Building a Rocket - Layout Check for group build

dansamp · Post by **dansamp** » Sat May 24, 2008 5:47 am

received my Rocket care package today

haven't had time to go through it yet (have several customer's amps on the bench)
but I did open the package and took a peek inside
can't wait to get started

thanks for all your efforts Bob.

Dan.......

angelodp · Post by **angelodp** » Sun May 25, 2008 5:58 am

I have also received my package and the craftsmanship is superb. Looking forward to the component purchase and build. Many many thanks to Bob and the members of this group, and outside advisors for the great rolling dialogue on getting this amp sorted out. As a very new builder I am learning with every post.

best ange

Fischerman · Post by **Fischerman** » Sun May 25, 2008 6:48 pm

Here's a couple of mid-build pix before I install the speaker jacks so you can see the power tube wiring. I'm new to EL84s and there's probably a bazillion different ways to do the power tubes but I did mine like shown. The cathode reistor wire and PT heater wires will connect to the far right tube. The two grid wires will connect to the two right lugs on the two terminal strips and the screen supply will connect to the left lug on the right terminal strip (the yellow wire on the other side connects the two left lugs). Then the OT primary wires will connect to the two center tubes (probably) and those two yellow jumpers connect the plates. The boards are my own layout but the circuit is pretty much per schematic, two of the bigger changes I made to the original shematic are shown here...470ohm screen grid resistors and 5.6k grid stoppers. Getting there!
[img:800:600]http://i108.photobucket.com/albums/n4/m ... mpKit1.jpg[/img]
[img:800:600]http://i108.photobucket.com/albums/n4/m ... Wiring.jpg[/img]

angelodp · Post by **angelodp** » Sun May 25, 2008 8:00 pm

Fisch, you will be firing up that baby in no time.... are you going to go for the half power set-up.

best ange

Fischerman · Post by **Fischerman** » Sun May 25, 2008 8:05 pm

No half-power or any other tricks. Everytime I try half-power I always like full-power better and the slight reduction in volume is never worth it. But I've never done it in an amp like this (i.e. cathode-bias, no NFB, etc.).

Ron Worley · Post by **Ron Worley** » Sun May 25, 2008 9:11 pm

Fischerman wrote: I'm new to EL84s and there's probably a bazillion different ways to do the power tubes but I did mine like shown. [/img]

Here are a couple of Liverpool shots that show how the EL-84s heaters were wired by KF... Same convention should hold on a Rocket I would presume...

Ron

Fischerman · Post by **Fischerman** » Sun May 25, 2008 9:56 pm

Thanks Ron, I've seen those. I wonder why he looped the heater wires around the power tubes towards the front? When I was planning my layout it seemed that since the heater pins are 4 and 5 that looping towards the back was easier so I did it that way.

Blindog · Post by **Blindog** » Mon May 26, 2008 12:22 am

Looking good Fischerman! What brand of 'lytics are you using?

Thanks!

Mark

RJ Guitars · Post by **RJ Guitars** » Mon May 26, 2008 5:11 pm

angelodp wrote:Fisch, you will be firing up that baby in no time.... are you going to go for the half power set-up...

I put together a drawing for the half power option. There have been some good AmpGarage posts on half power, particularly for the Liverpool. I'll make an effort to read up on these old posts. There is some good discussion on "if or how" it changes the amp sound as well as the technical "how to do it" stuff.

In the meantime would you guys mind taking a look and see if you think I have the half-power technology correct in my drawing...

thanks,

rj

RJ Guitars · Post by **RJ Guitars** » Mon May 26, 2008 5:17 pm

Hey Guys, glad the chassis sets are arriving and you are moving on with the builds... I'll be struggling to keep up with you all.

Here is my fist take using the power supply board that I sent out with the packages...

I'll implement the half power option using the scheme I've shown in the previous post.... unless it's totally wrong.

rj

angelodp · Post by **angelodp** » Mon May 26, 2008 10:15 pm

Bob, I am interested in the half power option. Does the BOM include what we would need for this. Where does this switch live ... front or rear?

best Ange

RJ Guitars · Post by **RJ Guitars** » Tue May 27, 2008 12:27 am

angelodp wrote:... I am interested in the half power option. Does the BOM include what we would need for this. Where does this switch live ... front or rear? best Ange

The two resistors and caps you see on my board are those two resistors and caps in the schematic above. In the BOM that I put together those are the alternative values for resistor 27 and capacitor 13.

The switch -- I plan to put it on the back panel. I do not think it is something that I'll recommend switching while the amp is hot so you don't need it handy on the front. It can go anywhere on that back panel. Of course I'd keep the wires as short as is reasonable and not run it way over to the other side... but I'm sure nobody would do that anyway. It is not on my existing BOM (good catch)... it will be soon. I think any SPST toggle will work and in fact you can use the very same one that is on the BOM for the power and standby switches.

I can make copies of the BOM available again upon request... or if I get a few requests I'll just repost it. I think Ron also has a pretty complete BOM but I don't know if his number correspond to the numbering I added to the Matt Taylor schematic.

I'll try to add a link to that schematic... https://tubeamparchive.com/viewtopic.ph ... c&start=75

rj

RJ Guitars · Post by **RJ Guitars** » Tue May 27, 2008 12:45 am

Hey guys,

I'm hearing bits and pieces about PEC pots... what are they?

I am curious if they have a longer threaded shank than the Alphas. As it is the Alphas are marginal to supply enough thread through the chassis and faceplate. I know I could counterbore the faceplate but I was wondering about the whole story on the PEC pots.

rj

fishy · Post by **fishy** » Tue May 27, 2008 3:59 am

RJ,
The PECs and Clarostats I have seen do have longer threads.
Its also worth noting that the depth of the pot is greater which is a consideration for the ground buss. If you have the ground lugs Ron was selling, it might not be such an issue. The ones I have make it difficult to run the ground behind the pots - its a real squeeze. PECs are not as deep as the clarostats though. Some people prefer the feel of the PEC over the clarostat too and I think the PECs run cheaper...

Frys electronics has some PEC pots, lonly a few linear values though.

gregarious · Post by **gregarious** » Tue May 27, 2008 9:00 am

I noticed that David Allen is now selling PEC's in 1 meg & 250k audio taper, and 100k linear for $12 each which beats Triode Electronics @13.95. Triode doesn't specify the taper.

Allen has a minimum $50 per order.

Tube Amp Archive

Building a Rocket - Layout Check for group build

Re: Building a Rocket - Layout Check for group build

Chassis received

Re: Building a Rocket - Layout Check for group build

Cool

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Re: Building a Rocket - Layout Check for group build

Half Power in the Rocket - How to do it

Rocket - Power Supply Board in the early stages

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Pec Pots - What are they?

Re: Pec Pots - What are they?

PEC pots