advertisement


New PCB for shoebox size NAC preamp part III

Status
Not open for further replies.
Jiiim said:
Not really what it's designed for.
Depending on the impedance of your headphones you might get away with it but it's not really a great solution.
You could consider the method used in many commercial amp - resistive divider off the output of the power amps.
Click to expand...

I think I have a channel imbalance and I was looking to wire up my headphones taking the amps and speakers out of the loop.
 
cutting42 said:
Bad news, my powered speakers have not arrived yet and I dare not test into my 90 or 160. I have been modding the shoebox case for phono's and locking Preh DIN sockets. The funny shaped hole is for the wall wart power connector.

Nearly at that most scary point of powering it up.

Cheers

Gareth
Click to expand...

That looks jolly tidy, well done! Have you powered it up and checked the voltages around the board compared to ground yet? Do that first, then all being well I'd plug it straight into your poweramp :)
 
That looks really nice :)

While you're waiting for the test speakers to arrive, you can get the NERT much closer than that ;) All you need to do is move the nert board from the 0V point nearest the Traco, to the power 0V star. The Traco's 0V is not connected to the Starfish 0V, so there's no point in connecting the nert at the end of the track between Traco 0V and fish 0V - best to connect it directly to the star.

I've no idea if it actually makes a difference that's audible, but it costs nothing to do...

Carl
 
Uzinusa said:
That looks jolly tidy, well done! Have you powered it up and checked the voltages around the board compared to ground yet? Do that first, then all being well I'd plug it straight into your poweramp :)
Click to expand...

Thanks, I will do that tonight, was out last night playing with the band (my other main hobby) and want a full evening to test this sequentially and carefully. Will let you know how it goes.

Cheers

Gareth
 
hacker said:
That looks really nice :)

While you're waiting for the test speakers to arrive, you can get the NERT much closer than that ;) All you need to do is move the nert board from the 0V point nearest the Traco, to the power 0V star. The Traco's 0V is not connected to the Starfish 0V, so there's no point in connecting the nert at the end of the track between Traco 0V and fish 0V - best to connect it directly to the star.

I've no idea if it actually makes a difference that's audible, but it costs nothing to do...

Carl
Click to expand...

Thanks!

Oh OK, I was following the wiring pin recommendations from the BOM to connect the 0v to the "c" hole in the differential filter block. Think I will test first and then alter after that. Thanks for the hint.

Cheers

Gareth
 
OK then power was applied and


SHE'S ALIVE!!!!!!!!!!!!!!!!! :D:D:D:D:D:D:D

Current measured at 132 mA but nothing at the regs, :confused::confused::confused: Hmmm what could that be..... nothing to do with wiring the choke across the output of the Traco surely :eek: Ahem, out with solder sucker re solder correctly this time - hope the Traco has short protection!

Try again, :cool::cool::cool: we have regulated power now as well! Now a question, I am getting 13.4v for the +ve and 11.4 for the -ve. Is this OK or should they be closer to 12v???

TIA

Gareth
 
Started my Starfish tonight, building the BOM 1.2 Simple asymmetric configuration to begin with.. Tonight I have sorted all the parts, got all the resistors in, double checked and soldered and all the wire links in. All in all it took around 3 hrs. Very happy with it so far.

The BOM in the link in the first post differs a bit to the one in the 1.2 manual I have, so need to source a few more parts. Never plain sailing is it! Jim - It might be worth breaking/removing that first link, or putting a disclaimer on it.

Next up is caps, should be able to do those tomorrow night.

:)

Pics tomorrow, I promise.

Sam
 
sam_cat said:
Started my Starfish tonight, building the BOM 1.2 Simple asymmetric configuration to begin with.. Tonight I have sorted all the parts, got all the resistors in, double checked and soldered and all the wire links in. All in all it took around 3 hrs. Very happy with it so far.

The BOM in the link in the first post differs a bit to the one in the 1.2 manual I have, so need to source a few more parts. Never plain sailing is it! Jim - It might be worth breaking/removing that first link, or putting a disclaimer on it.

