|
Post by davecarb on Mar 16, 2022 17:36:54 GMT -7
I really dig both for different reasons. Today was a 5751 day. What are you all using in your z28s?
|
|
|
Post by bubs42 on Mar 16, 2022 17:46:19 GMT -7
In my two older Z28’s I’m using 5751’s, and i’m assuming the MKII has 12AX7.
|
|
|
Post by loucardguitar (Johnathan) on Mar 16, 2022 19:47:47 GMT -7
Yeah if I remember correctly the Z28 started out with of course the EF86 front end and then a 5751 PI. Then at a later date the doc changed the PI to a 12AX7. I don't recall any Rectifier changes. I believe it's always been the 5AR4
|
|
|
Post by helmi on Mar 17, 2022 16:57:55 GMT -7
How much, and what, is the difference between the 5751 and the 12ax7 in the PI position? does it effect the gain of the amp that much?
|
|
|
Post by davecarb on Mar 18, 2022 3:25:34 GMT -7
I am no expert, but I believe the 5751 has about 70% the gain of a 12AX7. I find it is a little less mids, more of a fender feel, and a little clearer. I find the 12AX7 has a little more mids, a touch brighter, more aggressive sound. I really love the tung sol 12AX7 and a nos Jan 5751, but for different reasons. I do not like most other 12AX7s I’ve tried in this spot. That is why I am asking, to see if others have similar experiences, or have other tubes that work for them in this amp.
|
|
|
Post by Stephen on Mar 18, 2022 5:32:49 GMT -7
I have a 2011 model that I just bought “new” from Guitar Resurrection in Austin. It has 5751 on the tube chart but actually has a Tung Sol 12AX7 in it. Here is an AMA about the Z-28 but it doesn’t say when the change was made.
|
|
|
Post by davecarb on Mar 18, 2022 17:52:48 GMT -7
Love that video. Have watched it many times. It really is such a cool amp that does so many things. I really do love it both ways.
|
|
|
Post by Chilly Gibbons (Todd T.) on Mar 19, 2022 9:53:11 GMT -7
Great video. Doc refers to it as a simple circuit, and it might be (don’t own one), but when you see the chassis it obvious why we like Docs amps and why they are by far the best deal out there. As with all of his designs, prominently featured is a choke and lots of capacitance in the power section and of course, huge iron on the PT, expensive parts that some others try to design around to save money. Again, I don’t own a 28, but from what I read most people like it for it’s stridency and punch. Well, you can’t get that by skimping on the power section, which this amp (and Docs others) obviously do not. Now I’m going to plug into my Maz an have an experience…
|
|
|
Post by nick0 on Mar 19, 2022 15:08:50 GMT -7
The urge to get my hands on a Z28 is growing......
|
|
|
Post by adam on Mar 19, 2022 15:53:47 GMT -7
I think I've watched all the AMA videos a couple times and always seem to learn something. One of the more recent things that stuck from that was to make sure your volume pot on your guitar is full on or off when soldering to the housing so that you don't screw up the pot. I had no idea, and yes, had to replace a pot on a pickup change recently.
Back to the Z28, we must be talking about V2 since V1 is the EF86? Regardless, the one I tried (mk2), there was no want at all for clean headroom in that amp with the ef86 and 12ax7. I don't know for sure, so don't shoot me, but that amp had lots of clean and clean volume available. Very 3d and almost of hifi in a way. I'd also add that if you have a z28 and have a tube screamer lying around, try really gunning the tube screamer in that amp and it makes an orgasmic sound like you've never heard before. Just try it.
