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The YARRA Preamplifier/HPA for Melbourne DB Group Buy

Founder of XSA-Labs
Joined 2012
Paid Member
Hi folks,
The order for the Yarra board set just arrived and I can begin shipping the orders for all of you have placed orders on the past couple of weeks. This board has the issue of some orphaned ground pads on the input/output board fixed. Another beautiful masterpiece in layout by JPS64. Thank you, JP!

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It looks like someone got close to this question but I cant see that is was ever asked.

When choosing a transformer, I think a good middle ground would be 18V. What is preferred?

Use case for preamps and swapping around the offerings. (I have a Hakuin, Melbourne and Korg 6P1 I was planning on ending up with the Korg 6P1 but I keep hearing great things about the Hakuin so ill have to test them all!)

Also I have pair of Talema 70014k there smaller but could i use them?( they just happen to be on hand)

Best,
Shane
 
Founder of XSA-Labs
Joined 2012
Paid Member
Vunce has built all of them, and so have I.

They all sound great, and are separated more by intended purpose.

Melbourne was designed to drive large voltage swings so power F4 or MoFo or other 0dB output stages but have low distortion and a harmonic profile that is natural and non fatiguing. Classic SE Class A sound but lower than average SE Class A THD.

Hakuin is exceptionally smooth and yet resolving of transient details. Very wide sound stage and super imaging. Natural non fatiguing sound that makes you want to rediscover your music collection.

ACP+ is very natural sounding classic SE Class A signature, nice sweetness and fairly low THD, good soundstage. Can drive lower impedance headphones well.
 
Member
Joined 2014
Paid Member
Yup, I have all three built also. I get most listening pleasure from Hakuin (Toshiba devices). It just sounds a bit better in my system. The ACP+ is also excellent. I don’t use the Melbourne much because I have my AKSA Lender preamp set up perfectly to drive 0dB amplifiers.
 
Hi,

Excuse my ignorance ... I have the Talema 700K52 12v + 12v transformers and I don't think I get beyond 18v at the output of the Yarra power supply (I don't have a pcb yet). The Hakuin plate whose voltage recommendation is 24v will be fed ...
Will 18v (Talema 12 + 12v) be enough? Should I connect a jumper across the transformer output (serial output) to get 24v?

Thanks in advance
 
I was thinking of putting the amp modules in the amp prior to the amp board. Looks like that may not be as easy as I first thought. I have the WBA18 and the melbourne boards so far to try this once I build them out. I have a few questions. Most of the amps will have +/- 24V rails.

Which boards require coupling caps?
What are the voltage ranges required or acceptable for each board?
How much gain?
Is the gain adjustable?

I would like to try them all, but it appears that some will require a voltage adjustment or or coupling caps.
 
Last edited:
Founder of XSA-Labs
Joined 2012
Paid Member
The will all work on +/-24v or +24v. The single ended ones can be discerned by single rail supply (PCA, Hakuin, Korg 6P1, H2) and these need coupling caps. The ones that are dual rail (Melbourne, WBA18, ACP+) don’t need coupling caps on the output. I highly recommend caps in the input in all cases. The Melbourne and ACP+ can run up to +/-30v. The WBA18 might be able to also, although you might want to decrease the bias current on the outputs. Same with the ACP+.

Gain on Melbourne by default is 22dB I think. The PCA and Hakuin are around 12dB to 15dB. They can all be adjusted of course but some will take some theory or use the LTSpice simulator.