Your PCBs always look well laid out, Colin. What software do you use?

Hi Martin, Orcad, Mentor Graphic and Proteus. A mixed bang depending on the job and my patients I like Proteus the best, Mentor is to complex bloody good Naim use it also Orcad I normally use for PSU boards.

I also use LTC as a sim and Tina and occasionally Mathcad.

Just fun all the time here in the Log Cabin.

The 50W/Ch version has now been tested.
It has 8 complementary pairs of transistors at 25A each 140VCE matched HFE at 1A 27, and the PD are 125W on each channel ,just for the few techys here.
Each pair has complementary independent drivers transistors,16 in all, driven by a 5W SECA stage.
50W 8R, 100W 4R, 200W 2R, and only 380W 1R sorry about that, due to transformer loses.

BW 1Hz - 2MHz flat, -3db not a problem 1Hz - 2.8MHz, THD at full power less than 0.00001% Phase 1Hz - 1MHz -0.2Deg over all.

Peak test current over 200Amps.

I nice baby amp.

More to come

Both the 100W and the 50W will be from Elsdon Wonfor Audio i.e. E.W.Audio Ltd soon. With pre-amp and a 20W version plus a new Retro Claymore, I can,t wait to try them out.

The first 100w pair for bi-amping were delivered this weekend and my god it was lovely. Alan did a great job on the metal work thanks Alan.

Prices too

E.W. Audio 50W Stereo

BW 5Hz – 40KHz ±0dB
BW 2Hz- 100KHz -3dB
Out Power 50W/ch @ 8Ω
Output 98W/ch @ 4Ω
DC offset ≤ 10mV typically 2mV
Damping Factor ≥ 100 typically + 100
This power amplifier is design to produce the superb acoustic of a SECA design without the huge heat dissipation.
The 50W has a total of 8 high complementary power transistors all driven by the own pre-drivers, and a unique current sharing technique on the bass current and emitter current to insure a true balanced performance.
Each pre-drive is set to run in a SECA drive formation and all 8 of these is driven by a SECA stage which has the only voltage gain stage this allow us to use minimum feedback and reduces the sometimes drastic effects this has on the music. The main reason for this feedback is to keep the DC off set very low, this reduces the forced positioning of the voice coils in the speaker and thus less distortion.
The drive stage is biased as a SECA with a constant current load as the SECA designs in the E.W.Audio range. But it is only 1W thus the heat is minimal it works so well the amplifier runs cool or just warm and normal use.
The ouput transistor are rated at 160V 25A 150W and we use 8 a chanel so no stress and it allows us to have a I2T rating of 100s of amps.
The drivers and SECA stage of the circuit uses transistors with what would seem a extreme device but it give a perfect waveform following out rated at 100MHz + BW and 120V working should never be stressed and giving a long life.
The damping factor is unusual as it increases as the load is increased. Due to the unique bias technology the output impedance decreases as the current demand is increased.

E.W.Audio 20W Channel

BW 5Hz – 40KHz ±0dB
BW 2Hz- 100KHz -3dB
Out Power 25W/ch @ 8Ω
Output 38W/ch @ 4Ω
DC offset ≤ 10mV typically 2mV
Damping Factor ≥ 20
This tiny amplifier will fool you it is only 25W/ch but use the same unique circuit of the 50W.
Ideal for small rooms and bedrooms students will love it and paired with the right speakers will be to amp to keep.


E.W.Audio 100W Channel

BW 5Hz – 40KHz ±0dB
BW 2Hz- 100KHz -3dB
Out Power 130W/ch @ 8Ω
Output 255W/ch @ 4Ω
Output 420W/ch @ 2Ω
DC offset ≤ 10mV typically 2mV
Damping Factor ≥ 200
This amp is based on the same design as the 50W and the 20W but rated at 100W/ch.
It uses 16 output device and each channel as its own power supply including transformer. Biased more in to “A” Class region of the output devices and this will make the amplifier will run warmer in the music playing state. So we fit large heat sinks to allow this dissipation of heat more effectively.
It is a bridge amplifier design and this reduces the power rail voltages but does increase the current demand but there is no high current zero volts or earth return, this reduces the possibility of power supply modulation and increases the quality of the reproduction music

I need a shave taken before TQ at Catch XXII

www.hifianswers.com/2016/06/news-one4audio-m50-50w/

Well that photo was taken some 10yrs ago I need a shave and I am now much much more ugly and old, and all before TQ.
In my workshop at Lopen Somerset I was doing a tiny bit of work for Naim, lovely days I had my life then and no crap with health,ex-wife,ex trusted friends.
Bur free now and looking forward to making some nice sounds and loud sounds. with Alan.

Hi Martin, My old friend Alan and I merged it into Elsdon Wonfor Audio Ltd and we will be making products under that name, I acted as a consultant to E.W.A. Ltd.

Alan and I have a track record we made large power amps in the 1980,s called "Dreadnought" 200W and 300W MOSFET amps and a few SECA amps, and that were the original TOCA designs came from with a few changes. A lot of the idea for Magnum and Inca Tech came from this early collaboration. 

So E.W.A. will be making 2 pre-amps, a USB psu box a small 30W Amp, a 50W Amp and a 100W amp plus a SECA of 20W and new cables.

So One4Audio is doing little except a small run of kits and fixing the odd Inca Tech product include upgrades just to keep me busy and my two brain cells working in stereo.

E.W.A will also be designing non audio product include anti-pollution products involving chemistry and electronics.

So to answer your question One4Audio will be taking a back seat, the truth is many people read the SECA kit notes but very few had either the knowledge of confidence to build them so sales just about covered my costs. A shame but when you can by cheap junk and throw it away and buy cheap junk again why do you need good kit, the true audio industry is in it last death throws, OK maybe vinyl will bring the spark back but like 8 tracks I suspect not.

A bloody shame as the younger generation will loose the spark of good music to a "thump and a ting" on tiny headphones on a crowded tube train with everybody rushing about to make somebody else rich. Hey guys life is to short it really is get of the train NOW.