Hi All,
Have this next build in the works that clones Andres' upgrades to the Eico ST70 - http://www.tronola.com/html/st-70_hotrod.html
It was discussed on this forum - https://www.diyaudio.com/community/threads/eico-st-70-supermods.196790/
This will be clean sheet build using schematic from Andres, not a modified original ST70. I'll be using 6gm5's in place of 7591's.
I feel pretty confident that substitution.
I plan to evaluate performance similar to steps outlined in article to verify substitutions, once biases and balance settings are achieved.
Design question- Can I use single 6U10 ( 2 low mu, one hi mu triodes) to replace (2) 6sn7 and (1) 12ax7? https://tube-data.com/sheets/123/6/6U10.pdf
Related question- Are interelectrode capacitances important factors to compare when substituting tubes in design? If not, are there other chart characteristics besides Typical, Maximum Voltages and Gain that I should compare?
Thanks,
Jim
Have this next build in the works that clones Andres' upgrades to the Eico ST70 - http://www.tronola.com/html/st-70_hotrod.html
It was discussed on this forum - https://www.diyaudio.com/community/threads/eico-st-70-supermods.196790/
This will be clean sheet build using schematic from Andres, not a modified original ST70. I'll be using 6gm5's in place of 7591's.
I feel pretty confident that substitution.
I plan to evaluate performance similar to steps outlined in article to verify substitutions, once biases and balance settings are achieved.
Design question- Can I use single 6U10 ( 2 low mu, one hi mu triodes) to replace (2) 6sn7 and (1) 12ax7? https://tube-data.com/sheets/123/6/6U10.pdf
Related question- Are interelectrode capacitances important factors to compare when substituting tubes in design? If not, are there other chart characteristics besides Typical, Maximum Voltages and Gain that I should compare?
Thanks,
Jim
Hi Jim,
I'd say yes, triode 1&3 can replace the 6SN7, section 2 one half 12AX7.
WHile the heater is common, there should not be an issue elevating it a bit.
I'd say yes, triode 1&3 can replace the 6SN7, section 2 one half 12AX7.
WHile the heater is common, there should not be an issue elevating it a bit.
JC-
Thanks for valued opinion. I've done a PC layout including the 6U10, but wanted to ask the brain trust here before investing forward.
What do you mean about 'elevating it a bit'? Perhaps the heater voltage?
Jim
Thanks for valued opinion. I've done a PC layout including the 6U10, but wanted to ask the brain trust here before investing forward.
What do you mean about 'elevating it a bit'? Perhaps the heater voltage?
Jim
Yup, that's what I meant. The LTP cathodes in the schematic are at 110v, which is above the datasheet limit of 100V for the DC component vs the heater. You could elevate the heater to, let's say 50V, and that would keep all triode sections within the limits.