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 Post subject: Re: nomad mods
PostPosted: Fri Feb 10, 2012 7:46 am 
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Mark II
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Posts: 57
fretwhizzy wrote:

As a handy thing to share here in the spirit of sharing handy stuff .....I found out Tuesday night, while putting my Nomad back together for a recording session the next day (I'm kinda experimenting with having some kind of permanently-racked up head n fx setup) and not being able to locate my 7pin din cable for the footswitch, that in fact the footswitch seems to work 100% fine with just a regular 5pin din cable. Which is just your regular MIDI cable and a lot more readily/cheaply available in various lengths.

Having found that a MIDI cable works fine on my Nomad I also tried it on my formula pre. 100% fine again.. :)


I never saw any follow up on this but I have some new info to report. I tried using my Nomad 100 footswitch with a standard 5 pin MIDI cable and was able to select all three channels and the solo boost modes. I checked the reverb switch, and nothing seemed to happen, but I realized afterward I probably had the reverb turned all the way down so it wasn't a proper test (I don;t use reverb anyway so no biggie). The EQ light on the footswitch will light up, but it does not activate the EQ on the amp.

This was really good news for me. I use a pedalsnake to run my front end, effects loop, and power. I was having to run the footswitch cable separately, but now I can actually use one of the pedalsnake channels for the footswitch, and I am down to one cable from pedalboard to amp.

Also, one month in and the brightness, serial fx loop, and NFB mods to my Nomad are still sounding great.


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 Post subject: Re: nomad mods
PostPosted: Fri Feb 10, 2012 11:19 pm 
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Mark III

Joined: Sat Nov 29, 2008 12:52 am
Posts: 340
the recluse wrote:
Also, one month in and the brightness, serial fx loop, and NFB mods to my Nomad are still sounding great.


Like they say on thegearpage...its all BS until you post a soundclip :)


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 Post subject: Re: nomad mods
PostPosted: Sun Feb 12, 2012 12:04 pm 
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Mark II
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Posts: 57
Here's something that I wasn't able to find much about on the internet. At this point, the only thing that I'm not 100% happy with is the speed at which the channels change when using the footswitch in my nomad. There's a split second gap when switching from one channel to another.

Is there anything that can be done about this? Is there a different kind of relay that could be swapped into the switching circuitry to reduce the lag?


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 Post subject: Re: nomad mods
PostPosted: Mon Feb 13, 2012 1:13 am 
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Mark III

Joined: Sat Nov 29, 2008 12:52 am
Posts: 340
The store I bought my N100 from misplaced the footswitch, ordered me the one for the 55. I had researched it, and there is a N100 footswitch that has 3xCh, Reverb, EQ, Boost.

I bet that switch that isn't working for you may be selecting other functions.

Without a bit of expense, I think it would be difficult to get rid oof the lag. On these complex circuits a bunch of switches need thrown for a single click, and I think they select the switches for certain lag ratings so they do the right thing in a sequential manner. But, thats heresy or a guess. Your best bet is to talk to mesa about it.


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 Post subject: Re: nomad mods
PostPosted: Mon Feb 13, 2012 9:17 am 
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Mark II
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Posts: 57
I may have found my answer, straight from the horse's mouth:

http://www.mesaboogie.com/Reviews/guitarist-F-50/Designing_f-50.htm

“The problem is, they make huge popping noises when switching on and off (remember the old Mark II-Bs?). To solve this problem, I came up with a mute circuit (patent pending) triggered by the relays themselves, that cuts off the amplifier just at the moment the pop would occur. I don’t think you can even detect the moment that the amp is silent, it’s that brief. And it sure beats a huge pop!

Sounds like the gap is on purpose, and the alternative would be a pop. Hmmm...


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 Post subject: Re: nomad mods
PostPosted: Mon Feb 13, 2012 12:00 pm 
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Mark III

Joined: Sat Nov 29, 2008 12:52 am
Posts: 340
I don't get too cooked about it, mine has an acceptable lagtime. Must be lucky.

But the Boss EQ I run with my heartbreaker has a pop and too long of a lag, which is pretty unacceptable for simply patching in an active eq. There's a whole lot more going on in a channel switching amp.


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 Post subject: Re: nomad mods
PostPosted: Wed Feb 29, 2012 6:45 pm 
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Mark III

Joined: Sat Nov 29, 2008 12:52 am
Posts: 340
Channel 3, is not the bees knees....Just the bees.

I have had a little bit of luck in that by rolling my volume pot off on my guitar the bees go away and the supersaturated overdrive gets taken down to an acceptable level, as well. If you look at the schematic, it appear that the bees probably originate just before and at the gain pot in the circuit eg.. there is a hefty resistor with a bypass cap to force all the highs through.

