• From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Topic: New 2550 build

Hello Rick and Bluesbreaker!

This is a new spin off thread dealing with converting a Marshall 2205 (actually a 4212 combo) to a 2550 which relatively easy and due to the same transformers and appropriate controls is a killer conversion.  Especially if you consider there are two free tubes and 3 controls left on the original clean channel to play with - maybe a 3-way switchable 2203 or 1987 preamp with the 2550!  I just fired mine up a couple of days ago and did the final ready-for-stage clean up yesterday.

Bluesbreaker wrote:

Sounds interesting. How does your 2550 sound? I have to wait for at least 4 weeks, so tell me more. Should be pretty close to the original Silver Jub, is it? What speakers do you use? Perhaps stuff for a new thread?

It is probably about as close to a real 2550 as you can get.  I have no problem getting the core tone from Joe's albums and I love the wide range of the tone stack compared to standard design in my Marshalls and SLOs.  The clean mode is surprisingly good and the distortion mode really sounds good with a Strat which my SLO has a bit of trouble doing.  I haven't dug out my Les Paul and Jackson Charvel yet.

The speakers are original 12T-75s but I have an assortment of Celestions including some prototype V30s I got at a NAMM show, original 12H30s, and an 80 watter (my other guitarist put a screwdriver through one of my pair of 80s and threw it away so I wouldn't find out...  mad).  I'll try those when I get a chance plus I want to experiment some with an EQ in the effects loop.  Talk about a secret weapon on a 2550... hehe.  I had a bandmate that I worked with on his tone and with a 1/3rd octave EQ in the loop and about a month of subtle tweaking we ended up with the best "Marshall" tone I've heard live.  The Reverend Billy G. does the same thing and we know how he sounds  cool .

On a technical note, I have an output transformer made by an out of business company called OEI.  What a freaking unbelievable piece of iron!  To quote my friend Hogy of Komet Amps up the road in Baton Rouge "To the original poster, the OEI is better, but hard to get. Hogy". 

I have three and you can't have one  smile

I know lightning might strike me but from a tech/engineering viewpoint, the 2550 design is such that they can use really cheap 100v axial ceramic and multilayer ceramic capacitors in parts of the circuit where more expensive film capacitors are traditionally used.  http://www.amparchives.com/album/Marsha … ee049.html  Maybe it is the secret mojo to the sound so I always try to duplicate the original as close as possible and make changes only after the honeymoon wears off and mostly did so in this case.  I do find in a combo amp with this transformer that I can increase the phase inverter caps from .022uF to .047uF polypro and get some extra bass without flab.  Also, I used the Plexi style Presence control design just because I like it and didn't feel like changing it.  I think the Ceriatone 2550 does the same plus he substitutes film capacitors for most of the ceramics.  They look like excellent designs to me.

..Joe L

J0E L's Website

  • Registered: 2009-01-01
  • Posts: 665

Re: New 2550 build

Well, let me revive this thread before it dies a quiet death.

While I'm waiting for my amp, here's some dumb questions. I never played a Jubilee (clone nor original), so please be gentle with me.
I guess the rhythm clip switch engages the notorious diode clipping, right? To disengage the diode clipping does the toggle switch have to be down or up?
Is it true that Joe (i.e. Joe B.) uses the boost channel but no diode clipping -- that's why I ask. Is there still enough gain/OD on tap with the boost channel but without diode clipping?
Joe L, I suppose that's you on the ceriatoneforum http://ceriatoneforum.com/index.php?topic=1336.0 Tell me more about this ceramic vs. film capacitors business. Does it really make that much of a tonal difference? If yes, why wouldn't Nik use ceramic caps?

  • Registered: 2008-10-02
  • Posts: 373

Re: New 2550 build

I have a Jub 2553, I think the Marshall Amp Forum would be the best place to anscwer your question. But I think the diodeds are not used with the clean channel, and are added when you 1. Use the rythem clip or 2. use the lead channel, both are push pull knobs. Now from what I read the more volume you use will smooth out the diodes.

Couple other things a lot of people don't like the rythem clip sound, I think it sounds cool with a strat, but its not footswitchable which makes it useless. The other knock on the Jub is not having a master volume for the clean channel makes it next to impossiable to use as a channel swiching amp. There is a mod to add an extra volume and to make the clip foot switchable if your building this thing I would add those two features. Also on mine when the clip is on and I use the OD channel I notice it thins the sound out a bit, not sure why.

Can you share that EQ settings I have been experamenting with an EQ for awhile now.

