Wrapping my head around the infamous 105-PT

[MonacoElite]

I've heard folks promote these 105 power transformers like they're important, but it seems like from my admittedly very basic understanding, they aren't really optimal.

Based on what I'm told, these bigger 105 transformers run a higher voltage across the plates of the tubes which necessitates a lower grid bias. This lower bias essentially pulls the intended Class-A operation (~50% idle) towards Class-AB operation (~10% idle). I don't know how close it gets to Class-AB. Maybe someone can elaborate?

Anyhow, it seems to me that if someone really wanted Simul-Class, they ought to prefer the Simul-Class transformers with their lower voltages. That would be easier on the power tubes and allow true Class-A operation (which is the goal of Simul-Class). If on the other hand someone didn't like the idea of introducing Class-A, they'd be better off with with a standard 100w or 60w (non-Simul) model.

It seems to me that based on what I'm learning, my Mark-III DRG with its 105 is sort of "in the middle." I guess it's a "sort-of-Simul-Class" amp.


So, I don't get the hype of the 105 transformer. It's not maximizing any particular function. What is it specifically doing that makes it desirable?


And yes, I get that it's a way to associate your amp more closely with the IIC+ amps, but it's got to be more than that.

 

[Markedman]

It's all in the sound! Who, well you, but, who else really cares if something on paper doesn't work but in real life is the greatest thing ever. Paralysis by analysis.

 

[MonacoElite]

It's all in the sound! Who, well you, but, who else really cares if something on paper doesn't work but in real life is the greatest thing ever. Paralysis by analysis.

Well, haha, yeah, I guess.

To be fair, I'm just trying to match up what is technically correct with what notions seem to be general consensus online with what my own personal experience is.

The weird thing about this 105 issue is that it doesn't seem logical that folks on either side would prefer it since the design appears to place the amp somewhere between the Simuls and non-Simuls.

If you like the brighter Simul-Class sound the 105 isn't necessarily helping that because it pushes the amp away from Class-A operation. Yet, if you prefer darker, non-Simul tones then there's no reason to have a Simul in the first place.

So I'm hoping someone can straighten me out there because if that's correct, I'm having a hard time understanding why there's a draw towards the 105 transformer other than its mere association with the Holy Grail.

 

[xdg999]

Do like the way your Mark lll sounds now? If yes then maybe start with the R2 mod and some good tubes. I let you know how my 105 Mark lll+ sound when I pick it up this weekend.

 

[MonacoElite]

Do like the way your Mark lll sounds now?

Well, I'm purely an at-home enthusiast. I've played guitar for about 20 years and I'm a sharp player, but I'm not a professional musician, nor do I record and post things to YouTube. So what I do is pretty inconsequential in that it's purely for my own enjoyment jamming at home.

So do I like the way it sounds now? Well, that's tough. This is surely one of the coolest amps I've owned given the immense territory it covers and the fact I can get it sounding good without blowing my windows out. The clean is beautiful in a way my old Dr Z was--just really pure. The gained-up sounds are nice, but they're far from perfect. It's definitely too bright. Grainy is another word I hear used and that's also accurate. It's definitely kind of sharp and metallic in a kind of 80s way. It's thrashy. Then again, this ought to be a great basis for someone who's often jamming on Metallica and DT, right?

So I can't really think of another amp I'd prefer to have per se, but I can definitely imagine this one sounding better and more refined than it does. I mean, I think the + mod is exactly the kind of thing I would want to do.

My biggest concern now whether it's smart to keep dumping money into this thing or just cut bait and bite on a JP-2C.

If yes then maybe start with the R2 mod and some good tubes. I let you know how my 105 Mark lll+ sound when I pick it up this weekend.

Definitely let me know what you think about yours. I'm very anxious to hear back.

What exactly is the R2 mod? I thought it was just a volume control for that channel. Am I wrong?. I know that comes included with the + mod from Mike. But nonetheless, that R2 channel still seems like the least of my concerns being as how I only occasionally flip over to it for a fatter clean with my Antiquity-loaded Strat since R1 is so distinctly crystalline.

 

[modder]

The 105 transformer isn't the holy grail. It's a bit of a meme. 100s are fine, x101s are fine, 105s are fine, 60W transformers are fine. They're all slightly different. 105s have a mystique because they're the only big irons you can get on a III, along with the bigger export ones.