Back to the 5751, and maybe more related to a current Ghia thread, but I was using the 5751 in the phase inverter position of that amp an tried it in the P1 position for kicks (swap P1 and P2) and while both increase clean headroom on that amp (if that it is what you are looking for), the 5751 in P1 is really quite glorious there. It "seems" like it sort of retains the harmonic character of a 12ax7, but with less gain. My experience with trying to do that with 12ay or 12at tubes in other amps is that yes it does that cleaner thing, but it loses harmonic complexity of the amp. So maybe if you have some amp that you wish was a little cleaner, maybe the 5751 is worth a try for you, as opposed to the ay or at tubes.
|
|
|
Post by bubs42 on Mar 19, 2022 17:35:38 GMT -7
I think I've watched all the AMA videos a couple times and always seem to learn something. One of the more recent things that stuck from that was to make sure your volume pot on your guitar is full on or off when soldering to the housing so that you don't screw up the pot. I had no idea, and yes, had to replace a pot on a pickup change recently. Back to the Z28, we must be talking about V2 since V1 is the EF86? Regardless, the one I tried (mk2), there was no want at all for clean headroom in that amp with the ef86 and 12ax7. I don't know for sure, so don't shoot me, but that amp had lots of clean and clean volume available. Very 3d and almost of hifi in a way. I'd also add that if you have a z28 and have a tube screamer lying around, try really gunning the tube screamer in that amp and it makes an orgasmic sound like you've never heard before. Just try it. Back to the 5751, and maybe more related to a current Ghia thread, but I was using the 5751 in the phase inverter position of that amp an tried it in the P1 position for kicks (swap P1 and P2) and while both increase clean headroom on that amp (if that it is what you are looking for), the 5751 in P1 is really quite glorious there. It "seems" like it sort of retains the harmonic character of a 12ax7, but with less gain. My experience with trying to do that with 12ay or 12at tubes in other amps is that yes it does that cleaner thing, but it loses harmonic complexity of the amp. So maybe if you have some amp that you wish was a little cleaner, maybe the 5751 is worth a try for you, as opposed to the ay or at tubes. The MKII with the MV has a wider pallet than the MKI version. The 5751 IMHO is really a feel thing, it does change the sound a little less edge and a little rounder but it subtle. I prefer it in the MKI, but have no intent at the moment but maybe I’ll try it tomorrow in the MKII. I just came home with a brand new 5751 from my local shop.
|
|
|
Post by bubs42 on Mar 19, 2022 19:12:53 GMT -7
So I tried it in the MKII and frankly the 5751 is my preferred tube for V2. IMHO opinion I think it just makes the amp sound a touch sweeter. I had no qualms with the amp, but I put that tube in and I was like Oh ya that is what I like about the 5751. It’s down to personal preference and if you have a Z28 try it for yourself.
|
|
|
Post by gfreak on Mar 20, 2022 8:48:59 GMT -7
Love the 5751. One of the first things I did when I got the amp, 10 years ago, was change the PI to the 5751.
|
|
|
Post by DRZ on Mar 20, 2022 15:06:50 GMT -7
My simple explanation for the 5751 & 12AX7 PI is this :
In a Z 28 if you are looking for a more Blackface Fender tone install a 5751 in PI. The 5751 is a bit less gain which equals slightly more clean. But more it has a hollow tone, less Midrange drive like 12AX7's do. This allows for as they say " More Scooped Tone " really sounds rich with solid-body single coil guitar. Also since most Overdrive pedals boost the Mid's it doesn't overdrive the Mids too much with a 5751 and make them Clanky Sounding, nice and smooth with nice cut.
But remember a 12AX7 in the PI drives nice and hard in a Z 28. A bit more like a Brown Face Fender.
In a Ghia the 5751 does mostly the same in the PI , it smoothes out the sound and increases clean headroom slightly. I run a 5751 in my Ghia , a RCA Black plate Command series.
A 12AX7 in the Ghia gives the amp a bit more English attitude both 18 watt Marshall & VOX type tones. Strong Mid's More Clang , and more volume and drive.
I hope this helps. Remember these are not day & night changes subtle at best . Always if you like the sound of your amp LEAVE IT ALONE!!!!!!!
|
|
|
Post by Joey Beverages on Mar 31, 2022 11:41:54 GMT -7
I really dig both for different reasons. Today was a 5751 day. What are you all using in your z28s? 12AX7 on both my Z-28s. Turn it up and have some fun! Cheers always Joel
|
|