Zendrive 2 tube Swap ~ the definitive thread

[jw112]

there are a few threads here on this and i would like to combine the info here into one thread.

i just picked one up and i'm trying to decide which tube to try out. this thread in NOT to debate if the tube makes a difference or not. this is for peoples findings who have swapped out tubes themselves

 

[jw112]

dan-electro posted this:

I recently scored my second (sold the first a while ago) Zen 2... I hadn't been entirely "wowed" by it the first time around... in retrospect, I didn't experiment with tubes...

big mistake!

A seller here gave me a great deal on a used unit... arrived in good shape w/ the typical raunchy chinese 12ax7. Yuck. Thin, tinny, fizzy, and way 2d. Hmm.

I popped in a Tung Sol RI 12ax7 and things cleaned up / warmed up a bit...

Popped in an ANOS Tungsram 12ax7 and it got even better... but I was still "maxing out" gain wise around 2:00 / 3:00. Still a little "jagged" at higher settings and clarity was still not all there... Better though...

Tried a chinese mesa-branded 12AT7 (sounded like crap), russian EH 12AT7 (better than the mesa, still thin, bodyless crap), and a Mullard CV4024 AT7 (infinitely better than the previous ECC81's but the tungsram 12ax7 still sounded nicer).

THEN,

I remembered reading about Eric Johnson & David Gilmour using 12AU7's in their butler tube drivers to "tame the gain beast" so to speak... that being said, since the 12AT7's (even the mullard) sounded thin and relatively anemic, I was worried about an even greater reduction of gain in the circuit... (12ax7's have a gain factor of 100, 12at7's are like 60, and 12au7's are like 20).

I bought a new JJ 12au7 and popped it in...

it ROCKS. Harmonics are off the wall comparatively, pedal is more "open", warmer than the AT7's with none of the over the top grit of the 12ax7s. In spite of what I thought, I am still using the same gain range "knobwise".

For like 10 bucks you might as well give it a try Made it a keeper for me!

Zen on!

 

[jw112]

Clifford-D posted this:

I tried the JJ 12AX7 that Mr Hermida recommended.
It had less volume, was brighter and had a totally different distortion, more gritty. I haven't tried the Sylvania yet.

I prefered the original Groove Tube, louder, smoother,, but darker than I would wish for.

 

[jw112]

some info from BillyK

Want to know if the tube in the Z2 makes a difference? The answer is:
Yes.

Today I spent some time swapping tubes. I waited about 6 months (per Alf's suggestion) to make sure the original tube was burned-in and that I knew what it was capbable of.

The tubes that I tried included a bunch of new production and NOS 12AX7's, 12AT7 and 12AY7. The NOS tubes were excellent mid-60's examples of these tubes.

First off, I was quite surprised how much of a difference the tube makes in the Z2. The stock Mullard reissue is not bad at all. The collection I tried in the Z2 brought out a bunch of differenct voices and and a range of feel/response.

Out of this bunch, a new production Tung-Sol 12AX7 was the stand-out when using single coils through vintage Fender amps. The NOS 12AX7 tubes compressed more and sounded "sweeter" and laid back, but the Tung-Sol made the Z2 very "present", very articulate and the lower strings had way more definition. Tjhe gain structure is excellent with the Tung-Sol.

I was expecting the lower gain tubes (AT7, AY7) to be the shoe-in for me, but they all made the Z2 more "receding" and too "smokey". Not my thing at all.

So, if you have a Z2 and have been wondering if it's worth 30 minutes of your time to sxplore tubes, I'd say "Yes!". You may end up liking the stock tube best, or you may like the laid-back sound/feel of a NOS tube. But if you have a new Tung-Sol sitting around, do yourself a favor and give it a try. The Z2 really has improved "bark" and is very toneful with that tube. In some ways, it's closer to the original Zendrive.

The funny thing is that I never liked the Tung-Sol as a pre-amp tube in any of my Fender amps, that's why I had one available. Now it's got a new mission!

a post by pfflam

. . . I traded tubes and it seemed to make a big difference . .. I got a spare NOS RCA in there now and it is very smooth . . .
.

some info from markflo

I have a jan ge 12ax7 in mine and it's waaaay smooth just the way i like it!

this is what Rick1114 had to say

I tried a couple tubes in the Zen2. The Tung Sol 12AX7 makes gives the low strings a lot more "crunch", at the same time the higher strings sound thinner, which I thought was a drawback. I'll have to try it again though as I'm getting a little bored with the JJ12AT7 I've been using....I liked the GT5751 as well.

 

[jw112]

kenoflife posted this

It was the tungsol - but now that the original tube is worn it I love it the most!
The tungsol was a little fuzzy, less clear in the bottom. The original tube
seemed a little harsh at first - now its great.
I love this pedal for a lead pedal...

Rick1114 again

I put the GT12AX7-M back in mine as it's a great all around fit for the Zen. If your pedal is brand new, I did think it sounded better (smoothed out) after it was "burned in" for a while - not sure if that was the tube's fault or not! If you want the more crunch on those low E,A strings pop in the Tung Sol reissue, if you want to go all smokey, try a JJ12AT7.

jrigg said this

Although I sold the one I had, I did really like it a lot too. I agree that it sounded better after being "burned in". I kind of went crazy trying every possible tube in it and although the differences between tubes was really small, my favorite was a Telefunken ECC83 smooth plate.

jzucker posted this

By the way, I just spoke to Alf and whoever said the tube was not in the audio path in the other thread was totally wrong. Alf confirmed what was said about the mullard vs. the tung-sol reissue, vs. the at7. He also said you *can* run it without the tube but it'll be harsh.

