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Q Bias for Cary SLI-80

Cary co. says that proper bias for Cary SLI-80 is about 75mA.

But the allowed range of bias is from 75mA to 100mA.
Which one is the best from your experience?
I would share our information.

And, I heard that I can use EL34 or 6L6 outpu tubes instead of KT88/6550 and when using other output tubes, it should be same bias.

Is it right? If anybody knows it, please share it.

skyserve
stratoholic
4 posts
 
If you bias the EL34s at 75mA you will blow the AC fuse.  The Cary manual is unclear on bias settings for the different tube types.  75mA is good for KT88's.  EL34's should be biased at 50-55mA each channel.  I confirmed this with Cary.
unison77
50 posts
 
That's the case. I used to bias vintage Mullard EL-34 tubes at 60-65 mA but soon replaced them with GEC KT-88s. First I biased the GEC tubes at 75mA as recommended but did not like their sound. Now they are biased at 65 mA and sound much more open and transparent without being bloated.
broadstone's avatar
broadstone
310 posts
 
I have the SLi80 and recently found that increasing the bias to 90mA resulted in a significant change for the better (for my taste at least) in triode mode.  The upper mid and higher frequencies are more crisp and precise with improved firmness across all frequencies. In ultra linear mode, though, the sound became “glassy” and uncomfortable. 
testpilot
922 posts
 
The optimal bias setting will be different for each tube type.  KT88 and EL34 have different bias settings.  Check the tube’s specification for optimal bias setting. 
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