Western Electric Model 91A Clone
(WE91A) 300B Stereo Amp aka the "Dislocator"
2x 300Bs (Shuguan 300B-Z), 2x 310As (NOS CEI Holland), and 2x 6AX4
for 8 watts of SET power in Class A
Electric's WE-cored 9103 OPTs, custom toroid power transformer, Hammond Choke,
Hammond filament transformers, Furutech RCA input jacks, Cardas binding posts, all ASC oil caps,
and NOS Russian
Built for Dixon Chen of Malaysia
Completed on 2/3/10
"Hi Min, the amp has now been breaking in for 48 hours
now, this is what I'd like to comment about your amp :
I am running the amp with a Sylvania 5AR4/GZ34 rectifier
for the delayed B+ turn on, new Russian 310A drivers ( these are fantastic sounding) and the Shuguang 300 B-Z as what
I supplied you, firstly after turning it on, I noticed that there is not a hint of faint hum whatsoever, in other words the
amp is dead quiet! I hooked it up to the 76 line stage I got from you and fired up the system. Again I don't know how you
have done it, but both the amp and the linestage you have built me is just that quiet!
Firstly, the bass! This is not
the kind of bass I would honestly expect from a 300B ( and I have heard quite a few 300B systems that includes my previous
diy 300b amp that I built as a kit) , the vigour and how low it can go on the low frequencies, low enough to rattle the plaster
ceiling in my listening room actually....and they tell me that 300B's are notoriously weak in the bass department? well not
this one in particular!
This amp does not sound like a typical 300B at all, the way every note is produced with
such authority and forceful manner, the presence of each instruments being played, a very full musical sounding environment
( packs up the soundstage from wall to wall beyond my speakers) a very powerful sounding amp I would say, not the typical
thick sounding 300B character as I have always heard.
So this is the WE 91A sound, and I was worried all these while
it may sound vintage or old in character, well all I can say is that this amp is very neutral, authoritative but yet natural,
an amp you can listen to for hours without any kind of ear fatigue, well that 5 months or so wait was worth it, I mean there
were many different parts and changes I wanted ( thus the time taken) and like what you have promised, you have built
me an amp that is unique not like any other that you have built, firstly using the WE 310A driver as well as no electrolytes
in the circuit, for me this is good enough close to the WE91A amp that I have always wanted! Great built Min!! Regards"-
This one is chunkier than
Jouni's WE91A and I had promised myself that I would not build anything heavier and bigger due to health safety issues. Naturally, I quickly
have forgotten who had made such a fruitless promise and ened up making something like Dixon's amp. It's fittingly given the
name of the "Dislocator" - I felt like it had to be something more descriptive than the "Herniator". The
amp is built on 17x14x4 steel chassis and weighs as much as a fatted calf. See below for my comments on the build:
Moses somehow parted the Red Sea. I knew I could
somehow fit all these in one amp - I had to eventually go from 17x10x3 to 17x14x4 chassis.
Those Shuguang 300B-Z mesh plates sound pretty
nice. Very delicate and fine sounding, kind of like Sophia 300Bs. They seem to be solidly built with a ceramic base and gold
pins. I guess not all Chinese tubes are crap.
Furutech RCA inputs jacks and Cardas binding posts
This is what happens if you don't use any electrolytics (except
for the large Mundorf 100 uF 550VDC). I probably could have built the amp on a chassis half the size if I did. But I have
to say those oil caps were well worth it. The amp sounds very smooth and open. I especially like the bass response I get from
the amp. Really tight and punchy. Today I watched some movies through the amp and the whole time I felt like I had a subwoofer
For those of you who might want to
replicate this amp, I pretty much used Joe Roberts' schematic (Summer 1992 Sound Practices) with some modifications - I used
an 100 ohms 5W hum pot for the 300B heaters, and I also used an 100 uF/550VDC electrolytic cap after the 10H choke. These
two mods seem to give me the lowest hum level. I guess one could further reduce the AC hum by rectifying the 300B heaters,
but I generally prefer the sonic quality of AC heaters. Besides, I have to get my ears less than 1 ft away from my 98 dB/W/m
speakers to hear the hum (w/ no music playing!), which I can live with.
in all, it's a great sounding amp. Certainly one
of my better builds so far. I just hope that the amp will arrive at Malaysia in one piece!
Dixon wanted a couple of upgrades made - Duelund
PIO coupling capacitors and bias meters for the 300B tubes.
This is my high end CD player (aka Sony Play Station 1) used in
my lab. I think there is a fellow in Germany who does all sorts of crazy mods to PS1s and swears that it sounds better than
anything out there. Well, I just use it because it's small and cheap. It sounds pretty good too. Maybe I will someday bypass
the op-amp and add a tube buffer in the PS1. Notice the passive preamp that I conjured up using various junk parts lying around
the lab. Not too shappy for $0. Here is an article about the PS1 on 6Moons.
If you want to get one like this on ebay or trade
your PS3 for one, make sure that it's the 1st generation PS1. Notice the analog audio out on this unit.