MOSKY XP BOOST versus BOSS SD1 Review

[rayc]

I've used my Boss Overdrive Pedal as a boost pedal since Greg L suggested I do so. No DRIVE & no tonal changes usually - just level at maximum volume. This has helped get my amp sound more like it ought rather than a 1/2 souped broth.

xp boost.jpg

I recently bought a Mosky XP boost - AUS$30 delivered to find out if a "real" boost pedal would serve me better.
It was an interesting exercise but I was immediately disappointed in the Boost pedal - it sounded a little blah in the bottom end and seemed, to be fair, to just increase the level but without any magic results.
I decided to do a side by side comparison for my self & then thought to record it for posterity.
The Boss Overdrive is set at MAX volume and flat tone with NO drive. The XP is a one knob machine so I set it at a level that was approximately the same as the result of the max level on the Boss. To match the BOSS the XP was at about 11 o'clock so has LOTS of boost.
Squire Mustang, bridge pick up, tone & volume at max. The Marshall modded Superbass has ALL controls set at noon except the presence which is maxed.
For the last comparison I set the amp up the way I like to record it and ran the pedals through their paces.
I played clean tone, then the Boss followed by the XP and sometimes I added the XP at MAX.
You decide...
Sorry there's a long silent tail on the file - the noise finishes at 6.56minutes.

BOOST review2.mp3

[Greg_L]

Not bad [mention]rayc[/mention] . You got some usable stuff in there, and not not-so-usable. It's a little confusing though as to what is what in the clip.

[rayc]

Not bad @rayc . You got some usable stuff in there, and not not-so-usable. It's a little confusing though as to what is what in the clip.

Yeah, I know.
Clean, DS1, XP is the usual sequence & XP on full tilt is added sometimes.
I think the Boss wins every time as it cuts bottom end and adds some high end as well which the Marshall likes.
The XP seems to be a totally clean boost and that means bottom end and mids too so it seems to be simply more of everything which the Marshall doesn't like.

[Greg_L]

Yeah, I know.
Clean, DS1, XP is the usual sequence & XP on full tilt is added sometimes.
I think the Boss wins every time as it cuts bottom end and adds some high end as well which the Marshall likes.
The XP seems to be a totally clean boost and that means bottom end and mids too so it seems to be simply more of everything which the Marshall doesn't like.

I'm guessing that little XP is a clone of the EP Boost.

Try it before and after the SD1. It can push into the overdrive, or push after the overdrive. Either way could be an ah-a! moment.

[rayc]

I'm guessing that little XP is a clone of the EP Boost.
Try it before and after the SD1. It can push into the overdrive, or push after the overdrive. Either way could be an ah-a! moment.
[/quote]
I was thinking about that but didn't do it so as not to confuse the review & myself on the one day.
I definitely need what the SD1 does and, yes boosting that would be interesting either side.
I also thought about using it in front & behind the old Ibanez EQ thing I have as that also had boost - Hi & normal - but not a lot of it so the XP MAY offer something to that as well.
That's next weekend sorted then.

[Minerman]

Cool stuff Ray...

Nothing wrong with anything you posted here man...Swap the pedal order around like Gerg mentioned to see if there's anything different...Sometimes magical stuff happens on accident, & you could very well find the missing ingredient for your tone dude...

I can't remember if you told me this or not, but do you use an attenuator with your Marshall???

Am I right saying that amp has a master volume mod, or have I finally lost it???


I like the Boss OD sound better here, but I'm a gain-head from the 80's, so...
The Mosky EP Boost sounds like a pretty good clone at a pretty good price compared to the original...Good catch...

[rayc]

[mention]Minerman[/mention] ,
I used to have an attenuator but two techs told me that Marshalls don't really like them & mine blew fuses when using it so I sold the unit - it was a passive/heat dissipation type and worked but ta that stage, pre PPIMV, it didn't allow me to get to break up anyway. It may be better these days.
Yes, PPIMV mod done but, it seems, the tech didn't do a complete Superlead mod while in there - only partial so the amp needs a boost to get gnarly.

