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PostPosted: Sun Dec 11, 2011 1:54 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
After hearing the difference that some of these mods did for my Nomad 55 1x12 Combo, I concur that some of these mods are a must have if one is in anyway dissatisfied with the stock Nomad Tone. I realize that many are not instantly comfortable doing Mesa mods, I wasn't. I figure, having a visual overview of the mods would help people better evaluate their willingness to perform said mod.

All the mods shown are MY interpretations of the mods discussed in these treads:
http://forum.grailtone.com/viewtopic.php?f=4&t=36317 and http://forum.grailtone.com/viewtopic.php?f=4&t=56044
This is not definitive. I may have missed something. I may have omitted something because the discussion seemed to indicate it was better open way or another.

Please provide comment to correct any issues or clarify the "design" or intent of these mods.

Many thanks to all the people who contributed to this body of knowledge. Many a brave souls are out there pulling and replacing caps before evidence proved it safe. Many smart people thought long and hard while evaluating Nomad and the potential mods. Even more have stuck with the Nomad, not able to realize the full potential of the amp. I do want to acknowledge nomad100hd, Koresh, Tommy_G, shytfayse, jaquetapus, KozMcCharlie, earachemyeye, fretwhizzy, lerxst88, and all the people involved in the original threads for pioneering these mods.

This image is based on my Nomad 55 combo. I am assuming that all the Nomads are laid out in a similar fashion.

I will be filling in the details of the individual mods over the next week.

Nomad MOD Map

Image


Last edited by NomadExpress on Sun Dec 11, 2011 3:40 pm, edited 2 times in total.

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PostPosted: Sun Dec 11, 2011 1:55 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
1 - FX Loop Capacitance Mod

BEFORE: Image AFTER Image

Why?
If you do only one Mod for tone - This is it.
This cap value is reduced from 0.005 uF/5nF/5000pF to roughly 50 pF (my 47 pF cap measured at 50.1), that is 1% of the stock capacitor value.
This capacitor attenuates (to some degree) most frequencies above 100 Hz, Its not the preponderance of bass/lows in the Nomad that makes mud, it is the absence of highs. This mod gets you 90% of the way there. See Koreth's evaluation here: http://forum.grailtone.com/viewtopic.php?f=4&t=36317&start=90 proves that no other one mod does more for your tone than this one.

Materials:
47 pF, non polarized cap, silver mica or ceramic (stock)

Steps:
-Carefully remove .005uF (5nF) capacitor shown. - Use a low power soldering iron to heat the cap lead near the board while gently pulling on the heated cap lead with a needle-nose. The solder will heat and release the cap will then pull out.
-Prepare the 47 pF cap - Trim off some lead. Give your self more lead than the stock part.
-Using a needle-nose type tool hold the lead of the cap and place it like you would insert it into the holes from the removed cap.
-Install Cap - Heat New cap lead, close to board. When the lead gets hot enough the solder will melt. Gently push the lead 1/8" into the melted solder and hold. Remove iron, breath and then let go of cap.
- Install Cap - Do it again for the other lead.

Variations:
-Using a capacitor value greater than 47pF will begin to trail off the high end. 47 pF was selected for the flattest response across the guitar spectrum. If this mod is too bright for you, you can always add a cap in series to add to it. Another 47pF cap in parallel to the one added would yield a 94pF.This is one reason why you would want a longer cap lead on the replacement cap.


Last edited by NomadExpress on Mon Dec 12, 2011 9:21 pm, edited 4 times in total.

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PostPosted: Sun Dec 11, 2011 1:55 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
2 - Mud Mod

BEFORE: Image AFTER Image

Why?
This was the original Mud Mod that got all this going.
This has a subtle effect on your tone.
Reports are that you stand out in the mix better.
If you love the STOCK tone and just need subtle mid boost to be more present in the mix, this is the mod for you.

Materials:
None

Steps:
-Carefully remove one leg .120 pf capacitors shown. - Use a low power soldering iron to heat the cap lead near the board while gently pulling on the heated cap lead with a needle-nose. The solder will release and the cap will pull out, one leg at at time.

Variations:
-If you like the mod, clip the cap leads.


Last edited by NomadExpress on Sat Jan 14, 2012 8:12 am, edited 3 times in total.

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PostPosted: Sun Dec 11, 2011 1:55 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
3 - NFB Extreme Switch

BEFORE: Image AFTER Image


Why?
The Nomad 45 basically has this switch so it applies to 55 and 100 owners only. 45 owners can look to variations for some other ideas.
The extreme switch strips the negative feed back to the PA.
Some people simply remove the wire from the 8-ohm tap, this mod shows the installation of a toggle switch. This is a Mesa and we love our options, thus the switch.
Without the NFB The amp is very much "alive" and the high end brought about by the first 2 mods are tempered.

Extreme is a good word for it. The amp gets LOUD and is a monster in this mode.
Glibly speaking, I think this feature is so awesome, this amp is too good for the original price point, this the 45s got it

I run it in both modes so I welcome the switch.

I expect it will wear the tubes out sooner. This has not been confirmed or refuted with statistical evidence.

Materials:
Toggle switch (the one in the pix is rated for 125V)
18ga braided wire.

