Step Down Transformer - 240v supply to 110v MP-1

[CJR09]

Hey CRJ09, so you need to desolder the stuffed battery (under side of PCB) and solder in the battery holder (hopefully the pins line up) and get it the right way around (+ve and -ve).  It's not too hard to do but if you don't have a decent temperature controlled soldering iron and don't know how to do this stuff then take it to a decent tech to do for you.  The last thing you want is to damage the PCB traces and pads where it connects (which unfortunately is easy to do).  Once the holder is soldered in, future battery changes are then easy.

The 1.38 EPROM is the original, so order a 2.01 from MJMP (MJMP Mod Shop).  Swapping the EPROM is a little fiddly so you may want the tech to do that also (easy to bend/damage the pins).  Though no big rush, 1.38 works fine, 2.01 is a bit better but doesn't change the sound.

You can also get a battery holder from MJMP that is correct for the PCB holes if the Jaycar one isn't correct.  Although typically the jaycar ones are ok as far as I'm aware.

Tubes is a different rabbit hole, the GTs will be fine but there are better tube options.  Lets go there down that track after you get it working and having some fun.  You have to do the battery, all the other stuff you can do down the track.

The rear jack mod is also a good idea, again no rush.  But if you are ordering some bits from MJMP may as well get all the things you need so just one postage (MJMP is in Belgium).  Again the jack mod takes a bit of soldering skill.  MJMP also has a replacement transformer (MDRT) which can use 110v or 220v, he gets these custom made.  So then you don't need a step down transformer.  The MDRT does change the sound, it opens up the MP-1 dynamics, some prefer the original sound.  Currently MJMP doesn't have any 220v original MP-1 transformers, though he may have one tucked away .

Looks like a decent clean unit.  Looks totally stock except for the tubes.

All done - the Jaycar batt holder dropped straight in - bit fiddly to solder in though, you are right on that front.

I wont show you my soldering iron - its a $10 budget automotive jobby - I did however get some proper tinning jam and fine resin flux solder - scrubbed her up, tinned it and it worked a treat, I can see how that would go pear shaped though - would not have wanted it any trickier due to the size of iron!!

So put it back together, fired it up - seemed like it went through that testing stage forever - like at least 5-10 minutes. Got the presets loaded in - left it for a while - its late at night here so have not cranked it - but anyway, shut it down - left it for another 10-15 min - booted it back up - it test cycled for a little bit - maybe 30sec - I do get the ADA now after the 8888 and 138 flashing on the led screen - then she stabilized and settled on the preset I had it when I shut it down.

So likely a win there!

Find out tomorrow when I crank it :) 

Not sure what else I will do - probably the EPROM, and I'm open to swapping out tubes - what are generally the go with these? They are a rabbit hole and there is plenty of evidence floating around saying they make all the difference and plenty saying they make no difference - so who knows?!?

What age would the GT's be? 90's? any way to tell - are they date stamped?

Anyway - cheers for all the help and advice - its really appreciated and help take away the overwhelming feeling one gets moving to this sort of gear, cheers!!

 

Edit : just fired it back up again and from turning it on to getting to last used preset now takes only 5 or 6 seconds - so just out of curiosity - how long should it take?

This one cycles through the leds, the 8888's, the 138, and the ADA twice, then goes to last used preset

[rnolan]

  well done  .  So now you have a working unit, run it in stereo (if you can).  I used patch 1 (Marshall (ish) and modded it to my taste (when I used a MP-1), great starting point.

Ok, so tubes, don't know if you can date them .  But I can say "categorically" they all sound different.  Most tubes GTs included are rebadged (they wash off the labels and re label them).  There are only 3 (maybe 4) places that actually make tubes, Slovakia (JJs), China many and varied, and Russia (mostly Reflector factory) also many and varied.

Tube choice is very subjective, as they all have different (audio) characteristics, you can do 2 the same (as your unit is) or you can pick different tubes for V1 and V2.  V1 comes before V2 in the circuit.  When you have a hour or 2 spare, read some of the tube posts (Tubes).

My first tube swap in my old MP-1 was Boogie SPAX7s (because I could buy them locally).  Boogie buy and re-badge tubes but most often they are JJs.  They worked well in MP-1.  But it depends what you want/like.  Some are more High Gain than others and different internal designs sound different (e.g. Short plate vs Long plate).

I'm a huge fan of Mullard Long plates (Mullard Long Plates).  They are Russian tubes.  The long plate structure makes them more 3D (as in if you slightly change the pressure of your left hand finger on a note, you can hear it).  They are my choice for MP-2 but also work really well in MP-1.

But hey, that's my take on it, others like other tubes for various reasons.  Anyone who says different tubes don't make any difference in ADA preamps (or any guitar pre amp circuit for that matter) is full of shit.  E.g. Marshall's were designed around Winged C Russian tubes (from St Petersburg and no longer available), Sovtek tubes work well in those circuits (I've heard the comparison), and come from the same factory as the Mullard long plates.

But hey get your MP-1 up and going first, when you are more settled, a tube swap is a good idea.  Those GTs are probably a bit old, but how do you know?

[CJR09]

well done  .  So now you have a working unit, run it in stereo (if you can).  I used patch 1 (Marshall (ish) and modded it to my taste (when I used a MP-1), great starting point.

