Modifying the effects loop to serial

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ErickG
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Modifying the effects loop to serial

Post by ErickG » Sun Apr 04, 2010 7:27 pm

Hi,

This is my first post here. I have been reading up on the DC-5 here since I got mine about a month and a half ago. I really like the DC-5 a lot, as I have been Line 6 Flextone II user for years, the Flextone has served me well, but nothing like having a "real" tube amp, if you know what I mean? :wink: I have always leaned on the Mesa amps on the Flextone, my favorite has been the Dual Rectifier Tremoverb and the Mark IIC+ for clean and other heavy rhythm stuff. The DC-5 has really nice cleans and the lead tone for rhythm and lead is great! Very Mark IV like, from hearing recordings, with the 12AT7 in the Phase Inverter. Learned to make that change from this site as well. Definitely worth it. (I wanted a Mark IV for some time and decided the DC-5 would be a great "compromise", if you want to call it that, as it's really not, since the Mark IV going for twice the DC-5. The DC-5 holds it's own and is great sounding amp.)

Getting an amp with no built in effects required that I get a delay, so I got a new TC Electronics Nova Repeater. I have tried both in front of the amp and in the effects loop. It sounds best in the effects loop with the mix on the effects loop set at 100%, but I would like to try it with the loop modded to serial. Now reading about and having received the effects loop mod from Monsta-Tone. I have some questions about making this change.

Below is an overview of the inside of the chassis:
Image

What I have noticed is that my wires are not the same color that others describe, plus I thought that having some actual photos would be helpful to others that would like to have this mod done.

Here is a zoomed in view of the Send - Return - Mix Pot:
Image

Just to make this post useful, to not only myself, but others that may frequent the site, which wire goes where? (Think I know, but I just being a little overly cautious so as to not mess up my amp. :) )

Plus, can someone explain how the routing of the wires is working? Trying to learn more about what is happening here. The two white wires has me a little confused.

(EDITED POST: Found that the pictures were far too large... Sorry about that! ,Erick)

Thank you,
Erick

espexp
Mark II
Posts: 118
Joined: Tue Nov 14, 2006 8:17 pm

Re: Modifying the effects loop to serial

Post by espexp » Mon Apr 05, 2010 2:55 pm

The white wires are the signal from the preamp. The orange wire is the return signal to the power amp.
1) Remove the white wire from the mix pot and tape it off. It is not needed
2) Take the red wire and move it to the center post of the mix pot, or do what I did and remove the mix pot entirely because it will no longer work anyway, and just solder the brown orange and red wires together.
That's it' your going to be very happy with this mod.

The brown wire is the switch wire on the send jack, so if nothing is plugged in to the send jack you still have signal going to the power amp section

The red wire is the loop return signal

ErickG
Bottle Rocket
Posts: 19
Joined: Sun Feb 28, 2010 8:18 pm

Re: Modifying the effects loop to serial

Post by ErickG » Tue Apr 06, 2010 6:23 pm

Thanks espexp! I really appreciate the help. This is what I thought, but like I indicated in my post, I wanted to make sure. Plus, learn more about what was being done within the effects loop from a technical perspective.

Now hopefully this will make it easy for others to see how to do this mod.

Thanks,
Erick

ErickG
Bottle Rocket
Posts: 19
Joined: Sun Feb 28, 2010 8:18 pm

Re: Modifying the effects loop to serial

Post by ErickG » Sat Apr 10, 2010 9:28 pm

Just did this change a few hours ago and have been enjoying it by experimenting with it. Really does help the delay repeats to come out more clearly. And the my Chorus pedal, Boss Ch-1, sounds much better too.

I did notice that I have to use the effects loop or nothing comes through. Actually, I shouldn't say nothing comes out, but what I got without using the effects loop was a really thin shallow sound. Once I plugged in the cables back into the effects loop everything was fine. So I will need to address this soon so that it works without a "jumper cable" in the loop.

I also noticed the tone of the amp seems more alive. Really nice!

Image

In the photo above... Is the red circle on the send terminals 'switch'? In another post espexp mentions that if the red and the orange wire are attached to the send terminal switch everything will work without have the effects loop hooked.

Any help on this would be greatly appreciated!

