Rocket and Rectifiers

[dartanion]

What a lot of folks don't realize or just choose to ignore is that Ken pretty much used what he had on hand for a lot things. There are members here that knew Ken and can probably debunk much of the lore.

With that said, I would imagine (and this is just my guess) that Ken used a tube recto because the AC30 used one and the Rocket is a hotrod single channel AC30 right. As well, he probably had a nice stash of GZ34s that would be a shame not to put in an amp. I think a lot of us operate in that same mode...hey I've got these transformers, these tubes, and this chassis; what should I build?

So, what tube matters most for tone? I for one would say V1, then power tubes. The tube with the least direct impact on tone is the recto. I am not saying there is no difference because there are differences between tubes. What I am saying is that if it were my amp, I'd spend the extra dough to get good NOS preamp tubes and power tubes, and use a known good rectifier tube regardless of new, used pull, or NOS.

And about the tone of some these messages, let it go. No reason to nasty to each other, unless you're Randall Smith

[rawnster]

And about the tone of some these messages, let it go. No reason to nasty to each other, unless you're Randall Smith

Hey Dartanion, being a budding commercial amp builder, you can't sling other amp builder's names around like that. It's bad form.

And check this out: I've already got some nice preamp tubes on the way. Playing around with the recto tube has been fun and enlightening.

hmm, what to upgrade next. I was thinking that the amp light is a little dull and dreary. And I know that since it's connected directly to AC from the power switch, it's got to be affecting tone, at least psycho-acoustically. What's the best NOS amp lamp out there?

Just kidding!!!!!!!

[dartanion]

And about the tone of some these messages, let it go. No reason to nasty to each other, unless you're Randall Smith

Hey Dartanion, being a budding commercial amp builder, you can't sling other amp builder's names around like that. It's bad form.

Well, all joking aside, Randall has done a lot to fling doo doo at the amp building industry with all of his patents and frivolous lawsuits. It is what it is right. You don't have to be a rocket scientist (pun intended ) to know he is not a friendly figure in the industry.

[RJ Guitars]

With some of the recent measurements we can look at some of the differences between the Mullard GZ34 and the JJ GZ34 in Rawnsters amp... Ultimately, if we really want to understand things better we could put in one of those SS rectifier plugs and take some more measurements. Ron, I'll send you one if your up for the measurements?

Rectifiers are diodes, the simplest form of vacuum tube devices. In our use they basically help us change AC into pulsed DC. One interesting thing that Rawnster discovered was that the Mullard converted the AC to pulsed DC at greater efficiency rate than the JJ. By design specs, they might be the same but in practice the Mullard did things better than the JJ...

The fact that the difference is measurable is telling us something. The fact that most folks like the sound of the Mullard is telling us something. How does a solid state rectifier sound in a Rocket???

I think we all believe that the Rocket is considered a "stiff" power supply. It has the best of the tube Rectifiers running into a big ole 80uF capacitor and then into a decent sized choke. The design of that power supply is also telling us something about what KF had in mind.

Now about those recent measurements...

On V1, you had a voltage of something like 86V on the plate of the first gain stage using the JJ. Curiously, when the overall voltage should have gone up using the Mullard, you've now got 76V at that same spot (I can't remember the exact number but it was less). That seems odd to me and I'm curious if there is something else going on. If indeed it's the same tubes everywhere else in the amp, then could we ask for a recount?

Also, let me know if you want a plug in plug in SS diode unit... no charge except for the request to share the measurements and what your ears hear.

Rawnster, great thread and good info for us to explore.

Thanks,

rj

[rawnster]

RJ, always good to see your posts. I'd be more than happy to try the SS rectifier plug and post voltages again. Any day now I should be receiving a new trifecta of preamp tubes. It would be cool to start over with the voltage readings with the new tubes and the recto plug.

Thanks for the offer.

[rawnster]

Well, after some time with NOS mullard GZ34s in a dual rectified amp, I've decided to pull them out and return to the stock JJ's it came with. The NOS tubes were simply too dark; and it was ripping the heart out of the upper glassy frequencies. I guess too much of a good thing is too much of a good thing. This amp must have been voiced around current production tubes, for what tubes it came with sound fantastic with this amp. Oh well, this gives me more stock for my rocket build...which by the way sounds gorgeous with something like this:

[img:800:600]http://natubes.com/data/images/product/large_674.gif[/img]

[Zippy]

Well, after some time with NOS mullard GZ34s in a dual rectified amp, I've decided to pull them out and return to the stock JJ's it came with. The NOS tubes were simply too dark; and it was ripping the heart out of the upper glassy frequencies.

