The Boogie Board

Discussion Forum for Mesa Boogie Products
It is currently Wed Jun 28, 2017 9:01 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: Wed Mar 01, 2017 10:20 pm 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
So we all know it's a HRG. Here's what I don't know. Was it a factory or a modded c? Now, I don't care about that, what I'm getting after is I wonder what transformer is in it? More specifically which transformer did they use when they reverse engineered it for the JP-2C?

I've felt from the beginning of having mine that it has some sag. I've been reading about the differences between the 100 & X101 that ran more of a normal voltage out of the transformer and had some sag vs. the 105 that runs hotter and thus has more attack and headroom.

You guys have any thoughts on this?

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Fri Mar 03, 2017 1:08 am 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
Well, I measured what I have for comparison. The power transformer in the JP is 3 7/8" deep. The X101 PT in the IIC I just picked up (:D) is 3 7/8" deep. Hmm..

I read an old post where a guy said his 105 PT was 3 1/2" deep, maybe someone here who has one can verify? Same question to any guys who have a 100 PT?

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Fri Mar 03, 2017 6:47 am 
Offline
Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2104
Location: North Carolina
I am going to throw this out just because.... If they reverse engineered the actual transformer, it would have been destroyed in the process. However, what you may see on the outside does not mean you will have the same on the inside. Many things have changed over the years in terms of materials used, type of insulating system, varnish, copper alloy, laminations materials (what type of steel is it) and its efficiency. It is what is inside the core is what makes a difference. I would not go by outside dimensions as the means to verify if one is the same as the other that was made some 30-40 years ago unless you are comparing something that was made in the same era.

_________________
TC-50 HD
JP-2C HD
MARK V C
ROADSTER HD
RA100 HD
RA100 C


Top
 Profile  
 
PostPosted: Fri Mar 03, 2017 9:06 am 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
Well then, I guess it's time to see what plate voltage the JP PT is running. Copied from elsewhere-

Early 100 - 100-162318 - 448V
Simul/60-100 Power - 105-162318 -483V+
X101-162318 – Export - 448-460V
180W - 0180322 Coliseum - 500V+

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Sat Mar 04, 2017 8:19 pm 
Offline
Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2104
Location: North Carolina
That would definitely be a better comparison..... Voltage at load would say much more than the dimensions of the steel laminations of the Transformer if comparing models from different years vs something new and something old.

_________________
TC-50 HD
JP-2C HD
MARK V C
ROADSTER HD
RA100 HD
RA100 C


Top
 Profile  
 
PostPosted: Sat Mar 04, 2017 11:28 pm 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
I have a bias tester probe, just need to find the motivation to pull the chassis out!

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Tue May 02, 2017 9:11 pm 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
I tested my X101, the PV is 444v. I'll test my 105 & the JP later.

That said, I was chatting with Mike B. about something else & asked him this question- he told me that when designing the JP transformer the 105 was the objective, however they did back off the plate voltage.

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Wed May 17, 2017 11:00 pm 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
My 105 PT is running 515 PV. Learning more about this I can see why they chose to back it off- the only tubes Mesa has that will take that abuse are the STR-425s. I'm betting they backed it off so they could run STR-440s in it. At the 105 voltage you really should be springing for old 415 / 416s.

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Fri Jun 09, 2017 9:39 am 
Offline
Mark II

Joined: Mon Sep 29, 2014 12:17 pm
Posts: 130
Location: Canada
So why the suspence GJgo? What did the JP-2C measure at?

_________________
Mark V
Studio Preamp
formerly: Quad Preamp, Rocket 44 112


Top
 Profile  
 
PostPosted: Fri Jun 09, 2017 10:52 pm 
Offline
Mark III

Joined: Sun Mar 06, 2016 10:38 am
Posts: 178
Location: Western Colorado
Sorry, I'll have to pull the chassis to measure it & I haven't done that yet. When I do, I will report.

_________________
My Half Ass Tone Comparos


Top
 Profile  
 
PostPosted: Tue Jun 13, 2017 9:20 am 
Offline
Donating Member
User avatar

Joined: Mon Jan 24, 2005 10:36 pm
Posts: 1442
Location: DC Metro Area
The JP2C transformer was reversed engineered from the 105 PT. As stated earlier, they just reduced the plate voltage.

From everything I've seen, Petrucci's go-to Mark IIC+ amps have been factory originals. You can see the "Pull Deep" script on the faceplates of them. Being short heads, it would be very unlikely those were upgrades. Not impossible, but very unlikely. Not to mention Petrucci has stated how he studied up and learned the differences in upgrade vs non, transformers, etc.

_________________
Boogie user of 20+ years, previous owner of 150+ Rectos, author of the previous "2 Channel Recto User Guide" and current "3 Channel Recto User Guide" (in progress).


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group