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Post by goodez on Mar 31, 2019 9:22:36 GMT -7
I ended up ordering a Mullard Cv4024 12AT7 preamp Tube to increase headroom. After doing some research on here and briefly talking to Myles it seems the 12AT7 isn’t the best selection for tone but reverb circuits. I’m not sure if I can even ship the tube back if it’s unused? I’m now looking at 12ay7 pre amp tubes and would like to simply return/exchange if the store will allow it. Any suggestions are welcome. www.nosvacuumtubes.net/product/mullard-cv4024/The store has a NOS RCA version but I’m not sure it’s worth the cost. www.nosvacuumtubes.net/product/rca-12ay7/
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Post by zpilot on Mar 31, 2019 15:21:04 GMT -7
I bought NOS tubes for years almost exclusively from KCA NOS Tubes. However I recently have started purchasing from Brent Jessee recording since they seem to have a better selection and better pricing. I have not had any problems with the tubes I have purchased.
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Post by perryr on Mar 31, 2019 21:30:26 GMT -7
12AT7 is frequently used in phase inverters, which is where you would put it in the Z28. I agree, probably not the best choice for a V1, but should do Ok in the phase inverter, and that Mullard is a nice sounding AT7. The only other tube I might try is a 5751.
Another thing, the tone controls do effect gain in that amp, try the bass and treble at OFF and gradually bring them up and listen to what’s going on, very cool tone controls that do impact the drive.
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Post by Ridgeback on Apr 1, 2019 6:16:25 GMT -7
It was my understanding that the ef-86 was the only tube that could be used in V1 of the Z-28. PI is a different story.
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Post by perryr on Apr 1, 2019 7:28:11 GMT -7
Z28 V1 is EF86. V2 is Phase Inverter (12ax7)
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Post by goodez on Apr 1, 2019 8:49:29 GMT -7
12AT7 is frequently used in phase inverters, which is where you would put it in the Z28. I agree, probably not the best choice for a V1, but should do Ok in the phase inverter, and that Mullard is a nice sounding AT7. The only other tube I might try is a 5751. Another thing, the tone controls do effect gain in that amp, try the bass and treble at OFF and gradually bring them up and listen to what’s going on, very cool tone controls that do impact the drive. Thanks Perry. My EL84’s that I got from you are still sounding glorious in the Db4. Anyways, yes the intent was to run the 12at7 in the phase inverter slot but I started reading that it was better suited for amps with reverbs and noticed Myles mention in some posts that he ran 12ay7’s in z28 set ups when more headroom was needed. So the 12at7 doesn’t sound that bad in the V2 PI? Maybe I’ll give it a try once it gets here today. I’d hate to just lose out on a $60 Tube.
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Deleted
Deleted Member
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Post by Deleted on Apr 1, 2019 9:05:21 GMT -7
Yeah--you want an EF86 for V1. Good ones are increasingly hard to find.
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Post by daddyelmis (Greg) on Apr 1, 2019 11:21:40 GMT -7
Yeah--you want an EF86 for V1. Good ones are increasingly hard to find. That’s why I have 3 spare EF86’s in my “tube box” now - all Winged C. Figure that way I’ll have fairly consistent tone when I have to swap them out - and it didn’t break the bank.
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Post by goodez on Apr 1, 2019 16:27:31 GMT -7
Well, it just arrived today so sill give it a try in V2 and see how it sounds. Right now I run a brake lite on 2, the bass is nearly at zero and the treble is at 12 o-clock, volume around 9 0-clock. The fact that I’m getting hair at 9 o-clock lead me to search for more headroom with alternative tubes in the PI.
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Post by Ridgeback on Apr 1, 2019 17:08:29 GMT -7
You might want to check your bias. It should be pretty darn clean at those settings. Not sure the PI tube has that much impact on overall headroom. Good\fresh 6V6s? Good luck.
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Post by goodez on Apr 1, 2019 17:25:43 GMT -7
You might want to check your bias. It should be pretty darn clean at those settings. Not sure the PI tube has that much impact on overall headroom. Good\fresh 6V6s? Good luck. Yea, I purchased it brand new from Humbucker music last year. Pick ups are Lindy Fralin Big Single in the neck and Blues Special in the bridge.
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Post by Ridgeback on Apr 1, 2019 18:48:53 GMT -7
Sorry, I'm out of ideas then. I've owned a Z-28 for the better part of 13 years and something just doesn't sound right (no pun intended) with your tonal description vs the settings. Please let us know when you get it worked out.