[Greg_L]

@Minerman ,
I used to have an attenuator but two techs told me that Marshalls don't really like them & mine blew fuses when using it so I sold the unit - it was a passive/heat dissipation type and worked but ta that stage, pre PPIMV, it didn't allow me to get to break up anyway. It may be better these days.
Yes, PPIMV mod done but, it seems, the tech didn't do a complete Superlead mod while in there - only partial so the amp needs a boost to get gnarly.

Pre vs post phase inverter master vol makes a big difference depending on the amp. Your amp *should* have a POST phase inverter mv. Without getting too techy, a pre phase inverter mv kills all the drive in Super Lead type amps. Post phase inverter mv lets them get nasty. I know your Super Lead conversion was unfortunately left halfway done, but if the wrong master volume type was also installed, that could be compounding the problem.

My 50w 2203/Plexi conversion mod amp has both types of master volumes. I'll do some clips to show the difference. It's striking.

[Minerman]

[mention]rayc[/mention]
Is there another tech guy you could take the amp to in order to have the amp working the way you want it???

And if not, would you feel comfy maybe doing the work yourself???

Lemme know, I've got a hair-brained hillbilly idea...

[rayc]

[mention]Minerman[/mention] ,
Sadly, I'm incapable of a clean solder.
The next decent tech is about 50kms away.
What's your idea?

[rayc]

Pre vs post phase inverter master vol makes a big difference depending on the amp. Your amp *should* have a POST phase inverter mv. Without getting too techy, a pre phase inverter mv kills all the drive in Super Lead type amps. Post phase inverter mv lets them get nasty. I know your Super Lead conversion was unfortunately left halfway done, but if the wrong master volume type was also installed, that could be compounding the problem.

My 50w 2203/Plexi conversion mod amp has both types of master volumes. I'll do some clips to show the difference. It's striking.

I'd love to hear those samples [mention]Greg_L[/mention] .
Mine has the PostPIMV, I assume, well it sounds like it does. I didn't know about PrePIMVs. Interesting stuff.

[Greg_L]

I'd love to hear those samples @Greg_L .
Mine has the PostPIMV, I assume, well it sounds like it does. I didn't know about PrePIMVs. Interesting stuff.

I'll try to do the clips today.

Since your amp struggles to make the gain we hope and expect it would, I'm starting to wonder if maybe you have the wrong type MV installed.

Here's the in-a-nutshell explanation:

Marshall's non-master-volume-amps (Plexi/Lead/Super Lead/Super Bass/etc) preamps don't make a whole lot of gain and they rely on the "power section" to get the amp not only loud, but also dirty. If you turn down the signal via PRE phase interver master volume on those amps, it kills the signal feeding into the power section and you get a thin, clean output. It's like whispering into a megaphone. You turn down your voice and then the megaphone tries to amplify your whisper. You end up with a loud whisper. This arrangement works fine on the later Marshalls (like everything that came after those amps listed above) because the preamp stages on those amps are "cascaded" and they stack gain on top of gain. The signal is distorted before it even hits the master volume.

On the other side, with a POST phase inverter master volume, you're still cutting the signal before the actual power tubes, but you're allowing the phase inverter tube to overdrive. And in some cases you can get even more gain from the amp this way because the negative feedback circuit collapses and things get even dirtier. So now you've got the preamp combined with the molten overdriving phase inverter signal, which is dirty, going into the power tubes. Even if you cut the level of this signal the dirt is still in there. This arrangement works on any amp, but it can allow too much meltdown on cascaded amps, which is why the PRE version works well on cascaded amps. PRE P.I.M.V. for cascaded preamps, POST P.I.M.V. for non-cascaded. Your amp is non-cascaded.

And it's basically very simply a matter of where you put the volume pot. There's a little more to it, but it's really pretty simple.

"JCM 800" 2204 with a PRE PIMV.

2203 pre.jpg

"Lead" 50w 1987 circuit with a POST PIMV

1987 post.jpg

The ONLY differences...cascaded preamp on the 2204. The amps are nearly identical otherwise, but where you put the MV really matters.

