Building a Rocket - Layout Check for group build

[Mark]

Dear RJ

The best advice I can give is keep experimenting with speakers and cabs.

Though if I were pushed for an answer I would say have a look at Vox like speakers and and cabs.

[angelodp]

I agree, a couple of Blues would be really cool.

ange

[Lonely Raven]

Question for you all who are reading this.

Does the rectifier tube make much of a difference in feel? And dare I ask, tone?

Right now the only GZ34 I have is a Weber Copper Cap. I'm afraid it might muck with the feel of the amp. Suggestions on a good current and/or good NOS?

Also, any substitutes that won't hurt the amp or tube?

I have some coke bottle 5U4G and 5V4 and probably a couple other odds and ends that I never got around to selling. Any use in those here?

[Curbdog]

RJ, so far, I have not liked 10" speakers for my Trainwreck style amps, in any combination. I have tried open back and closed back 2 x 10s, ported, 3 x 10, open and closed, and keep coming back to the 12" speakers. I like my Express style amp through a 1x12" closed back for small venues, with or without a DIY Airbrake, and like it even better with a closed back 2x12. I expect the Rocket will also my cabs with 12" speakers. FYI, I am putting the VVR in my Hybrid Rocket, in place of the Stand-by switch. I am going to use the VVR as the stand-by, if that is OK with everyone? I read an earlier post that said this would work, and I also don't want to mess with the beautiful faceplate from Lonely Raven.

[Structo]

Lonely Raven, you probably know this but those copper caps are merely some diodes, resistors and a cap or two inside.
Basically, they are a solid state rectifier.
So it would stiffen up the feel quite a bit.

[Lonely Raven]

Lonely Raven, you probably know this but those copper caps are merely some diodes, resistors and a cap or two inside.
Basically, they are a solid state rectifier.
So it would stiffen up the feel quite a bit.

That's why I figured it would change the feel.

What are the recommended Rectifier tubes for these amps?

[Zippy]

A GZ34 is also pretty stiff when operating in this current range. The Webber Copper caps are purported to give much the same response (voltage drop per amp) as the tube components they emulate. The whole 'wreck power supply looks pretty stiff to me - and the Trainwreck Notes, as I recall, specify that that was Ken's intent. One can certainly design a solid state circuit that emulates the GZ34 - that's what a "sag resistor" is all about, it's just not inside a glass envelope.

[Mark]

I'd stick with a real GZ-34tube. I think the chinese ones are the closest looking to a real Mullard (branded Philips) GZ-34 that I have.

Also there have been some negative opinions about the Copper cap, I've never owned one or had any experience with one so I can't confirm or deny anything. Personally, I don't think it is such a hassle to buy a GZ-34, get one and save the Copper Cap as a back-up should/when the valve rectifier fails.

As far as Trainwreck amps and speakers go. I think t is best to bear in mind the circuit of the Express and the Rocket in regard to speaker needs.
The Express rolls off a lot of bass response and is quite a bright amp. A sealed 4 X 12" cab suits this amp as there is a greater bass response and the highs are "veiled". The Rocket is basically an AC-30 without any real limitations placed on it's bass response. I have tried both open and closed back cabs, and for my tastes, I found the open back cab to sound the best.

[guitarsnguns04]

I am considering using both in a parallel bypass..I will probably end up with a 5u4 rectifier

[tubetek]

Tom's opinion follows...
If you doubt the reasons/need for a real 5AR4/GZ34, consider that the other amps KF built all had the same (sand recto) PS circuit. Since the "Rocket" was referred to (by Ken himself) as being kin to the Vox AC30 I would think he intended the GZ34 for authentic feel/response. If you have issues with the tube recto, why not just build a Liverpool? Of course, don't expect it to sound/feel like a Rocket. I think the Rocket would be different enough with a SS recto that it would no longer be a Rocket. I guess what I'm tryin' to say is are you intending to get as close to a real Rocket as possible or will you be happy to build an amp that is "inspired" by KF but not a clone? I don't think there is a right or wrong answer, just personal preference. Why not do both and decide what you like the best personally?
EDIT> Ted's claims notwithstanding, I can feel the response difference between a real GZ34 and the "Copper-Cap" designed to mimic it.(and I'm FAR from a great player AND have 50 year old tired, abused ears!)
Hope I haven't overstepped and pissed anybody off here but I'm somewhat passionate about this stuffLOL!

