The YARRA Preamplifier/HPA for Melbourne DB Group Buy

[gary s]

Great work X, thanks a lot for the sim results and adding the option to the PCB.

 

[gary s]

Hi again X, with regards to your comment re low impedance, are you talking about changing the value of R102 in this circuit from 47K as shown down to 51 ohm - or are you referring to a resistor on the Yarra main PCB, if so what is that resistor number, thanks?

 

[xrk971]

No, R126 and R136 on the main board. If you have the output coupling cap on the main board, you don’t need it on the daughterboards. Or vice versa. For those with DC coupled output boards, the on board coupling cap C112/111 are we useful.

 

[gary s]

Hi again X, thanks for the correction on my assumption for the resistor change, much appreciated.

Now another tech question for you, seeing you like to answer them. I wonder what this new circuit would sim like if one were to use the Toshiba 2SJ313 instead of the IRF610 (same pin outs). If OK that would give an all Toshiba active device circuit for all who are nostalgic about these great but now obsolete devices. By the way, the genuine Toshiba 2SJ313 is still available from a few sources around the globe.

 

[asuslover]

I was really happy with the bom of this project, I see no reason to complicate the things ....

 

[xrk971]

You can use the Toshiba J313 - it won’t sound any better really, just cost you more. I have tried them before and they have similar sound as MOSFETs go. There are no changes needed really. The Fairchild FQP TO220’s actually sound very good too and worth trying. Not expensive either.

 

[gary s]

Thanks again for your quick reply X, good to know as I have all of these including the FQP's. I know Nelson likes these as well.

 

[xrk971]

Hi Gary,
JPS64 completed the layout and post processing of the PCA Yarra daughter board already - last Friday actually. The layout looks like it has two sets of SMT pads for either BF862 or 2SK209. The 2SK170 would fit on the 2SK209 pads but there are no TH provided. You will need to bend a little “foot” on the legs of your beloved 2SK170 and solder it to the SMT pads. Sorry but I don’t think JP has time to redo the layout to add the TH pads. Hope you are cool with that but looks like you are the only one requesting that feature.
Cheers,
X

 

[gary s]

No problems at all with that X - I can handle that with ease.

 

[aljordan]

Presenting the Yarra v2 for GB2, now with tented vias (covered with solder mask). Also, the extra pads for the triangular holes on the rotary switch have been added, negating need for an additional and separate I/O board. These should be much easier to build and less prone to solder bridges. They do lose that cool golden porous matrix look though:

Thanks for making these boards even better JPS64!

Is this the version that will be shipped if we order on Etsy?

Thanks

 

[xrk971]

Is this the version that will be shipped if we order on Etsy?

Yes

 

[gary s]

Hi X, can you advise what is the max diameter of the 470uF caps C121, C123 and C125 on the PCA Yarra DB, thanks.

Also the screen printing for output caps C111 and C112 has been transposed from the schematic - or the other way round.

 

[xrk971]

The big 1000uF C112 cap is 16mm dia with 7.5mm pitch on leads
The 470uF caps (C121123/125) are 8mm dia with 3.5mm pitch on leads
It does indeed look like the silk screen has the numbers for C111/112 transposed. Good eyes!

Will let JP know this - not sure if it is significant enough to warrant another Gerber though.

For completeness, including the schematic:

 

[xrk971]

WBA18 GB1 & Yarra GB2 (and Melbourne) status update.
Thank you to those who have placed Pre-orders on Etsy. Don't forget to put in a note saying what your DIYA handle is so I can cross reference the lists.

JPS64 - 2 boards
xrk971 - 2 boards
Vunce - 2 boards
Roundtoit - 2 boards
Carl Huff - 2 boards
Gary S - 2 boards - Pre-order placed
Meanie - 2 boards
Big E - 2 boards
Kokanee - 2 boards + 1 Yarra MB
MD_Stryker - 2 boards + 1 Yarra v2 + 2 Melbourne credit - Pre-order placed
arthur - 6 boards+3 Yarra boards - Pre-order placed
afoor - 2 boards - Pre-order placed
Russellc - 2 boards
jhofland - 2 boards - Pre-order placed
Oracle1 - 2 boards
skunark - 4 boards, 1 yarra board - Pre-order placed
TungstenAudio - 2 boards - Pre-order placed
bologna1 - 2 boards - Pre-order placed
windwardmt - 2 boards
ZUM911 - 2 boards
Batty - 2 boards - Pre-order placed
bk856er - 2 boards (+ interest in a surface mount version)
Modman - 2 boards
sampsonite - 2 boards
TboneAK - 2 boards - 1 Yarra board set - Pre-order placed
BEYoung - 4 boards - Pre-order placed
mordikai - 2 boards
Asuslover- 2 Melbourne boards+ 1 Yarra board set
vvs07- 4 boards + 2 Yarra board sets
BDP - 2 Melbournes - 1 Yarra board - Pre-order placed
BRN - 2 boards

 

[jwjarch]

Hi X, I’d like to get in on the PCA daughter boards if they become available. Should we start a new list?

 

[xrk971]

Let’s add it the list we have for the WBA18. Specify WBA18 or PCA boards.
Thanks,
X

 

[aljordan]

WBA18 GB1 & Yarra GB2 (and Melbourne) status update.
Thank you to those who have placed Pre-orders on Etsy. Don't forget to put in a note saying what your DIYA handle is so I can cross reference the lists.

I ordered on Etsy with a note on my handle, but I don't know the protocol of adding myself on this list.

 

[jwjarch]

WBA18, PCA GB1 & Yarra GB2 List

JPS64 - 2 boards
xrk971 - 2 boards
Vunce - 2 boards
Roundtoit - 2 boards
Carl Huff - 2 boards
Gary S - 2 boards - Pre-order placed
Meanie - 2 boards
Big E - 2 boards
Kokanee - 2 boards + 1 Yarra MB
MD_Stryker - 2 boards + 1 Yarra v2 + 2 Melbourne credit - Pre-order placed
arthur - 6 boards+3 Yarra boards - Pre-order placed
afoor - 2 boards - Pre-order placed
Russellc - 2 boards
jhofland - 2 boards - Pre-order placed
Oracle1 - 2 boards
skunark - 4 boards, 1 yarra board - Pre-order placed
TungstenAudio - 2 boards - Pre-order placed
bologna1 - 2 boards - Pre-order placed
windwardmt - 2 boards
ZUM911 - 2 boards
Batty - 2 boards - Pre-order placed
bk856er - 2 boards (+ interest in a surface mount version)
Modman - 2 boards
sampsonite - 2 boards
TboneAK - 2 boards - 1 Yarra board set - Pre-order placed
BEYoung - 4 boards - Pre-order placed
mordikai - 2 boards
Asuslover- 2 Melbourne boards+ 1 Yarra board set
vvs07- 4 boards + 2 Yarra board sets
BDP - 2 Melbournes - 1 Yarra board - Pre-order placed
BRN - 2 boards
jwjarch - 4 PCA boards

 

[jwjarch]

I ordered on Etsy with a note on my handle, but I don't know the protocol of adding myself on this list.

Hi Al. Just copy and paste the list and add your DIYA handle and the number of boards you want and pre-order status

 

[gary s]

Hi X, thanks for the Cap info, it might be easier just to change the output caps designation on the BOM and schematic to match the PCB layout.