Marshall Code - 100 / How to convert it to make it usable with an external head?

[John_Bub]

Hi,

I trust you are well and thank you for taking the time to read this.

I am a newbie here so I hope this post is appropriate in this section.

I just bought a secondhand code 100 for about 100USD and I would like to :
1. use it on its own;
2. use it with a positive grid bias head (I could plug it via the line out but I would fancy using the powered output as I recall it changed the sound).

Is that possible (if yes - how to or where to find the information)? Could they run simultaneously (like a double chain)?

Subsidiary (stupid) question: the code 100 has an 8-ohm output "loudspeaker" - I guess there is no way to "reverse" it and make it an 8 ohm input?

Second subsidiary question: I read that the code 100 speakers are not great. What would you recommend instead (I would rather go with something I might find secondhand - which is the way I buy my music gear ).

Thanks again and best regards!

John

 

[fitz]

I just bought a secondhand code 100 for about 100USD and I would like to :
1. use it on its own;
2. use it with a positive grid bias head (I could plug it via the line out but I would fancy using the powered output as I recall it changed the sound).

Is that possible? Could they run simultaneously?

Subsidiary (stupid) question: the code 100 has an 8-ohm output "loudspeaker" - I guess there is no way to "reverse" it and make it an 8 ohm input?

to the forum.
If by simultaneously you mean both amps through the CODE speakers at the same time - no, don't send two powered amp signals to one speaker cab, but you could use the MP3 input from a headphone out from the PG Bias.

I'd leave the existing speaker out jack alone; CODE amps aren't exactly wired like a normal amp - they look more like a calculator on the inside...
But it should be fairly easy to add a switching jack to the speaker leads that isolates the speakers from the amp when an external amp speaker cable is inserted.

Second subsidiary question: I read that the code 100 speakers are not great. What would you recommend instead (I would rather go with something I might find secondhand - which is the way I buy my music gear ).

Yes, the CODE speakers suck.
FRFR (full range flat response) speakers would be useful if you plan to use the speaker emulations in the CODE or PG Bias, but any guitar speakers would work if you just want that speaker voicing.
Make sure replacement speakers have combined power handling for a 100w amp (or more) and will match the 8 ohm impedance (2x 4 ohm in series, or 2x 16 ohm parallel).

 

[John_Bub]

Hi Fitz,

Thanks for the (super fast) answer!

So, if I understand correctly:
1. it would be possible to add a speaker cable's jack (I have no clue how to name it) to the Code to connect the BIAS Head to the Code - used as a cabinet;
2. it is also possible to change the speakers.
3. there is no way to use the "loudspeaker" output as an input nor to power a speaker cab with to amp powered.

So - I am super happy learning those things are possible. But... how can I do that? Do you know about a guide or videos I could follow - and also things not to do?

Same for the speakers, would you recommend something? I have no clue about speaker quality except that PG makes Celestion's IRs as a paid add-on so I assume it is a good brand xD

Thanks again for your kind help and sorry for not being as fast as you in replying.

Best regards,

John

 

[fitz]

Hi Fitz,

Thanks for the (super fast) answer!

So, if I understand correctly:
1. it would be possible to add a speaker cable's jack (I have no clue how to name it) to the Code to connect the BIAS Head to the Code - used as a cabinet;
2. it is also possible to change the speakers.
3. there is no way to use the "loudspeaker" output as an input nor to power a speaker cab with to amp powered.

So - I am super happy learning those things are possible. But... how can I do that? Do you know about a guide or videos I could follow - and also things not to do?

Same for the speakers, would you recommend something? I have no clue about speaker quality except that PG makes Celestion's IRs as a paid add-on so I assume it is a good brand xD

Thanks again for your kind help and sorry for not being as fast as you in replying.

Best regards,

John

Hi John,
I've had at least one of every Code amp except the 100w 212 combo.
These amps are very different internally than a typical solid-state or tube amp.
When I had my 100H & 212 cab, I tried running my PG Spark40 headphone out into the Code instrument input with an adapter cable.
I also used this set-up with my Spark into a Code25 modded into a mini-stack.
With the Code set on no amp / no cab sim, it worked fairly well.

The answer to your points 1 & 3 are intertwined.
The existing speaker output jack on the Code is for an external speaker cab.
(not sure if it disconnects the internal speakers when used)
It's integrated into one of the computer-like circuit boards in the amp.
Trying to repurpose it for a speaker cab input would be more work than just adding another jack for that purpose.

If you are going to the expense of replacing speakers, and modifying the Code to use it as a cab for the PG, why not just get another speaker cab for the PG?
Probably won't cost much different and would be much less of a project.
Not sure where you are on the planet, but lots of gear retailers sell cabs that are hardly more than the cost of just the speakers alone.
You could also check the local used market for a deal on a cab for the PG Bias.

 

[John_Bub]

Thanks again for your reply!

Ok, so probably I will drop the idea and just use a normal line out on the BIAS and connect via the FX Loop.

Just a question - as now I have a bit more time to try the Code 100.
When I turn on the volume on certain presets I have a kind of vibration like something is not properly screwed in it. I enclosed an audio for example:

Is that correct or could it come from something else?

If it is something unscrewed, can I just open the back of the amp and tighten the screws? Do I have to be careful of something (I never did this)?

Thanks again for your kind help !

 

[fitz]

Thanks again for your reply!

Ok, so probably I will drop the idea and just use a normal line out on the BIAS and connect via the FX Loop.

Just a question - as now I have a bit more time to try the Code 100.
When I turn on the volume on certain presets I have a kind of vibration like something is not properly screwed in it. I enclosed an audio for example:

Is that correct or could it come from something else?

If it is something unscrewed, can I just open the back of the amp and tighten the screws? Do I have to be careful of something (I never did this)?

Thanks again for your kind help !

Open it up and have a look around.
IIRC, the screws are star drive (Torx) and not a Phillips head.

There's not much in there but the speakers and some computer-like circuit boards.
I've seen picks of the transformer / main power board coming loose.
That vibration may also be a loose speaker, or just the junk speakers to begin with.

 

[John_Bub]

Thanks again for your help !

Sorry for not following up fast enough on this (not so much time lately).

I have a few more questions:

- is there any risk when opening it? It is written that there might be electric shock - any recommendation on how to open it ?

- I tried the fx loop and I have a hum/cracking sound when I use the sent/return. I don’t have this sound when I directly plug into the return (so the chain goes - bias head - pedal - boss rc600 - code 100). Doesn’t it mean that the jacks might be dirty and could I use some contact cleaner to clean them ?

- do you know if the return of the fx loop is stereo ? If no, could the mp3 mini jack input be?

Thanks again if you have the time to read this.

I wish you a very nice day!

Cheers,

John

 

[fitz]

- is there any risk when opening it? It is written that there might be electric shock - any recommendation on how to open it ?

Opening the CODE is not as much of a risk as a tube amp.
There are some little capacitors in there, but if you're just looking for loose parts that may be causing the vibration, looking won't hurt you.
Open it by removing the screws around the back panel.

- I tried the fx loop and I have a hum/cracking sound when I use the sent/return. I don’t have this sound when I directly plug into the return (so the chain goes - bias head - pedal - boss rc600 - code 100). Doesn’t it mean that the jacks might be dirty and could I use some contact cleaner to clean them ?

Dirty loop jacks can cause these issues and some Deoxit would not hurt anything - worth a try.

- do you know if the return of the fx loop is stereo ? If no, could the mp3 mini jack input be?

Loop is not stereo, MP3 jack is.