I have some of the old AWA classroom speakers which contain a six inch driver with line transformer and a four or five way selector for a volume control (which I won't bother using). I will most likely hook up a pair of these to the Currawong when I build mine.

I don't think it's a question of if a kit will be released but when. We've (me and thousands of SC readers) been filling Leo Simpson's ears with requests for this for a long time and I doubt SC would commit to the project unless they thought it would remain in demand. Bank on a kit being available very soon I reckon.

There was even talk of some sort of 'blueprint' upgrade at a later time with a higher power output and other things. I am hoping bass and treble controls make their way into such an upgrade. That said, 10 watts per channel is ample for listening in one room of a house.

The PSU is a Solid State Design with Slow Warm up for HT

That is to mimic the equivalent warm up of a rectifier valve which is a form of self-preservation for a valve lineup in an amplifier, radio or television.

Sounds interesting Brad, good to have some old gear to use

Yeah I am sure it will probably happen in Kit form, just these days with so little interest in kits and even electronics as a hobby I'd guess Altronics or Jaycar would be thinking hard due the the costs involved in producing this as a kit, thought kits make life a lot easier for builders

I remember when you could get a kit for just about every major project done by EA ETI via either DS Jaycar etc
(Bill Edge Rie whom ever back in the day)

Thanks for the info on the talk of a "Blue print" upgrade, I am sure quite few will tailor it to there own wants anyway.

Yeah I thought about that slow warm up and thought you do here a lot saying just whack in silicon diodes with radios etc, its how some did it in the later old days, these days you really probably want to preserve your Valves unlike in the old days were they were figuratively speaking "a dime a dozen" and a dead valve was probably a good thing for manufactures and easily replaced then
(so manufactures probably didn't care if it possibly kills your valves a little sooner)

These days with what people are paying for those old Valves and you can be sure theres a lot that will use their brand X made at such and such a plant in such and such a year, well they aren't being made no more so being kind to them is good I suppose

I thought more so you dont see much info on this on the net that it would be useful for people (aka noobs like me) to look at if you do want to use a silicon rectifier (retro for radio,old guitar amps with dropping resistor) for a Valve Amp

I was sure it wasn't a new idea in its self but maybe a useful one to know and understand.

I was around in the sunset era of valves but went down the Silicon Road so I never learned much about them (and what I did was forgotten long ago)

Anyway it will be interesting to see the response on this Amp from people building it

I am thinking about it but it will probably be a bit by bit long term project for me.

Cheers Brad, All

When I get around to building mine I reckon I will customise it a little bit, make my own Tassie Oak cabinet for it and maybe replace the Perspex (or part of it) with some matte black bronze mesh or something like that. If any of this happens there'll be another thread in Special Projects.

It has been mentioned in the December issue of Silicon Chip that Altronics will make a kit available for this project. It's good news for those interested in building the Currawong that they will not need to scrounge for the necessary parts.

As with any non-trivial SC project, I'd wait a few months after publication of the final part for the errata and omissions and suggested modifications to be published based on feedback from builder experience.

There's no issue with that - I usually procrastinate a bit before making such purchases, probably more so in this case because I have to travel to Auburn to grab it.

I too have been watching with interest with the Currawong project. I was a bit miffed at first with the teaser that stated 10 watts per channel with a pair of 6L6's or KT66's. You'd think a pair of those valves would deliver more like 20 watts. I have also been for years following Leo Simpsons stance towards valve amplifiers and Silicon Chip's vow to never feature one in a project.

After reading the first instalment for the Currawong I now know why Silicon Chip has relented. The Currawong uses cheap $10 line-output transformers and if it wasn't for this fact this project would never have seen the light of day. And it also answered my question as to why it is only 10 watts per channel.

I will not be building the Currawong myself, but I am most interested in hearing the results from those who are building one. Using line-output transformers wired back to front may just be a very ingenious way of a affordable valve amplifier project using readily available parts. How will the Currawong compare to the more conventional valve amp designs? I guess we'll see.

For anyone building the Currawong using KT66's, I recently found some original Osram (MO/V) data sheets:-

KT66 Power Amplifier Valve.

