The YARRA Preamplifier/HPA for Melbourne DB Group Buy

[Algar_emi]

Are you planning an other run of the Hifi2000 custom chassis?
SB

 

[yourownbuzz]

Hey X - gonna place an order for these as well - whats the best way to get a set of 2SA1837 added onto the order (and price)? Just add a message at etsy checkout?
Thanks!

Hi Gary,
The Hakuin DB's are now available on my shop here:
Hakuin DB for Yarra | Etsy

You only need to use one JFET, either 2SK209BL ot 2SK170BL, so ignore TH pads if using SMT and vice versa. For the BJT, the 2SA1837 is the best of course, but can also use TTC004B, or the small DZT5401 SMT option. Depending on which option you use, the resistor setpoints are different. However, same settings for 2SA1837 with either 2SK209BL or 2SK170BL. So only 2 transistors needed per amp module (1 JFET and 1 BJT).

 

[yourownbuzz]

Also, were there any revised resistor values to run the BF862 in this? I thought I may have seen something in this or the other thread but can't find it again. Asking cuz I have a bunch of them left from PCA building, and 2SK209BL can't seem to be found.
Closest I got was at Arrow, you can request a quote. (digi now has QTY 2 - VERY limited! doesn't seem like a viable source lol)

 

[xrk971]

Hey X - gonna place an order for these as well - whats the best way to get a set of 2SA1837 added onto the order (and price)? Just add a message at etsy checkout?
Thanks!

I’ll add an option to have the 2SA1837’s included. Standby.

I will have to run a simulation with BF862. It’s possible but probably not a good idea to run the amp above 20v.

 

[xrk971]

For the CRCRC, I should add that the R121/122 could be made smaller like 4.7R for a 0.7v drop and leave at 22R for a 3v drop depending on how much voltage drop you like. Higher R’s give better stereo separation if using common psu. Also gives better noise filtering of your psu is not particularly low noise (like typical main rail of power amp CRC like a Pass M2X). If using with Yarra dual mono low noise PSU, you could omit the Rs entirely with a jumper.

 

[xrk971]

Are you planning an other run of the Hifi2000 custom chassis?
SB

If you can round up interest for 20 cases, it can be possible to do it again.

 

[xrk971]

The option for including 2SA1837's is now in the shop. There is an "Options" drop down button.

Hakuin DB for Yarra | Etsy

 

[Algar_emi]

I would be interested in one case... SB

 

[xrk971]

All of the Hakuin preamp DB’s have been sent out. Most folks opted for the 2SA1837 to be included.

 

[yourownbuzz]

Thanks! Ordered - can't believe you got it sent out within the hour!

The option for including 2SA1837's is now in the shop. There is an "Options" drop down button.

Hakuin DB for Yarra | Etsy

 

[TboneAK]

Hakuin's on the way! I have a stash of 2SK170BL's, un-matched. I'm assuming that a match is preferable, but how tight?

 

[xrk971]

Within 5-10% is probably fine. I pulled two random 2SK209’s from same tape strip but not consecutive and got better than 1% match on resulting bias current (lucky I suppose). I don’t think it’s that important unless you want critically matched channels.

 

[xrk971]

Thanks! Ordered - can't believe you got it sent out within the hour!

😎

 

[yourownbuzz]

Now that the boards are on the way I've been searching for somewhere to get the 2SK209BL / 2SK170BL.
> There seem to be two sellers - one in the UK and one in the US selling of a stash of NOS 2SK170BLs - shipping is crazy from either (thanks ebay global shipping program) but this might help someone else. (~$6.85 ea unmatched, $15-20 matched, or ~$4.5 ea in a lot of 20 from USA seller - 200 lot also available. GBP14 ea , matched from UK seller)
> HK seller "jims audio" has 2SK170BL - not sure about trustworthiness from that part of the world though - anyone know? (~$8 ea matched)
> There's an Aussie eBay seller supposedly selling NOS 2SK170BL in lots of 20 - the most affordable/reasonable option, but seller has 0 feedback though - is this someone from DIYA? (~AU$4.6 / ~US$2.70 ea)
> 2SK209BL - no one really seems to stock these. I put in a quote for QTY 10 at Arrow to see if it's available. Digi still has the QTY 2 remaining, long lead on more.
> DIYA Shop has LSK170s readily available - would these be viable instead of the 2SK?

Thoughts?

Aussie seller: Genuine NOS Toshiba 2SK170BL Small Signal Low Noise J-Fet 5052406627379 | eBay
UK seller: 2SK170 BL Low Noise N Channel JFET (NOS) | eBay
USA seller: Toshiba 2SK170 LAB MATCHED OCTET to 0.03mA / 4mV (8 matched FETs 9-10mA range) | eBay
JimsAudio: 2SK170BL low noise N-channel J-FET matched Idss to 0.1mA 1 pair !! - JIMS Audio

 

[gary s]

Hi yourownbuzz

I have not seen genuine NOS Toshiba 2SK170BL Jfets with kinked legs or supplied as tape and reel as the Aussie seller shows. His price is too cheap for real devices.

The ones shown in the photo from the UK seller have different printing to original ones - suspect!

The US seller (punkydawgs) devices are genuine for sure.

Jim's Audio should be genuine as well - unlike all other HK and China based sellers.

How many do you need? I can help out with original Toshiba devices, send me a PM. I have sent some to other Aussie members.

Cheers,

Gary..

 

[aljordan]

Will Hakuin boards mounted on the Yarra drive an amplifier well, or are they best suited to headphones only?

 

[xrk971]

They can drive an amplifier very well. I have been using them for just that over past 2 days. Use it to drive a low distortion Class AB and it imparts the SE Class A sound to it. It won't have the huge swing that the Melbourne is capable of though so is meant for amps with some gain (not 0dB gain like some).

 

[gary s]

Hi Vunce,

Have you made any headway yet with the Mouser shopping cart / BOM as X has mentioned in post #1199 back on the 15th March for the Hakuin pcb?

Cheers,

Gary..

 

[Vunce]

Thanks for reminding me Gary! Sorry about the delay.
Yes, it’s been finished. I’ll post it in time for your Sunday afternoon cocktails 😀

 

[gary s]

Thanks Vunce, not sure about Sunday afternoon cocktails - maybe a cold beer instead.