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Post by gfreak on Jul 12, 2013 20:50:14 GMT -7
My Z-28 came with a Tung Sol 12ax7 (that's what it is labeled) even thought Dr Z's website and the tube chart in the amp say it should be a 5751.
Did I get an amp with the wrong tube?
Is the Tung Sol 12ax7 similar to a 5751?
What tube do you use in the phase inverter?
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Post by brayks on Jul 13, 2013 2:37:28 GMT -7
Not sure what my Z28 has but both tubes will work as PI tubes. However due to the the difference in their current output and transconductance, each will have a different effect on the performance of your amp (output tube distortion, touch, output dynamics). Here's a link to a Myles Rose publishing you might find interesting and of value: www.guitaramplifierblueprinting.com/files/Phaseinverter.pdfI seem to remember the Doc saying at a Z-Fest he likes long plate tubes in the phase inverter and indeed most (not all) of my Dr. Z amps have balanced Sovtek 12AX7LPS tubes for the PI. I did however read somewhere that long plates are not a good choice for cathodyne (high cathode voltage) PI circuits but good for long tail circuits (don't know what the Z28 uses). I believe the general consensus is a balanced PI tube is the best choice. 5751 or 12AX7? I'm thinking let your sense of hearing and touch be your guide. Long Plate or not: might want to check with the Doc on the Z28 as he publishes the use of a non-long plate 12AX7 on his web-site. |
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Post by pcns on Jul 13, 2013 7:03:32 GMT -7
I typically go with the tubes that Dr Z ships the amps with. Every time I try something different I ends up sounding better with stock tubes.
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Post by bwc on Jul 13, 2013 7:30:28 GMT -7
I read somewhere that he used to use a 5751 and switched to a 12ax7. Not sure where that was but I think it was somewhere here on the forum.
My z-28 had a 5751 in it and I recently switched to a 12ax7. Gigged it last month and Didn't need distortion pedals to get a real heavy crunch, and used a Timmy just for solo boosts.
The 5751 will get you less gain if that's what you're after.
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Post by gfreak on Jul 13, 2013 13:43:47 GMT -7
BWC you were right just found this on the website:
Z28: V1: NOS EF86, V2: Tung Sol 12AX7, V3/4: JJ 6V6 (matched pair), V5: Sovtek 5AR4
(http://www.drzamps.com/tube_info.html)
brayks thanks for the link.
pcns just played the amp and it sounded great as is.
Thanks to all for the help.
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Post by digiTED aka 'Ted' on Jul 13, 2013 14:04:03 GMT -7
One of the many things I love about the Z28 is how much you can tune its character with tube choice. Both the 12AX7 and 5751 work well as PI tubes in the Z28. 12AX7 = earlier breakup 5751 = more headroom Try them both and let your ears decide which is best for you; the Z28's happy either way  |
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Post by DRZ on Jul 14, 2013 14:51:59 GMT -7
I felt that a 5751 gave the Z-28 a more Fender ( Brown face Deluxe ) type tone.
More scooped and a bit hollow, but it is almost impossible to find good 5751's at decent prices and large quantities lately.
I found the Tung-Sol to be a nice replacement smooth, not brittle with a touch more mid's .
I found it very important to limit drive signal to a 6V6 for optimum tone.
Z
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Post by gfreak on Jul 14, 2013 18:08:56 GMT -7
Thanks Dr.!!! Great info to have. I took the amp to a jam last night and as always it sounded amazing.
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Post by gfreak on Aug 16, 2013 19:59:20 GMT -7
I put a NOS 5751 in the phase inverter. I love it. It seems to have some more chime and a little less mids.
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~ Ted in SF
