DRD300b Welborne amps designer - 33dot33rpm - Tubes Asylum

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DRD300b Welborne amps designer

In Reply to: Shuguang Treasure 300b in DRD300b Welborne amps. posted by Michael Samra on April 9, 2014 at 02:54:45:

Hi Mike,

I’d like to give credit where credit it due. Welborne’s DRD amps are derived from designs by Jack Elliano of ElectraPrint. Jack took the old Lofton White circuit and enhanced it with a reactor choke for the driver tube and inserted the “Ultra Path” cap to the cathode of the 300b. Pretty snazzy design!

http://www.electra-print.com/300bdrd.php

Subsequently John Atwood made some modest changes to the ElectraPrint 300b DRD circuit and did a number of DIY amp classes @ the Randall Museum in San Francisco.

I took the class and later made some changes to the circuit tailoring the sound to my liking.

One tip I’d like to pass on is in the power supply. In the Randall build, 0.01 uf ceramic disc caps where used in the snubber network. Those caps made the filter choke buzz. I replaced them with film caps Mouser cat. No. 5989-1.2KV.01-F. Buzzing gone! If the Wellborn build did the same thing I recommend you replace the caps. BTW that change was recommended by the lead engineer at a well know Silicon Valley company that needs to remain anonymous.

33dot33rpm.

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Follow Ups Full Thread

Topic - Shuguang Treasure 300b in DRD300b Welborne amps. - Michael Samra 02:54:45 04/09/14 (11)

DRD300b Welborne amps designer - 33dot33rpm 12:26:31 04/10/14 (0)

Why don't you try a pair of these and report back? - Ivan303 08:48:31 04/09/14 (7)

Well I will tell you - Michael Samra 18:28:33 04/09/14 (2)

RE: Well I will tell you - SETdude 11:09:56 04/10/14 (0)

I currently have the 'new production' WE-300B's and have run them for about 10+ years... - Ivan303 18:43:59 04/09/14 (0)

RE: Whoa - Rick R 15:32:26 04/09/14 (1)

Good point... - Ivan303 20:55:43 04/09/14 (0)

RE: Why don't you try a pair of these and report back? - SETdude 09:44:47 04/09/14 (1)

I baught a very early version of the TJ's, Globe perf plate 300B with 2.5V fil..... - Ivan303 09:57:30 04/09/14 (0)

RE: Shuguang Treasure 300b in DRD300b Welborne amps. - SETdude 06:26:28 04/09/14 (0)

RE: Shuguang Treasure 300b in DRD300b Welborne amps. - slippers... 03:10:54 04/09/14 (0)

Follow Ups

DRD300b Welborne amps designer - 33dot33rpm 12:26:31 04/10/14 (0)

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