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

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

Haven't had a chance to update last two months.. the a10 preamp was completed with a little help from my dad and is now integral part of my setup. I even put my Linn magik up for sale.. it's that good.

Last month I started to gather the parts for the objective2 headphone amp. I got about 50-100 units worth of PCB and parts. I will start to package them as kits and sell some assembled. It will be my first try at selling here.

Last two weeks I finish building and rebuilding my Ck2iii headphone amp. The initial build was with an outboard power supply and headphone amp. The cost was running a little high since I build it using momentary switch, etc..

Then I rebuild it two days back into a single enclosure with a switch at the IEC instead. Cut cost down a lot since I no longer have to deal with umbilical cord, etc

-joe

After multiple digikey and mouser packages, after one big amb package.. i have started my new winter project.

the alpha 10 preamp.. basically it's a backplane board for all the different amb projects. it ties up all the different pcb together into a preamp.

the pictures of a wire free chassis was what sold me on this idea. and the fact that I can replace each module if and when they get upgraded is great.

i think that this is something others can "copy" .. make a generic backplane that you can plug different modules into to make amps, etc

-joe

I have been side tracked lately. not enough time to do the F5 like I wanted.

I ended up digging up the BOM for mini aleph and ordered the parts for that.. started to solder the parts and found that I needed to soldier mount the resistors because they are way too big for the PCB

I need to double check all the blank spots, clean up the flux on the board and start on the power supply..

It's been fun to do simple head amps (RA1 clones) and chip amps (audiosector, chipamp.com) and then move onto 4 chip TDA boards off ebay into big heatsink chassis

Along the way I learned a lot about sourcing parts (a pain), chassis work (bigger pain) and component layout for optimal cable distance and distortion

My last finished project, the b1 buffer, was the best result so far.. it's simple, but it blew away my friends big name preamps.. enough that they are making a shift to DIY their own!

Time is a commodity that a lot of DIYaudio guys lack.. other responsbilities means we have very little time to devote to projects we start and a lot of times projects get drop to the wayside.

My latest project is the F5 and I hope to get it done by the next burning amp meet.. I want to see if I can convince papa to autograph that and the B1