New amp day - Mesa Mark III - no stripe - #25

[sloanthebone]

After getting my Mark IIB, I have been peaking around for a Mark III and found this guy locally. It is #25 of the Mark III series dated 4/85. DRG, 105pt, g12-125 speaker and Imbuia hardwood cabinet (or Imbuya, not sure of correct spelling, someone educate me, got mixed results from the wisdom of the internet). Has all 3 pedals which I think is kind of rare since I don't see many for sale with them all.

The guy I bought this from got this in 1985 in a store up in Baltimore Maryland after someone ordered 2 of them and returned them the next day because he hated them. MSRP was $1,800 and he walked out with one for $1,250. Had a great time talking to this guy because he was from my neck of the woods and used to go into Paul Reed Smith's guitar shop before he became what PRS is today.

Anyway, the amp is in fantastic shape and sounds even better. I played this as is and then ran it through my Fryette PS2 attenuator and 2x12 vertical cab. The attenuator is great for cranking everything up and getting that metal sound but there is something special about playing this as is through the combo itself. Not sure if it's the wood or the speaker or the combination of both but it is just beautiful sounding. Quick comparison with the Mark IIB attenuated and the Mark III can definitely get heavier but I think the IIB hung in there very well. Still some experimenting to do to see how close I can get them.

Thank you to Electric Mayhem for your advice!

Enjoy an absurd amount of pics!

 

[sloanthebone]

Gut shots +

 

[Darkstar2]

THAT is one NICE score - congrats! I need me one of these...

 

[kmanick]

Congrats!!!!!

 

[Klugster]

Sweet!

 

[user 41014]

Just beautiful. Worth the trip. Many times over.

 

[user 41014]

Hey I know we talked about service at Petaluma but even tho your filters are 1984, your 30uF's have red ends and your 220's have black ends. You do not have filters in there that need to be changed like the poly ended ones if they are not bad. And if just one goes bad I might be able to hook you up to keep that thing original.

With the ATOM chemicals fiasco, IC not making them, and BMI no longer making them your best option for 30uF filters may be sitting already squarely in the amp you just bought. I have tested Mallory's from the 80's I've replaced that, not all, but some blew the replacements out of the water for ESR and were easily within spec.

Mike will tell you there is a lot of filtering going on anyway, but in your case if it's not broke don't fix it.

I would not touch a thing and before you send that to the factory I bet there is something in my arsenal we could trade for.

Edit: I would check the pair of big honker .1uF coupling caps hanging over the top right of V5 when looking from the back. Make sure they are not 400V and if so get 630V ones in there.

2nd edit: And a nice padded road case

 

[Craig E.]

Very nice amp. I saw it for sale here in Florida. I would have bought but I sent money on a simul satellite for my mark IV 2days before this was listed. Enjoy!

 

[rarebitusa]

Dang that's a total score!!! Congrats

 

[spawnofthesith]

That is incredible!!! Congrats!!

 

[xdg999]

Nice! I've been playing through my No Stripe DRG lately. It also has the 105. I sent it to Mike B. for service and the R2/+ mod. I have Chinese Square Getters and 415's / 416's in it. They're great amps. Very close to a c+.

 

[sloanthebone]

Nice! I've been playing through my No Stripe DRG lately. It also has the 105. I sent it to Mike B. for service and the R2/+ mod. I have Chinese Square Getters and 415's / 416's in it. They're great amps. Very close to a c+.View attachment 3513

Looks very familiar! Was “EQ Auto” an option? Your on light looks to be orange where mine is blue also. Always cool seeing the differences in each one.

 

[xdg999]

Mine has a leftover Gain Boost faceplate. I found some orange pilot lights so all of my Mark 3's have them instead of the blue ones.

 

[sloanthebone]

Mine has a leftover Gain Boost faceplate. I found some orange pilot lights so all of my Mark 3's have them instead of the blue ones.

Oh yes it does! What # is yours?

 

[sloanthebone]

Hey I know we talked about service at Petaluma but even tho your filters are 1984, your 30uF's have red ends and your 220's have black ends. You do not have filters in there that need to be changed like the poly ended ones if they are not bad. And if just one goes bad I might be able to hook you up to keep that thing original.

With the ATOM chemicals fiasco, IC not making them, and BMI no longer making them your best option for 30uF filters may be sitting already squarely in the amp you just bought. I have tested Mallory's from the 80's I've replaced that, not all, but some blew the replacements out of the water for ESR and were easily within spec.

Mike will tell you there is a lot of filtering going on anyway, but in your case if it's not broke don't fix it.

I would not touch a thing and before you send that to the factory I bet there is something in my arsenal we could trade for.

Edit: I would check the pair of big honker .1uF coupling caps hanging over the top right of V5 when looking from the back. Make sure they are not 400V and if so get 630V ones in there.

2nd edit: And a nice padded road case

It’s appears they are 400v. Why does this matter?

 

[user 41014]

They go over-voltage at 400V, one usually shorts and then one half of your power tubes starts to redplate. Better to get them out of there proactively and the Mesa store sells the .1uF / 630V. There is also a resistor Mike beefs up the watt rating on. I'll have to look up which one or someone else can chime in.

https://store.mesaboogie.com/products/capacitor-film-met-poly-1uf-630vdc.html

 

[Henz]

They go over-voltage at 400V, one usually shorts and then one half of your power tubes starts to redplate. Better to get them out of there proactively and the Mesa store sells the .1uF / 630V. There is also a resistor Mike beefs up the watt rating on. I'll have to look up which one or someone else can chime in.

https://store.mesaboogie.com/products/capacitor-film-met-poly-1uf-630vdc.html

The 680 ohm LDR supply resistor?

 

[user 41014]

The 680 ohm LDR supply resistor?

Please tell me about that one- I am not familiar.

I was thinking the "reverb mod" that might be beefing up the wattage of a resistor I can't recall - maybe the plate of the reverb driver? Memory doesn't serve me on it.

 

[RayBarbeeMusic]

Lottery win, grats!

 

[Henz]

Please tell me about that one- I am not familiar.

I was thinking the "reverb mod" that might be beefing up the wattage of a resistor I can't recall - maybe the plate of the reverb driver? Memory doesn't serve me on it.

Sure. I'm basing this on my C+. I have zero experience with any other MK. While on stand by for app 3 hrs one eve , I opened studio door and its filled with smoke. Sent it to Mike. He rebuilt The affected area. He told me that those resistors get pretty hot. This was mid 90's. Since then , I believe he puts 3 watt wire wound in now instead of the factory 2 watt carbon. Tell me more about this reverb mod please. Is that just for MK III ? Because in my C+ there's no resistor on the driver plate. Upstream it has the 10k 3 watt off B+. Is that what you're referring too? Just lead from verb transformer on tube plate pin. My verb output plate has a 100k .