Marshall Silver Jubilee

sinner · Post by **sinner** » 12 Jun 2013, 17:59

Since I have a lot of free time recently and I'm trying to learn as much about valve amps as I can. I decide to jump on tagboard (VOX style) layout for this amp. Mainly because is more advanced than other layouts I did before - Relay switching, odd tonestack, diode network clipping stage... Sounds like fun, large field to learn for noob

But... I am a little girl when it comes to amps... still...

I'm looking on relay and the basic operation is clear to me, but some parts in relay switching schemo tells me nothing

When we look at the schematic made by SMD the relay switching shows few additional components. The first diode coming from heaters transfers - as I understand - AC signal to DC, am I right?

The other diode and two big capacitors do what?

I have lots of questions about this amp, but lets focus on the relay for now

ppluis0 · Post by **ppluis0** » 12 Jun 2013, 22:32

Hi Sinner,

The 470 uF cap after the diode you mention is to smooth the resulting rectified 6,3 volts from the transformer heather secondary.

The remaining diode and the 22 uF condenser connected across the relay coil normally does not conduct but -when the relay is de energized- that couple of components absorb the kickback voltage self induced on the relay coil.

It's an usual solution to avoid noises each time the footswitch is operated.

Cheers,
Jose

rcustoms · Post by **rcustoms** » 13 Jun 2013, 04:55

hi Mr sinner you maybe need this

and this

regards

sinner · Post by **sinner** » 13 Jun 2013, 18:42

Thanks rcustom, I have it already, this is from http://www.drtube.com, am I right

I'm up for my own layout, it's great learning process for me

ppluis0 wrote:Hi Sinner,

The 470 uF cap after the diode you mention is to smooth the resulting rectified 6,3 volts from the transformer heather secondary.

The remaining diode and the 22 uF condenser connected across the relay coil normally does not conduct but -when the relay is de energized- that couple of components absorb the kickback voltage self induced on the relay coil.

It's an usual solution to avoid noises each time the footswitch is operated.

Cheers,
Jose

Oh, thank you

Meanwhile I googled this

http://www.geofex.com/article_folders/r ... _signa.htm

http://electronicsclub.info/relays.htm

Very good read

I just wondering - to switch more than two points of the circuit, let's say 4 points, do I need to get 14pin 4PDT relay or I can simply use two DPDT relays and share (connect together) pins 1 to 1, and 12 to 12?

rcustoms · Post by **rcustoms** » 13 Jun 2013, 18:58

sinner wrote:Thanks rcustom, I have it already, this is from http://www.drtube.com, am I right

I'm up for my own layout, it's great learning process for me

ppluis0 wrote:Hi Sinner,

The 470 uF cap after the diode you mention is to smooth the resulting rectified 6,3 volts from the transformer heather secondary.

The remaining diode and the 22 uF condenser connected across the relay coil normally does not conduct but -when the relay is de energized- that couple of components absorb the kickback voltage self induced on the relay coil.

It's an usual solution to avoid noises each time the footswitch is operated.

Cheers,
Jose
Oh, thank you Meanwhile I googled this

http://www.geofex.com/article_folders/r ... _signa.htm

http://electronicsclub.info/relays.htm

Very good read

I just wondering - to switch more than two points of the circuit, let's say 4 points, do I need to get 14pin 4PDT relay or I can simply use two DPDT relays and share (connect together) pins 1 to 1, and 12 to 12?

use 2 dpdt, for more ideas see this mod of engl 530
use 3 of then

okgb · Post by **okgb** » 21 Jul 2013, 01:02

Nice thread , thanks !
I had a silver jub before that guy made them unaffordable sold it and always wanted another ,
was looking at the ceiratone , but I discovered the jcm 900 's will make a good platform
the dual reverb has room for the gain & masters , just pull out the preamp board , use the i.c. power for relays
and thanks to the diagram above , I have a plan !

allesz · Post by **allesz** » 23 Jul 2013, 14:40

Hallo Sinner, really nice project here;
I am a ex silver jubilee (combo 1x12) owner, I sold my old mate because it was just too loud for my needs (maybe an el84 version would be a nice idea) and I have a question: why do you want to replicate the crunch and drive channels?
I mean, this amp as one great channel with a good working eq (a strange thing for a marshall, and this is what really make it stand out), but the drive is a little bit outdated (not vintage, but not modern enough), and silicium based; the crunch is not so bad, but it sucks a lot of volume, and it's again a diode clippers affair (I mean, if I have to use diodes for the clipping, I prefer a dirt pedal that I can select and, eventually, change).
Why don't you just make it single channel, without all the bells and whistles?

sinner · Post by **sinner** » 23 Jul 2013, 16:24

allesz wrote: Why don't you just make it single channel, without all the bells and whistles?

