Best tubes for the Rocket

[rooster]

I've had some help here so it occurs to me that I should pay it forward myself. I know we've all had a history with solving our own problems and I salute this trait, but this is not about that. This is about Ken's idea of tone and how - after you've built what hopefully is a decent copy of what Ken designed - you can realize what he had in mind. I know there are transformers to choose from and parts, etc., but I am writing this assuming you have not built something from washing machine parts. This said, I am even hoping you have found some great parts of the type that Ken would have used. [Oh, no surprise, I also realize this post is a bit ambitious because there are those magic Celestion Blues or Silvers of the '60s that are magic and not to be duplicated as of yet. (One cab that Ken loved was actually not his, but Chris Merrin's, on loan but never given to Ken and never to be returned, BTW.)]

So, assuming this is has happened, your amp is built, here's the tube lowdown for the Rocket as I have experienced it thanks to some great input from certain ppl who knew Ken, an article or two in the early Vintage Guitar mag, and of course that great tube emporium, eBay, a counterpoint to when NOS is $120 per 12AX7. Yes, I have spent that kind of money on NOS to learn something and I don't begrudge myself the expense. Education has a cost.

So let's begin. I will assume you are here out of curiosity along with a hope that you can make your Rocket experience the best that it can be. Also I should note that I have built a few Rockets and they sounded fine I thought, but now I realize they could sound better just by better tube selection. Also, what I have ended up with here in my amp arsenal is a Rocket/AC30TB/AC30-4, an single amp that can do the 3 circuits, Normal Channel, TB Channel, and EF86 Channel (found in the AC30-4). I have not built the tremolo circuit, BTW, so I have plenty of room within the chassis. Oh, let's talk about youtube for a second. Youtube is great, no problems with it here, but there are elements that are never really explained properly, IMO, and especially regarding recorded guitar amps. In a nutshell, the player is king, he can make or break a demo and, if he's really good, can make shite sound like god in a box. The particular guitar is another factor, as is the room and the miking technique, and any pedal that might be involved, typically reverb or delay is an obvious one, sometimes a not so obvious OD pedal, but there is also limiting and compression that is rarely mentioned but is always in the game. It's a slippery slope, be aware. One video shows a guy playing into his '61 AC30 that he mentions has been gone over completely, caps changed, etc., original speakers, and finally some delay added. The demo sounds very good, but what else is going on here? I would also add that he actually says 'the amp doesn't have a lot of bass'. This is incorrect. The original speakers (alnico) roll off a lot of the bass that the amp produces, but the circuit has a lot of bass. Case in point, his demo switches between the Normal Channel and the Bright channel (there is no TB on this amp and he has added an EF86 channel), with the Cut control on about 3/4 (note: the English built has a REVERSE log pot in it's circuit so what looks like the Cut is on about 1/3 up from 'Off', it is really 3/4 engaged), you know it's the Normal vs. the Bright channel but they sound somewhat similar, the Normal channel being muddier or woolier. This is not what you experience with the Rocket/TB channel vs. the Normal channel in the AC30 TB amp. The Rocket/TB has more gain and a ton of bass available via the 'Bass' control, and likewise a ton of Treble, and this of course feeds into the Cut control, post PI, for another tonal variation.

Tubes. We know [edit: maybe I should say that 'I know' because 2tone below makes a comment that counters my statement. I remember reading this info in a VG mag article that Ken used to write where he talked about the EL84M tube - BUT - going through my partial collection of VG mags I could only find a reference to the 'Standard Sovtek El84', and in two different articles. Also note Ken used the word 'love'. Hm. That's 3 against 1 and I have no documentation, maybe we better listen to 2tone on this subject?] that Ken like the Russian 'EL84M' tube, what perhaps might have been the Saratov 6P14P. In 1993 these were - POSSIBLY - branded EL84M and sold by New Sensor/Electro Harmonix. (I say POSSIBY because I have seen these tubes in the day, the Sovtek EL84M branded tube - HOWEVER - these tubes did NOT have the 6P14P label or Saratov logo work so there is still some confusion here as to whether or not these 'EL84M' tubes were the Saratov 6P14P tube.) Once you play them (at this point I am talking about the Saratov 6P14P) you begin to understand why Ken liked them enough (conjecture on my part at this point!) to say a few nice things about them in a Vintage Guitar mag at the time. They were cheap, available, rugged, and survived some pretty brutal treatment at higher voltages and biased hot in a stock AC30TB and his Rocket. Were they better tubes than NOS Mullards and Amperex 7189s? No, not to audiophiles. However, I've heard all three in the same vintage VOX TB amp and I finally decided that the original speakers evened out the playing field dramatically. Could you hear a difference, yes, but the bias point was static. I couldn't tell you what the mA draw was on any of the tubes or how close they were to optimum, it was simply plug and play situation. The NOS Mullard and Amperex tubes were smoother with different midrange presentation, let me say that. However, typically a guitar amp is not a 'smooth' environment. Said another way, the Saratov/(possibly)EL84M tube in a guitar amp has more clarity and more crunch.