Edit: I just realized that's actually the wrong schematic for a cascaded preamp 2204, but the master volume part is the same.

[Minerman]

Minerman
Sadly, I'm incapable of a clean solder.
The next decent tech is about 50kms away.
What's your idea?

Well Ray, I was thinking since you're such a good guy, you deserve to have your amp operating how you want it man...I was thinking of asking a couple/few of us here pitch in & foot the bill for your proper master volume mod, depending on how much it's gonna run of course...A few of you really helped me out a few years ago, so maybe it's time for me to re-pay the favor...

I'm not sure how involved the mod would be, are you positive you can't brush up on your soldering skills???

Think on it for a while & try to come up with a number...Christmas is just around the corner you know...

[Lt. Bob]

I'd love to hear those samples @Greg_L .
Mine has the PostPIMV, I assume, well it sounds like it does. I didn't know about PrePIMVs. Interesting stuff.

I'll try to do the clips today.

Since your amp struggles to make the gain we hope and expect it would, I'm starting to wonder if maybe you have the wrong type MV installed.

Here's the in-a-nutshell explanation:

Marshall's non-master-volume-amps (Plexi/Lead/Super Lead/Super Bass/etc) preamps don't make a whole lot of gain and they rely on the "power section" to get the amp not only loud, but also dirty. If you turn down the signal via PRE phase interver master volume on those amps, it kills the signal feeding into the power section and you get a thin, clean output. It's like whispering into a megaphone. You turn down your voice and then the megaphone tries to amplify your whisper. You end up with a loud whisper. This arrangement works fine on the later Marshalls (like everything that came after those amps listed above) because the preamp stages on those amps are "cascaded" and they stack gain on top of gain. The signal is distorted before it even hits the master volume.

On the other side, with a POST phase inverter master volume, you're still cutting the signal before the actual power tubes, but you're allowing the phase inverter tube to overdrive. And in some cases you can get even more gain from the amp this way because the negative feedback circuit collapses and things get even dirtier. So now you've got the preamp combined with the molten overdriving phase inverter signal, which is dirty, going into the power tubes. Even if you cut the level of this signal the dirt is still in there. This arrangement works on any amp, but it can allow too much meltdown on cascaded amps, which is why the PRE version works well on cascaded amps. PRE P.I.M.V. for cascaded preamps, POST P.I.M.V. for non-cascaded. Your amp is non-cascaded.

And it's basically very simply a matter of where you put the volume pot. There's a little more to it, but it's really pretty simple.


The ONLY differences...cascaded preamp on the 2204. The amps are nearly identical otherwise, but where you put the MV really matters.

Edit: I just realized that's actually the wrong schematic for a cascaded preamp 2204, but the master volume part is the same.

you should be a teacher ......

[Greg_L]

you should be a teacher ......

Lol. No freaking way.

[rayc]

you should be a teacher ......

Yes, or instructor - perhaps wiseman on the mountain top.
He knows his oats.

[rayc]

Christmas is just around the corner you know...

Money isn't an issue at the moment - I've been doing some work to accumulate some $$$ for that sort of thing.
Access to a tech for motorcyclist me is more an issue.

[rayc]

The amps are nearly identical otherwise, but where you put the MV really matters.

Excellemt explanation for a layperson like myself.
I'm learning - you're teaching.

[Minerman]

Christmas is just around the corner you know...

Money isn't an issue at the moment - I've been doing some work to accumulate some $$$ for that sort of thing.

Well Ray that's good you've been puttin' $$$ away, but I'd like to help ya man...

Access to a tech for motorcyclist me is more an issue.

Not quite following you on the motorbike thing, but again, I'd like to help you get your Marshall to roar a little more...

[Armistice]

Christmas is just around the corner you know...

Money isn't an issue at the moment - I've been doing some work to accumulate some $$$ for that sort of thing.
Access to a tech for motorcyclist me is more an issue.

Join a car share service temporarily? I'm sure there are plenty around who can do the actual mod.