Aikido octal all-in-one

JohnR · « **on:** 19 Jun 2010, 11:47 am »

This is a new board that I hadn't seen before - http://glass-ware.stores.yahoo.net/octallsahpapcb.html

And I do have a few 12SN7s sitting there on the shelf...

wushuliu · « **Reply #1 on:** 19 Jun 2010, 10:03 pm »

Yes, I'd be interested to hear more people's opinions on the Aikidos...

JohnR · « **Reply #2 on:** 20 Jun 2010, 03:56 pm »

Everything I read is very positive. So, I've just ordered the kit - everything except the actual tubes. I decided to keep it simple, just build it, and see how I like it.

Looking forward to a nice project, it's been a long time

Now for the chassis and transformer.

JohnR · « **Reply #3 on:** 20 Jun 2010, 04:08 pm »

For the chassis - I found these a couple of days ago. It's a little tight but if I'm careful it should work well and come up nice too -

http://cgi.ebay.com/Tube-Amp-Chassis-13x9x3-Aluminum-Amplifier-Preamp-Case-/250637306547

A Hammond/Bud chassis would of course be cheaper but here in AU surprisingly not as much as you might think.

poseidonsvoice · « **Reply #4 on:** 20 Jun 2010, 04:09 pm »

Yes J.Broskie has a whole wealth of cool designs all on the Aikido theme. That Janus Regulator is pretty sweet as well. He tries to accomodate every diy'ers little audiophile nervosities (sp?) but stays true to excellent topologies and circuit design.

If I just didn't have so many projects on my plate...

Anand.

JohnR · « **Reply #5 on:** 20 Jun 2010, 04:42 pm »

Thanks Anand - yes, I'm trying not to redesign/respecify on the fly, as it were

It's so easy to do!! And then it never gets built. I've been needing an active line stage for a while and the chance to try the very interesting Janus reg as part of the bargain is too hard to resist.

Now, the power transformer. I've been looking into this and let me just first say that I have a problem. Hah hah... no, I mean that my wall voltage is 240V nominal, and so selection is limited for me. And then I have to choose carefully, as shipping iron halfway across the world is not exactly cheap. For this board, there are a couple of challenges that stymied me for a while, if i wanted to use just one power transformer that is. I'll go into more details on all that at a later time, but the solution is here:

http://www.diyhifisupply.com/node/638

Yup - the right amount of volts and enough amps to supply every single rail, with a 240V (ish) primary as well. A dropping resistor needed for the tube rectifier, but that's a minor inconvenience.

poseidonsvoice · « **Reply #6 on:** 20 Jun 2010, 04:53 pm »

Very nice! Strong work my friend. Yes, you could probably order a Hammond, but you would end up paying more, even if there is distribution in Australia. And if you directly ordered it from the U.S. the shipping would eat you!

Anand.

sts9fan · « **Reply #7 on:** 20 Jun 2010, 07:01 pm »

Awsome. I am building the same thing but with separate Janus board. The boards are so high quality I love it. I am using three transformers. One Edcor 550vct, one Hammond 6.3v and one Hammond 5v for my vume control and the rectifier heater. The Edcor actually has all the voltages but I figured I would strain it less and it was only $60 more.
Now I just need a case. I am still in the "I am gonna build it from scratch" delusion. It will pass though.

Kris

JohnR · « **Reply #8 on:** 21 Jun 2010, 09:39 am »

Cool. 5V for volume control? Which one is that?

My chassis is ordered and should be on the way soon. Transformers too - but those are coming by boat

BTW there are a few 6V rectifiers - may not work with the boards but for a p2p build might. 6Z4, 6ca4 that I know of. Then there are the diodes like 6ax4 and 6d22s - overkill for a line stage though...

sts9fan · « **Reply #9 on:** 21 Jun 2010, 12:54 pm »

Its a relay volume control and source selector. Some guy from China sells them over on DIYaudio. It has a remote and the small board has a digital display.

strider · « **Reply #10 on:** 21 Jun 2010, 03:06 pm »

Quote from: JohnR on 20 Jun 2010, 03:56 pm

Everything I read is very positive. So, I've just ordered the kit - everything except the actual tubes. I decided to keep it simple, just build it, and see how I like it.

Looking forward to a nice project, it's been a long time Now for the chassis and transformer.

How complete is the kit as offered on that page? For instance, if one were to order the PCB and the selections from the drop down options, would it just be chassis, transformer and associated hook up items, and volume control left to figure out?

I'm feeling my way through DIY audio, have built a couple of kits from Hagerman and others, but haven't much experience building a component around a board such as this one. It looks very interesting, suits my needs, but I don't want to get in over my head if possible.

