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Tube Audio Lab 300B Stereo

Modified version of JE Labs 300Bdx

Split rail power supply with different cap values, 5Z3 rectified

2x 300Bs, 2x 76s, and 2x 6sn7

8 watts per channel, pure class A

Single Ended Directly Heated Triode

Completed on 2/26/09


Built on 17x 10 x 3 steel chassis painted in hammertone grey.


Notice the different layout this time - I usually group OPTs together and have the PT on the one end of the chassis. I mostly did it for my entertainment. It turned out pretty good, in my humble opinion. Maybe I ought to try this layout more often.





It's no fun to see your beloved 300Bs and precious preamp tubes blow up on power up. This is why I always use a time delay circuit board to warm up the tubes first before the HT plate volts kick in. 


One of the input driver (76 tube) section, notice the cloth lead wires. I am trying to keep things look vintage, even inside. I love those NOS Sprague Atom 'lytics, as well as those huge Russian military PIO coupling caps.


I find those James 6123HS 20W OPTs to be a match made in heaven for JE Lab circuits. They are an excellent cost-effective alternative for those that want Hashimoto-like performance.


Beauty is only skin deep - I have tendency to put in more efforts to keep the inside more beautiful than the outside. Careful planning in layout keeps sound artifacts and hum out. Notice there are more irons under the amp than the above.

I am a big fan of JE Labs' designs. The 300Bdx certainly is one of them. I built a monoblock version of it before and it was very well received by my buyer (Vern's amps).  I wanted to build it in stereo, but I wanted to use a split rail PS with a choke in each channel. I also wanted to use the 5Z3 rectifier instead of 5U4G, so I redesigned the PS accordingly. The result of this is tighter bass and improved channel separation. The amp sounds really good. This probably is one of the most transparent amp I've heard. This amp certainly will please any SET fans that like all triode driven 300Bs. I have also built a linestage using the same combination of preamp tubes (6sn7 and 76) with a great success. The linestage seems to work great with the 300B.

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