have a look at this SL-X mish-mash

drucifer · Post by **drucifer** » Fri Jul 15, 2005 10:38 am

Hello! First post!

Take a look at the linked-to picture here:

http://www.cranusmetal.com/img_0940.jpg

Specifically at R29. By my calculations, approx 4.34K worth of resistors there. What exact purpose is this serving? Also, take a look at R28. Looks like someone got a little excited with their iron.

It's an SL-X 2100 I purchased from ebay. Of course, no mention in the auction of any modification to the amp. Also, a potential buyer had asked the question "5881 or EL34" to which the seller answered "EL34". I have since gathered that if he could not visually discern between a Philips 6L6WGB and pretty much any EL34, he would therefore probably not have the mental wherewithal to remove the chassis and give it a once-over.

rjgtr · Post by **rjgtr** » Fri Jul 15, 2005 11:21 am

It looks like they modified the bias circuit. Possibly to convert from 6550s or 6L6s to EL34s. Or maybe to 6L6s. The obviously didn't have the right values and just used what they had to get to the value they wanted. The formula for figuring out the final result is (R1 * R2 * R3) / (R1 + R2 + R3). I can't see the resistors so I can't tell what you've got in values, but the 4.7k might be right. I think the burn marks are left over from someone trying to convert from 6L6 to EL34 and then later removing that mod.