2xel84 rocket

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

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KT66
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Re: 2xel84 rocket

Post by KT66 »

To anybody who downloaded my 2XEL84 Rocket Reverb layout on this page of this thread : http://ampgarage.com/forum/viewtopic.ph ... c&start=90

There was a mistake in the connection of the reverb recovery stage's coupling capacitor which I fixed and have uploaded an updated version that is basically exactly as I built it and it works fine. Sorry for any inconvenience this has caused anyone.
Ryan

Music is the best. F.Z.

http://Classictubeamps.com
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M Fowler
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Re: 2xel84 rocket

Post by M Fowler »

I downloaded it Ryan :lol:

Thanks for updating the info for everyone.

Mark
telentubes
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Re: 2xel84 rocket

Post by telentubes »

If anyone is interested, I got an Edcor XPWR156-120/125 power transformer, and an Edcor GXPP15-8-5K output transformer for my 2XEL84 Rocket, which is still just a pile of parts. I don't know how theses transformers will work out but the numbers look good.
mbailey
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2xel84 rocket screen grid wiring

Post by mbailey »

In kt66's dwg of Mfowlers 2xel84 amp is the screen grid wiring correct? it doesn't look like it makes any sense and doesn't match Mfowlers chassis pics?
I am not picking on this i'm just in the middle of building this and trying to get it right? thanks
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KT66
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Re: 2xel84 rocket screen grid wiring

Post by KT66 »

mbailey wrote:In kt66's dwg of Mfowlers 2xel84 amp is the screen grid wiring correct? it doesn't look like it makes any sense and doesn't match Mfowlers chassis pics?
I am not picking on this i'm just in the middle of building this and trying to get it right? thanks
You are not picking at all, and you are correct - the screen grid wiring does not make any sense, so after I post this I will fix it and post a revision, thanks for catching it. The problem occurred because I originally drew it with 1 1K resistor feeding both screens which were connected with a green wire ( as the pics of Mark's amp clearly shows ) but in my correspondence with him about the amp, he told me that he changed it so that there were 2 1K resistors, 1 for each screen, so I changed it on my layout but forgot to remove the green wire connecting the screens. I also should have noted that originally also because it makes the layout not match the gut shots exactly.
Ryan

Music is the best. F.Z.

http://Classictubeamps.com
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bandade
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CLIPS

Post by bandade »

Does anyone have or know were I can find clips of a 2 EL84 rocket?

I have an 18 watt tranny set from an old lite build and would like to put them back into service.

thanks
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M Fowler
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Re: 2xel84 rocket

Post by M Fowler »

One thing about gut shots is the amps usually get changed later on so you can use them as a guide to how the parts are laid out but should not totally rely on the picture alone. The new layout should be accurate now though.

Mark
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Deric
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Re: 2xel84 rocket

Post by Deric »

Just thought I'd post a follow up. Been playing with this off and on for a while. Stumbled on a thread over at ax84.com with an interesting MV idea so thought I'd give it a try. Just a pot in series with the PI cathode resistor. I'm sure I've seen it posted somewhere here (Ampgarage) before... Seems to be what Mojave uses... I recall some saying it didn't work well... I've read of people using anywhere from 50k to 100k. To me, seemed like 25k was plenty. Much more than that started to sound dark and fizzy. 25k was still more of a volume drop than my Airbrake on the lowest setting (not including turning down the "bedroom" control) and sounded just as good...maybe better. Ended up using a 50k pot so I could go lower but doubt I'd ever want to. There is some DC on the pot so it makes a little noise when turned but not much.

Also picked up a drawer kit/cab from Woodcraft. 8)

[IMG:160:120]http://i40.photobucket.com/albums/e243/stumper1/Half%20Power%20Rocket/th_HalfPowerRocket014.jpg[/img]
[IMG:160:120]http://i40.photobucket.com/albums/e243/stumper1/Half%20Power%20Rocket/th_HalfPowerRocket013.jpg[/img]
[IMG:160:120]http://i40.photobucket.com/albums/e243/stumper1/Half%20Power%20Rocket/th_HalfPowerRocket.jpg[/img]
Deric®
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M Fowler
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Re: 2xel84 rocket

Post by M Fowler »

Looks great.

