opinions and input appreciated for my next JTM45/100 build

[Dom]

Hi forum members,

I'm going to build my second JTM45/100 clone and before starting to assemble it I want to get some input from you which decisions to make:

-input resistors: 68K 0.3W Pihers or 0.5W AB CCs ?
will the Pihers close to 0.5W ones?

-PI resistors: Piher or AB CCs 1M resistors?

-Rifa or F&T 33uF caps?

-Larry grounding scheme or original grounding scheme?

-Bias dropping resistor: is 220K or 150K the original value?

If anybody has a 82K or/and 470R 0.5W Pihers and is willing to trade or sell it, please PM me.

Currently specs:
head from George
boards from Brian H.
OT from Brian W.
PT and 5H choke from George.
22uF Vishay preamp filter cap
milled aluminium endblocks
laser cut chassis (endblock style - dimensions)

I'm just waiting on three to four parts, then i'll start to build it.

Thanks for your reply!

Cheers,

Dominik

[shakti]

I'd recommend RIFAs over F&Ts. I haven't tried RIFAs in a 45/100, but tried both F&T and RIFA in my JTM100 black flag, and preferred RIFAs overall.

The Larry grounding scheme made a vast improvement in my 45/100.

150k before the diode in the bias circuit.

On the input grids you don't have any serious voltage, so I doubt 0.33w vs 0.5w makes a difference on the 68ks.


Where did you get the chassis and endblocks, and do you have a photo??

[Dom]

Ok, here are some screen shots of the end blocks in 3D CAD.

At home home I can upload some pics of the milled end blocks.
The chassis will be lasered and bended next week and I hope that it will well fit to the end blocks.

What's the best place to get those Rifas?

Cheers,
Dominik

[neikeel]

How did I miss this thread

Look here:http://uk.rs-online.com/web/search/sear ... &R=2267306 although didn't Roe have some spares?

[VintageCharlie]

From what i've read most people who had the chance to compare, prefer the RIFA's. Also Brian W. suggested to go with RIFA's for a 45/100. I got them from Elfa - it's a company that is quite widespread in Europe and i think they also do have a store in Germany, or, at least, they ship to Germany. They're not cheap, but also not more expensive than F&T, IIRC.

I'd go with 1/2w 68k pihers - especially if you have a full, or nearly full set. You got a PM, by the way

For my build, i'll go with the Larry grounding scheme - so much good stuff about it is written here on the forum. Only reason to go with the original grounding scheme would be if you're after a 100% authentic build, but that is not possible, as there will always be some modern parts and this would also not be the right place to be too "period correct" about.

Wish you luck for the build and hope you'll keep us posed with lots of tasty pics, etc.

Regards,

VintageCharlie