So how do we make this amp sound better, what tubes should we use in V1, V2 and V3? Ken like the Amperex Holland (also branded Philips Miniwatt ECC83 - Philips is the original manufacturer, tubes were rebranded by Amperex and others) 12AX7 tubes best in V1 and V2. V1 should be marked 'I63' etched in the tube glass at the base. 'I61' and 'I65' exists, but he apparently like I63s best in this position. V2 could be I63 or I65. V3 is different in this amp. I never heard of a preference here referenced by Ken from anyone I have talked to, but I can tell you what I have tried and what works best, IMO. (Also, let me add, there is no room for a Blackburn Mullard in this circuit in any position. It will turn the chime into a blur of midrange that dwarfs the amp.) Moving on, I have tried many tubes here and to my ear, the best is an RCA 12AX7 from the '70s thru early '80s, short plates, like the type used in Fender amps at the time. It is a very 'clean' tube, it does not encourage too much 'bass', or in this case, in the PI, what I will call 'wobble'. It's a hard description to qualify, but if you had the three tubes, say the Amperex, Mullard, and the RCA, hands down you would choose the RCA if you wanted the Rocket circuit to do what it was designed to do.

Alright, done. I have to add that in the AC30TB, V1 is split between the inputs of the TB and Normal channel. This is different than in the Rocket circuit that uses V1 for both the first and second stage of gain. Likewise, in the TB circuit V2 is split between the 2nd and 3rd gain stage of the TB channel, where Ken only used 1/2 of V2 for the 3rd stage. So they are different. I have to use an I63 in V1 and V2 in my AC30TB amp.

[pompeiisneaks]

Thanks! Wow that's a lot to digest

~Phil

[M Fowler]

I'm not claiming to be a Rocket expert but I have never built a bad sounding Rocket.

I do have to choose my rectifier tube carefully because what we are buying from current production rectifier tubes is hit and miss. Currently I took Dr Z's advise and switched to Sovtek for rectifier.

The best sounding power tubes EL84's are JJ , while my Saratov 6P14P are in my Zwreck clone but don't find them to be better.

The phase inverter and the two preamp tubes I mostly use JJ $9.00 ones.

Yes I will tube roll on some amps with JJ, TAD, new tung-sol, new Mullard, and organ pulls.

After years of use, the customers still enjoy the Rockets especially in combo format and I prefer heads so I can match that with a JCM800 50w head into split lead 4x12 cabinet.

I also have to add that no two builds are the same, different chassis, different transformers, caps, resistors, pots etc.

It is just plain a great circuit to build a fine sounding amplifier. Some based on musical tastes I clean up the headroom by lowering the plate from 220k to 120k.
Add PPIMV and switch the bright cap in and out of circuit. (bright switch) 100pf/off/350pf are perfect.

Thanks goes out to all the Ampgarage guys, especially Rooster.

Mark

[2tone]

The early Russian tubes Ken liked were the commercial EL84, not the EL84M, which he said were not as sweet sounding. He used Groove tubes labeled commercial Russian tubes, till they were depleted of the older ones( the more recent ones he didn't like as well)..So Ken had a preference for the cheaper, but sweeter mids sounding regular non military tube..They were around $ 2.60 per tube back then, I would buy a box of 50 from New Sensor...

[rooster]

Mark, I have used the J/J tubes, as well. I can't dis this product as I know these are some of the best tubes being manufactured today. J/J the company is something I want to exist for a long time and I do use many of their tubes. However, that said, there were fantastic tubes being made in years gone by that were the hallmarks of what they are currently manufacturing. In my situation, for my personal amps, I try to source these originals. Sincerely, the Amperex Holland I63 and I65 tubes are fantastic 12AX7s as I'm sure you know. Do I like buying $40-$50 used pulls or $120 NOS versions? Haha, not really. But I do have quite a few of them at this point because I do hear a difference.

Oh, and BTW, I didn't mention the Mullard rectifier, but yes, this is mandatory and Ken's preference in his Rockets. This info comes from Dave Funk for one.

