nomad mods

Dual/Triple Rectos, Maverick, Blue Angel, Nomad, Road King, F-Series, Lone Star & Stiletto

Moderators: Grandor, ned, Guitarzan, Platypus

Optical
Bottle Rocket
Posts: 3
Joined: Mon Apr 16, 2018 6:39 am

Re: nomad mods

Post by Optical » Fri Oct 26, 2018 9:43 pm

Thanks to the people who have posted in this thread. I have a Nomad 45 which I have spent some time modding.

I have done the mud mods - PI plate caps removed and the FX loop cap swapped to 47pF. Preamp low pass output cap removed
Crunch and Lead reverb return resistors are paralleled with 100k resistors to get it loud enough for my taste. I experimented with the reverb send stage in case those diodes were clipping but it didnt make a difference, didnt explore further.

Now - there are some good mods to be made to channel 3 to make it significantly less mid-scooped and give it less bees.
Short the 1k resistor in series with the V3b 0.47u cathode cap
The 680k treble peaker resistor sounds much better at smaller values,I settled at ~390k (680k and 1M in parallel) for a good modern sound. 470k sounded good too.
This was combined with reducing the value of the gain pot - i used a 220k resistor across the existing wiper and ground. The wiper resistor tightens up the lead channel a bit, reducing the treble peaker resistor brings out the mids.

Here is what I ended up with. The lead channel sounds very close to the dual rec now. Crunch channel isnt substantially affected. I call it the Bees mod :p


Image

sentari
Bottle Rocket
Posts: 1
Joined: Sat Jan 05, 2019 3:31 pm

Re: nomad mods

Post by sentari » Sat Jan 05, 2019 4:19 pm

It seems the pictures that Normad100 posted have been gone for some time. Can someone post them or point to/give some specific instructions to the mud and reverb mods?

balokker
Bottle Rocket
Posts: 7
Joined: Mon Nov 17, 2014 10:06 pm

Re: nomad mods

Post by balokker » Mon Jan 21, 2019 6:05 pm

Thanks for the mod list Optical.
I found that treble peaker to be a critical voicing factor as well. I went with 235k (two 470s in parallel) and 681pf.
What did you get from changing that 1M to 220k on V4a? Looks like it will boost the signal working with the other 1M on the grid.

Optical
Bottle Rocket
Posts: 3
Joined: Mon Apr 16, 2018 6:39 am

Re: nomad mods

Post by Optical » Thu Oct 31, 2019 10:19 pm

The 220k raises the rc filter frequency made with the coupling cap.
Essentially a tighter bottom end

j.micka@outlook.com
Bottle Rocket
Posts: 6
Joined: Wed Oct 09, 2019 7:04 pm

Re: nomad mods

Post by j.micka@outlook.com » Sun Jun 14, 2020 11:50 am

Hi all,
Reading this thread for a while and I must say a lot of work was put into this.
You guys are great taking the time to tweak these amps in for an improvement.
Well I have a question as I'm about to try a different output transformer on a Nomad 45 for a test.
The Nomad 45 I have has a blown output transformer, makes me wonder why its blown. I took it apart and found the short, the inner windings shorted through as they turned on the core at only one spot, this is a rewind job.
I noticed the circuit board previous owner did the mud mod I guess lifted the 2 little ceramic caps. (I replaced them back on the board)
Now I have added the SoundGuruMan Mod, (I'm sorry having lack of name) beefier power supply capacitance he stated took care of muddiness and he mentioned adding 68k resistance at the input jack. Also I added the parallel resistance to the reverb.

Anyways back to the output transformer, I'm going to try a Marshall 50 watt and was wondering if anyone tried this yet?
This transformer is about 5 times more steel on it than the standard one.
Some things that make me question is I don't know the impedance of the standard transformer and the winding ratio.
The Marshall really was built for 2 EL34's.
Also it would be interesting to hear the output of the beefier Marshall transformer (maybe).
I believe primary impedance is I believe 6.4kohms or 3.2k plate to plate and the Marshall has added a 16ohm speaker tap.

j.micka@outlook.com
Bottle Rocket
Posts: 6
Joined: Wed Oct 09, 2019 7:04 pm

Re: nomad mods

Post by j.micka@outlook.com » Sun Jun 28, 2020 4:43 pm

I don't know any better.
When the Marshall 50watt output transformer was installed I got a huge hum from the speaker.
Tested another speaker still monster hum.
Only thing I can guess is a mismatch.???

Post Reply