Thank you,
Erick
Last edited by ErickG on Tue Apr 13, 2010 12:23 pm, edited 1 time in total.

espexp
Mark II
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Joined: Tue Nov 14, 2006 8:17 pm

Re: Modifying the effects loop to serial

Post by espexp » Sun Apr 11, 2010 7:21 am

Erick, That black wire is the ground for the send jack.
The switch wire is the brown or the red ( I can't see it ) wire that comes from the bottom terminal of the send jack.
If the switch wire is still hooked up on both ends then you probably need a knew switch jack. I put a new one in mine because Monsta, the DC guru, says that while your doing the mod it never hurts to put a new jack in. It's just a mono switch jack that can be gotten from any electronic parts store.
It won't hurt anything if you use it as it is. If you want to use the amp with nothing in the loop just plug a patch cable from send to return and your good to go.

ErickG
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Re: Modifying the effects loop to serial

Post by ErickG » Sun Apr 11, 2010 4:02 pm

Thank you for your help and putting up with my dumb questions. Just thinking there are others out there thinking the same thing and this information will help them as well.

The red wire is from the return jack. I have some photos that I took earlier from another angle and I don't see a brown wire coming from the send jack. So may be my setup doesn't have one? But I think your suggestion is a good one and I will get a new send jack and swap out the old one and reconnect everything. Even though I can use a jumper cable it would be nice to have it function as if it came from the factory this way.

You can see in the photo a bare wire, it's coming from the return jack and is connecting to the center post on the mix pot. Should this be removed? Thinking that this is a switch terminal on the return jack instead of the send and causing the opposite condition for my setup.

Thanks again for the help,
Erick

espexp
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Re: Modifying the effects loop to serial

Post by espexp » Sun Apr 11, 2010 4:16 pm

First of all, there are no dumb questions and I'm happy to help.

Secondly I thought the bare wire was a brown insulated wire. If its not insulated, it probably should be. That is your return signal wire.

ErickG
Bottle Rocket
Posts: 19
Joined: Sun Feb 28, 2010 8:18 pm

Re: Modifying the effects loop to serial

Post by ErickG » Sun Apr 11, 2010 4:51 pm

Image

Here is another angle to view the bare wire from the return jack.

espexp, are you saying that its likely that the send jacks switch function is worn out or just non-functional after all these years? I just did some research view Google for new mono 1/4" switched jacks. There are a lot of different ones out there to choose from. :shock: :)

I will get a new one and redo the connections proceed from there.

Thanks,
Erick

espexp
Mark II
Posts: 118
Joined: Tue Nov 14, 2006 8:17 pm

Re: Modifying the effects loop to serial

Post by espexp » Sun Apr 11, 2010 7:21 pm

You may be able to adjust the switch jack so it will work. When you pull the plug out of the send jack the contacts at the bottom of the jack should connect, sending the signal from the white wire terminal to the switch terminal. Essentially closing the switch. If you take the jack out you will see how it works. Then just adjust the contacts so they touch when nothing is plugged in but don't touch when you plug into the jack.
I hope this makes sense.

Looking closely at your picture I noticed that you have a DC-5A. That send jack is a little different than mine I think. Where does that red wire go after it goes under the send jack?

ErickG
Bottle Rocket
Posts: 19
Joined: Sun Feb 28, 2010 8:18 pm

Re: Modifying the effects loop to serial

Post by ErickG » Sun Apr 11, 2010 9:07 pm

Thanks, I understand your explanation.

The red wire goes to the Return Jack which is on the bottom. I do have DC-5A as you have noticed. And from your's and Monsta-Tone's description of the wiring, I am beginning to think that Mesa wired the send jack differently on the DC-5A than the DC-5B. But, I will look at the send jack again and see if I can determine if the switch part is making contact to complete the circuit when nothing is plugged in. Looking at my last photo again and needing to look at the Send Jack more closely, I am beginning to think the Return Jack has the switched terminal and not the Send Jack, but this doesn't make sense with what you have shown me about how the loop works. Is it possible to use the return jack for the switching capability? Hmm, don't know.

Thanks again for your help. I am learning a lot. It has been quite some time since I have done this kind of electronic type stuff and it's been fun to learn it again.