2tone, you're killin' me! Haha! In the article (Ken's column) I read in Vintage Guitar in 1993, Ken said he really liked the EL84M tube and that's my reference. But let's reference this other tube that he suggested/reccomended to you. A picture is always nice. And to be transparent, I have talked many times with my guy at New Sensor, Gary, who tells me the Sovtek EL84, the cheapest one available from them, is what all the amp builders are buying. Sure, I've tried these - and apparently they are not what you purchased years ago? - but they don't really get me excited. And I'm sure the new Sovtek EL84 is what Fender is using in their BJrs via the white label GT version, and God knows they can take a beating. Tone? No comment. HOWEVER - 2tone - I notice you haven't presented the preamp tubes your amp arrived with and what Ken had to say about these? Sharing is always good!

[rooster]

Are these the tubes you are talking about, 2tone?. I have a quad coming so I'll A/B the Saratovs and these when they arrive.

EL84.PNG

[2tone]

That looks like one. I'm posting one of mine.. I don't know how the article had it EL84M.. Ken definitely preferred the commercial , cheaper tube for sweeter harmonics. Lots of people knew this. This tube in attachment is one of 50 I bought during the era Ken was buying the same tubes..

[gktamps]

I've built a bunch of Rockets and my own variants, and have tried many different tubes. I had a stash of various NOS American brand tubes, and when those were exhausted, I bought matched quads of JJs, but some drifted quickly. I've tried current production Gold Lion, Sovtek, GT, and Mullard, and they all sounded OK, as long as they lasted (not just in Rockets, but Marshall 18 watt amps). I've also used NOS EI, but the ones I've really liked are the Russian 6p14p like this one I just matched with another 3. I bought about 40 tubes from Russia some years back when they were still quite inexpensive ($4-5 ea.), and find that they last, and sound great to me. Wish I had bought more!

[rooster]

Alright, thanks, 2tone and gktamps. First off, on the home front, with maybe 6 hours on this 6P14P quad, the amp sounds really really good. Honestly, I don't think it has ever sounded better. It makes me think I had a bad quad in there before? The amp is really quiet at idle and I've never heard it like this before. I always thought the PT was a little dodgy but now I've changed my mind. But, as I said, I do have a quad of the Sovtek coming. I'm told ones I bought are dated prior to 2000 but I'll wait and see.

[rooster]

Also of note, I went through my old copies of Vintage Guitar mag and found about 10 articles written by Ken in his column at the time. Have any of you ever found these on the net somewhere? I cannot find them anywhere. I'm thinking these are important enough to reprint here. Is there a place or need for them - or are they here somewhere and I can't find them? For example, did you know he did a lengthy review of the Klon OD?

[M Fowler]

https://tubeamparchive.com/viewtopic.php?f=3&t=30598

[rooster]

Hm, I just posted something and included two pics of two different articles from Ken...I they didn't post. Is there something going on with the site??

[rooster]

Let me try this post again.

The Rob R info is very well done, wow, what a lot of work!! Thank you for the link!

Getting back to the EL84 discussion, I went through my old VG mags to see if I could find the article where Ken talked about the EL84M. Damn, I could not find that issue. Arrg, I had more of these mags but they are gone. There are at least 10 more articles by Ken (he had a monthly column in VG mag) besides what I have in house. I know that Gerald Weber has a chapter in his book that presents some of these columns, but not all. IMO, the beauty of these columns is Ken's writing style and how there are these 'pop-up-gold' moments as he delves into something else. Case in point the two pics I have posted, taken from the body of the two columns. They DEFINITELY support 2tone's claim of Ken's EL84 preference. I may never have a rebuttal to this, but eh, no matter, here are Ken's words that I could find. And it is duly noted, 2tone, that Ken used that four letter word: LOVE.

[nworbetan]

The questions that come to my mind immediately are: How long ago was that article written? Has Sovtek made any changes to their EL-84s since then?

[rooster]

!994 and 1995, twenty three years ago.

BTW, the Tesla (which became J/J) EL84 tube was out at this time and yet I never read or heard Ken talk about this tube. Seems odd. This said, the J/J company has modified their production equipment and tube building techniques so I think we can consider it a 'new' tube relative to Ken's experience. But are there any others? I think it's all J/J, Sovtek, and other Russian facilities for new production these days.

If you were asking has the Russian manufacturing process changed in 23 years I will assume it has but I have no facts on the subject.

So where were you going with your question, nworbetan?