Next up is caps, should be able to do those tomorrow night.

:)

Pics tomorrow, I promise.

Sam
Click to expand...

The simple asymmetric is a great sounding preamp. You can wire it so it's directly swappable with the likes of a 72. It's interesting to hear what a difference a properly thought out PCB design holding an essentially similar circuit can make.

I usually suggest going straight to the V1.2 BOM and not mucking around with the earlier versions - the V1.2 really is miles ahead.

Of course, if you want to 'do the journey' - even the most basic build sounds pretty decent and it is interesting to hear how it develops. Just means you have to take care to change components correctly at each stage.


The thing I really like about the fall battle rigged version is that it will run from a wall-wart and still sound great - to bastardise a phrase "I blow my nose at your silly bigcap power supplies"


Jim.
 
Is there any benefit/point to running Super Teddy Regs with the starfish?

I want to end up with my starfish being the best it can be, and it will be going into a custom chassis (as opposed to a 72 or the like) so space is not really at a premium. Will probably end up in a 2u chassis the same as my Gain clone.

If you were building one for the optimum sound quality, what would you do.. Internal PSU/wall wart? Super teddy regs? What source selector/attenuation?

Thanks again,
Sam
 
External teddyregged PSU is what I'm going to do ... thought many seem to think one of the great things re the Starfish is its relative insensitivity to PSU....so I may be wasting my money/time - ah well better than watching Coronation St!
 
sam_cat said:
Is there any benefit/point to running Super Teddy Regs with the starfish?

I want to end up with my starfish being the best it can be, and it will be going into a custom chassis (as opposed to a 72 or the like) so space is not really at a premium. Will probably end up in a 2u chassis the same as my Gain clone.

If you were building one for the optimum sound quality, what would you do.. Internal PSU/wall wart? Super teddy regs? What source selector/attenuation?

Thanks again,
Sam
Click to expand...

No really much point in going overboard for the raw supply.
I'd suggest a nice toroid and maybe a stage of so of lm317 type regulation to feed the onboard traco - at a pinch a hicp would do nicely LOL. Mine runs quite happily from a linear wall wart.

Good quality selector switches and pot can bring dividends - although I've used cheapish ones in my current build - alps blue pot and lorlin selector - and simply havent worried about it since.
 
Just ordered a second pcb, one is going to end up as a basic/cheap build into a single case along with a pair of gainclones as a nice integrated setup for use with my computer, and the other will be the all out posh build for the nice setup downstairs :)

I already have a 50k alps blue to hand, along with a 50k stepped attenuator (one of those bargain ones from ebay).. Still need to source a few bits n bobs, hopefully have it (the first one) finished next weekend.

:)

Got all the caps soldered this evening, realised I am missing the 22pF poly film caps so have to pop to RS sometime. Off for a run now, will get the BC550C's and 560C's soldered when I get back.

Thanks again,
Sam
 
Saw your post on another thread, seized the moment :)
This one is definately waiting for BOM 1.3...
 
Starfish populated so far:

(Click for images on Flickr)


Is where I have got to in 2 evenings. Its based on the BOM in the "Preamp build manual-v06.pdf". Just deciding now if I should do the Insert the power connection links step, or wade straight into a Local regulated asymmetric configuration.

Any thoughts?

Sam
 
sam_cat said:
Starfish populated so far:

(Click for images on Flickr)


Is where I have got to in 2 evenings. Its based on the BOM in the "Preamp build manual-v06.pdf". Just deciding now if I should do the Insert the power connection links step, or wade straight into a Local regulated asymmetric configuration.

Any thoughts?

Sam
Click to expand...

Depends - if you are intrigued to hear how it evolves as you add more to the circuit then build the simple one first. Otherwise just stuff the board according to V1.2 and spend the time saved listening to music :)
 
Status
Not open for further replies.


advertisement


Back
Top