260 volt tap

[Jackie Treehorn]

I'm thinking about using the 260 volt tap, but adjusting the power supply resistance to maintain the voltages on the preamp tubes... all in the interest of prolonged tube life/less attenuation, of course.

Has anyone tried the 260 volt tap on the Heyboer transformer? What did you think?

[Wayne Alexander]

I've used it without adjusting any of the other values (except bias resistance). It sounds better to me. I use my Express with 6V6's and it's the only 6V6 amp I've ever had that I like. The 260V tap also sounds good with EL34's, but to my ears, not as good as it does with 6V6's. The slightly lower voltages compared with the 300v taps are better for the 6V6's anyway.

[Jackie Treehorn]

Well, I switched over to the 260 volt tap last night, and probably played with it for 30 minutes or so with 6V6's and EL34's. I changed the 18k resistor to 11k in the power supply, which gave me only slightly lower preamp voltages. Bottom line, it's less punchy more sustainy, not as bright, more harmonically rich, but it doesn't seem to work as well for me. With the 6V6's, it definitely is a little too small sounding. The volume with the EL34's is just about perfect, but the amp doesn't respond to the guitar volume knob as well as it did before and the range of tones aren't as good.

I'm going to try it at band rehearsal, but I'm fairly positive I'll be back at 300 volts. I like to bias at -30; sounds the best to me, but the tubes don't last long!

[Omar]

Jackie,
I had a similar experience with my T-wreck using the 260V taps. The dynamics of the amp were gone and it became very compressed, especially with 6V6s - almost mushy. I think the 260V tap might be usefull for that one sound but that's about it. I ended up leaving it on the 300V tap for good.

Omar