This amp must have been voiced around current production tubes, for what tubes it came with sound fantastic with this amp.

I don't get your idea that this amp is voiced for a) current production tubes or b) dual rectifiers.

If you have this thing drilled for dual rectifiers and two is too much, just pull one of them to listen to the difference between "Stiff" and "Way Stiff".

FWIW, looking at Gary's voltage compilation, your first stage voltages (V1b) are the lowest of all Rockets represented - even though your V1a is higher than most.

[UR12]

What you guys need to do is get yourself 100 of those Mullards and try them one at a time in your Rocket. I think you'll find some that may improve the sound, some that may sound awful and some that make no difference at all. You can't test a couple of tubes and make a blanket statement that ALL Mullards make you amp sound better and I personally have a very hard time believing that. They are just like 12AX7s or any other tube for that matter. I have 6 NOS Mullard 12AX7s and 3 of them sound great and 3 of them are the noisiest, hissiest and non musical sounding tubes I have in my whole caddy.

[rawnster]

I don't get your idea that this amp is voiced for a) current production tubes or b) dual rectifiers. If you have this thing drilled for dual rectifiers and two is too much, just pull one of them to listen to the difference between "Stiff" and "Way Stiff".

I started this thread to discuss my findings around an old rectifier tube in my rocket build. I found that an old mullard kills in the the rocket. Also, I mentioned, back on page 2 of this thread, that I also tried two of these rectifier tubes in my Two Rock Classic Type 3...THIS AMP is dual rectified. My earlier post today was about sharing my conclusions with the Two Rock, NOT the rocket. The rocket build, in my mind, is leaps and bounds better sounding with a NOS recto like the mullard gz34. The Two Rock, on the other hand, sound better to my stupid ears with the stock JJ gz34s.

I hope this clears up any confusion. I was very reluctant to mention the name "Two-Rock". The last time I did that was in the Dumble forum, and got completely lambasted for doing so. For this reason, I'll never post there again...but that a discussion for another time.

[rawnster]

What you guys need to do is get yourself 100 of those Mullards and try them one at a time in your Rocket. I think you'll find some that may improve the sound, some that may sound awful and some that make no difference at all. You can't test a couple of tubes and make a blanket statement that ALL Mullards make you amp sound better and I personally have a very hard time believing that. They are just like 12AX7s or any other tube for that matter. I have 6 NOS Mullard 12AX7s and 3 of them sound great and 3 of them are the noisiest, hissiest and non musical sounding tubes I have in my whole caddy.

Well, I can only afford two of them. So far, the two I own sound pretty dang good.

Seriously though, I agree, and consider myself adequately corrected.

[Zippy]

...Also, I mentioned, back on page 2 of this thread, that I also tried two of these rectifier tubes in my Two Rock Classic Type 3...THIS AMP is dual rectified. My earlier post today was about sharing my conclusions with the Two Rock, NOT the rocket...

Please forgive me for not knowing which amp you were thinking about.

I was mislead by the Subject header "Rockets and Rectifiers".

My mistake. I'd like to say that it won't happen again but it may.

Hmmm, what was the question? Was there a question?

[rawnster]

No worries, Zippy! Hugs all around.

[M Fowler]

You guys didn't compare the weber copper dohinky or what ever the heck he calls his SS rectifier replacement. Soooooooo your not done yet!

Could you mail those Mullards to me so I can check them out in my Rocket and Asteroid, thanks.

Mark

[Richie]

You guys didn't compare the weber copper dohinky or what ever the heck he calls his SS rectifier replacement. Soooooooo your not done yet!

I'd rather piss in an electrical outlet, than use one of those..

[rawnster]

You guys didn't compare the weber copper dohinky or what ever the heck he calls his SS rectifier replacement. Soooooooo your not done yet!

I'd rather piss in an electrical outlet, than use one of those..

Wow. Now that's a statement! The early picture was just something I pulled off of google. Here's the actual tube. Sorry for the bad pic, but all I've got at the moment is the camera in my phone.