Thanks,
Erick

espexp
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Joined: Tue Nov 14, 2006 8:17 pm

Re: Modifying the effects loop to serial

Post by espexp » Mon Apr 12, 2010 3:53 pm

Yeah, it looks like the return jack is the switch jack on the DC-5A version. The schematics I've seen show the switch on the send jack just like the DC-5B.

OK, this might be confusing but I think I have it figured out. If you take the white wire that you disconnected and hook it to the terminal on the return jack that is only active when nothing is plugged into it, that should complete the circuit.
The white wire being the preamp signal and the terminal on the return jack being the conduit for the signal to return to the orange wire and on to the power amp output.
Just make sure that your return jack is indeed a switch jack and verify which terminal is only active when the switch is closed( nothing plugged in).

ErickG
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Posts: 19
Joined: Sun Feb 28, 2010 8:18 pm

Re: Modifying the effects loop to serial

Post by ErickG » Tue Apr 13, 2010 12:16 pm

Thanks, I will take another look at it this weekend. I really appreciate the help.

From what I understand about the switch jacks it should have 3 terminal points on it instead of 2 for a normal mono non-switch jack. I would think that this is the "indicator" of such a jack. Would you agree? Since the jacks are the enclosed type I am not sure of any other way to verify the type without just referring to the terminal contact points.

Okay... I started thinking more and more about what you were saying in your last post and I think I finally really understand how the loop is working on my amp. Looking at my first post entry and the photo showing most of the chassis you see two white wires. Both of these are coming from the preamp section, one is going to the mix pot and the other is going to the send jack. When no cable is into the send jack and the return jack, really the return jack in my case, if you are following me here, the sound from the preamp is going to the both the mix pot and the send jack. This is all the time. The white wire on the mix pot allows the sound to flow to the center post where the orange and the "switch wire" (from the return, if it is true in my amp) are also located this allows the amp to function with nothing in the loop. (Also to note this would allow the sound to flow through whether to mix pot was at either 0 to 100%) So when I plug cables into the effects loop and turn up the mix pot I am blending or adding sounds from the effects loop the the primary signal which is also going to the white wire on the mix pot to the center post. In other words the red wire is receiving sound and adding to the orange wire in center of the mix pot as the white wire is receiving sound straight from the preamp. This is what makes it a parallel loop. Duh, I know, and for any of you out there reading this that already knew this. But I am hoping this will help others that come to the forum that need help.

So I think you are right, espexp, that if the return jack is a switch type jack then the sound would still work without the cables in the loop, if I attach the white wire to the switch terminal. Also occurred to me that if I had left the white wire on the mix pot it would have worked still too, but I am not sure what would happen if the mix pot was "turned up". Thinking this is not a good idea anyway. (The mix pot in my case is blending how much is received rather than how much is sent to the loop. Something more that occurred to me.)

Thanks again for your help and for putting up with me! If I am wrong let me know. :)

espexp
Mark II
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Joined: Tue Nov 14, 2006 8:17 pm

Re: Modifying the effects loop to serial

Post by espexp » Tue Apr 13, 2010 3:26 pm

I think you got it figured out.
I think you may have to do one more thing though. The bare wire ( I think that is the one that is inactive when the loop is in use) would have to be removed completely. So, when you attach the white wire to the bare wire return jack terminal, the signal would go thru the jack and on to the output. Basically white, thru the switch, to red to orange and back to the board. Otherwise the bare wire would allow the signal to go to the output (orange wire) all the time. You want to break the circuit when you plug into the jack.

ErickG
Bottle Rocket
Posts: 19
Joined: Sun Feb 28, 2010 8:18 pm

Re: Modifying the effects loop to serial

Post by ErickG » Tue Apr 13, 2010 7:08 pm

Yes, I understand what you are saying and it does make sense. Cool! 8) Switch will be closed continuing the circuit through the red wire as you mentioned. I didn't think of this earlier.

Thanks again for your help and I will let you know how it turns out.

Best regards,
Erick

Fei Fong Wong
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Re: Modifying the effects loop to serial

Post by Fei Fong Wong » Thu May 16, 2013 10:51 pm

Hey guys, I would like to try this mod too. I have a DC-5a. If you did figure this issue out, can you post a pic of the correct wiring?

Thanks

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