Fender Mustang II - adding a "real" Line Out
By vinic on April 29 - 2014, 11:01 - Permalink
I've been asked to add a Line Out jack to a Fender Mustang II amplifier.
This amp already has a kind of Line Out as you can use the Phones output, but it mutes the speaker...
Let's open the amp.
Not much to see!!! The amp is very light and cheap and you can easily understand why!
All we need is to pick the signal sent to the Phones jack and to bring it to the back of the amp with a comfortable capacitor, electrolytic 470µF 40V here.
Job done!
Just curious... the amp spec tells :
1/8" headphone jack (doubles as a speaker-emulated line out)
Let's see what the emulation does by feeding a pink noise in the amp.
The amp detects when a jack is plugged in the Phones socket and automatically adds filters to the outgoing sound (and mutes speaker). As you can see, it cuts low and high frequencies and boosts a few dB around 3kHz as a standard guitar amp speaker does. My "quick" Line Out does not provide this emulated signal but it is an easy job to achieve on a mixing console.
Hope this helps!
Comments
Hi Carl,
will this mod work with Mustang 1?
does sound still come thro,spkr ?
so as to use as monitor.
Thanks in advance John A
Hi John,
hmmm... Who's Carl?
Whatever...
I think Mustang 1 and 2 are exactly the same amps but the power amp part. So yes, it should be exactly the same on Mustang 1.
And yes, that was the point of this mod, to keep sound on the speaker while plugging the new LINE OUT, because the PHONE output don't.
Have fun!
Aloha!
This is a great mod...I have a Mustang 1 that I use to practice and experiment with different amps models. Is there a away to mod an effects loop so I can use a looper pedal while using the internal speaker.
I found the schematic for this amp but not sure where to intercept for the send/return circuits. Also would I need to add buffers?
Thanks in advance!
Rud
Hi Rud
Not sure to understand your question... Could you be more precise please?
Please send the schematic to vinic@free.fr
Hi,
Simply I would like to add an effects send and return to my Fender Mustang 1. Exf send and return is only on the Mustang 3 and 4 models. I want use an external looping pedal (rc20xl) with my M1.
Hoping the Exf send could be added after the amp's effects then return to the amp.
I'll send you the schematic for the mustang 1 and 2.
Thanks
Rud
I read your initial question once again and it was quite clear... Must be tired
Anyway... Answer sent. Quite an easy job once you know where to go!
Hi,
Could I also have the infos for the Mustang 1 mentionned in previous comments ?
Thanks in advance.
I share it for everyone.
I HAVE NOT TESTED THIS MOD... but it really should work fine
schematic here : http://vinic.blog.free.fr/public/mu...
Effect loop should be inserted on Pin 1 of J103 (page 6 : "To AMP board") which goes to power amp section, you guessed that one, on J400 (page 2)... via the ribbon cable if I remember correctly.
You should try to wire this way : http://vinic.blog.free.fr/public/mu...
(I don't know if a buffer is needed...)
Please send feed back if you do the mod! This may help others!
Have fun!
vinic
Great job man..
* but why did u add the capacitor ?
* another question, i see that you used a mono 1/4" socket .. if you plugged it with a stereo plug, will it be balanced left and right channels ??
Anyway that was great blog *thumbs up*
Thank you Maged!
* The capacitor I added is here as a "coupling capacitor". It is used to prevent potential DC voltages from upstream, to go downstream. This is common use.
* Don't mix it up. Balanced and Stereo signals are different things. (Stereo can be unbalanced) Google is your friend here. Whatever... I had a mono signal to plug, so I put a mono jack socket. No brainer!
Have fun!
Wouldn't J103 Pin 1 also effect send the aux signal?
Wouldn't J201 Pin 1 be a better spot for a mono effects loop? or after R121/R141 for a Stereo effects send?
Yes, J103 will also send the AUX input to the line out.
J201 is the input jack for the guitar, so no, this is not a good spot at all. Signal must first be amplified.
If you want a stereo effect send, you could eventually pick signal BEFORE R121/141. By the way, this would avoid to pass through the MASTER potentiometer, which may be a good thing, indeed!
Would you please Identify the places on the Circuit Diagram where you attached the ground and signal wires ? The Photo does not look like at the phono 1/8 plug but somewhere before ?
If you wanted to send a signal using a line or an XLR output that avoided the Master pot where would you recommend to attach it ? It would work like the Mustang III and IV XLR outs then leaving the Master for the players monitor and send the result to a Mixer. I'm not great at locating stuff on PC boards, so If you had a photo that would really help.
Hi John!
The wires have been soldered under the 1/8" jack, for sure!
If I had to pick the signal before the Master pot, I would pick it between U102-A pin 1 and C113 (or U102-B pin 7 and C135) using a capacitor too. See page 6 grid C-5.
A XLR would be pointless as this is an asymetrical signal. A 1/4" jack is enough.
Hope this helps!
Have fun!
Thanks very much for your reply. The Mixer that one group I am in, is a Behringer X32 Snake connected to a X32 Core mixer, so we have had to use a DI Box to input instruments into it. I think I'll purchase a cheap $30 Canadian passive DI box (ART PDB Passive Direct Box) and disassemble it and Then connect it to the 1/4 output points you have recommended. Since you used a coupling capacitor on the 1/4 connection do you recommend anything like that for the reused DI Box circuit ? The DI boxes that I have been looking at just use an isolation transformer.
Thanks again for your help.
Regards,
John
It is quite good use to put a coupling capacitor between stages of an audio signal chain... Not always "necessary" but it may avoid some troubles...
Vinic based on your last comment, one more question please. It may seem to be a dumb question, but I just want to be 100% sure. The photo looks like you put the electrolytic 470µF 40V capacitor in line on the line connecting to the Tip , and not between the ground and tip. Is this correct ?
Indeed John! This is a "coupling capacitor". Its goal is to transmit AC signal only to the next stage and thus, to remove DC.
http://www.learningaboutelectronics...
A capacitor connected to ground is a "bypass capacitor" and its goal is to send AC signal to ground and keep a clean DC signal.
http://www.learningaboutelectronics...
Thanks so much for your patience, great reply !
It has been 50 years since I took electronics in college and worked at Bell Northern Research utilizing some of those skills. Now retired I have a great deal of pleasure with my music, both playing and figuring out how to make things sound great.
Best Regards,
John