hey Tube Gurus!

[78pbass]

I have an '86 Laney Pro Tube AOR g--tar amp that I believe has the original caps. its been retubed and biased recently. In doing some research, I have come to the conclusion that the lack of low-end and general mediocrity of its tone is due to old caps.

 

i have an '86 just like mine in my jam room that sounds thick, glassy and bell like unlike mine. We're running the same JJ el34's (I know, don't mention it) and mostly the same pre tubes.

 

My question is, if I recap the filter caps, do I need to rebias as well? I just want to know if I need to invest in bias probes (or if someone is willing to loan me some). I have a lot of money going out right now and the caps are relatively cheap. Adding bias probes throws my budget out.

 

Thanks in advance!

Corey

[misterhinkydink]

The bias being different between the two would affect the tone more than the capacitors. I'd put a scope on the power supply and see how much sag and ripple you get before changing them.

[78pbass]

 

The bias being different between the two would affect the tone more than the capacitors. I'd put a scope on the power supply and see how much sag and ripple you get before changing them.

 

 

I sold my scope some time ago (nice Tektronix) for good money, so that's out. it was recently biased when the new tubes were put in a year ago (previous owner, but I have no reason to doubt him).

 

It is my understanding that the Laneys, while designed on the plexi design with an additional gain stage, are very finicky amps. I can attest to how it likes (and dislikes) preamp tubes - more than any amp I've ever owned by a LONG shot. As I mentioned, there have been others that have the same scenario that recapped with tremendous success in the tone department.

 

So back to my question: do I need to bias after a recap, or no? If yes, I'll mess with it at the end of the summer when funds arent being so allocated.

[The Real MC]

When my 25 year old Mesa Boogie MKIIa started getting farty and losing low end, a recap fixed it. You should not have to rebias after a recap.

[Guttermouth]

 

So back to my question: do I need to bias after a recap, or no? If yes, I'll mess with it at the end of the summer when funds arent being so allocated.

 

 

if the recap is done *right* you may have to rebias.It all depends on how much the dropping resistors have drifted and how worn the caps are.

if your aor is one of the models that have the good caps in it (lcr -iirc) i would only change them if they were leaking or otherwise pulling your voltages down and instead start suspecting worn output tubes or the bias being out of whack because of said tubes or drift.

[misterhinkydink]

 

I sold my scope some time ago (nice Tektronix) for good money, so that's out. it was recently biased when the new tubes were put in a year ago (previous owner, but I have no reason to doubt him). It is my understanding that the Laneys, while designed on the plexi design with an additional gain stage, are very finicky amps. I can attest to how it likes (and dislikes) preamp tubes - more than any amp I've ever owned by a LONG shot. As I mentioned, there have been others that have the same scenario that recapped with tremendous success in the tone department. So back to my question: do I need to bias after a recap, or no? If yes, I'll mess with it at the end of the summer when funds arent being so allocated.

 

 

Recapping will likely change the bias which will change the tone. Play with the bias first before doing an unnecessary capacitor job.

[78pbass]

all good advice - thanks all, I'll wait and get the bias probes and run through the chassis. Thanks for making me do it right. sometimes you need to be told what you already know, right?