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Post by goodez on Apr 1, 2019 18:55:30 GMT -7
Sorry, I'm out of ideas then. I've owned a Z-28 for the better part of 13 years and something just doesn't sound right (no pun intended) with your tonal description vs the settings. Please let us know when you get it worked out. Don’t get me wrong, I don’t think there’s anything wrong with the amp. It sounds really good. I’m just experimenting with ideas to get a more of a “fendery” tone out of the amp with a Reverb pedal. I could probably bump the brake lite up to 1 or turn it off but at that point I’m wondering if I’m out of the tonal rpm range with the volume knob being that low. I know this amp is loud but I’m just trying to move that “slight hair” on the notes slightly higher.
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Post by bigben55 on Apr 12, 2019 14:32:08 GMT -7
Right now I'm running an NOS Westinghouse 6267/EF86 and a JAN GE 5751 in mine, along with JJ 6V6s and a Gold Lion ri GZ34. I'm as happy as I can be with the compliment.
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Post by daddyelmis (Greg) on Apr 12, 2019 16:51:26 GMT -7
You might want to check your bias. It should be pretty darn clean at those settings. Not sure the PI tube has that much impact on overall headroom. Good\fresh 6V6s? Good luck. Yea, I purchased it brand new from Humbucker music last year. Pick ups are Lindy Fralin Big Single in the neck and Blues Special in the bridge. I'd still check bias. I can run Fralin Vintage Hot on my strat into my z28 at those settings and its clean ... maybe not Twin Reverb crystal clean, but really clean. i usually run mine at 3-11-3 for that awesome grind.
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Post by goodez on Apr 12, 2019 16:56:01 GMT -7
Actually, I did try turning the volume up and the treble down from 12 and that seemed to help. I ended up putting the 12ax7 back in the phase inverter as I found the 12at7 seemed to bring down the overall volume (could be in my head but idk).
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Post by meanslide on Apr 15, 2019 9:08:10 GMT -7
I just went through a complete retube of my Z28. JJ 6V6's, NOS Sylvania 5AR4, NOS RFT EF86 and the tube that made the biggest difference in tone, V2. Mine came with a Sovtek 12AX7 and when I switched it to a 60's NOS RCA 12AX7 there was a huge difference in tone. Just sweeter sounding all around. Smoother even when the amp is set clean. I usually run mine at 11-11-11 with a Tele loaded with Fralin Blues Specials.
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Post by Telemanic on Apr 19, 2019 22:44:18 GMT -7
I have tried ANY number of vintage EF86's in Z28 and Rt.66, from Mullard, Telefunken, Amperex, Genelex, other German and French, etc etc. To be honest they were all about the same! Lol..... The biggest tone difference I got was rolling tubes in the PI position (v2). 5751 if you want a more American, little less aggressive sound. 12ax7 if you want more punch. Beyond that it's just a matter of finding a tube that you like the sound of the best in that amp. Doing it for headroom can sometimes be self defeating tho. With the lower gain tube Like 12at, or ay, in V2 you may find yourself turning the amp volume up more to find the sweet spot, and now your kind of back to where you started. I found I stuck with a 12ax7, but just tried a bunch till I found one with a cleaner gain structure and frequency emphasis I liked. I love early 70's Amperex Orange Globe logo 12ax7's. Telefunken for instance can sound almost sterile because they are so balanced and linear. In some guitar amps it almost sounds like the mids are subtracted a bit. Mullards tend to have a mid warmth that in the wrong amp can sound a bit congested. Amperex right in the middle. Can't go wrong with good old GE clear glass 12ax7's either. Best all around 12ax7 for the money imho.
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Post by bigben55 on Apr 21, 2019 7:42:22 GMT -7
Telemaniac, are you able to elaborate more and maybe post a pic of that early 70's Amperex Orange Globe logo 12ax7? I'd like to try one. I'm currently running a NOS JAN GE 5751 and like it. My favorite NOS 12AX7, an RCA 7025, is starting to go microphonic so I swapped it out and dont have a REALLY good NOS 12AX7 to try.
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Post by perryr on Apr 21, 2019 11:03:06 GMT -7
In about 1970 Amperex revised their 12ax7, the version type code is I66, which would be etched in the glass. They are pretty easy to spot as the getter up top is a flat saucer with about 8 dimples around the edge, very unique. They were still made in Herleen and will have the right angle triangle factory code etched under the version type code. To me these are a little crisper up top than a 60’s short plate Amperex (I65), and likely do sound great in the Z28 or Route 66 Phase inverter (V2). 1970-1971 Amperex 12ax7 with dimpled getter, one on the end is the earlier halo getter: Close up you can see the dimpled getter and codes near the base, I66 type code and the right angle triangle identifying it as manufactured at Herleen (where all the great Amperex were made):
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