The YARRA Preamplifier/HPA for Melbourne DB Group Buy

[meanie]

@Vunce,

According to Fab's manual, i use +/- 15Vdc.
Not sure if i can go higher.
At above voltages, i am listening to my system at 10 o'clock position.
Do let us know if you did use higher voltages.

Cheers!

 

[xrk971]

GB2 Status Update:

xrk971 2 USA
shanebou24 1 USA
Buyer "RC" on Etsy 1 USA *Pre-Order Placed*

4 boards so far, 6 more to go!

 

[aljordan]

I have an extra Yarra power supply board built up and it seems to be the right voltage for a Pearl II phono stage (26 to 35 volts at 100 ma). The pearl has its own regulators on the boards. I was thinking of using the Yarra PS board for the Pearl II. The pearl article says the positive rail will be sourcing more current than the negative rail. Is that a problem? Is there any reason the Yarra PS board should not be used for a pearl II?

Thanks

There is no issue with one rail using more current than the other, as long as within the range of the power supply. Each rail is provided by an indepedent trafo secondary and its own cap multiplier. 100mA is no problem for a Yarra PSU.

I did wind up building the Pearl 2 using the Yarra power supply. The results are very good. No noise at my chosen low output moving coil gain, and a big, warm sound. Thanks for your earlier feedback.

 

[Vunce]

Hi X,
Does the ACP+ have any other supporting docs(stuffing guide and part list) besides the schematic? I can only find the schematic. I’m going to start building a pair shortly
Thanks!

 

[xrk971]

Hi Vunce,
Yes, let me get that info posted. It’s a great sounding preamp.

 

[Vunce]

Great! Thanks X.
My parts are due to arrive today, Yahoo!!

 

[xrk971]

Here is the BOM, as built for the ACP+ board.

This prototype board has a trace error - you need a jumper at location shown on schematic:

Here is how I did the jumper:

 

[STUNTfingers]

Is there likely to be another run of the modushop Yarra cases?

 

[xrk971]

Hi Stuntfingers,
At present I do not see folks rallying for another minimum of 20 cases to build. There may be someone who is willing to sell you theirs. I think member Kokanee may have a case and even board set? You might PM him. If that fails, let's see if anyone else on this thread has a spare.
Thanks,
X

 

[STUNTfingers]

Thanks X, I’ll ask Kokanee. Fingers crossed.

 

[xrk971]

The Yarra main boards have arrived.

 

[xrk971]

Hi Folks,
The GB for the Pass ACP+ daughterboards is open in case anyone is interested. This preamps sounds very nice. Super powerful and deep bass.

ACP+ Preamp/HPA for Yarra Preamp

 

[STUNTfingers]

Hi X, I messaged Kokanee but didn’t hear back. Does anybody here have a spare Yarra case they’d like to sell?

 

[redjr]

Yarra 2 Pre Update?

Hi X,

Any update on Rev 2 of the Yarra pre you teased us about late last year? Is it on your radar, with any design coming along yet. Or, have you been busy with other projects. Just thought I'd ask. I remember you offering a date window of late this year. Anymore insight into the project status you can mention?

 

[meanie]

Hi X,

I have just changed my trafo to 22Vac output, i am trying to get a standard +/- 24Vdc rails for most of the daughtercards.
However, i can only manage to get minimum +/- 30.8Vdc from the lowest pot positions. I can't get any lower.

Is there anything i can do, to achieve +/-24 without changing out the 22vac trafos?

Is it safe to use 30v rails for those daughtercards? Hakuin, Melbourne and H2 etc..

Thanks

 

[xrk971]

Hi Meanie,
I run Melbourne at 30v, and have also run WBA18 there. Some of the other ones like Hakuin need 24v, and may run at 30v but will require some adjustment to setpoint resistors. Related to Redjr's question, we are working on the "Regulated Yarra PSU" which uses 78xx format TI TPS7A4xxx LDO regulators, and with that, we can get +/-24 easily As the original Yarra PSU is a cap Mx based PSU, it was not designed to provide regulated voltage, only ripple-free voltage. There may be a resistor or pot change that can get the lower voltage. Let me look into it.

@Redjr: we have many many variations of the next Yarrra proposed and JPS64 is working on the overall architecture. One thing we are wondering is if folks would like their Yarra to have DAC modules, Bluetooth, balanced in and balanced out, etc

 

[Vunce]

Hi Meanie,
I also run 22v trafos in the Yarra capMx psu. The way I reduced the voltage is increase the CRCRC resistors on the daughter board itself to lower the voltage.
My PCA’s use 47R and 33R in those locations for approximately a 7-8v drop. I don’t remember what my Hakuin values are. Use Ohms Law to calculate what the resistor values need to be for your voltage drop.

Enjoy!

 

[meanie]

Thanks Vunce!

Will do that for my newly built Hakuin.
For now, let see how Melbourne sounds like @ 30V rails.

 

[Vunce]

The Melb’s are fine with 30vdc. They are the ideal match for ‘no-gain’ amplifiers such as MoFo, F4 etc...

The Hakuin DB’s are my favorites with ‘regular’ gain amps.

 

[xrk971]

Thanks for reminding me of that Vunce. The built in CRC is awesome for that and with higher R’s you get even better ripple reduction (not that there was much to start with).