A few months back I was looking for the Hakko or a Weller. Unfortunately the Weller ones seemed considerably overpriced here in Greece. I then searched for Hakko with no luck. The internet had much better prices, but the shipping costs most of the time were ridiculous. I ended up buying an ERSA which was on sale at a local hardware store, and never regretted it.
Still going strong with no issues and I really like the timer safety stuff.

As an example, the original circuit specifies +18 V DC power. To obtain this, you would use a 18 or 20 V Zener, and a transformer with 18, 20, 22, or 24 VAC secondary.

I bought a Hakko 936 many years ago and have never regretted it. The only regret I had was not buying one sooner!! The FX-888 was it's replacement (and now the FX888D)

I've not used the newer models but I have never been anything but 100% happy with my 936.

Tony.

I think the Hakko FX-888 is no longer a current model, it is replaced with the FX-888D with a digital display and push button controls.

I picked up one of these... not bad for what I'm doing.

Hakko FX-888 Soldering Station: Amazon.com: Industrial & Scientific

i have the wes51 and i love it

The sound review is online.

Hi great job thank you, can you clarify the voltage with the zener ? I am a bit noob and my English are not so good, so a more detailed explanation would be appreciated.
Regards

Looking forward to your results. Even though I'll probably never buy them.

No I am not going to be much more specific in this instance as I didn't listen intently enough to understand what the colourations were. I just didn't enjoy listening to this circuit as much as the earlier passive one. But I can give you a hint from the kinds of music I listened to - on piano at the top end of its register, some notes sounded too right to be true (like hyper-real) and others missed the mark. Leonard Cohen's voice wasn't as sexy, brass lost some of its intense bite and became more electronic--y. This could easily be caused by having resonances in the power supply impedance at particular frequencies but its just speculation.

The original reason I did the active filter was to get a more portable (smaller size primarily) solution but when I'd optimized the power supplies with enough caps for low impedance at HF I realized there was practically no size advantage after all. So passive wins on all fronts but ease of manufacture. Probably I'll find someone to wind the coils with sufficient precision so even this will get sorted...

Interesting. Could you be more specific about precisely what those "upper-end colourations" were? This is the area where one is more and more balancing on the knife edge of "correct" sound, and the slightest weakness anywhere in the whole chain can be severely emphasised ..

From personal experience, the best sound is often directly adjacent to some of the worst sound: 1' of an arc to the left, unlistenable; 1' of an arc to the right, tediously dull; inbetween, just right ...

Looks like Soulution have been listening to what their products actually sound like too, : Soulution 701 monoblocks and 711 stereo amplifier

Ground planes are great for RF work, I am not so sure though at audio they're the best solution. For audio we're not so concerned about inductance in the supplies as at RF - because the frequencies are so much lower. I tend to consider cross-coupling in grounding (common ground impedance coupling) a bigger issue to fix than supply inductance, hence I go for star earthing rather than planes. But each to their own!

All food for thought... one would hope that each device would work on an individual bases and its PSRR wouldn't be effected by the outputs being in parallel with other devices. Abraxalito, I recently read a paper by Analog Devices about decupling techniques and it covers some of the areas you mention. However, the question still remains about any additional effect brought about by running devices parallel...

I would hope that with proper decupling to a low impedance ground plane on each of the devices supply pins, plus with a suitable power supply, any issues would be kept to a minimum.

My initial thinking is that at HF, normally the PSRR is limited by parasitic device capacitances. So I figure that paralleling chips is only going to worsen PSRR because that's putting the stray capacitances in parallel. But then as a caveat, if the PSRR is capacitance dominated it will surely depend on what load resistance is used - the datasheet does not specify any along with the PSRR graphs.

At the lower frequencies I don't know what causes the limited PSRR - is it related to the early resistance of the output emitter followers? If so then paralleling more followers will make the PSRR worse.

Just my initial thoughts - would appreciate feedback!

My guess is that it would make no difference at all: if you consider each of the paralleled units as working in isolation with their own supplies, and then simply summing currents in the speaker load, then I can see no advantage or disadvantage to the method as far as PSRR is concerned ...

But, the real benefit is that one is forced to engineer a more substantial power supply, to make sure that none of the chips are starved during a peak, and that's the real gain of the matter ...

The simple answer is I don't know, but would love to find out...

I'm curious - how does the PSRR of an array of paralleled LME49600s compare to the (datasheet) PSRR of a single one? Any ideas?

Thanks, been a fan of his writings for quite some time now, I'll check it out. My first introduction to elliptic filters as products was through the company he worked for at the time, Kemo. This is going back some time, mid 1980s.

Kendall Castor-Perry did a write up on active eliptic (Cauer) filters pretty recently in Electronic Design magazine. Should be online, free... several parts, which makes it difficult to read without printing it all out... might help.