Common man, it's nice to learn new things like relay operation and crap, this is why ;]

sinner · Post by **sinner** » 23 Jul 2013, 16:45

Here's the little preview BTW. It's not finished as you see, and the look possibly will be modified as I didn't decided where I want the relay switching - on the tagboard as was done with Cornford amps, or on the piece of stripboard as I see it myself

I think I will go with early JCM800 PA and PS - better filtering, Marshall went with poorer PS in Jubs and later JCM800's as far as I learned

I'm moving slowly as nothing rushes me, plus - before I used to make 5 projects at ones, today - I do 20

I call this disease EE-ADHD

I don't know what you guys think, but to me - that kind of appearance is cool beans

sinner · Post by **sinner** » 24 Jul 2013, 03:35

Alright, enough for today

Just BS, PS, and PA left to do

What you think?

sinner · Post by **sinner** » 25 Jul 2013, 13:00

Common guys, nothing? No input? Lead dress recomendation? When I do it here, publicly - do you really think I do it only for myself?

sinner · Post by **sinner** » 26 Jul 2013, 16:57

Nevermind, lets forget about it.

iq01221 · Post by **iq01221** » 26 Jul 2013, 17:20

Hi, sinner!!
I've just seen this

Look, I'm not a really supporter of 2, 3, 4... channels in a tube amp; 'cause it means more tubes ($$, time to assembly, heaters and workin' current and high voltages, debuggin', and a lot of etc...).
With those 2 power, a phase splitter and 2 preamp tubes, U can split a few components and get a veeeery different amps.
I think, it's an interesting bread-board-like proyect.
I mean, do it first with no relays, no diode clippers and stuff. Than, install diodes, one network by one, and so... Do it one by one, talking 'bout new/experimental fun stuff. Just 'cause U dont wanna debugg'it, right?

Do U have a new schem or some?

Really nice proyect!! I should try with some of these someday

Best regards!!!

sinner · Post by **sinner** » 26 Jul 2013, 17:24

Hi iq01221, I moved my files but later today I'll start new topic at ampgarage.

Schemo will be included

Best regards

sinner · Post by **sinner** » 24 Oct 2014, 10:26

Just to let you know guys I'm half way with replica pcb. Some pictures are on my Facebook page. When done I'll post my files here on fsb

okgb · Post by **okgb** » 24 Oct 2014, 14:25

That's exciting!
I'm waay behind in finishing projects so I never got to my conversion, still have a 900 combo
seems you could pick one up cheaper than buying the full ceriatone kit.

I was also considering building it as a rackmount preamp with a second channel being AFD

sinner · Post by **sinner** » 23 May 2015, 23:01

Two years fast forward

I became quite obsessed with Silver Jubs up to the point where I have something to share

This is not the job done jet, I still have a lot of work to make some final conclusion and put the whole project to bed

Fucking jubs, guess what. There is at least three PCB revisions.

Two are attached below, the third is 90's Slash Signature (based on Silvers as we all know), the SL is indeed different when you look on the board pictures, I had no opportunity to have a look under the skirt to proper exam it myself, so it still remains a mystery.

The boards attached are JM112B (early Jub) and JM112C. Main differences aside from slightly different layout are located in Rhythm clipping network (lack of clipping smoothing cap across the diode network in "B" prefixed board revision), FX Loop (parallel vs series), relay matrix and tonestack. There are some component shifts in coupling cap values too

They may be JM112A board too. That could take us up to (at least) 4 PCB revisions but it also could be that JM112A board never went to production and remained as a proto, pre production board. Well, at least I never seen anything different component location-wise than the two boards attached... And I've seen hundreds of them

On aside note. JM112C board is my trace of the amp I had here for service job, it was 1x12 combo. Apart of the board itself, the amp had differences in PS. It uses resistor in place of choke

Forgive me the lack of proper schematics, they're in works

If we have here any Jilver/Black Jubilee or 90's Slash Sig owners - please get in touch with me. We can complete the amp spec history and I will finally have some sleep

DrNomis · Post by **DrNomis** » 25 May 2015, 23:44

sinner wrote:Alright, enough for today

Just BS, PS, and PA left to do

What you think?

Looks pretty cool so far, you could try pm-ing blackbunny about that channel-switching with relays since he does a lot of amp-tech work, he built himself a valve guitar amp with two different preamps in it, one was a Mesa/Boogie channel and the other was a Marshall channel, he even used Marshall style knobs for the Marshall Channel and Mesa/Boogie knobs for the other channel, I've played through the amp and it does sound great....

sinner · Post by **sinner** » 26 May 2015, 00:14

Mate. My relay related question was asked 2 years ago. I have managed to understand that well since that time

DrNomis · Post by **DrNomis** » 26 May 2015, 00:27

sinner wrote:Mate. My relay related question was asked 2 years ago. I have managed to understand that well since that time

Doh!!!......

See....I'm still a noob, aren't I?.....my bad, I should have read the posts more carefully, serves myself right for not having my morning coffee to wake myself up.....

.....