  • Registered: 2009-01-01
  • Posts: 665

Re: New 2550 build

Big E wrote:

I think the diodeds are not used with the clean channel, and are added when you 1. Use the rythem clip or 2. use the lead channel, both are push pull knobs. Now from what I read the more volume you use will smooth out the diodes.

The Ceriatone has small toggle switches instead of the push-pull knobs. That's cool. Is it possible to use the lead channel without the diodes or are the always on when switching to the lead channel?

Big E wrote:

Couple other things a lot of people don't like the rythem clip sound, I think it sounds cool with a strat, but its not footswitchable which makes it useless.

The Ceriatone has a footswitch for that. Again, pretty cool but...

Big E wrote:

The other knock on the Jub is not having a master volume for the clean channel makes it next to impossiable to use as a channel swiching amp. There is a mod to add an extra volume and to make the clip foot switchable if your building this thing I would add those two features.

... I won't need that because I intend to use the amp as a one-trick pony. I had the same problem with my Ceriatone OTS, i.e. quite a big volume jump between clean and OD channel. I finally gave up and only use the OD channel. No problem at all because the amount of OD can be controlled wonderfully with the guitar volume.

Somebody tell me about the kind of gain/OD the 2550 has (with and without diode clipping on the lead channel, if the latter is possible). Enough? I hope I won't need a pedal except to boost solos.

  • Registered: 2008-10-02
  • Posts: 373

Re: New 2550 build

The diodes are always on with the lead channel and there is no way to turn them off. As I remember someone on the Marshall Forum removed the diodes from his and said there wasn't much gain without it and he quickly put it back together.

As for Gain on tap it depends on the music you playing, blues/blues rock and classic rock you have more than enough, older metal and 80's hair band stuff your good. New metal high gain stuff you will need something to push it a little more. I run my gain around 5 I think anything over 8 it tends to not sound very good. The EQ on the Jub is really really effective one of the best I have ever seen on a marshall you can get a lot of tone just by turning the knobs.

  • From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Re: New 2550 build

Bluesbreaker wrote:

I guess the rhythm clip switch engages the notorious diode clipping, right? To disengage the diode clipping does the toggle switch have to be down or up?

In the UP position, the rhythm clip is a single set of diodes that clip in a way that generates more odd harmonics than the lead clipping and as such will tend to sound harsher.  The gain is also higher with the clip on.  However, the capacitor that bleeds off the harsh harmonics on the diodes is twice the value on the clean clip as opposed to the lead clip to help compensate for this.  I do like the effect with my Strat.

Bluesbreaker wrote:

Is it true that Joe (i.e. Joe B.) uses the boost channel but no diode clipping -- that's why I ask. Is there still enough gain/OD on tap with the boost channel but without diode clipping?

I can hear the clipping on Joe's tone in high gain mode.  It's in there.

Bluesbreaker wrote:

Joe L, I suppose that's you on the ceriatoneforum http://ceriatoneforum.com/index.php?topic=1336.0 Tell me more about this ceramic vs. film capacitors business. Does it really make that much of a tonal difference? If yes, why wouldn't Nik use ceramic caps?

Ah, that is the question...  First off, Nik does use some ceramic caps and I'm sure he did some research or his considerable experience before releasing his version.  But I'm a cajun and we all have our own recipes for taste and tone and just like a new gumbo recipe, the first time I'll cook it exactly as it is written.  The next time I will make adjustments from my own experience and taste to see if it is better.

I have looked at every cap on the board and can't say that I disagree with Nik's choices but I believe the original has as many ceramic caps as it does just to save a few bucks on the bottom line.

On mine, C2, C14 and C25 are not ceramic and I don't think they should be.  C26,C9 and C10 are in the tone stack and are subject to debate but so far I like the ceramics.  Every where else they are used is cool with me and if I was just following a schematic building one from scratch, I would use ceramics. 

Now what complicates things is that research (google "sound of capacitors") shows that lower voltage ceramics are not as linear than higher voltage ones.  I used 500v to 1000v disc ceramics where the original, from the best I have been able to determine, uses 100v axial ceramics. 

But that may be the final 2% mojo that makes the 2550 what it is because we are making instruments and anything goes if it doesn't smoke.  Tubes, speakers, cabinets, pickups, your fingers are going to make a much bigger difference.

But you know what, even though I like to analyze these things to death for fun, the chick with the big ones in the front row could care less. lol

..Joe L

J0E L's Website

  • From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Re: New 2550 build

Big E wrote:

I run my gain around 5 I think anything over 8 it tends to not sound very good. The EQ on the Jub is really really effective one of the best I have ever seen on a marshall you can get a lot of tone just by turning the knobs.

Isn't that a killer EQ stack!!!  I love it and agree totally with you.  I am tempted to try it in one of my SLO builds before I rip it apart. 

