The YARRA Preamplifier/HPA for Melbourne DB Group Buy

[xrk971]

I was surprised to see how much interest in the PCA option with all the ore-orders coming in.

 

[jwjarch]

Regarding the PCA, X, I've been wanting to build a Pocket Class A or Desktop Class A for a while now. So this was the next best thing without starting a whole new project. It's amazing that the Yarra is so versatile to be able to swap these daughter boards in and out and see what works best for each user.

 

[xrk971]

Hi Jwjarch,
Yes - the modular amp core idea was orifinally used in the Aksa Lender motherboard and daughterboards, We were thinking that the daughterboards could be swapped out to allow changes to gain or components. But different amp topologies is very nice to have. Just remember to follow maximum voltages for the PCA. It ideally likes to run at 18.2v at the drain of the MOSFET. If you have a 24v supply from the Yarra PSU, then the specified CRCRC with the 22R's will drop down to 18v. If you have less, adjust the R accordingly to get less drop, or more drop if your supply is higher than 24. If your supply is at 18v, just put a 0.22R (or 0R jumper) across those and that will be close enough. The filter is not really needed as the Yarra PSU is already very quiet.

For those wanting to experiment with the PCA sound on their original Aksa Lender preamps (Twocents' request), JPS64 has just designed some new PCA daughterboards for the Aksa Lender card format. That preamp is already cap coupled in and out so we did not have to have any of that on-board.

Here is the initial render:

and schematic:

For those maybe not familiar with Aksa Lender card format:

 

[twocents]

Oh wow - this is absolutely amazing! A crazy idea just a few hours ago, and now it is already done! Thank you very much X and JP - you guys are truly amazing.

If you start a GB I will take 4 boards, otherwise the Eagle files will do. Not sure how many Aksa Lender builders will be interested in the PCA daughterboards?

 

[xrk971]

GB Status Update:

Note that all Yarra's henceforth will be v2 (with tented vias). A little house cleaning on the list to spell out WBA18 since we are mixing several boards here. the Etsy shop pre-ordering system is working well though because I have no more fears that I will miss an order and the mechanics of order fulfillment are very clear and streamlined.

JPS64 - 2 WBA18 boards - Pre-order placed
Vunce - 2 WBA18 boards - Pre-order placed
Gary S - 2 WBA18 boards - Pre-order placed + 2 PCA boards (to order later)
MD_Stryker - 2 WBA18 boards + 1 Yarra v2 + 2 Melbourne credit - Pre-order placed
arthur - 6 WBA18 boards+3 Yarra boards - Pre-order placed
afoor - 2 WBA18 boards - Pre-order placed
jhofland - 2 WBA18 boards - Pre-order placed
skunark - 4 boards, 1 yarra board - Pre-order placed
TungstenAudio - 2 WBA18 boards + 2 PCA - Pre-order placed
bologna1 - 2 WBA18 boards - Pre-order placed
windwardmt - 4 WBA18 boards + Yarra - Pre-order placed
Batty - 2 WBA18 boards + 2 PCA- Pre-order placed
sampsonite - 1 yarra + 2 WBA18 + 2 PCA - Pre-order placed
TboneAK - 2 WBA18 boards - 1 Yarra board set - Pre-order placed
BEYoung - 4 WBA18 boards - Pre-order placed
Asuslover- 2 Melbourne boards+ 1 Yarra board set - Pre-order placed
BDP - 2 Melbournes - 1 Yarra board - Pre-order placed
BRN - 2 WBA18 boards - Pre-order placed
jwjarch - 4 PCA boards - Pre-order placed
poseidonsvoice - 2 WBA18 - Pre-order placed
aljordan - 2 Yarra, 2 WBA18 - Pre-order placed
bk856er - 2 WBA18 + 2 PCA + 1 SLB - Pre-order placed
Billc - 1 Yarra + 2 WBA18 - Pre-order placed
bologna1 - 2 PCA - Pre-order placed
Urien - 2 WBA18 + 1 SLB - Pre-order placed
Roundtoit - 2 WBA18 boards - Pre-order placed


Carl Huff - 2 WBA18 boards
Meanie - 2 WBA18 boards
Big E - 2 WBA18 boards
Kokanee - 2 WBA18 boards + 1 Yarra MB
Russellc - 2 WBA18 boards
Oracle1 - 2 WBA18 boards
ZUM911 - 2 WBA18 boards
Modman - 2 WBA18 boards
mordikai - 2 WBA18 boards
vvs07- 4 WBA18 boards + 2 Yarra board sets

 

[xrk971]

Oh wow - this is absolutely amazing! A crazy idea just a few hours ago, and now it is already done! Thank you very much X and JP - you guys are truly amazing.

If you start a GB I will take 4 boards, otherwise the Eagle files will do. Not sure how many Aksa Lender builders will be interested in the PCA daughterboards?