There are were four GEC KT66s going on Ebay as a set and they are not cheap I have to say. I can't find the listing now but last time I saw it the bids had got up to over $730.00 for the set of four valves. I have two of the same vintage, NOS, scavenged from Gladesville Hospital's old assembly hall which had a proper movie projection room complete with two large projectors, valve amplifier and mercury-arc rectifiers for the arc lamps in the projectors. The projectors also had standard and cinemascope lenses.

I scored the valves just prior to the developer's bulldozers shifting in to level the joint. Not sure of what ever became of the projectors. Most likely they went with the building. I would have grabbed them too if they didn't require four weightlifters to move.

I have also been for years following Leo Simpsons stance towards valve amplifiers and Silicon Chip's vow to never feature one in a project.

Leo Simpson was a guest speaker at the recent HRSA RadioFest, where he handed out hundreds of copies of SC magazine gratis to attendees. I gather he spoke about SC's declining readership and my guess is that by doing this project (and perhaps others in future) he is trying to appeal to those who stopped reading SC a long time ago.

I just hope that decline doesn't transfer into a loss of Silicon Chip to the nation. It's not that many years ago that we had three or four major monthly publications, one of which was the second oldest electronics magazine in the world.

Still, if our governments keep taking to the manufacturing sector with a nine inch angle grinder then scenarios like this are one of the results of such action. Our politicians and bureaucrats have to stop sitting on their brains.

Actually, now that I think of it, Leo Simpson, the editor-in-chief, has likely given thought to retirement at some stage given that his career started in the 60s. I wonder if there are any handover plans should this occur in the next few years.

I wonder if there are any handover plans should [retirement] occur in the next few years.

My guess is that any such "handover" would be the result of a sale of the business to fund said retirement. Given that he has admitted to a declining readership, and the hard grind that is magazine publishing these days, it may be difficult to find a willing buyer.

Jaycar ads probably fund a good percentage of its revenue budget.

Print media isn't the easiest business to run these days, that is for sure. I think it was Fairfax who said a while back that they were going to shut down their huge printing plant at Chullora (both Fairfax and News have factories in the area) and shift the printing of their Sydney papers to a smaller operation near Windsor. They could do it easily as content in the SMH is lacking these days. Remember back to the days when Saturday's SMH was a broadsheet about 40mm thick when folded. About 30% of the hundreds of pages was their trademark employment section.

I also remember back about ten years or so when Kerry Packer put the kibosh on The Bulletin and the uproar that followed that. Then years before that, even before the Internet existed in any substantial form, Fairfax ditched The Sun and News got shot of The Daily Mirror. The times I spend in my childhood waiting for the paperboy to pass by after school were over.

I suppose one of the hardest things to keep on top of is remaining in tune with what the readers want. Electronics Australia made a costly mistake when they mis-interpreted a reader survey and converted from the format they'd had since 1939 into what was pretty much a product showcase. Their move was a reflection of a sign of the times but the issue was that EA readers weren't quite done with kit-building and experimenting yet. It's these people that are currently keeping SC and shops like Jaycar still in business.

My own personal view is that once Gen X has moved to a better place there will be little, if any, print media. Publications that manage to survive will be online and retailers like Jaycar and Altronics will be selling other things. I sit somewhere in the middle when it comes to the cost to society versus the benefits. The positive is that less paper is used and people can print what they need, when they need it. The negative is that Australia, and the world, is losing the will to be inventive and build things for themselves.

I much prefer paper to reading a phone/tablet/pc. Easier on the eyes and last longer. I have publications dating back to the 1920s, yes they are fragile in some cases, but they way technology moves will there be methods of retrieving 100 year old files?

Even if you reproduce the compression/clipping distortion issue, there's also the issue of the "pleasing" even order valve harmonics Wa2ise.
"Tubes tend to emphasize even-order harmonics, which are octaves and fifths, and harmonize with the root note naturally. The resulting sound is not so much distorted as it is fatter, i.e., more harmonically complex."

"Tubes tend to emphasize even-order harmonics, which are octaves and fifths, and harmonize with the root note naturally. The resulting sound is not so much distorted as it is fatter, i.e., more harmonically complex."

Interesting. Has that been proven/shown to be the case anywhere? That is, can we see a side by side comparison on an analyser?