A Bassman with an SLO shoehorned in it.

http://webpages.charter.net/jlemoine/BassmanSLO.jpg

This weekend I am going to put my SLO and X88R clones into the 2550 effects loop to get an idea of how it sounds.

..Joe L

J0E L's Website

  • Registered: 2008-10-02
  • Posts: 373

Re: New 2550 build

I have a 68 Bassman and I have thought of having the Bass side moded to be more of a marshall sound. Hummm...

  • From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Re: New 2550 build

Big E wrote:

I have a 68 Bassman and I have thought of having the Bass side moded to be more of a marshall sound. Hummm...

Just try not to drill on the front panel.   As you can see, my SLObassman uses the input jack holes for the extra controls.   I do have a SF bassman that I drilled an extra hole on the front that I built my Mesa Mark III clone in and I regret it. 

..Joe L

J0E L's Website

  • Registered: 2009-01-01
  • Posts: 665

Re: New 2550 build

J0E L wrote:

But you know what, even though I like to analyze these things to death for fun, the chick with the big ones in the front row could care less. lol

..Joe L

lol  lol  And that's what counts in the end, doesn't it?

Great info on those caps, though. I'll wait for my 2550 to arrive and then play it to the ground for a couple of days/weeks. See how it sounds stock first.

  • From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Re: New 2550 build

Bluesbreaker wrote:

Great info on those caps, though. I'll wait for my 2550 to arrive and then play it to the ground for a couple of days/weeks. See how it sounds stock first.

It is pretty obvious from those scope traces that 100v ceramics are not going to sound like 1000v/500v ceramics that I used or the Mallory 150s that Nik uses.  But believe me, Nik wasn't trying to save money because ceramic caps are pennys a piece compared to Mallorys.

Also, the reliability between the two designs isn't even close.  My 4212 is like a 2550 in that the pots and input jack are soldered directly to the circuit board and there is no other support for it.  Solder is NOT intended to be load bearing and the input jack and one of my pots became intermittent because of this.

But you have the right idea.  Forget about what is inside and use your ears and fingers to find what sounds are available from the amp.  The design is true to the original and the tone stack is very wide in range so you will be able to dial in some great tones.

"Play it like you stole it!"

..Joe L

J0E L's Website

  • From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Re: New 2550 build

Big E wrote:

Couple other things a lot of people don't like the rythem clip sound, I think it sounds cool with a strat, but its not footswitchable which makes it useless. The other knock on the Jub is not having a master volume for the clean channel makes it next to impossiable to use as a channel swiching amp. There is a mod to add an extra volume and to make the clip foot switchable if your building this thing I would add those two features.

I can easily use the DI output jack for a clean clip footswitch and the 4212 front panel has a Reverb knob right next to the Master volume so a switchable master is a piece of cake.  That's what is so cool about the 2205 to 2550 conversion.  If you can DIY and are not concerned about looks it is a no brainer.

Big E wrote:

Also on mine when the clip is on and I use the OD channel I notice it thins the sound out a bit, not sure why.

That is easy if you understand that massive circuit driving V2A.  There is a lot going on there and it is impossible for there not to be plenty of interaction between modes.  If you turn on the clean clip in Lead mode you are grounding R9 (47KΩ) which bleeds off gain going to the input of the third gain stage.  You are doing almost the same thing if you turn off the Lead Master in Clean/Clip mode which puts one side of R11 (47KΩ) to ground.

All of this could be solved with extra controls and switching but as I have said, IMHO that board is made as cheaply as possible.  I bet the engineers and accountants had a cage fight and the accountants won.

Big E wrote:

Can you share that EQ settings I have been experamenting with an EQ for awhile now.

It's been 24 years and the only info I have is that it was a 1/3rd octave DOD in the effects loop and I have a HiFi vcr audio recording of a gig somewhere in the house here.  I haven't seen the guy in 20 years and tried to locate him without success.

Sorry for such long responses.  I do tend to ramble on.

..Joe L

J0E L's Website

  • From: Detroit
  • Registered: 2006-06-02
  • Posts: 5,807

Re: New 2550 build

If I don't plan on using the effects loop, is this still one of the better choices out there for amp heads?

- Nic from Detroit... posting on JB's Forum since 6-2-2006
Ask me about my handwound Great Lakes Guitar Pickups
Since 2010, Bonamassa fans have taken advantage of my JB friend discount = my cost + shipping. cool
  • From: North of Lake Pontchatrain
  • Registered: 2010-09-04
  • Posts: 12

Re: New 2550 build

Big E wrote:

The other knock on the Jub is not having a master volume for the clean channel makes it next to impossiable to use as a channel swiching amp. There is a mod to add an extra volume

Well, let me ask an obvious question.  Why do you need the Output Master in Lead mode since the main problem is the Clean volume is too loud?  Why can't it be switched out in Lead mode and we'll all agree to call it a Clean Master.

