My first Rocket... Need help!

[angelodp]

removed -

[showsii]

Are you reading Pin 9

Woops, no pin 2.. :/

I need to measure pin 9?

Ian

[sunnydaze]

Pin 2 is where to measure this. Yours are probably OK - the side reading .8 MV may be a little high. Mine was leaking 2 - 3 volts on one side. At the time, I didn't realize the amp could produce really nice cleans. Once I corrected, made big difference.

Good luck
Mike

[rawnster]

showsii, crank the amp to 12oclock on the volume. Turn your guitar volume down to about 5, or 1/2 way. It should be nice and clean. Roll the guitar's volume up for more dirt. You said you had the amp at 10oclock. I bet it was pretty dang loud with the guitar volume all the way up, right? Turn the amp down to about 8:30-9:00 with the guitar volume all the way up. Should be clean and still pretty decent volume. A lot of the time I run my rocket build about 9:30 on the volume. It's completely clean; I then use dirt pedals to bring in crunch and such. The thing to remember with trainwrecks is that working the guitar volume is key to getting great tones. I made some clips of my rocket a while back that illustrates what I just mentioned to you. You should be able to find them here on the forum.

[amplifiednation]

Great job on your second build! Everything is so much cleaner, a marked improvement!!

Everything looks good to me, including your voltages. Your clip actually sounds pretty good too.

I might have to agree with some of the other guys, you might be just getting the natural breakup of the rocket.

So my rocket is lined up with your voltages pretty well. I just did a test...at full GUITAR volume if I put the amp up to 10 I get breakup, at 12 I get a lot of breakup. The amp is NOT clean. BUT if i back off on the volume of my Les Paul it cleans up real nicely at any of those volume settings and retains tone. The cut control works well too to bring out some sparkle you might lose by turning your guitar down.

That's what single channel amps are all about (my opinion).

My only other thought is to check your pot values if you can. Maybe you swapped one out by accident for a different value. A long shot...

I feel bad I don't want you to be disappointed!! Try the guitar volume. You might be surprised and maybe with a little noodling you can figure out how to fly that thang.

[amplifiednation]

showsii, crank the amp to 12oclock on the volume. Turn your guitar volume down to about 5, or 1/2 way. It should be nice and clean. Roll the guitar's volume up for more dirt. You said you had the amp at 10oclock. I bet it was pretty dang loud with the guitar volume all the way up, right? Turn the amp down to about 8:30-9:00 with the guitar volume all the way up. Should be clean and still pretty decent volume. A lot of the time I run my rocket build about 9:30 on the volume. It's completely clean; I then use dirt pedals to bring in crunch and such. The thing to remember with trainwrecks is that working the guitar volume is key to getting great tones. I made some clips of my rocket a while back that illustrates what I just mentioned to you. You should be able to find them here on the forum.

+1
I'm clean about 9:30 but no higher than that without backing off the guitar. with the guitar backed off I can blow the doors off the house with clean tones.

[overtone]

Ian,

Your workmanship has really taken a major leap forward but in the second clip I really sense your disappointment. The concept of headroom can be rather subjective and is certainly relative. It is difficult, I guess for any of us here, to grasp how loud your amp is at 10, or for you to grasp how loud ours are. It is dependent on the room and probably many more things besides.

The points from Rawnster above are very good. Ultimately the flexibility of a Ken Fischer type of circuit is lost, or remains unknown, if you do not ride the volume control and learn to "fly that thang", as Taylor Cox so admirably put it.

The magic of the amp comes into play if you forget how you used any amp before. Do try setting the amp volume at 12 noon just as Rawnster said and roll the guitar volume right back to the point where you want to be. I can usually quickly find a spot on any guitar where I can get a snarl just by digging in more. That is where I like to be. I am not a great twiddler and prefer just to riff straight down the road. (like a drunkard trying to walk a straight line…)

I use much less bass than you, because it drives up the overdrive. Out of interest I ran the last Rocket that I made at the settings you used in the last clip, Vol 10 / Bass & Treble at 12 / Cut 2 and I assumed a guitar volume of 10. The results were very dependent on the guitar - a homemade Tele, an old Gibson Junior and an old Gibson ES-295. In general the onset of clipping does certainly seem to be around volume 10, but that is not how to get the most from this circuit. The homemade Tele, which is normally my number 1 guitar, would not really clean up. Taking the amp to 12 and rolling the ES-295 volume around really gave me the shakes. A quick aside: this old guitar has paint markings on the controls at rolled back settings. I use those and they are spot on.