JohnR · « **Reply #11 on:** 21 Jun 2010, 03:45 pm »

Quote from: strider on 21 Jun 2010, 03:06 pm

How complete is the kit as offered on that page? For instance, if one were to order the PCB and the selections from the drop down options, would it just be chassis, transformer and associated hook up items, and volume control left to figure out?

I think the answer is yes, although I'm not entirely sure. It does look like most of it is covered. The page says 2-3 weeks lead time so it will be a while before I can say for sure!

JohnR · « **Reply #12 on:** 22 Jun 2010, 04:25 am »

I changed the link to the chassis to the US EBay site as I realized that the link to the AU site may have been showing you the shipping price to here and I wouldn't want anyone to be put off by accident

Keith the seller is a very nice chap. As it turns out, I bought two (one in 13x9x3 and one in 13x10x2) as the shipping was only about $5 more for the both. (The other is for a small power amp - next project!)

Looking into power transformers a bit more - Antek have some new ones that are not on their site but listed on EBay - this one would be adequate for the B+ and the octal tube filaments:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250578128487

It is not a center-tapped secondary, but the Janus board supports a full-wave bridge so I assume this one does too. The operating point would be different of course - Broskie lists a range of operating points for various tubes here:

http://www.tubecad.com/2006/05/blog0064.htm

For the rectifier filament a separate 5V transformer would be needed, such as this one:

http://www.antekinc.com/details.php?p=7

The best part is they are small enough to be shipped by air to AU for only $15.

In the Edcor range the XPWR009 fits the bill in a single unit but unfortunately for me it's not available with a 240V primary. The XPWR147 could be pressed into service, at the low end of the B+ range and with a dropping resistor for the rectifier (or use a 6V rectifier)

JohnR · « **Reply #13 on:** 22 Jun 2010, 05:24 am »

Quote from: JohnR on 22 Jun 2010, 04:25 am

For the rectifier filament a separate 5V transformer would be needed, such as this one:

http://www.antekinc.com/details.php?p=7

I'm going to unrecommend that one as I see now that it won't deliver 2A at 5V. So I'll be getting this one instead and using a small dropping resistor:

http://www.antekinc.com/details.php?p=18

That way I can also use 3A rectifiers (gz-33, gz-37)

JohnR · « **Reply #14 on:** 22 Jun 2010, 05:35 am »

Now, for the attenuator... I have a ladder that is not yet used, but it's rather long and will probably interfere with the board. So a quick look on eBay and there are some very cheap stepped attenuators e.g. -

http://cgi.ebay.com/DACT-Type-21-Stepped-Attenuator-Potentiometer-50K-300B-/160442765420

You wonder about the quality at the price, but then again, maybe it's worth a try.

wushuliu · « **Reply #15 on:** 22 Jun 2010, 05:41 am »

Quote from: JohnR on 22 Jun 2010, 05:35 am

Now, for the attenuator... I have a ladder that is not yet used, but it's rather long and will probably interfere with the board. So a quick look on eBay and there are some very cheap stepped attenuators e.g. -

http://cgi.ebay.com/DACT-Type-21-Stepped-Attenuator-Potentiometer-50K-300B-/160442765420

You wonder about the quality at the price, but then again, maybe it's worth a try.

They are very high quality pots as has been noted over the past couple years across different forums, and pretty durable as I've soldered and unsoldered my 20k a dozen times and its still going.

JohnR · « **Reply #16 on:** 22 Jun 2010, 06:36 am »

Cool - thanks! I bought one - hard to argue with the price... crikey.

sts9fan · « **Reply #17 on:** 22 Jun 2010, 12:37 pm »

Quote

In the Edcor range the XPWR009 fits the bill in a single unit but unfortunately for me it's not available with a 240V primary.

Hi John,

I know you were saying this one is not in 240v but I think that you will want at least 6.3V@4.5A to power the heaters. If you are doing 6SN7 or 12SN7.
Thats why I went with the XPWR007 but then bought some extra little transformers.
http://www.tubecad.com/2008/09/blog0149.htm

JohnR · « **Reply #18 on:** 22 Jun 2010, 02:35 pm »

Ah.... hm. OK, thanks for pointing that out... I need to work that out again.

JohnR · « **Reply #19 on:** 30 Jun 2010, 02:37 pm »

Parts starting to roll in... received the chassis and the attenuator today courtesy of the ever-efficient postal service. The chassis are very nice - far nicer than anything I could make myself. Smell nice too.. (walnut sides)

. The AL seems to be buffed for painting, I'm not sure yet whether to paint or leave it unfinished. If all goes well with my new projects I'll be getting some larger/custom chassis made by Keith in future.

The attenuator is tiny - smaller than a regular carbon pot. I thought it was a mistake at first, but yep, there be a whole lot of teeny SMDs in there.

The kit itself from John Broskie should be here soon, it's on the way.