I suppose that the volume and tone pots on a guitar are there for some reason, but I have noticed that many amps don't perform really great at less than full guitar output. I do not have a bright cap (treble bypass) wired into my guitar volume pot, so this bright cap in the amp sortof works like such a thing would work if it were in my guitar. Of course, the high gain circuitry simply crushes those higher order harmonics into a mash of white noise.

One would think that a bright cap on the guitar and use of the tone control to manage brightness would be a preferred approach, with the amp channel producing TONE.

I've read, I think on thegearpage and elsewhere that they hate amps that have bright caps in their circuitry, and they make hay by clipping them all. Channel 3 is a prime candidate for a bright cap clip, I believe. Perhaps that will prove the correct insecticide for the bees in this channel, and may be the best mod yet.

In fact, this channel, which seems very scooped to me sounds better with the neck pickup and Channel 2 crunches very nice with the bridge pickup.

Maybe I'm on to something, in terms of how to use this amp in accordance with its as yet undiscovered design purpose....(which I notice boogie never gets to writing about amongst all their glowing multi-layered BS in their manuals....Time to get techies writing manuals, and not their marketing department, I venture to suggest.)


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 Post subject: Re: nomad mods
PostPosted: Sat Aug 02, 2014 9:29 am 
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Mark I

Joined: Tue Jul 18, 2006 7:25 pm
Posts: 24
What a great post


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 Post subject: Re: nomad mods
PostPosted: Thu Nov 20, 2014 10:18 pm 
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Bottle Rocket

Joined: Mon Nov 17, 2014 10:06 pm
Posts: 6
One more mod to try on your Nomads: desolder one of the wires on the presence pot on channels 2 and 3. This circuit is a variable low pass filter that loads down the signal even when the pot is at 100k. I was was very happy with the extra punch I got.


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 Post subject: Re: nomad mods
PostPosted: Tue Dec 02, 2014 8:52 pm 
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Bottle Rocket

Joined: Mon Nov 17, 2014 10:06 pm
Posts: 6
Can any techs here explain how the vintage modern switch works on the Nomad? From the schematic it looks like selecting vintage throws another 220k onto the top side of the 100k MV pot, effectively lowering volume. But vintage has a slightly warmer sound as well. Not sure why that happens.

link to schematic:
http://schems.com/manu/mesaboogie/boogie_nomad100.pdf

edit: I think I see whats happening. That 220k resistor effectively gives you what amounts to a 320k pot without a bright cap, hence the darkening in vintage mode. Seems like a better solution might be a small switchable bright cap...? That would be an easy mod to try as well..


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 Post subject: Re: nomad mods
PostPosted: Sat Jan 24, 2015 1:31 pm 
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Bottle Rocket

Joined: Sat Jan 24, 2015 1:16 pm
Posts: 1
Hey Gang,
Better late than never, but longstory short, I bought a Nomad 45 2 x12 back in '02-'03, used it a little, packed it away, now I'm breaking it back out to jam, etc.
What Mods should be done to improve it's sound? I also use a POD Pro Rack Amp Modeler, and I have used the Nomad just as a power amp (pumping Pod signal into "Return" on the effects loop with a 1/4 plug inserted into the "Send"), but overall, I guess I'm underwhelmed with this amp...Had a Studio .22 back in the late '80's that I regret selling, thought that this 45 with 4 EL-84's would be greater...
Somebody convince me to keep this guy and mod it, or what is the market like for selling it?

Thanks for any ideas!

Franz in NJ


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 Post subject: Re: nomad mods
PostPosted: Sun Jan 25, 2015 10:26 pm 
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Mark III

Joined: Sat Aug 11, 2007 9:14 am
Posts: 215
balokker wrote:
Can any techs here explain how the vintage modern switch works on the Nomad? From the schematic it looks like selecting vintage throws another 220k onto the top side of the 100k MV pot, effectively lowering volume. But vintage has a slightly warmer sound as well. Not sure why that happens.

link to schematic:
http://schems.com/manu/mesaboogie/boogie_nomad100.pdf

edit: I think I see whats happening. That 220k resistor effectively gives you what amounts to a 320k pot without a bright cap, hence the darkening in vintage mode. Seems like a better solution might be a small switchable bright cap...? That would be an easy mod to try as well..


I will have to find the frequency response graphs from the simulations I did of this part of the circuit, but you are effectively correct. With the resistors in place, there's more attenuation of the signal, in the highs especially. But the overall gain structure isn't changed.

