Currawong

the thermionic watercooler

Re: Currawong

Postby Gingertube » Sun Sep 13, 2015 8:31 pm

Once you get it all up an running you may wish to consider modification. The phase splitter design is err.. sub-optimal is the kindest expression which comes to mind.
Just look at the values of the 2 anode load resistors.
Those "cheap" motorised pots (volume control) don't have great tracking between the 2 gangs. Silicon Chip used these for their 5000 Series preamp too. I substituted the ALPS motorised pots in the 3 preamps I have built. They are physically larger. You would need to check if they can be fitted. The preamp boards had alternate mounting holes to accommodate the ALPS pots.
Cheers,
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Re: Currawong

Postby soundbrigade » Mon Sep 14, 2015 8:53 am

Thanks for the advices. Guess the potentiometer I've got isn't the very best, but I want to stick with this one for some time. There are some 10+ projects more I have to do something with (like finish ... :/ ) and some of them are "better" than this one.
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Re: Currawong

Postby soundbrigade » Wed Sep 16, 2015 2:08 pm

The sockets I ordered from Finnish company Ural-Tone has arrived and they are OK ... They fit the holes in the PCB like a foot in a glove, and that is OK too ...
Image

But ... the barn metal retainer that is supposed to keep the socket mechanically in place still doesnt line ut for the holes. I plan to bring the sockets with me to job tomorrow and try to grind some ceramics off to fix that problem.
Image
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Re: Currawong

Postby tomlang » Wed Sep 16, 2015 3:32 pm

Magnus, where did you read the comparison article about the Hashimoto vs. the Altronics M1115 transformers?

FWIW the M1115 is a 8k p-p transformer with 41-42% UL taps per my calcs.

With AU dollar exchange to US right now at quantity 4 to include shipping these are about $18 each.
Last edited by tomlang on Thu Sep 17, 2015 6:51 am, edited 1 time in total.
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Re: Currawong

Postby EWBrown » Wed Sep 16, 2015 6:56 pm

Check the orientation of the four octal sockets, they appear to be rotated off axis by 45 degrees, counter-clockwise.
Tube Socket pin one is inserted into the PC board's hole for pin 2, etc (see attached photo)
The octal base "key" should be pointing directly to the left side of the board, else the tube socket's connections will all be wrong.
The "key" is pointed between pin 1 and pin 8. (Rotate the sockets 45 degrees clockwise, in order to properly orient them).
That should also "fix" the problem with the "off axis" orientation of the mounting brackets. No need to grind the ceramic sockets, that could also break them...

Image


/ed B
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Re: Currawong

Postby soundbrigade » Wed Sep 16, 2015 10:51 pm

I should check that up BEFORE soldering the sockets in place. That's right ... ;)
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Re: Currawong

Postby soundbrigade » Thu Sep 17, 2015 9:21 am

STUPID! STUPID! STUPID! STUPID! STUPID! STUPID! STUPID! STUPID! STUPID!

I started to check the PCB connections from the socket and "accidently" noticed that I hadn't turned the sockets the right way. Now, that I have gotten it all right the sockets have turned 90 degrees and the retainer lines up perfectly.

Did I write STUPID! ? :o)
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Re: Currawong

Postby tomlang » Thu Sep 17, 2015 10:42 am

Transformers ordered. A couple of ideas, using some 807's I have and El84's.
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Re: Currawong

Postby soundbrigade » Thu Sep 17, 2015 1:07 pm

I almost had the idea of ordering a bunch of transformers more. I just got a pair of ECLL800 and .... well ... *)
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Re: Currawong

Postby soundbrigade » Sat Sep 19, 2015 3:28 am

Leiturst pigtures.
I am halfway through with the wooden box that will hose the board. Four pieces of wood with slots whre the PCB will slide. Transformer from Germany has arrived - looking good. Have to find insulating stuff for the transistor and regulator on the (homemade) heatsinks.
Have to dig up some connectors, power switch a mains inlet and figure out how to connect the pieces for the remote control. Do I need a separate 12V transformer maybe??



Image

Image

Image
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Re: Currawong

Postby tomlang » Sun Sep 20, 2015 7:19 am

Magnus, it appears there is another footprint for larger output transformers. Is that for using the M1120 transformer?
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Re: Currawong

Postby soundbrigade » Sun Sep 20, 2015 7:43 am

I did notice that but paid not much attention, but maybe it's like that. Got to write and ask.
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Re: Currawong

Postby IceFyre13th » Mon Sep 21, 2015 12:51 pm

Looks like we could order the whole kit now, http://www.altronics.com.au/p/k5528-cur ... ifier-kit/

As well as the remote http://www.altronics.com.au/p/k5529-inf ... for-k5528/

Might be a nice winter project this year.
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Re: Currawong

Postby soundbrigade » Mon Sep 21, 2015 2:01 pm

There's a Swedish guy who assembles a complete kit: http://acurrawong.blogspot.sg/.
I don't kno if he invested in the remote control, but from what I remember it was a bit expensive, at least as I had the details already.


Nothing "visible" really happens right now. I am working on the wooden plinth, but could have made the slots one mm deeper or hadn't been so generous when I cut the wooden pieces.
There's a package coming in any days with insulation stuff for the transistors.
There's a DIY meeting oin October and I really wanted to go there an bring my Currawong, but I haven't decided yet.
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Re: Currawong

Postby soundbrigade » Sun Oct 25, 2015 8:05 am

Darn! I have a narrow slot in the front wooden piece to cut a few Angstroms deeper. AND I need to fix the backplane where the speaker and input and mains sockets to be placed.

I just ordered a bunch of PTFE-insulated cables in various colours, hoping that would help me finish all projects I have started, including the Currawong.
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