JE Labs Simple 46.

[reinderspeter]

Very tidy!
Nice work

[je2a3]

The project looks great! What output transformer will you use?

JE

[Chris65]

Hi Joseph,

Firstly, many thanks for sharing your design and good to see you here! Output transformer is James Audio, I managed to get a pair just after they stopped manufacture.

[je2a3]

Nice! That must be the 6115HS...

Enjoy!

[Chris65]

Completed the amp (mostly) at little while ago:

   

Power supply is RCLCLC, first capacitor is series 47uF caps paralleled with 100k resistors which act as voltage divider & bleeder. B+ ended up being close to target at 300Vdc with 5V4G or 5Z4G. Tried 5Y3 (too low at 275Vdc) & GZ34 (too high at 315Vdc) also.

FT-3 coupling caps bypassed with some vintage Sangamo 10nF paper-in-oil capacitors
Amp is very quiet, no hum at all just some tube rush when volume turned up to maximum.

   

However, I put it aside after first finishing it because it sounded, well...not very good. Seemed strange, as voltages looked ok & nothing obviously wrong. Know of the reputation of the FT-3’s taking time to break-in from Peter & others, but thought that they shouldn’t sound this bad .
Took some time away & after a bit of thinking, realised I made a wiring mistake which will be changed which should fix things.

[SteveM]

Very nice, the underside looks as good as the top side!
Put some sturdy legs on the top & a clear bottom cover then turn it upside down 
Good luck sorting it out.

[low pitch]

Those single mounting point tag strips are neat, where do they come from? Couldn't find them on ebay.  Nice build.

martin

[Marc VdM]

Hifi Collective in the UK has nice ones.



Marc

[Chris65]

Thanks Steve, I did actually put a clear base on my Reduction Phono https://www.lencoheaven.net/forum/index.php?topic=13041.150 but I don’t use it upside down .

Martin, the tag strips are from eBay, try searching for ‘tag terminal strip’. Usually get these parts from sellers ‘GD Parts’ or ‘super-market8’, both have been reliable.

[mred]

Beautiful build Chris
Glad you found the issue, I know how it feels  
FT3 caps are awesome.

[Chris65]

Thanks Ed .

Fixed the wiring & added some resistors to the filament/heater supplies as they were 10% high - expected that as the wall voltage here is quite high most of the time, around 240-245VAc.
Added the final parts, complete for now. Will change the first R after the rectifier to drop just a few more volts to get closer to 290Vdc on the #46 plates, ordered some Mills 12W.

   

   

   

[paul300b]

Many years later…….
Hi Chris, how was this amp? Did you like it, and what are you using now?
Cheers,
Paul

[Chris65]

Many years later indeed Paul ...time flies too quickly.
Sorry for the belated reply, but yes, been very happy with this amp, gets rotated through the system along with the others in my collection.

[rfgumby]

I hadn’t seen this before Chris.   Beautiful work.   I happen to be a large inefficient speaker (often acoustic suspension), so low power is not my bag.   But at least one friend is a super flea power aficionado, and his system has cool attributes- so I get it!  The one friend is a field coil hyper exotic Japanese driver guy, and the kids are sublime.

I have a rather extensive tube collection, do you have enough 46 tubes, or would you like me to keep an eye out for you?   I bet at that plate voltage and minimal current they take forever to wear out, but I thought I’d ask.

Again, nice work.  And I’m quite picky about builds like this, so great job.

(edited. I was on my phone again, and I'm amazed at the typo's I see when looking at my posts later. I can't even blame spell check this time)

[Chris65]

Thanks Scott.
I guess you mean 46 tubes - thanks for the offer, I'll keep it in mind if ever needed.