bluesswing

Myles -- great to learn that this method works, saves me the trouble in finding the adapter. What does Laney mean by "current limiter" here? Is it a resistor? If so what kind? Where I need to connect it? How to "turn it on and off"? Many thanks for your help here again!!

Thanks Myles for your response! One additional question about biasing the output tubes: My amp thus is Laney LC-15 -- I don't know if you have the circuit diagram but here is one: http://www.freeinfosociety.com/electronics/schematics/laneylc15.pdf , the bias pot is PS1. And for your information Laney's tech told me this about how to rebias this amp: ------------------- Rebiasing : Make sure the speaker is unplugged. Switch the amp on (with current limiter!). Allow to warm up for 90 seconds. Switch the current limiter off, and adjust for -11.5 v at between R37 and R38 See attached diagram ------------------------- What do you think about this method? Wouldn't it be more accurate to use the current adjusting method (voltage over one ohm resistor)? If so, do you who sells bias probes with such a small diameter that they can fit into the sockets through the small openings in my amps metal shield (the holes are just little larger than the tube diameter). Thanks again.

Myles, This question probably has been asked several times before but I would hesitate to read the whole thread to find the answer: Do output tubes of the same type with different bias point (or gain) produce similar sound and overdrive characteristics in and around the clipping point, just the output volume level being different? I am especially interested in dual EL84 applications (Laney LC-15). Thanks!

Hi Myles, I apologize for this delay in replying -- I meanwhile added a connector for external speaker cabinet to the amp and I can see that the hi-freq noise is there only if I use the amp's internal speaker or have the amp sitting on top of the speaker cabinet. Are aging tubes vulnerable to external vibration that may cause this or do you think the cause may be tube clips that vibrate when paying through the amp? Do you still recommend me to push components for troubleshooting or is the presence of external vibration anough to find the problem? Tks blues&swing

Hi Myles, I an really a novice to this website but I am impressed about the number of people participating and about the pro advice I have received so far. I have here a couple of questions that you probably are one of the most experienced individuals to anwer to: - I have a Laney LC15 15W tube combo. I play it upside down since I want the tubes to release heat upwards (PCB is on the top (in normal position) and tubes are attached to it. The tubes have clips that hold them in place. When the amp is placed in any position there is a pretty high frequency "sizzling" noice heard from the amp -- difficult to say if it it mechanical and electronical noice. What could be causing this noice? Could it be a symptom of old tubes that need replacement? Or perhaps the holding clips are causing the noise? Are there any ways to isolate the cause? In general, when do you know if tubes need to be replaced? - Secondly, I also have a Tube Works hybrid combo (tube preamp, solid state power amp)and when I place it on a tilted amp stand its reverb does not funtion at all. In a straight vertical position there are no problems whatsoever. Is it common for amps with spring reverb do this? Thank you very much for you advice, in advance! Edit: I place these questions to the general guitar forum too.