2A3 PSE reincarnation.

[pre65]

hi-i am looking to make my first home build valve amp to replace my modified Quad 11's.I have narrowed the choice to a 2A3 pse as the WAD design from June 2002 or possibly the "Panzer" 6C33 Audion.
My design needs to work sucessfully with standard KLS3 speakers and both my choices would put out 8-15 watts.
I would like to consider the Loftin and White S/E version but not sure if 3.5 watts is enough for KLS3.
Can any member who had experience of the WAD 2A3 PSE kit let me know their impression of sound quality and possible improvements (output transformers ? ) and possibly a copy of the build manual ?
Any suggestions would be welcome.
regards Philip

[Paul Barker]

I thinka single 300b is better

[Clive]

The parallel part of parallel single ended seems to kill part of the magic, as Paul suggests a single valve of double the power should be better.

[andrew ivimey]

Philip, I used KSL3 with PSE2A3 for over a year. They sound nice together but ultimately too 'warm & soft'. 300b is much better when right and it is very easy to get right ( pentode driver, forget triode input valves!).

If I'd have had a pair of silver amorphous output transformers (i.e expensive and v. high quality) I'd have tried them on WAD2A3 PSE because I suspected that the weakeness was in the supplied output transformers, but never gotto prove this.

WAD2A3SE was sharper, clearer though quieter. Loftin White actually was louder fuller and altgether better.

I played with 6C33s for a couple of months; loud but hard, they are beautifully ugly. I still have some gathering dust and will give them another go as I have the output transformers for them too, but ... eventually.

I used KSL3s with several amps - they are very good speakers indeed. The loftin white would drive them of course, but how big is your listening room?

[Richard]

I too would have asked how big is the room and what levels and type of music. I often think valve users get away with low powered amps due to the soft clipping.

SE amps generally do not do bass well and may not be a good choice with big speakers. The Quads aren't particularly powerful sounding but I think you may be underwhelmed by the 2A3.

The following is offered as illustration and not as criticism of an amp which many users enjoy,

2A3PSE nto 8R (power is less into a higher or lower load),

20Hz 1.6W
30Hz 3.2W
40Hz 3.4W
50Hz 3.8W
100Hz 5.8W
200Hz 7.6W
Then power held 8.5W 300Hz to 10KHz, above 10KHz it rolled off gently.

The power supply is beefy and max power 1KHz was actually 14.5W/8R at heaven knows how much distortion - which really brings us back to the first paragraph.

Rich

[pre65]

hi again-thanks for the suggestions so far.
my main room is 14 ft wide x 18 ft long.
the speakers are 7 ft apart and i sit 12 ft away.
i found the Quads bass much better after a revalve,got the KT66 from Jibbles on e-bay and GZ37's.
i have a wide rangeing taste in music but love simple choral music.
with my EAR 834L preamp i dont have to turn the volume knob up very much to "fill the room" with sound.
i see the "Phil Ramsey" Loftin and White 2A3 circuit mentioned on the WAD board,anyone got a copy ?
thanks again all.
regards Philip

[ColinA]

The 2a3 design sounds much better with one valve than 2 ie
SE rather than PSE and not much quieter.
The sound is superb and clean on female vocals.
With 89Db speakers
It works well with accoustic music
However is suffers when playing large orchestral works or loud rock.
I would suggest looking for a good SE 300B design
Mine is being "Rested" in favour of Chinese 845.

[NickG]

Give Phill a call, I am sure he will be only too happy to describe the LW 2a3 to you :-)

[andrew ivimey]

Yes, let me guess, 'its f@@@ing awesome' and rightfully too. But your room is too big I think for 2A3 and KSL3s. If you have even 3dB more senstive speakers (6dB and you are home and dry) the game would be worth playing.

Valve heads get away with murder with distortion figures simply because the amps sound good. With SS, distortion is immediately 'orrible.

If you speak to Philip don't be surprised if you come away having ordered the stuff for his version of the WE91 (I think); a 300b amp with a 6SJ7 (pentode) driver. Now that does sound v.very good indeed but is undoubtedly best if you monoblock it to make best possible use of a beefy power supply.

If I didn't have the Loftin white and knocked up a 'WE91 - with those powerful czech 30bs', I'd be happy. As I have both, I am more than happy and fascinated by the differences.

good luck

[Gideon300b]

Following the 300b theme, I'm in the last throws of building one of Phil's 300b steroe power amp. Still a few problems whihc I should iron out ina week or so. It looks stunning, I'll post my diary when I get it finished. I'll be driving a pair of IPL 4tl's into a 12' by 16' room so the results should be interesting.

The 91 circuit is pretty straight forward to build.

Enjoying this BB so thought it was time I contributed.