So ARE there any known F-50 Mods?

Besides the Parallel to Series mod for the FX loop? (I might use a DPDT switch or push-pull pot to be able to choose)

I LOVE the amp, and have messed with a couple tubes. So far I like the C90 best with the amp I think. However I'm curious if there are mods that can be done from the amp that can help make it from "Great" to PERFECT!

Specifically the Lead channel/Contour Mode. I'd Ike it a hair brighter normally and just a little darker (Not as boosted in the highs) in contour mode. I saw on HC there's a review for the subway rocket where a guy talks about some mods, but I don't trust his instructions are close enough to follow with the current amps.

Also would love to mess with LED's for the Footswitch. (The Express spoiled me here). I saw a schematic for the footswitch in the F-series lounge on HC and wonder if anyone's messed with it. Be cool to change the Channel LED to Green/RED, Contour to constant on or off, and an LED for Reverb. This is obsessive of course, but just curious. I'm not an EE so really don't have the experience to engineer it. Though I could follow a basic schematic of what to do with instructions I think.

Basically, the F-series contour mode uses the same inductor EQ circuit used on the Marks and Dual Calibers, except the knob positions are set permanently by fixed resistors.

In theory, you can change the balance of the frequencies my modifying these resistors. There's some maths involved for working out the value of the resistor for a certain cut-off frequency in each band (based on the inductance, capacitor and center frequency) - forget about that just look at the Mark EQ schematic and work out the max. and min. values of the slider pots, and aim for an eq "shape". The F-series eq is permanently set to the "V" shape.

jvk said:

Basically, the F-series contour mode uses the same inductor EQ circuit used on the Marks and Dual Calibers, except the knob positions are set permanently by fixed resistors.

In theory, you can change the balance of the frequencies my modifying these resistors. There's some maths involved for working out the value of the resistor for a certain cut-off frequency in each band (based on the inductance, capacitor and center frequency) - forget about that just look at the Mark EQ schematic and work out the max. and min. values of the slider pots, and aim for an eq "shape". The F-series eq is permanently set to the "V" shape.

Click to expand...

Yeah I just wish I knew WHICH resistor to change!

I would be very interested in a Contour mod. I currently use an EQ in the loop instead of contour mode.

lactose said:

I would be very interested in a Contour mod. I currently use an EQ in the loop instead of contour mode.

Click to expand...

When you use the EQ, can you replicate the Contour mode EXACTLY? Or does it sound like there's something else that's going on too? (Besides the EQ change)

NuSkoolTone said:

lactose said:

I would be very interested in a Contour mod. I currently use an EQ in the loop instead of contour mode.

Click to expand...

When you use the EQ, can you replicate the Contour mode EXACTLY? Or does it sound like there's something else that's going on too? (Besides the EQ change)

Click to expand...

With contour mode "on", changes are made to V2a and V3a (the bright pull no longer works) and the EQ is turned on.

jvk said:

NuSkoolTone said:

lactose said:

I would be very interested in a Contour mod. I currently use an EQ in the loop instead of contour mode.

Click to expand...

When you use the EQ, can you replicate the Contour mode EXACTLY? Or does it sound like there's something else that's going on too? (Besides the EQ change)

Click to expand...

With contour mode "on", changes are made to V2a and V3a (the bright pull no longer works) and the EQ is turned on.

Click to expand...

Cool, I remember reading about all the stuff that goes on in RS's article/interview.

Anyone have a schematic for the F-series? So if the cap and the inductor determines the frequency, I imagine the resistor determines the amount? Since the sliders are really variable resistors. I think it'd be cool to put a trim pot in there! I could mark "Stock" and also have a custom setting.

When you use the EQ, can you replicate the Contour mode EXACTLY? Or does it sound like there's something else that's going on too? (Besides the EQ change)

Click to expand...

It sounds different, much better. Closer to the sound I used to get on the lead channel of the Mark IV with the EQ scooped. IMO, contour mode falls short and does not scoop enough.

With the EQ in the loop (and preferably one before the input to tighten up the bottom end, removing bass) I get two nice high gain sounds, one kinda Marshall, one kinda Recto.

It's usually pretty easy to change to different color LEDs. Just make sure you get the polarity right (plus wire & minus wire), and don't overheat the LED with your soldering iron. You can use needlenose pliers to heat sink each lead by grabbing it between the end you are soldering and the LED body until the solder cools.

This of course assumes that you can get the footswitch or amp apart so that you can get to and replace the LEDs in the first place.

With the EQ in the loop (and preferably one before the input to tighten up the bottom end, removing bass) I get two nice high gain sounds, one kinda Marshall, one kinda Recto.

Click to expand...

I'm am interested in this as well.
What EQ do you use up front/in the loop?
Would a fish'n'chips do the job in the loop with a bad monkey to bring down the bass up front?

Denver

The Mesa Eq is actually a very good circuit - ultra quiet and very effective, albeit it has only 5 bands.

Here's a suggestion to get the amp sounding as you want it to. Replace the fixed resistors with pots, and tune it exactly how you like.

The EQ circuit is exactly the same as the Nomad 100/Mark IV/Dual Caliber circuit - you should be able to easily locate the resistors, unsolder them and replace them with PCB mounted pots.

If you take some hi-res shots, I'll gladly help you guys out in performing this mod.

Good luck!

jvk said:

If you take some hi-res shots, I'll gladly help you guys out in performing this mod.

Good luck!

Click to expand...

Not sure if this is High Res, but here ya go. Anyone have a schematic?

What EQ do you use up front/in the loop?
Would a fish'n'chips do the job in the loop with a bad monkey to bring down the bass up front?

Click to expand...

I use a Carvin 7 band in front and an MXR 10 band in the loop.

I don't know the Bad Monkey well, but if it could remove some bass that would help. I am not familiar w the fish n chips, but 7 to 10 bands should do it.

That was a brilliant idea adding the pots in. Now I am getting tempted.

NuSkoolTone said:

jvk said:

If you take some hi-res shots, I'll gladly help you guys out in performing this mod.

Good luck!

Click to expand...

Not sure if this is High Res, but here ya go. Anyone have a schematic?

Click to expand...

Btw, can't see the image.

Please let me know when one of you has taken plenty of hi-res pics.

adios

jvk said:

NuSkoolTone said:

jvk said:

If you take some hi-res shots, I'll gladly help you guys out in performing this mod.

Good luck!

Click to expand...

Not sure if this is High Res, but here ya go. Anyone have a schematic?

Click to expand...

Btw, can't see the image.

Please let me know when one of you has taken plenty of hi-res pics.

adios

Click to expand...

Hmm, Can anyone else see it?

Image fixed. See above.

We need better hi-res and clear images to work with.

hey whats up,,Im sure some of you guys know about this sight but i figured I would make mention of it for you F series owners. real nice,I wish they had a sight like this for all boogies.
http://acapella.harmony-central.com/forums/showthread.php?t=885856&highlight=f-50+lounge

jvk said:

We need better hi-res and clear images to work with.

Click to expand...

How about these?

Overview:



Hi-Res composite: (I filled the background PCB green so easier on the eyes)



Any suggestions now?

Thanks!

Nice amp porn!

I wish Mesa sold their amps as kits I would LOVE to put one of these together.