But returning to your circuit, the break up sounds rougher than I am used to. I wonder if all possibilities have been exhausted, for instance I have noticed that this circuit reacts more to different tubes in the preamp than others. Possibly because the circuit is essentially so minimal. Am I right in understanding that you have swapped out the EL84s, but not any preamp tubes?

I see something minor - which will not actually make any difference in the headroom issue - look on the rectifier socket:
this time you have taken your DC supply for the first filter cap from pin 2 of the GZ34. The rectifier will work like that, but the cathode of the GZ34 is on pin 8, so it is usual to see the DC supply taken off pin 8, not pin 2.

Let us know how you are getting along. Maybe your concept of headroom demands a 4 x KT88 Rocket...
Best, tony

Perhaps for reference or general interest, this is the set up of the Rocket that I last made:

B+1 283V / B+2 277.5V / B+3 199V / B+4 183V / B+5 174V
Plate dissipation 11.75W each
GZ34 Mullard
V1 Mullard short plate
V2 Mazda (Mullard) long plate
V3 Telefunken ribbed plate
EL84: 4 x Telefunken matched (+/- 1/2mA)

Deviations:
Screen g2 resistors 1k
Old British PT of unknown make 260-0-260V apr. 400mA
4K OT from Ampmaker UK
Choke Hammond 159M
PIG control
No standby
Own layout

[showsii]

Hey everyone,

Thanks for all the responses! I messed around with my guitar volume like you guys suggested. I found it to help for sure! I was telling Ange that I guess is was time for me to suck it up and learn to play with my volume knob and become a real guitar player. However I still had this feeling like I wanted to to sound just a bit different. So after much research on TAG I found a few things I could tweak to maybe get a bit cleaner sound. So I did the following.

1) removed the cathode bypass cap from V1b- helped a little but not quite there.

2) changed the plate resistor on V2 from 220k to 136k- helped a little but not there either.

So after all this, I decided to play it through a different cabinet of mine and a friends as well.

Before I hooked the new cabs up I decided to switch some tubes out again. Here is what I put in..

V1- Brand new JJ
V2- Brand new JJ

V3- OLD Siemens dual triode

V4,V5 sovtek El84
V6. V7 New JJ


So when I plugged the amp in and turned it on...... wait for it.....

SOUNDED AWESOME! Sooooo good. The amp cleaned up just like I wanted to hear and still had some great dirt on it. Wow, this amp sounds fantastic. I am beyond pleased. I am assuming that the old Siemens tube is what cleaned the amp up. This is teaching me how crazy of a difference tubes can make in the total sound in an amp, who would have thought? (I also put all stock values back in the amp on all components)

So, A huge thank you to everyone who has helped and given advice and feedback. I am excited to build more amps and share the experience with everyone.

The head cabinet and matching 2x12 are almost finished. I will post pictures as soon as they are done to see what everyone thinks!


Thanks again everyone


Ian

[angelodp]

Bravo Ian, blast-off.


Ange



Now come the tweaks and add-ons

[amplifiednation]

Nice work brother! It is a cool amp. Wait until you really start figuring out the tones you can get

[Ian444]

Good news Showsii. Determination and tenacity is GOOD

Now a question for everyone. Why does the Rocket voltage chart show a 21V difference between the anodes of V3, the PI, and a difference on the V3 grids as well?

[overtone]

Ian, this is really great news! I think you are going to enjoy this amp

Now a question for everyone. Why does the Rocket voltage chart show a 21V difference between the anodes of V3, the PI, and a difference on the V3 grids as well?

Thanks for bringing that up, I saw it, wondered a bit, became sidetracked, and forgot it. But it must be a mistake.
There used to be a compiled voltages table in TAG, but I cannot find it anymore here. Eventually I found the file on my drive and below is a screen shot of the compiled V3 voltages.

Best,
tony