Just placed my order for this. I am customer no. 00028!

47 Labs web page

I figure I owed it to them. 47 Labs has been good to me, and the DIY community over the years, one way or another: gainclone, phonoclone, even the DAC-of-the-Klones.

Besides, several reasons:

1. I really want to finally hear 47 labs gear, instead of trying to reverse engineer it all the time!
2. It will be interesting to compare it against the sapphire amp.
3. I'm sure it will be fun to build and examine up close.
4. It's my Christmas present.
5. And hammertone. Finish a audio product in grey, or even better, green hammertone, and its as bees to honey...

Will blog the unboxing, building, and testing right here.

In 2009, Penultimate Zen aka Zen V4 was my first solid state build. I used the parts that were available, did not know much about making it work well, and did not have test instruments beyond a cheap multimeter. Also, I did not have a preamplifier to work with it or speakers sensitive enough to enjoy its 25W. As a result, the amplifier turned out not quite satisfactory and for two years has been gathering dust and my wife's complaints. I was thinking about scrapping it and reusing the enclosure for something more useful. Instead, I reworked it.

I removed one of the two power transformers (moving from dual mono to stereo configuration), replaced my original dodgy Chinese PSU filter caps with Mundorf M-Lytic HC, replaced internal low voltage wiring with thick speaker wire, reconfigured grounding (so it is finally safe!) and installed balanced inputs with input transformers. What a change in sound! With my Exposure CD player, B1 clone preamp and Heresy III speakers, the amp...

Back by popular demand, I have decided to go ahead and prepare full kit version of the VSPS300, Phonoclone 3, and Sapphire projects.

10 kits of each project will be available - contact me to reserve.

Phonoclone Kit : $125 (10 availble) Set of two boards and components to populate.
VSPS 300 Kit : $117 (10 available) Set of two boards and components to populate.
Sapphire Kit : $113 (10 available) Set of two boards and components to populate.

Kits will be shipping shortly after the New Year.

Current status: necessary parts shipped from Mouser, should be able to assemble kits this weekend. Also have to prepare the documentation.

RJM Audio Kits

I always ground my pot to the star ground on my other projects.. seems that for some reason this shuts down the left channel on my sapphire..

went through the whole diagnostic to narrow it down to the pot.. (or so i thought) and replaced it with a new one.. i got it working.. then i grounded it and it didn't work again..

on a hunch i removed the ground wire.. and VIOLA.. sweet sound from both cans!

-joe

Hard wired the left output to the right side (running mono R on both headphones)

testing the sound of the amp.. it's truly amazing.. nothing i have compares to it..

need to get it to the store to put it on demo.. no time to work on fixing this one.. worked til 2am last night and woke up at 4:30am.. too tired

i will probably end up building another set of boards and swap it out and debug later..

-joe

The sapphire amp is done. I ended up building an external power supply, not enough room in the hammond to put everything.

I had overheated Q3 on one of the boards and the DC output was at 8vdc! luckily I always check offset before I plug headphones in.

Ended up replacing it and it works fine..

I had originally wired the chassis for dual mono output into a Y harness back to stereo.. then my friend suggested that i wire it directly for stereo.. no sense in spending time on the harness..

upon rewiring, the left channel refuse to work.. i didn't even touch it..

i must be jinxed

-joe

Someone pointed out that it's interesting to see all the components in a system, rather than discuss them individually. I liked the idea - I think it also shows what projects ended up actually useful - so here are my systems (I have four with diy components).

The music I listen to is an eclectic mix of classical music (such as Rachmaninov and Tchaikovsky), opera (mostly arias), jazz (Armstrong) and some pop music.

The first system is the one I listen to the most:

• exposure 2010S CD player with Tentlabs low-jitter clock
• B1 clone preamp
• F5 clone
• Vintage Celestion DITTON 15XR speakers

The second system is the testbed for whatever project I may be working on:

• Audio Analogue Crescendo CD player
• B1 clone preamp
• Zen V4 with SiC power JFET in the gain stage
• Klipsch Heresy III speakers

The third is the best sounding so far, has the highest WAF and is likely to stay around for some time:

• Sony CDP-XB920 CD Player
• Elekit TU-879S integrated amp

...

Another weekend, another project.

Started on the RJM sapphire headphone amp this weekend. Having a bit of trouble with the transformer I ordered. According to the BOM they specified a Triad 25VA unit.

I got them from Mouser and it was huge, the wires were unwieldly and I didn't think I would use them

Looking at the pics posted by RJM, they used Amveco, which is my normal brand.. DOH!

So off to digikey to order yet another set of transformers..

Also need to figure out if I would use the bridge rectifiers I already bought, or use Peter Daniels rectifier PCBs and use the MUR280 instead.. the latter will be faster and cost more.. the former might not perform but it's cheap

-joe

On Counterfeit Chips in US Military Hardware bunnie's blog

My brother was complaining about his vocals not coming through clearly in his (rather modest / amateur) band. It turned out that he was trying to use some old hifi speakers we had as kids!!!

I had a bunch of Beyma 12G125 bass drivers and some P.Audio PA-D26 compression drivers, so offered to throw some proper speakers together for him.

There were a couple of illustrations of design principles in here that are worth reiterating:
- The horn driver has a massive (and by this I mean both acoustically and electrically) resonant peakj just below 2KHz.

To use this driver and avoid horrible the resultant upper midrange peak, it is essental to put a trap on the tweeter to flatten out the impedance.

this at least gives the crossover a hope of working...

- The horn driver still has a big fat peak at 2KHz.

- The horn was CD - and needed compensation to bring the top end up to "flat".
...