JTM45/100 build questions...

[Notthedocter]

Hi All..first off...Thanks to all the members who contribute,have learned a ton...
I am starting a JTM4/100 build. It is my first build, and have a few questions(ok a ton of questions, but will limit it to 2 at this point)..
1. I am using Belton octal micalex sockets for the power tubes. They have 2 holes on the lugs. Can I use both holes when running the heater wiring. If so, is there any advantage/disadvantage of running the wires this way? I checked out the Metroamp 100w instructions, and it looks like that is what they are showing. I just wanted to be 100% before I got going. (I am kinda expecting the "thats what they are for" but I cant take it.

Also, the PT that was supposedly recommended was the Mercury Magnetics P100JM-MMF. I cant even find this on there site. It has dual primaries, I dont think I have seen this used on any other 45/100 builds, at least to limited knowledge. I was pretty much trusting the person I was buying it through. But I came across an article that with this type of PT I would need to use a full wave grounded center tap rectifier circuit, not the full wave bridge voltage doubler like on most Marshall 100w. I really have no idea what either is. But it sounded like it made no sense to use this for a 45/100 build..any thoughts?
The wiring for the transformers are
PRIMARY:
0V=Brown 120V=Brn/Wht 0V=Black 100V=Blk/Wht 120V=White
SECONDARIES:
350V=Red 0V=Red/Wht 350V=Red
Green/ Grn/Yel/ Green = 6.3V @ 6A Filament
Yellow/ Yellow= 5V @ 4A Rectifier
Any thoughts on the above are appreciated...
Thank you

[danman]

Feel free to use both holes on the pin to wire the heaters. As for the PT, I don't have much experience with the MM products. I usually prefer to use the Classictone or Heyboer iron that Marstran and Metro sells. Both make excellent products and will save you some coin also! I will ask though, are you working from a particular layout or set of instructions that uses the MM PT? If this is your first build, it can get pretty confusing trying to figure out the different wiring color schemes used by the different transformer makers. Changing the power supply setup to suit a particular PT can cause headaches also, especially if it throws off your bias voltage. If the instructions you are using for the build are calling for that particular PT then that would be the best bet but if you are working from the Metro layout, the Heyboer may be the way to go.

[Notthedocter]

Thanks for the reply...10-4 on the holes..ty
I started out with a Ceriatone kit purchased through Will @ ToneAmps. After getting the kit, I discovered they shrunk the chassis to 22". At this point, I had already ordered the transformers/choke through Will for this build, so I was locked into this layout. I was told that this is what Mercury Magnetics recommended.? I was able to get a pretty good deal(PT/OT/Choke under $500) I returned the kit and picked up a chassis from Valvestorm, and sourced most of the other parts through Will.
What triggered me questioning the PT was being told I could not hook up a regular voltage selector(when I bought it, was told this would be no problem). I started looking more at why dual primaries? why the 5V rectifier? I did send an email to MM as well.
Here is the layout I am following:
http://i1194.photobucket.com/albums/aa3 ... iatone.jpg
Thanks again...any and all tips and insights are welcomed!

[danman]

Alot of the aftermarket PT's will have a 5v tap in case you intend on using a tube rectifier instead of a ss rectifier. You can also wire the amp with both types if you want to have the option to switch between them.

You mentioned dual primaries. Did you mean to say dual secondaries? Some PT models will give you the option of dual secondaries so that you can wire the amp up for a higher or lower B+. Some of the Classictone PT's that I have used in builds will come with three secondary voltage options. This will give you the ability to fine tune the sound to your liking.

[Notthedocter]

Cool..ty..this makes me feel a bit better about it. The switching between the two sounds pretty interesting. I will probably not go down that road at this point just to keep it as straight forward as possible. Straying a bit further, if I wanted to convert this to a Black Flag type build(el34/tube rectified) would that be possible? Albeit, I would have to change some other values on the board. Not it my plan at the moment, but interested to know if it is an option.
For the Secondaries..it has 2-350V taps, with a 0V tap in between them (center tap?). I think this would be considered dual secondaries? On the sheet that came with the OT it states" on dual primary PT's, both primary winding must be used. If you look values listed for the primaries(all taps listed in order in the first post) there are 2-120V's tap listed 2-OV's and one 100V. For 120V usage, it says to tie the 2-OV's taps together, and tie the two 120V's together. It can be wired up for 10V/120V/220V/230/240V. This is all new to me, but on most transformers diagrams I have looked at, I see a 0V-120V-220V-240V taps? I was forwarded an email from the Mercury Magnetics Rep they were dealing with stating that this was the transformer they had that would give about 470 B+ which is Nik had said to look for, so I guess it is what they had that would work. I just wish I would have been told it would not do the voltage selector, cause I would have probably went with something else,...I more than likely would not have used the voltage selector, but I would like to have it on the back panel. Live and learn to ask more questions I guess.(although,I was told it would work no problem initially though).
Any thoughts on the dual primaries?
Thanks again

[danman]

I am not familiar with that type of primary so I don't want to give you any wrong info. The secondary side is not a dual secondary like I was referring to in some of the Heyboer and Classictone PT's. With that style you will only have the option of one B+ voltage.

[Notthedocter]

Fair enough...I heard back from Mercury Magnetics today. It is a Universal Voltage Primary, and can be wired for 120V or 240V. So I can use the voltage selector that will match the impedance selector, and just wire it two 120V. Dang...kinda wish they had just told me that in the first place...
Thanks again