If I do make a GB, it will need to be listed in the Aksa Lender GB thread, else too confusing and off topic here. My fault for posting in wrong thread.

 

[meanie]

Updated my order, thanks....


JPS64 - 2 WBA18 boards - Pre-order placed
Vunce - 2 WBA18 boards - Pre-order placed
Gary S - 2 WBA18 boards - Pre-order placed + 2 PCA boards (to order later)
MD_Stryker - 2 WBA18 boards + 1 Yarra v2 + 2 Melbourne credit - Pre-order placed
arthur - 6 WBA18 boards+3 Yarra boards - Pre-order placed
afoor - 2 WBA18 boards - Pre-order placed
jhofland - 2 WBA18 boards - Pre-order placed
skunark - 4 boards, 1 yarra board - Pre-order placed
TungstenAudio - 2 WBA18 boards + 2 PCA - Pre-order placed
bologna1 - 2 WBA18 boards - Pre-order placed
windwardmt - 4 WBA18 boards + Yarra - Pre-order placed
Batty - 2 WBA18 boards + 2 PCA- Pre-order placed
sampsonite - 1 yarra + 2 WBA18 + 2 PCA - Pre-order placed
TboneAK - 2 WBA18 boards - 1 Yarra board set - Pre-order placed
BEYoung - 4 WBA18 boards - Pre-order placed
Asuslover- 2 Melbourne boards+ 1 Yarra board set - Pre-order placed
BDP - 2 Melbournes - 1 Yarra board - Pre-order placed
BRN - 2 WBA18 boards - Pre-order placed
jwjarch - 4 PCA boards - Pre-order placed
poseidonsvoice - 2 WBA18 - Pre-order placed
aljordan - 2 Yarra, 2 WBA18 - Pre-order placed
bk856er - 2 WBA18 + 2 PCA + 1 SLB - Pre-order placed
Billc - 1 Yarra + 2 WBA18 - Pre-order placed
bologna1 - 2 PCA - Pre-order placed
Urien - 2 WBA18 + 1 SLB - Pre-order placed
Roundtoit - 2 WBA18 boards - Pre-order placed
Meanie - 2 WBA18 - Pre-order placed

Carl Huff - 2 WBA18 boards
Big E - 2 WBA18 boards
Kokanee - 2 WBA18 boards + 1 Yarra MB
Russellc - 2 WBA18 boards
Oracle1 - 2 WBA18 boards
ZUM911 - 2 WBA18 boards
Modman - 2 WBA18 boards
mordikai - 2 WBA18 boards
vvs07- 4 WBA18 boards + 2 Yarra board sets

 

[xrk971]

If I do make a GB, it will need to be listed in the Aksa Lender GB thread, else too confusing and off topic here. My fault for posting in wrong thread.

A new GB for the Aksa Lender PCA (AL PCA) daughterboard is now available:
AKSA's Lender Preamp with 40Vpp Ouput GB

 

[bk856er]

Do the D45H11/D44H11 require electrical isolation from the heatsink, or just a dab a thermal compound?

BK

 

[Vunce]

Hi BK,

Yes, isolate with pad and plastic shoulder washer

 

[Kokanee]

Hi X,

To pre-order like you suggest , does one register and create an account or sign in, or do we just click on the items that we want. Thanks for the help.

Myles

 

[Kokanee]

Hi X,
Disregard post above. Figured it all out and submitted order.

Myles

 

[Kokanee]

Updated the pre-order list


JPS64 - 2 WBA18 boards - Pre-order placed
Vunce - 2 WBA18 boards - Pre-order placed
Gary S - 2 WBA18 boards - Pre-order placed + 2 PCA boards (to order later)
MD_Stryker - 2 WBA18 boards + 1 Yarra v2 + 2 Melbourne credit - Pre-order placed
arthur - 6 WBA18 boards+3 Yarra boards - Pre-order placed
afoor - 2 WBA18 boards - Pre-order placed
jhofland - 2 WBA18 boards - Pre-order placed
skunark - 4 boards, 1 yarra board - Pre-order placed
TungstenAudio - 2 WBA18 boards + 2 PCA - Pre-order placed
bologna1 - 2 WBA18 boards - Pre-order placed
windwardmt - 4 WBA18 boards + Yarra - Pre-order placed
Batty - 2 WBA18 boards + 2 PCA- Pre-order placed
sampsonite - 1 yarra + 2 WBA18 + 2 PCA - Pre-order placed
TboneAK - 2 WBA18 boards - 1 Yarra board set - Pre-order placed
BEYoung - 4 WBA18 boards - Pre-order placed
Asuslover- 2 Melbourne boards+ 1 Yarra board set - Pre-order placed
BDP - 2 Melbournes - 1 Yarra board - Pre-order placed
BRN - 2 WBA18 boards - Pre-order placed
jwjarch - 4 PCA boards - Pre-order placed
poseidonsvoice - 2 WBA18 - Pre-order placed
aljordan - 2 Yarra, 2 WBA18 - Pre-order placed
bk856er - 2 WBA18 + 2 PCA + 1 SLB - Pre-order placed
Billc - 1 Yarra + 2 WBA18 - Pre-order placed
bologna1 - 2 PCA - Pre-order placed
Urien - 2 WBA18 + 1 SLB - Pre-order placed
Roundtoit - 2 WBA18 boards - Pre-order placed
Meanie - 2 WBA18 - Pre-order placed
Kokanee - 2 WBA18 boards + 1 Yarra MB - pre-order placed