Ok, so tubes, don't know if you can date them .  But I can say "categorically" they all sound different.  Most tubes GTs included are rebadged (they wash off the labels and re label them).  There are only 3 (maybe 4) places that actually make tubes, Slovakia (JJs), China many and varied, and Russia (mostly Reflector factory) also many and varied.

Tube choice is very subjective, as they all have different (audio) characteristics, you can do 2 the same (as your unit is) or you can pick different tubes for V1 and V2.  V1 comes before V2 in the circuit.  When you have a hour or 2 spare, read some of the tube posts (Tubes).

My first tube swap in my old MP-1 was Boogie SPAX7s (because I could buy them locally).  Boogie buy and re-badge tubes but most often they are JJs.  They worked well in MP-1.  But it depends what you want/like.  Some are more High Gain than others and different internal designs sound different (e.g. Short plate vs Long plate).

I'm a huge fan of Mullard Long plates (Mullard Long Plates).  They are Russian tubes.  The long plate structure makes them more 3D (as in if you slightly change the pressure of your left hand finger on a note, you can hear it).  They are my choice for MP-2 but also work really well in MP-1.

But hey, that's my take on it, others like other tubes for various reasons.  Anyone who says different tubes don't make any difference in ADA preamps (or any guitar pre amp circuit for that matter) is full of shit.  E.g. Marshall's were designed around Winged C Russian tubes (from St Petersburg and no longer available), Sovtek tubes work well in those circuits (I've heard the comparison), and come from the same factory as the Mullard long plates.

But hey get your MP-1 up and going first, when you are more settled, a tube swap is a good idea.  Those GTs are probably a bit old, but how do you know?

Cheers for the run down...   how long 'should' the mp1 take to boot up and is a bit of 'cycling' normal?

The tubes in this one are at least 20yr old - the last it was used was for an album recording circa 2003/2004

[rnolan]

No  worries , it should boot fairly quickly, it's been a while since I used MP-1 but it never took very long.  My MB-1s ( the bass variant) take a long time to boot , but MP-2 and MP-1s boot very quickly (or should) but it's not instant, the tubes need to warm up to be usable.

[rnolan]

Re tube date/age, tubes deteriorate over time with use, they have a burn in phase (a few hours/days), then they settle, then over time (if being used) they change and get a bit fuzzy eventually, and hey some like that sound. If they are not used, they last a long time.  The big difference between the life of modern vs vintage NOS tubes is the vacuum.  In the "old days" let me get my walking stick LoL, they used to "pump" the tubes (create the vacuum) much longer.  The better the vacuum, the longer they last (same as a light bulb). So back in the day they used to "pump" the tubes for 2 hours or so maybe more??, these days  they "pump" them for 30 or 40 mins.

[CJR09]

Yeah cheers for the links and info - not sure if I am keen to do the transformer upgrade, don't really want to alter original tonality/character of the MP1 too much

So far - keen to try your Mullard long plates, JJecc83, or sovtek

Kind of like the idea of a mullard in V1, JJ V2 perhaps

As for sound - I like big and open, but also want definition / clarity - kind of always been drawn to soldano, and had an OG 5150 stack back in the day but was too big to be carting everywhere for the clubs we used to play so mostly ended up with 50/100w combos, only recently started getting back into heads and cabs with the advent of the lunch box stuff

always played a bit of everything - punk / hard rock / metal - 87 to 92 golden years - but basically just like anything that is good and well written

[Iperfungus]

Very good score!!
You've a working MP-1 at home now.

My first MP-1, in the first 90s, was a 1.38 like yours that I bought used from a friend.
I sold it many, many years later...and I started missing it many, many years later on...

So I bought a used 2.01 in 2016 or 2017 and I subscribed to the Depot.
And here we are.

MJMP modified my MP-1 so that it will be ready for the next 30 years (all pots have been replaced, battery mod, noise mod, new TubeBoard for MDRT transformer and, of course, a MDRT transformer).
I had other tube and solid state MIDI preamps after that (Marshall JMP1, Digitech GFX-1 Twin Tube, Tech21 PSA-1, Rocktron Chameleon...), but I sold them all and kept my MP-1.
Because I love it.

The original transformer has been used by MJMP to repair the MP-1 of another Depot user (Danny Joe Carter) at that time and I remember that it was hard to find an original one.

You can live with the stepdown transformer or go for a MDRT, but you'll need MJPM in that case!
As Richard said, the MDRT opens the MP-1 sound a lot and adds some headroom: tubes are powered by 240V, instead of 190V from original transformer.
You loose some original MP-1's "creaminess" (I mean compression) and if you like it or not it's a matter of tastes.
Personally, I love it a lot after mods.

About tubes, I did some tubes rolling (you can find threads around here) and I ended to put a couple of Ruby selected JJs ECC-83.
I love it.
I still have its original red labeled 12AX7-A chinese tubes.
GT-7025 tubes work nicely inside the MP-1: my 1.38 had GT tubes inside!
It had PM chinese tubes when I bought it, but I replaced them quickly with the GTs.
Preamp tubes have long life, so your GTs could be still alive and kicking.
The original tubes of my MP-1 are still plenty of life.

So...welcome here and have fun! 

[Harley Hexxe]

CJR09,

  It's normal for the MP-1 to cycle through self-testing mode before starting up, and yes, they typically go to the last preset you were on when it was powered off.