[RJ Guitars]

From "The Trainwreck pages" in Gerald Weber's "Desktop Reference of Hip Vintage Guitar Amps".

In his own words, Ken Fishers thoughts on rectifier tubes:


Begin Quote


Rectifier Tubes

The common rectifier tubes used in guitar amps are the 5Y3, 5AR4/GZ34 or 5U4. These tubes are directly interchangeable in most guitar amps. However, each tube produces a slightly different tonal characteristic in the amp. The 5AR4 produces a sound closest to solid state silicon rectifiers that are most common in amps today. This is because this rectifier has less of a characteristic known as "sag"; that is, as the amplifier draws current, the voltage across the tube drops (there is a voltage drop across the tube that increases with current draw).

The 5AR4 has the least voltage draw. The 5U4 has slightly more voltage loss with current draw than a 5AR4/GZ34. The 5Y3 has the most loss of voltage with current draw and therefore has the 'softest' sound. Also, if you have an amp that "eats" output tubes, it will be easiest on the amp to use a 5Y3. One can substitute these tubes and judge for one's self which one provides the basic tone that one likes.

Many companies make a solid state replacement for these rectifier tubes. These solid state units tend to 'tighten up' the sound, make it more dynamic. However, they also tend to remove the "singing" quality in certain amps. If you are going to substitute, make sure the voltages will not exceed the voltage ratings of your output tubes and power filters!...


End Quote

[Mark]

Hey, shouldn't I be listening to Rocket MP3's now?

[RJ Guitars]

Hey, shouldn't I be listening to Rocket MP3's now?

Mark, I will go to work to accommodate you... I am sending my amp to the studio next week and hopefully I will get a few good sound samples back. Note I say that the amp is going to the studio but for some reason they didn't ask me to play - must have been an oversight?

Since you are the very much the Godfather of the Rocket due to your early efforts, would you also provide us a clip? I am curious how close we come to your earlier efforts...

The built mic on the camera is awful, as you might expect.... but here is a tease of recordings to come to AmpGarage sometime in the near future.

http://www.youtube.com/watch?v=sm4QzK7F_IQ

rj

[RJ Guitars]

Well Rocket Fans,

I am really enjoying this new amp. I started the amp off with some old tubes that were expendable in the event the amp melted down. These tubes included an unmatched combination of Fender (Sovtek) El84's for the power, and two recent vintage Chinese 12AX7's, and an old stock RCA in the phase splitter spot.

The amp worked from the onset and since then I really haven't tweaked anything at all.... yet.

Of all the output tubes I've tried, the Old Stock Russian Saratov EL84's seem to have the best overall tone. They seem slightly smoother than the JJ matched quad I tried.

I am using a set of Mullard NOS 12AX7's for the preamp work and they also sound quite good.

This combination actually sounded quite good and all the differences I've heard since then are subtle variations, nothing really drastically different.

I'm curious what the best set of contemporary tubes for a Rocket are? Especially the preamp tubes. I know I will never find another set of MOS Mullards.

rj

[Bear]

The built mic on the camera is awful, as you might expect.... but here is a tease of recordings to come to AmpGarage sometime in the near future.

http://www.youtube.com/watch?v=sm4QzK7F_IQ

Nice sounding tease. The roar of it is pretty impressive for what is supposed to be a more staid 'Wreck. Something about that makes the Brian May/AC-30 thing make more sense.

Bear