Carl Huff - 2 WBA18 boards
Big E - 2 WBA18 boards
Russellc - 2 WBA18 boards
Oracle1 - 2 WBA18 boards
ZUM911 - 2 WBA18 boards
Modman - 2 WBA18 boards
mordikai - 2 WBA18 boards
vvs07- 4 WBA18 boards + 2 Yarra board sets

 

[mordikai]

Updated the pre-order list


JPS64 - 2 WBA18 boards - Pre-order placed
Vunce - 2 WBA18 boards - Pre-order placed
Gary S - 2 WBA18 boards - Pre-order placed + 2 PCA boards (to order later)
MD_Stryker - 2 WBA18 boards + 1 Yarra v2 + 2 Melbourne credit - Pre-order placed
arthur - 6 WBA18 boards+3 Yarra boards - Pre-order placed
afoor - 2 WBA18 boards - Pre-order placed
jhofland - 2 WBA18 boards - Pre-order placed
skunark - 4 boards, 1 yarra board - Pre-order placed
TungstenAudio - 2 WBA18 boards + 2 PCA - Pre-order placed
bologna1 - 2 WBA18 boards - Pre-order placed
windwardmt - 4 WBA18 boards + Yarra - Pre-order placed
Batty - 2 WBA18 boards + 2 PCA- Pre-order placed
sampsonite - 1 yarra + 2 WBA18 + 2 PCA - Pre-order placed
TboneAK - 2 WBA18 boards - 1 Yarra board set - Pre-order placed
BEYoung - 4 WBA18 boards - Pre-order placed
Asuslover- 2 Melbourne boards+ 1 Yarra board set - Pre-order placed
BDP - 2 Melbournes - 1 Yarra board - Pre-order placed
BRN - 2 WBA18 boards - Pre-order placed
jwjarch - 4 PCA boards - Pre-order placed
poseidonsvoice - 2 WBA18 - Pre-order placed
aljordan - 2 Yarra, 2 WBA18 - Pre-order placed
bk856er - 2 WBA18 + 2 PCA + 1 SLB - Pre-order placed
Billc - 1 Yarra + 2 WBA18 - Pre-order placed
bologna1 - 2 PCA - Pre-order placed
Urien - 2 WBA18 + 1 SLB - Pre-order placed
Roundtoit - 2 WBA18 boards - Pre-order placed
Meanie - 2 WBA18 - Pre-order placed
Kokanee - 2 WBA18 boards + 1 Yarra MB - pre-order placed


Carl Huff - 2 WBA18 boards
Big E - 2 WBA18 boards
Russellc - 2 WBA18 boards
Oracle1 - 2 WBA18 boards
ZUM911 - 2 WBA18 boards
Modman - 2 WBA18 boards
mordikai - 2 WBA18 boards + 2 Melbourne + 1 Yarra - pre-order placed
vvs07- 4 WBA18 boards + 2 Yarra board sets
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[bk856er]

Hi BK,

Yes, isolate with pad and plastic shoulder washer

For reals? Bummer, need to get more shoulder washers.

New question. The R1043/R1041 combination is a bit goofy. I'm supposed to solder both parts and get a little creative about fitment, correct?

BK

 

[Vunce]

New question. The R1043/R1041 combination is a bit goofy. I'm supposed to solder both parts and get a little creative about fitment, correct?

BK

Yep, creative

 

[xrk971]

I think one or the other is fine for a ground loop breaker.

 

[bk856er]

Found some shoulder washers. Mostly done. Is there a recommended power-up/setting/testing procedure for the PS?

BK

 

[xrk971]

I connected alligator clips to the output and monitored on DVM. Power up and have finger on switch tonturn off if you smell any smoke etc. stand back in case you have a cap in backwards as it can blow. After 2 minutes it’s safe to get close to it and adjust screws to get voltage output adjustment. Set for about 3v drop from after filter caps to output.

 

[bk856er]

PS powered up just fine, LEDs working, heatsinks warm not hot after 30min, +/-25V at the outputs. Trimmers have very little effect? Kinda tricky to figure out the X161 pinout, hopefully I've got that bit right.

BK