That PI mod is what colossal and I posted awhile ago after looking at an Egnator Rebel 20 Watts Control. 25kL pot controlling the PI acts as a sort of MV. I used it on several of my amps. This circuit (limiter) is also shown on the Carlsboro 60-TC amp.

Mark
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Gee
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Re: 2xel84 rocket

Post by Gee »

How does the 2xEL84 Rocket differ in sound from a Vox AC15 TB channel or Top Hat Club Royale ?

From a circuit point of view they appear very similar - or have I missed something?
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hans-jörg
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Re: 2xel84 rocket

Post by hans-jörg »

M Fowler wrote:Looks great.

That PI mod is what colossal and I posted awhile ago after looking at an Egnator Rebel 20 Watts Control. 25kL pot controlling the PI acts as a sort of MV. I used it on several of my amps. This circuit (limiter) is also shown on the Carlsboro 60-TC amp.

Mark
Hello Mark, hi Dave,
am I right, when I think that those two kinds are a little bit different?. Wich one works better (or no different)?
Is this the "golden egg" for TW kinda amps?
How react the poweramp when you turn down?
Is there a loss of "sparkle" and highs?
Does it go faster to saturation (like with LaMar, o.e. MV. I had this LaMar in but it changes the Amp because of the direction that saturation in TW takes - from the back)?

I´m burning for answeres ...

Best Regards
Hans-Jörg
mark enger
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Re: 2xel84 rocket

Post by mark enger »

Im gonna pull this topic back up as im working on (mfowler layout drawn by kt66), I had a few things im not to sure of on the layout like is there any hum issues with all the filter caps grounded too one point? Im building this one with some vintage iron kind of like a prototype, ive also used a cap can for first filter cap a 32-32 mark
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M Fowler
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Re: 2xel84 rocket

Post by M Fowler »

Hello Mark, hi Dave,
am I right, when I think that those two kinds are a little bit different?. Wich one works better (or no different)?
Is this the "golden egg" for TW kinda amps?
How react the poweramp when you turn down?
Is there a loss of "sparkle" and highs?
Does it go faster to saturation (like with LaMar, o.e. MV. I had this LaMar in but it changes the Amp because of the direction that saturation in TW takes - from the back)?

I´m burning for answeres ...

Best Regards
Hans-Jörg
I didn't realize we left you hanging with questions Hans. Just a plain 18w amp Hans nothing special. I find the TW Rocket darker in tone with some chime from the EL84's and very quiet amp.

Mark, you would be better off separating your grounds I did it this way because I had seen other builders do this without issues and I haven't had issues with grounding problems in past Rocket builds. I do think following the more common practice of separating the grounds is the proper way to go; however.

Mark
mark enger
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Re: 2xel84 rocket

Post by mark enger »

Thanks mark. this one is really just a warm up for when i do a full rocket, i screwed up this chassis when i was drilling it but it will work fine for 2 el84 amp. mark
surfsup
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Re: 2xel84 rocket

Post by surfsup »

am I right, when I think that those two kinds are a little bit different?. Wich one works better (or no different)?

Hans I agree. They are different. One seems to bias the PI into cutoff using the pot in series with the 820R. The other seems to form a voltage divider between the PI balancing resistor and ground.

I was thinking of putting a trimmer on the balancing resistor to allow adjustment from 4k7 to 54k7 (4k7 with 50k trimmer/pot in series) to adjust the headroom on the PI. These are each slightly different and would also appreciate some further comments on how well they work.
Last edited by surfsup on Wed Sep 05, 2012 11:30 pm, edited 1 time in total.
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