More rocket fun

Express, Liverpool, Rocket, Dirty Little Monster, etc.

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andresound
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Re: More rocket fun

Post by andresound »

Hi Mike,

I play the express around noon. It sounds best there. I do have a VVR installed, which helps. Have tried LOTS of tubes! Will try the MF for plates. Will 1/2 watt do in that position?

BTW, who is your mate in Durbs?. If you are originally from Cape Town, you might know Kevin Gibson? He used to jam with us back in the day in Durbs. What a drummer!!!
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guitarmike2107
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Re: More rocket fun

Post by guitarmike2107 »

I would go for 1watt or higher on the plates, the first triode is the most important one.

Sorry don't know Kevin, but I know finding good drummers is hard
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Re: More rocket fun

Post by guitarmike2107 »

Finally got to finish off the cabinet for this amp, here it is:

The material is red with yellow metallic bubbles, but it actually looks orange but the tone of the colour changes depending on lighting and the angle you look at it. I am not an orange fan but this turned out well.
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ampmike
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nice

Post by ampmike »

Very Very nice work,A+ Topshelf.Have fun with it :D
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JoshBernstein
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Re: More rocket fun

Post by JoshBernstein »

What kind of caps are those you've got on the cathodes of v1 and v2? Ive seen them in other builds but i cant figure out what they are.
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norburybrook
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Re: More rocket fun

Post by norburybrook »

Looks great Mike, I think I might even prefer telex covered TW clones to the wood cabs :D.


I've found in the studio the rocket is too noisy to put pedals in front of unless it's a loud band track. There's so much gain and having the volume down on the guitar doesn't help with the overall amp noise level, you have to turn the amp down, and you lose something then.

My friend came down the other day with his express and he'd put a VVR in which worked well.


Here's a pic of our comparisons....

Marcus
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M Fowler
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Re: More rocket fun

Post by M Fowler »

To knock the noise down in my TW builds I had to isolate the input jack from ground and separate the B+4 & 5 filter cap grounds from B+3.

Grounded B4 & 5 with the input jack and V1 cathode resistor/bypass cap to a chassis ground tab near the input.

PPIMV using dual gang 1ML pot not 1MA pot works great.

Mark
Bob S
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Re: More rocket fun

Post by Bob S »

For Rockets Do like Mark said and try lowering the first stage plate resistor value to 120-150k. Still enough gain on tap & more versatile.
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norburybrook
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Re: More rocket fun

Post by norburybrook »

I have a 120k in there now and also I think my grounding is as you describe already.

Here's my layout from Mike, is that what your describing?

Does a VVR work better than a PPIMV?



Marcus
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guitarmike2107
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Re: More rocket fun

Post by guitarmike2107 »

Hi Marcus, I have very little noise with my amp, no hum and not a huge amount of hiss either, you can try the grounding suggestions above but the way the grounds where laid out on the layout was done in a logical manner to keep the noise floor down, you can try isolate the input jack and the speaker jack but I don't honestly think that will solve it, a PPIMV would allow you to turn the pre up amp and keep the power section cleaner, and it does reduce the perceived noise floor.


But if it is really bad then you may have a bad resistor/ solder joint or valve in the amp causing it, have you tried to mute the grids of each pre-amp tube to see where all the noise is getting in? if I mute the input grid on my amp it s pretty quite, so much so you may not even know the amp was on.

Some tubes can be noisy too BTW, I got some pre-amp tubes from Hotrox a few years ago that when straight into the bin they were so noisy.

Here is my latest video of the amp, the distorted tones are with the volume at 2 o'clock, low output guitar.

https://www.youtube.com/watch?v=rtWdSks ... e=youtu.be
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Re: More rocket fun

Post by guitarmike2107 »

JoshBernstein wrote:What kind of caps are those you've got on the cathodes of v1 and v2? Ive seen them in other builds but i cant figure out what they are.
They are made by Vishay, you can probably get them at Mouser in the states
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norburybrook
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Re: More rocket fun

Post by norburybrook »

Mike,

two things; when one says 'isolate' the input jack do you mean give it it's own chassis earth separate from the others?

how do you mute the input grids?

nice vid :D

my amp sounds great, just too noisy with pedals in front in a quiet environment . My studio has a noise floor of -80db so it's VERY quiet so obviously any noise is more noticeable.


Marcus
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Re: More rocket fun

Post by guitarmike2107 »

the outer ring of the input jack touches the chassis and grounds the guitar directly to the chassis, since this layout only uses 1 connection to the chassis it should not be a problem, unless you have grounded the circuit elsewhere.

you can try a dirty fix by just unscrewing the input jack and disconnecting it from the chassis, floating in the air , just make sure it is supported and does not touch anything with high voltage... or any voltage.

Where there is no DC voltage in the signal chain you can normally ground that point, so the input grid for the first stage, the middle lug if the volume control, the middle lug of the treble control etc

is the amp quiet with nothing plugged in? or is there still some noise, the only noise injector I found was a little bit of heater hum to the input to the phase invertor, once I moved the wire 2mm away from the heater wire it was gone.
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Re: More rocket fun

Post by guitarmike2107 »

That video is a bit bright, so will hopefully get some more done, is it bad that I am starting to think 30w is not very loud....
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Littlewyan
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Re: More rocket fun

Post by Littlewyan »

The video is a bit bright, but definitely not unpleasant. I quite like a bright tone.

You don't think 30W into some Cream Alnicos is very loud? I hope you're wearing ear plugs when you say that! My Express into my old Eminence GB128s was near unbearable without an attenuator and they're pretty much the same sensitivity as your Cream Alnicos!
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