As a side note, John Mayer is using a couple of these along with a new dual boost pedal alf's coming out with. I hope to be able to do a video demo of the dual boost pedal when they are available. It's currently in the prototype stage.

 

[JB Eckl]

What tube comes in it from the factory? I've never opened it up. I still like it with the original tube, but I suppose I'll eventually try it with others though after some of the comments here...

 

[jw112]

.....My ZD2 came stock with the new Mullard 12AX7M - after a couple of different tubes I realized the Mullard was my least favorite! Very grainy and dull. The Zendrive is magic in a BF Fender, the ZD2 felt lifeless. I don't have many spare tubes but a Sovtek 12AX7LPS was good but a regular EH was even better.

alf responded with

Johan:

Sorry to hear about the 12AX7M. I also suggest the 12AT7 made by JJ. what settings have you tried on the pedal? Try setting everything around 12 'o clock, and the tone at around 2 to 3 o' clock. Email me if you have any questions.

Alf

 

[jw112]

alf himself posted this:

When designing the ZD2 I had to become a tube collector. The NOS work great but difficult to get in consistent quantities. From the commercial variety the GT 12AX7M (supplied with the pedal) works well (don't max out the Voice), the JJ 12AT7 are good (tone), the Svetlana 12AX7 is also nice and the Mullard 12AX7 done by New Sensor. I've also tried 5751 etc ... its really up to each person if you decide to start experimenting with different tubes... please please please: play the pedal for a while so you break in the tube and the components. You'll notice a difference. Also, try different settings...don't always try to max out every knob. The range on those knobs is very wide. It works like the regular ZD in the sense that when you play soft or dig in the pedal will follow.

Alf

stevie2600 said this

I use a JJ E83CC in my Zen 2. I plug it into a slightly overdriven Two Rock, with the gain @ 3:00, voice @ 2:00, tone @ 4 or 5:00 and volume to taste. Sounds really great, to me.

 

[lespauldoc]

wow. I think we have answers!!

 

[jw112]

I just bought a JJ 12au7 and will report my findings

 

[jzucker]

you realize the tube is not in the audio path?

 

[Angle Loss]

you realize the tube is not in the audio path?

It is in the audio path, but it is not used for amplification as in a tube amp--which is probably what you mean.

fwiw, it is only used like diodes for clipping in the negative feedback loop of the opamp (which really what is providing the gain stages). In fact you can take the tube out altogether and it works just fine, just sounds a little different.

You will find some subtle changes in sound by changing tubes, but it will not correspond to how a tube sounds in an amp. What sounds warm or has a lot of gain, etc., in a tube amp will not necessarily correspond to how a tube change affects this pedal. When I had one, I popped in a few different tubes but it really didn't make too much difference--you probably wouldn't be able to tell live. Obviously, in true tube pedals (Matchless Hotbox/Dirtbox, Soldano Supercharger, Varidrive, etc) the changes will correspond because they are using gain stages and clipping like what you would find in an amp. I noticed a bigger benefit in half-breed tube pedals or low voltage pedals like the Tube Driver by switching tubes.

Mind you, it will change the sound a little, but I'd recommend using your NOS tubes for where they will really benefit you--in your amp. I don't remember...but I think I like a 12at7 or 12au7 a little bit better than the stock tube. Of course in all things, do what sounds best to your ears. I hope this will help you in your quest for picking the right tube. I like the Zendrive 2, and maybe I'll get one in the future again when the used prices become realistic, but until then I'm rocking an original Zendrive...the MOSFETS sound good!

 

[jzucker]

It is in the audio path, but it is not used for amplification as in a tube amp--which is probably what you mean.

fwiw, it is only used like diodes for clipping in the negative feedback loop of the opamp (which really what is providing the gain stages). In fact you can take the tube out altogether and it works just fine, just sounds a little different.

That's the bias line for the opamp. That's not the audio path.

 

[Angle Loss]

you realize the tube is not in the audio path?

Originally Posted by jzucker
By the way, I just spoke to Alf and whoever said the tube was not in the audio path in the other thread was totally wrong

A little confused are we?

The tube, used as a set of diodes is clipping the waveform in the negative feedback loop of the opamp. Not sure where you are getting the bias stuff from, because the opamp is being biased there. I reversed this pedal myself. Here is how you can use a tube to clip an audio signal just like the diodes do in a Tube Screamer:

A 12A?7 tube works as two diodes if you heat the heaters and ignore the grids. In pentodes, you must open circuit all three of the grids.

In indirectly heated tubes, where there is no internal connection between the heaters and the other electrodes, you may have voltage between the heaters and the cathodes since they are not connected. They are insulated to about 300V by an oxide layer between the heater and the cathode proper. So since the heater is not connected to any electrode in a duotriode, you may use the two diodes independently.

A single 12AX7 can be a clipper pair. Connect pin 1 to pin 8, pin3 to pin 6, leave pins 2 and 7 open. Supply power to pins 4, 5 and 9. You will need 6 or 12V to power the heater. If you connect pins 4 and 5 together, you can run it on 6V at 300ma between 4&5 and 9. If you leave pin 9 open, you can run it on 12V between 4 and 5. If you want individual diodes, both plate pins (1 and 6) are anodes, both cathodes (3 and are anodes (that's the bar across the diode symbol).

 

[Teleman76]

Resurrect an old thread here. I have quite the collection of old tubes. However, i Just tried a new Genalex Gold Lion ECC83 & whoa!! This is impressive. Must try for all you Zen 2 owners. Really, Really impressive.

 

[dmecham]

After some experimentation I liked the EH 12au7 the best. But after a few months it only got better. No doubt in my mind that going through the tube burn in time things get better. It became smoother and less fuzzy over time. I'm using Zendrive 2 with the gain about 10 o'clock and the voice about the same with tone at 0.