Hi X,
I'm will be building two Yarra's. I have both the 15v and 18v trafo's. I also have a stash of 2sk170bl's. Will the R103-106 values work with either Yarra build? One will be a HPA and the other will be a Preamp.
The Korg DB looks awesome! I have the DIY store korg board and tube waiting until I get the Yarra built. This might change up my plans.
Hi TboneAK,
Yes, if you plan on using the BL’s - the resistors show. Will work for either trafo voltage.
Yes, if you plan on using the BL’s - the resistors show. Will work for either trafo voltage.
I forgot to mention that the Korg 6P1 preamp circuit was based on Pete Millet’s design (used with permission - thanks, Pete Millet!). It does have a modification to run parallel triodes so the current drive will be more powerful.
Can someone, who has finished building the Yarra Preamp post a pic or two, on how to physically mount the vol pot onto the chassis.
Mine vol pot was aligned properly behind the faceplate, but there is no way I can tighten it to the faceplate. So it's kind of dangling behind but still sings perfectly.
Thanks
Mine vol pot was aligned properly behind the faceplate, but there is no way I can tighten it to the faceplate. So it's kind of dangling behind but still sings perfectly.
Thanks
Hi meanie,
I didn’t feel comfortable leaving the volume pot board un-soldered. I soldered pins to the bottom side of the volume pot board and then soldered that directly to the motherboard to keep close as possible to the MB without touching. Then I soldered jumper wires from the volume pot to the volume pot board and mounted the volume pot to the face plate.
Attachments
Thanks, Vunce.
I was thinking of soldering it directly using those pins as support, but I have not decided which brand of pot that I want to use.
Love the look of your pot, what brand is that?
What is the pot impedance you using?
One questions open to all, what is the sonic significant of using various different pot impedance? example 10k, 50k or 100kohms?
I noticed in valve sets, some uses as high as 500k to 1Mohms resistance.
Sorry for so many questions, I just hope to get the optimum pot for this Yarra Preamp.
I was thinking of soldering it directly using those pins as support, but I have not decided which brand of pot that I want to use.
Love the look of your pot, what brand is that?
What is the pot impedance you using?
One questions open to all, what is the sonic significant of using various different pot impedance? example 10k, 50k or 100kohms?
I noticed in valve sets, some uses as high as 500k to 1Mohms resistance.
Sorry for so many questions, I just hope to get the optimum pot for this Yarra Preamp.
No prob meanie 🙂
It’s a Penny & Giles 10k pot.
Unfortunately, I don’t think they are made anymore.
I have mostly used 10k pots on my preamps and headphones amps. Sometimes a 50k pot. I think most sources can drive a 10k pot with no issues. Maybe some tube output stages like to drive 1M? Higher input impedance pots pick up RFI noise easier. I think 10k pots tend to be very quiet from EMi/RFI standpoint.
I still haven’t gotten into boutique pots yet so can’t really say - but a decent quality $3 Alps RK09 series has served me well on countless projects.
I have bought a stepped attenuator fitted with SMT resistors. I need to try it out. Although I think the next thing will be a digital pot from Maxim controlled by a WiFi Aduino nano and a phone app.
I still haven’t gotten into boutique pots yet so can’t really say - but a decent quality $3 Alps RK09 series has served me well on countless projects.
I have bought a stepped attenuator fitted with SMT resistors. I need to try it out. Although I think the next thing will be a digital pot from Maxim controlled by a WiFi Aduino nano and a phone app.
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Count me in for two, as well. With a M2X and two Yarras in the works, why not have all the options for DB’s. 😀
Could someone please tell me the values for R154 and R174 of the Yarra (beside the transformers).
All I can find is TBA.
Also I can't find the WBA18 cct diagram.
All I can find is TBA.
Also I can't find the WBA18 cct diagram.
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I guess we can start making an interest list for the Korg 6P1 (Pete Millet based) preamp core board.
Meanie - 2 boards - Singapore
TboneAK - 2 boards - USA
Meanie - 2 boards - Singapore
TboneAK - 2 boards - USA
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Same as any of the other Yarra preamp core modules - same bolt pattern. You need to provide a connection to GND via the connector. There is a 3.3v regulator for the Korg, the Vcc can be up to 30v so 24v to 25v +ve rail of an M2X is fine. With that said, this remains to be tested.