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107.213.0.240
I've haven't worked on but very few single ended amps and most of those were pentodes which I found to be very polite in their presentation.I just got these Welbornes in for repair as they both had shorted diodes from a power surge and I replaced them with Schottkys as opposed to what was in it previously..They are working now and these are very nice amps..I really like the Elektra-Print iron as well as the direct coupled circuit and I love those 300b Shuggie Treasures..
It has a motorrun in oil in it but it also has a pair of 560uf JJ electrolytics in it hooked in series after the rectifier.My hats to Ron Welborne on these.
Honest amplification is better than excessive 2nd order distortion anytime.
Follow Ups:
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.
On sale for only $835, but that's for a PAIR!
Inquiring minds and all that...
Link below:
The owner of these amps had the Western Electric 300b,and the TJ music carbon plates which aren't cheap as well as the Treasures that you see.
He said the TJs were the best for extension and the Shuggies were next best overall..The Western Electrics didn't extend as well at either end and lacked bottom end..If these 900 dollars are a sonic copy,you might be disappointed.
I personally like the Single ended pentodes really well.I heard a KT88 SE amp that Kegger built with Edcor iron at the AK Fest and it could have been the best sounding single ended amp at the show.It was really well done and had mostly all motor run caps in the power supply with well selected components for everything else..I got the recipe for that amp and I would love to build one.
Honest amplification is better than excessive 2nd order distortion anytime.
Yeah I want you to build me one too. No kidding. I like SEP's. I'll send you an e-mail.
My WE 300B experience mirrors yours. The TJ mesh were better in my Laurels.
Have an earlier version of the TJ perf. plate globes with 2.5V fil. for AC fil. duty, but they are the earlier microphonic version.
Also have an older pair of KR Enterprises 300B, they would be microphonic as well.
Have enjoyed the WE300B for all of these years but have tried a pair of Emission Labs 300B-XLS as well as the 5V 520B for a very short time as they were not my tubes.
Might give the regular EML 300B's a whirl next, or perhaps the 5V EML 300B-XLS. Would not be afraid of the ST shapes TJ perf plate either as I understand they have the microphonics under control now days, with much better support micas.
For that amount you can get a pair of EML 300B's from Tubeaudiostore, and have a couple of hundred bucks for other tubes, or taking your lady out for dinner. I have a pair of the EML 300B's and they sound excellent. I have not tried any of the latest Chinese, so can't comment on them.
If they are anything like the EML tubes of the past, might well prefer them anyway.
Only $835. That's why I am digging single ended pentode amps. When I had my Laurels I preferred the TJ perforated plate over new production WE's.
Weird but true.
That allowed me to run my 300B Kit Monoblocks using AC on the filaments with a minimum of hummmmmm.
If you recall the earlier TJ Globes were quite microphonic, later cured with better support structures for the tube's innards.
Ended up with the 300B 'new production' and liked them a lot but they are now over 10 years old and likely tired(no getter left at all).
Time to do a serious overhaul on the amps, so might just swap out the 300B's while I'm at it.
Yeah, that's more than I paid for the 'new production' WE300B's.
I had Ron's Laurel II 300B's. He had great products. The SS Reveille phono pre was amazing. A teenage daughter and a divorce damn near ruined him.
From what I understand about Ron and Welborne Labs is you get a great product....if you ever get the product you ordered.
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