Beijing Foil Getter 12AX7's & Winged C's. The JAN Philips ECG and US Tung Sol's were also really good, not as aggressive or punchy as my 2 favorites, but more warm and pretty sounding. Also, Mullard, Bugle Boy, Valvo, Telefunken and Siemens were really good if you want more mids and Euro flavor. The only pre tubes I didn't like in it were JJ's and other newer stuff. Actually the Japanese 12AX7's could've even been my 3rd favorites
 
braintheory said:
I don't know the answer to your question about plate voltage, but what I can tell is that I've tried them all with different power tubes in my 1989 SLO and those JAN Philips ECG 5881's AKA 6L6WGB's were my favorite sounding power tubes in it (though haven't tried yet any BAD era SLO's). I biased it around 28ma (not sure yet what's optimal). I definitely preferred 5881's in it to 6L6GC's. They just bring out more warmth, richness, growl, tonal complexity, better mids. They're not as tight or crisp as 6L6GC's, but SLO's aren't that way anyway by nature. I also really liked the 5881's by RCA, GE and US Tung-Sol, but JAN Philips were my overall favorites. I've not had any issues using those tubes in it. I actually thought my Sovtek 5881's were my least favorites in it of what I've tried despite being the "tubes for it". I even liked my JJ 6L6GC's more, but the older Sovtek 5881's sounded quite good in it. FWIW, the BAD SLO's might have different tube preferences vs my '89

For preamp tubes my 2 favorites (really for most compressed high gain amps in general) were Beijing Foil Getter 12AX7's & Winged C's. The JAN Philips ECG and US Tung Sol's were also really good, not as aggressive or punchy as my 2 favorites, but more warm and pretty sounding. Also, Mullard, Bugle Boy, Valvo, Telefunken and Siemens were really good if you want more mids and Euro flavor. The only pre tubes I didn't like in it were JJ's and other newer stuff. Actually the Japanese 12AX7's could've even been my 3rd favorites
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Thanks for the feedback, much appreciated.
I’ve read the original SLO100’s had over 500+ volts on the plates and the 6L6WGB could handle a lot more voltage then the suggested 400v max rating.

I actually have a few of those foil getter Chinese tubes laying around, might give those a try when it’s time to replace the tubes.
 
I had a brand new BAD SLO, the PV at whatever my wall voltage was that day was 483pv.
 
Sovtek wafer bottom 5881s, biased 28-32 whichever sounds best. Pre tubes Chinese Bs or 6N4s sounded best to me; but the stock Sovteks sounded good too.
These numbers/tubes are what I used in the 3 pre bad SLOs I had. I’d imagine the BAD versions have similar PV specs to the original. I tried Sylvania/Winged C 6L6, and KT66s and the 5881s still won out by a good margin.
 
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