Steps:

Image

Image
NOTE: you have to watch out for the output transformer when you locate the switch hole. Mine missed as planned but was a little close. The hole location is up to you, but the stock wire is only so long. Without adding wire, the hole location is limited.
Image

Variations:
Variable NFB defeat using a push-pull 1Mohm pot shown,
Image


This is another a variation to the "extreme switch". Just using a pot and resistor so the effect can be dialed down a bit depending on how much resistance is applied to the NFB loop circuit. Added resistance means less NFB and visa versa. The 1/2 watt 500k linear pot and 1/2 watt 270k resistor wired in parallel gives a range of 0-177k where the stock setting is 39k. More (resistance - less NFB) could be added by increasing the size of the resistor but I found this to be a good range for my tastes.
Image
Image
Image


Last edited by NomadExpress on Tue Jun 05, 2012 10:02 pm, edited 4 times in total.

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PostPosted: Sun Dec 11, 2011 1:56 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
4 - Reverb Mod
Note: While I am considering it, I have not performed this mod. This is how I understand the mod to be performed.

BEFORE: Image AFTER Image

Why?
Reverb in channels 2 and 3 are weak.
Decreasing the resistance allows more of the reverb signal to come through

Materials:
(2) 220 kOhm Resistors

Steps:
-Solder a 220 kOhm resister in parallel to the 330 kOhm resistor as shown by shytfayse's image below.
Image

Variations:
There are some Cap replacements but I have not seen anything that I would hang my tone on.


Last edited by NomadExpress on Mon Dec 12, 2011 2:59 am, edited 4 times in total.

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PostPosted: Sun Dec 11, 2011 1:56 pm 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
5 - FX Loop Mod - Parallel to Series
Note: While I am considering it, I have not performed this mod. This is how I understand the mod to be performed.

BEFORE: Image AFTER Image

Why?
You rather have a series FX loop instead of a parallel loop.
This was one of the first mods discussed. The mix level pot is one other component that the signal simply does not need to go through.

I have seen very little evidence in the discussions where this mod is clearly effective as a "tone mod." There are better places to look for tone. (Mods 1, 2 and 3 above)

I would personally do this because.- Sans-Nomad reverb, I want reverb last in my loop and that means I need a good dry signal and parallel loops with wet/dry mixes creates complications with a delay that can kill the dry signal. My setup would match the Express's.

Materials:
None

Steps:
-Pretty straight forward...
Image

Variations:
- Simply remove wire 1 and connect to position 2 (1 & 2 connected). Remove and insulate 3.
- Simply jumper solder jumper between connection 1 and connection 2 (1 & 2 connected). Remove and insulate 3.
- Use a push-pull pot or on off switch to choose parallel or series operation.

UPDATE:
If you do this mod, you need a patch cable between the send and return if not in use. See discussion below.

the recluse wrote:
Having done the parallel to series mod on my Nomad 100, I can confirm that you need to run a patch cable from send to return if you are not running effects in your loop. I installed a Push/Pull pot so I can do Series or Parallel so I don't need a patch cable when I'm not running my normal effects loop stuff.


Last edited by NomadExpress on Tue Jun 05, 2012 9:45 pm, edited 2 times in total.

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PostPosted: Mon Dec 12, 2011 2:41 am 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
6 - Other Mods
Reserved for Other Mods


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PostPosted: Wed Dec 21, 2011 11:11 am 
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Mark II

Joined: Mon Feb 27, 2006 5:41 pm
Posts: 115
Great thread. The pictures make doing the mods very easy.

Thanks again. :)


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PostPosted: Thu Jan 26, 2012 11:42 pm 
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Bottle Rocket

Joined: Wed Jan 05, 2011 10:45 am
Posts: 19
Will this switch work for the nbf?
It says 250 volts ac...
Image

Is this the correct cap for mod 1?
Image


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PostPosted: Fri Jan 27, 2012 2:20 am 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
Yes on the switch. Mine was rated for 125V.
No on the cap 0.047uF=47nF=47000 pf. This will increase muddiness as stock is .005uF=5000 pF
you want a 47 pF cap (0.000047uF or 0.047nF)


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PostPosted: Fri Jan 27, 2012 6:50 am 
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Mark III

Joined: Wed Mar 02, 2011 11:42 am
Posts: 421
I wish this information was assembled and available for Tremoverbs.

Excellent thread.

_________________
Ibanez Jem 7VWH > Bad Horsie II Wah > Radial JX-2 ABY Switch > Two Tremoverb Combos
Mesa Channel Switch DTDP & Mesa FXLoop Switch DTDP
TC Electronic G-Major & Ernie Ball Volume Pedal & Behringer FCB 1010
Assorted Tubes
Series FXLoop


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PostPosted: Fri Jan 27, 2012 8:49 am 
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Bottle Rocket

Joined: Wed Jan 05, 2011 10:45 am
Posts: 19
How about wattage for the 47 pf cap?
is 50 wvdc good?


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PostPosted: Fri Jan 27, 2012 10:49 am 
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Mark II

Joined: Fri Dec 02, 2011 10:19 pm
Posts: 124
timgman wrote:
How about wattage for the 47 pf cap?
is 50 wvdc good?

50w dc is fine. A high power cap is not required here


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PostPosted: Wed Mar 28, 2012 4:38 pm 
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Bottle Rocket

Joined: Tue Mar 27, 2012 9:38 pm
Posts: 7
I'm new to the forum and want to say thanks for the info. Gonna try these mods but I have one question. I bought the 47pf cap and its a 1kv. Is this cap ok to use or should I go back and order the 50v? 1kv is all they had in stock at the moment. Sorry to bring up an old thread but I dont want to mess up here. Thanks again for any response.


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PostPosted: Mon Apr 02, 2012 2:50 pm 
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Mark III

Joined: Sat Aug 11, 2007 9:14 am
Posts: 215
A rating of 1kV will be fine. That particular cap doesn't ever see anywhere near 1000 Volts across it, so a cap rated for 1kV is in no danger of failing.


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