That's not going into Coliseums either.

 

[MonacoElite]

The 105 transformer isn't the holy grail. It's a bit of a meme. 100s are fine, x101s are fine, 105s are fine, 60W transformers are fine. They're all slightly different. 105s have a mystique because they're the only big irons you can get on a III, along with the bigger export ones.

That's not going into Coliseums either.

Ok, I appreciate the info.

Can you give me any actual perspective on how the 105 compares to others in tone or response...or even whether what I described was accurate? I'm going off what I've learned by reading a Randall Smith pamphlet I have. ; )

Is it like going from a 50w Plexi to a 100w version for instance, where the 100 is bolder and more percussive?

I'm trying to get a sense of what people actually see in the 105. I understand this is a particular question, but that's why I'm asking it directly. I understand this kind of puts people on the spot but hopefully someone's got sufficient experience comparing (similar) models with and without the 105.

 

[xdg999]

My Mark lll+ with the x101 is closest to my upgraded DRG c+. It’s 99.99% there. The 105 Mark lll is a whole different animal. It didn’t sound or feel like any of my c+s but it’s still an awesome amp. If you lived near Chicago I’d let you try the amps. I can’t wait to pick up the Mark lll. I also have to pick up another DR c+ combo I just bought.

 

[woodbutcher65]

How does the export model (switchable voltage) transformer stack up against the 105 and other types?

 

[gts]

How does the export model (switchable voltage) transformer stack up against the 105 and other types?

Not sure what info you're looking for but some consider the Xport tranny to be a Holy Grail of sorts when found in a fully loaded (DRG) IIC+ (DRG = Simul, EQ, Reverb)

As for voltages of the various PT's being asked about

Early 100 - 100-162318 - 448V
Simul/60-100 Power - 105-162318 -483V+
X101-162318 - Export - 448-460V


I've had various C+'s in different configuration and PT's.
The best 'head to head' comparison would be a DRG with the 100 to one with the 105
Slight bit of sag with the one with the 100 but so subtle most people wouldn't know it.

The only C+ I had with the X101 was a 60/100. It was a very sweet sounding amp.
Sold it a couple of years ago. Not sure what I was thinking.... well I do but I'm not telling ;-)

 

[iamrobk]

How does the export model (switchable voltage) transformer stack up against the 105 and other types?

Not sure what info you're looking for but some consider the Xport tranny to be a Holy Grail of sorts when found in a fully loaded (DRG) IIC+ (DRG = Simul, EQ, Reverb)

As for voltages of the various PT's being asked about

Early 100 - 100-162318 - 448V
Simul/60-100 Power - 105-162318 -483V+
X101-162318 - Export - 448-460V


I've had various C+'s in different configuration and PT's.
The best 'head to head' comparison would be a DRG with the 100 to one with the 105
Slight bit of sag with the one with the 100 but so subtle most people wouldn't know it.

The only C+ I had with the X101 was a 60/100. It was a very sweet sounding amp.
Sold it a couple of years ago. Not sure what I was thinking.... well I do but I'm not telling ;-)

Just curious, I have an SRG with the Export transformer (but no export switch... I'm guessing Mesa just had extra X101's). Is mine just running at 448V, while the X101's on the 100W and Simul-Class run at 460V? Sounds killer either way.

 

[candletears7]

My take is that the X101 is spongier and compresses up a little bit nicer than the 105 which is bolder and more high headroom.

 

[GJgo]

I have a couple 105s & a X101 IIC+ / ++. I've had a few Mark IIIs.

The 105 has an amazing feel. The IIC+ has an amazing tone. Combined they're incredible. Synergy is a thing.

IIIs are more harsh, a III with the 105 is nice but it's not the same. My red stripe was still the best III I've played.

Here's a bunch of my tone comparos you might like, including the III vs. JP2C, C++ 105 vs C+ X101, and more.
https://www.youtube.com/user/fast13b/videos

All personal preference of course, but at the end of the day I've sold (or am selling) all my Marks but my C+ 105s.

 

[xdg999]

My lll+’s are not harsh sounding at all. I had Mike B. reduce the brightness when he did the lll+ mods. The lll+ 105 is smoother than the lll+ x101 but both are awesome amps. I let another forum member try the lll+ 105 yesterday and he agreed it’s really close to a c+.