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Post by smolder on Mar 15, 2022 17:34:52 GMT -7
So, if I put a 5751 or other tube in the PI slot for more head room, will I sacrifice volume?
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Post by adam on Mar 15, 2022 18:04:19 GMT -7
I'm going to go out on a limb here and say my experience with that tube in a Ghia PI position results in a little more clean headroom. Like the amp is a little cleaner at that same volume. Changes the tone a little too (I think). Bottom line, you might like or not, but no real harm in giving it a shot.
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Post by smolder on Mar 15, 2022 18:23:57 GMT -7
Thanks… I guess what I’m asking (and I’ll try it later this evening) is… does tube gain in that slot, in this circuit impact volume?
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Post by dcarver on Mar 15, 2022 20:20:58 GMT -7
" does tube gain in that slot, I n this circuit impact volume? "
Great question! Let us know what you find out.
After you try the 5751 in the PI position, give it a try it in V1. I have a Maz 8 which shares the pre-amp section with the Z-Plus. I currently have a TAD 5751 in V1. Sounds great.
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Post by smolder on Mar 15, 2022 21:34:08 GMT -7
" does tube gain in that slot, I n this circuit impact volume? " Great question! Let us know what you find out. After you try the 5751 in the PI position, give it a try it in V1. I have a Maz 8 which shares the pre-amp section with the Z-Plus. I currently have a TAD 5751 in V1. Sounds great. I love this amp. And… I’m trying to push it’s limits. I love playing straight in with no dirt or effects. It’s also the first amp that I’ve tried to extend the clean head room.
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Post by dcarver on Mar 18, 2022 10:56:49 GMT -7
A 5751 in V1 might give you little more clean headroom. It did in my Maz 8. Also, when I do push the Volume to where V1 starts to clip, the 5751 has a better overdriven sound to my ear that a regular 12AX7. Best of luck.
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Post by G'OlPeachPhan on Mar 18, 2022 14:35:10 GMT -7
If you find a PI slot on a Z-Plus, let us know. 😉
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Post by KeithA on Mar 18, 2022 15:30:48 GMT -7
If you find a PI slot on a Z-Plus, let us know. 😉 Lol….I was thinking the same thing!
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Post by smolder on Mar 19, 2022 9:57:07 GMT -7
If you find a PI slot on a Z-Plus, let us know. 😉 Good call… what was I thinking… er, drinking.
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Post by perryr on Mar 19, 2022 20:22:48 GMT -7
There is no phase inverter, though there is a v5 and it is driving the output as a phase inverter would. V5 in a Zplus uses just half the 12ax7 (one side) to drive the output, and changing that will have impact. Putting a 5751 in might clean it up a bit and max preamp overdrive (with master set low) would be reduced some i’d guess (because v5 would have less gain).
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Post by zpilot on Mar 20, 2022 0:32:01 GMT -7
I think a 12AT7 would be a better choice than a 5751 as a power tube driver if you are wanting more headroom. I know this sounds silly but have you tried using the LO input?
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Post by smolder on Mar 20, 2022 10:50:45 GMT -7
I put a 5751 in, but didn’t notice it cleaning up dramatically or lower volume… but it’s not a radical change in tube gain. I’ll though a 12AU7 in when I’m back at the shop.
I didn’t try the low input… I was thinking it was primarily a volume change… but will.
PS: I have some 12DW7’s… you can get a really great tube for very little if you need only half of it. Will have to see how that socket is wired.
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Post by premiumplus (Dave) on Mar 21, 2022 6:30:15 GMT -7
I'm interested in hearing how that 12AU7 works out. Offhand I'd think it wouldn't be so good, but I've never tried one for an output tube driver.
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Post by smolder on Apr 11, 2022 9:35:26 GMT -7
Follow up… spent some more time with preamp tubes in the last slot. The RCA 5751 and GE 12AU7 significantly reduced volume… which was not what I was after. I put the 12AX7 backed in.
I then put a very old vintage 30 in the amp… it’s significantly louder, giving me a bit more clean at moderate volume. I have 1x12 cabs with JBL D120, Celestion Blue, and a Jupiter that I’ll be trying over time. I’ll update here when I’ve put in the time.
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Post by daddyelmis (Greg) on Apr 11, 2022 9:54:46 GMT -7
I’ve learned from experienced Z brothers on this forum that the best/fastest way to affect headroom or breakup volume is by changing speakers to more or less efficient ones, respectively. A 3db or 5db more efficient speaker may do more for headroom and volume than any tube swap.
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