Before

http://webpages.charter.net/jlemoine/2550%20Master.jpg

After

http://webpages.charter.net/jlemoine/25 … Master.jpg

No extra control needed.  cool

..Joe L

J0E L's Website

  • Registered: 2009-01-01
  • Posts: 665

Re: New 2550 build

So my 2550 has arrived. I've test-driven it briefly and first impression is good. Tons of OD, so no need for pedal. I tried some settings that people have suggested and so far have settled on
Presence 4
Bass 8
Middle 7
Treble 4.5
Output master 8
Lead Master 2
Input gain 4.5

I biased it at about 35mV. What I noticed was the amp is rather bright, in fact too bright for my taste. There also seems a bit of a fizz or harshness with the guitar volume full up (I wonder if it's the diodes?). I have the guitar's tone controls down at 4-5 (bridge) and 8 (neck). I'm a bit surprised because I expected the amp to be smoother and certainly darker. Will that change, once it's properly burned in? I'd definitely like the amp to be darker (which should make it smoother too). Any tips?

  • Registered: 2008-10-27
  • Posts: 176

Re: New 2550 build

Bluesbreaker wrote:

So my 2550 has arrived. I've test-driven it briefly and first impression is good. Tons of OD, so no need for pedal. I tried some settings that people have suggested and so far have settled on
Presence 4
Bass 8
Middle 7
Treble 4.5
Output master 8
Lead Master 2
Input gain 4.5

I biased it at about 35mV. What I noticed was the amp is rather bright, in fact too bright for my taste. There also seems a bit of a fizz or harshness with the guitar volume full up (I wonder if it's the diodes?). I have the guitar's tone controls down at 4-5 (bridge) and 8 (neck). I'm a bit surprised because I expected the amp to be smoother and certainly darker. Will that change, once it's properly burned in? I'd definitely like the amp to be darker (which should make it smoother too). Any tips?

Yes it will change. Some components need about 100 hours of burning in to be running at their full potential. Most of the components only need about 20 hours though... A new amp is always stiffer! Stick with your amp and don't change a single thing until it's really burned in!  wink And check your bias after a few hours of playing because it may drift as tubes and new components burn in...

  • Registered: 2008-03-07
  • Posts: 508

Re: New 2550 build

twistingcrow wrote:
Bluesbreaker wrote:

So my 2550 has arrived. I've test-driven it briefly and first impression is good. Tons of OD, so no need for pedal. I tried some settings that people have suggested and so far have settled on
Presence 4
Bass 8
Middle 7
Treble 4.5
Output master 8
Lead Master 2
Input gain 4.5

I biased it at about 35mV. What I noticed was the amp is rather bright, in fact too bright for my taste. There also seems a bit of a fizz or harshness with the guitar volume full up (I wonder if it's the diodes?). I have the guitar's tone controls down at 4-5 (bridge) and 8 (neck). I'm a bit surprised because I expected the amp to be smoother and certainly darker. Will that change, once it's properly burned in? I'd definitely like the amp to be darker (which should make it smoother too). Any tips?

Yes it will change. Some components need about 100 hours of burning in to be running at their full potential. Most of the components only need about 20 hours though... A new amp is always stiffer! Stick with your amp and don't change a single thing until it's really burned in!  wink And check your bias after a few hours of playing because it may drift as tubes and new components burn in...

what speaker are you using ? do not waste time and get an evm12l ...... green back will do at a push but honestly you are wasting your time with any other speaker  . and yes burn in will smooth out a littlle but the jubilee is a jcm800 with a built in fuzz box IMHO  it needs cranked to smooth out ,but with a EVM12L you will get good tones low volume    yikes

"Everybody's entitled to my opinion. wink
  • Registered: 2009-01-01
  • Posts: 665

Re: New 2550 build

twistingcrow wrote:

Yes it will change. Some components need about 100 hours of burning in to be running at their full potential. Most of the components only need about 20 hours though... A new amp is always stiffer! Stick with your amp and don't change a single thing until it's really burned in!  wink And check your bias after a few hours of playing because it may drift as tubes and new components burn in...

I've had it on all afternoon without no guitar plugged in but both volumes cranked while I was at work. I'm planning to do this every day now and see how it sounds at the weekend.
I'll check the bias every evening, as well. What is the recommended value? I have it at about 35mv at the moment. Is this too hot?