IMO, these resistors would be better placed between the 2nd and 3rd gain stages (V4a, & V3b) of channels 2 & 3. Altering the value of either of the two 1Meg resistors between V4a and V3b would let you affect how much of the signal from V4a is fed into V3b, and thus how hard V4a drives 3b and causes it to distort. This would have a much larger effect on the tone of Channels 2 and 3 than the stock vintage/modern switches do.

If I can find my old simulations of the Nomad's circuit, I'll play with them and see what I can come up with.


Last edited by Koreth on Fri Jan 19, 2018 1:04 pm, edited 1 time in total.

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 Post subject: Re: nomad mods
PostPosted: Wed Sep 16, 2015 2:51 pm 
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Bottle Rocket

Joined: Wed Sep 16, 2015 1:53 pm
Posts: 1
Hi there, I bought my Nomad 55 about two weeks ago, and having completely revalved it - I'm beginning to have fun with it. However, having spent weeks reading up on these amps I'm inspired to go ahead and do a couple of the recommended mods. I'm gonna do the efx cap mod and the NFB mod.
My main question is: can I just disconnect the reverb-three wiring from its pot. and re- use the pot as a variable NFB control? If so, do I need to put a resistor somewhere in the circuit, and what value do I need to use? If that pot isn't suitable- perhaps somebody could give me an idea of which components I would need for this mod.

I have found that by reading the manual a few times and then sitting and playing with the controls for several hours I have come up with some pleasing settings. However, I am hoping to gain some clarity in the sound and lose some of the buzzy overtones I am hearing.

By the way, I am super-impressed by the dedication and generosity of the members of this forum. Seriously, if it wasn't for the postings on this forum, I would be thinking that I had just spent a lot of money on a very average sounding amp. Clearly all is not lost, and I'm looking forward to turning my Nomad into a tuneful fun-to-play amp.

Many thanks for reading/ heeding my cry for help.


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 Post subject: Re: nomad mods
PostPosted: Wed Dec 27, 2017 8:51 am 
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Bottle Rocket

Joined: Fri Sep 16, 2016 8:13 am
Posts: 17
Hi, I've bought a Nomad 100 head (done mud mod and reverb mod).
I just want to know if it's possible to do a mod to channel 3 adding gain (I want to know if it can sound like if it's boosted by an od. I mean, I want the sound and amount of gain like when I push it with my TS Mini).
I red that changing a resistor near V3 will add more gain to CH2 and CH3.
What should I do? Can You help me?

I don't want to need an OD to have a badass sound on my lead solos.

Thanks!


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 Post subject: Re: nomad mods
PostPosted: Fri Jan 19, 2018 2:19 pm 
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Mark III

Joined: Sat Aug 11, 2007 9:14 am
Posts: 215
Andree88 wrote:
Hi, I've bought a Nomad 100 head (done mud mod and reverb mod).
I just want to know if it's possible to do a mod to channel 3 adding gain (I want to know if it can sound like if it's boosted by an od. I mean, I want the sound and amount of gain like when I push it with my TS Mini).
I red that changing a resistor near V3 will add more gain to CH2 and CH3.
What should I do? Can You help me?

I don't want to need an OD to have a badass sound on my lead solos.

Thanks!


Take a look at the schematic here. There are a few resistors near V3a or V3b that if changed, will increase the gain of the channel 2/3 circuit at that point. If you don't understand tube circuits enough to pick out which resistors they are and why, I'd recommend against trying to mod for more gain by swapping a resistor near V3. Blindly swapping out resistors without understanding what they do and why runs a risk of damaging the amp.

However, I don't think increasing the gain late in the channel 2/3 circuit is going to get you what you want. It's not going to have the same effect as boosting the amp with an overdrive pedal. An overdrive pedal, depending on its settings, adds compression and clipping of its own, changes the eq balance of the signal going into the amp, and raises the signal level. That in turn causes V1a to drive V4b harder, which in turn drives V3a harder. A change in the signal entering the amp has effect through the entire cicruit, which will be difficult, if not impossible to replicate by making changes to the end of the preamp circuit.

Probably the simplest and easiest way to get the sound you like is to continue doing what you're doing now: boost the amp with an OD pedal. If you don't like having to do the foot pedal dance when switching to your lead tone, there's a number of devices you can buy that can switch multiple pedals with a single stomp.

If you want to make further mods to your Nomad 100 to improve its tone, check out the power supply mod described by soundguruman here. I've not done it yet, but his reasoning is sound. Unfortunately, it's involved. You have to disconnect multiple leads from the board so you can take it out of the chassis and get to the power supply capacitor leads on the underside. If you're not already experienced with soldering work and don't have access to a temperature-controlled soldering iron (that's important, you risk frying the board otherwise) and desoldering tools, you're better off to take the amp to a tech to have the mod work done.


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