DQ828

I thought this was a good find until I went on the website and found some of the data on the site was quite different to this document. 12ax7_comparison.pdf

Well thats VERY annoying, I stuffed up my calculation for the number of turns I needed and when I did the first test I had 244v not 150v!!!!!!!!!!!!! No idea where I went wrong, so I had to remove 220 of the turns that I so carefully put on. The first photo shows the plump and great looking 244v version and the second is the final voltage test, at least that parts done. Oh may aching back

Look useful thanks

Thank you, but I cant claim the geckos as my brother made them for me. I wouldn't recommend you spray waterbased over automotive paint like I did, the adhesion can be a problem.

I haven't used the FW Sanding Sealer for quite a while but I always found it clogged the sandpaper bigtime, in the end I stopped using it, maybe the formula has changed. I normally use the MR MDF which I think absorbs less and obviously will standup better if damp/slippage ever becomes an issue. With the last boxes I made I mitered the corner joins so there wouldn't be any raw edges there, and then coated the ends (Open Baffle no front and back) with hard drying glue, spray the boxes with Duratex water based Texture coat, over sprayed with automotive colour and then overcoated with Mirotone water based satin wood lacquer 😊 If you think about it I have broken a few rules but the finish still looks good with no peeling after 7 years.

Didn't even know they existed !

It took me about 1 hr to go around the ring one more time and my back had given by them, doesn't like the stooping over! I have no idea how many more times I need to go around, I wish I had put some markers in the holder as I wrapped the wire on there so at least I would have some idea. At this point I'm going to guess 3ish.

Lots of other things needed doing today but I made a bit of progress anyway. I wound 2 strands 220 times around the holder which hopefully is the right amount. Half way through I thought I made the holder capacity a bit too small & I was right! It did fit on but it was threatening to jump off at any moment. I went around the loop once before I rang out of time. If you ever want to do this, I highly recommend you grow a third arm first Even if this works, I'd be surprised if I would do it again, if all I was after was a low voltage supply then fine, or to tweak a transformer voltage output, but not 1450 turns to get 150v! Starting with a prebuilt transformer is definitely a winner.

Made some progress, Iv'e rewrapped the 9v secondary with the original wrap. I now have the copper for the 150v secondary but was silly enough to take the tape off both rolls at the same time and then spent a good while chasing coils around the workshop before I took the photos. Due to the coil mayhem I decided to make a jig to hold both wire rolls. I will be winding 94m of both onto the slender wooden holder and then will use it to wrap the coil.

Last night I finally got around to testing the RPi Streamer using 5v power bank. I'll have to say it was a worthwhile experiment as I believe there was a noticable improvement in the SQ. I'm planning to set the Powerbank/Charger up so when I turn the DAC on, the charger for the PB is disconnect from the AC Mains, hence removing the PSU switching element. I'll probably put another trigger outlet in the DAC to achieve this. When I bought the original PB I stuffed up and bought one that wont supply power while charging so in the switchover the Streamer would get turned on and off, not what I wont. So of course I forked out more money get get a BP that does what I need. Just another thing to add to the list

Valve porn The easy bits done, I removed some winds and took the opportunity to replace the leads with something a little more friendly. I better pull my finger out and order the wire for the 150v. If this works I might encase it in resin

The original Tube-i-Zator (which I made some years back) talked about 120v-150v but the latest board only notes 150V so I thought I'd stick with that. Always happy to hear a thought I need 0.1amp out so I thought I'd go for the 30awg which has a maximum of 0.142amp. I will probably wind the wire on a stick doubled over first so I only have to go around 700 times, yay.

I'm toying with putting a Tube-i-zator valve output stage in my other BIII DAC and I need a transformer with 150V & 9V secondaries for this built. I sent an email to Harbuch Transformers who have made custom transformers for me in the past, I haven’t heard back so I thought I'd have a go at making one myself. In the end I thought it would be much easier to buy a transformer of the right size and put on the 150v secondary myself. Of course, this could all end up in the bin I bought a 120VA, 9-9v transformer from Element 14 for less than $40 and have removed one of the 9v secondaries. I tested the 9v outputs before I dismantled it, and as usual I have more volts out than the rated voltage, 10v in this case, with 230v coming in. There is another benefit in doing this, I can remove some of the turns on the other secondary and reduce the output voltage to 9V. It turns out that about 98 turns gets you 10 volts out, which means I’m going to need about 1400 turns to get what I want, hmmm thats a lot of turns, better not loose count 😊 The wire for the 150v will cost between $15-$25 dollars so all up it should cost about $60. The last couple I had made cost close to $200 plus postage and their output voltages were higher than I ordered. I need to choose the wire size and then get about 200lm of it. I may save $150ish but I’ll earn my money doing the winding. All a bit of fun.

Well the Squeezebox Touch wins over the Rpi Streamer but it's not by a big margin, shame the Reclocker had to be removed as it would have been very interesting to see if it made a difference the the RPi.

I ended up finding the Input valves I needed at the Valve Store (6N2P-EV ) and Neil managed to up sell me (wasn't hard) a pair of JAN G.E 12AT7WC ECC81 6201 for the Output valves. I'm very glad to say that the Preamp is now making some sweet music, which is being streamed from the RPi/Volumio player. I haven't run the SBQ through it yet to see how they compare but so far so good. I think it was Red who was down on the 12AT7's but I can vouch that these sparkle in all the right ways. I have no idea if the Valve Burn-in thing is real but I guess there is the possibility that the sound will get better in the days ahead.