David, Re your question about the Chinese explaination. I think that they are 'technically'correct' in thier verbiage and we understand the process backwards, i.e. you reduce bias by increasing voltage not increasing voltage increases bias - we just assume so because we are watching a meter which is measuring voltage (not the actual bias). I'm not a techie - this is just my understanding. But, FWIW, if you think you should start with your bias pot anywere but the maximum counter-clockwise position don't do it without specific clarification. I've never seen a bias pot work 'backward' and I've seen quite a few. :-)
Newbie needs advice choosing and biasing new tubes
Hi, I received my first tube amp today - a chinese made Yaqin MC-100B. Unfortunately one of the 4 KT88 tubes that came with it is damaged (glass smashed), despite the fact that everything was well packaged. Anyway, what I intend to do is seek out a replacement set of tubes tomorrow as I'm really itching to get my new 'toy' powered up and working. I'd appreciate some guidance on the following.
I've heard a lot about the Svetlana 'Winged C' KT88's and these are available at my local stockist. However, they also have the 6550C version - are these two types of tube really interchangeable? Which would you go for?
The tubes are sold in matched pairs. How would I install these? One matched pair in V1 and V2 and the other in V3 and V4?
The amp has testing points for each tube and an adjustment slot. The manufacturer states that the "working point setup of this unit shall be 0.55v-0.60v." Does that range apply regardless of which brand of tube is installed?
Any do's and don'ts that I should be aware of when setting the bias? I have a 'cheapish' digital multimeter. the instructions talk about setting this to DC1V and then adjusting the volume to minimum.
Is it dangerous to turn the amp on without all the tubes inserted? If it's not then I'll put all except the broken one in this evening so that I can practice measuring the voltage of the 3 good tubes.
Sorry for the torrent of pretty basic questions and thanks in advance to anyone who takes the time to respond.
David
I've heard a lot about the Svetlana 'Winged C' KT88's and these are available at my local stockist. However, they also have the 6550C version - are these two types of tube really interchangeable? Which would you go for?
The tubes are sold in matched pairs. How would I install these? One matched pair in V1 and V2 and the other in V3 and V4?
The amp has testing points for each tube and an adjustment slot. The manufacturer states that the "working point setup of this unit shall be 0.55v-0.60v." Does that range apply regardless of which brand of tube is installed?
Any do's and don'ts that I should be aware of when setting the bias? I have a 'cheapish' digital multimeter. the instructions talk about setting this to DC1V and then adjusting the volume to minimum.
Is it dangerous to turn the amp on without all the tubes inserted? If it's not then I'll put all except the broken one in this evening so that I can practice measuring the voltage of the 3 good tubes.
Sorry for the torrent of pretty basic questions and thanks in advance to anyone who takes the time to respond.
David
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- 6 posts total
- 6 posts total