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The YARRA Preamplifier/HPA for Melbourne DB Group Buy

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K

karucho

Member
Joined 2012
Yes X, thanks for the note. The only point to the chassis that I have connected is the spacer of the screw in the photo. I have sanded the black paint off the base and tightened the hex spacer so that it is "nailed" directly into the aluminum base of the case. I have also checked it with the continuity tester. I think this is what you were referring to.
Greetings

8224C2B2-B60E-4F14-BBDA-CE2F4B4C9293.jpeg
 
Vunce

Vunce

Member
Joined 2014
Paid Member
That is the only point I have earth ground chassis connection also. My Yarra main board connects to chassis ground via a single wire connected to the ground tab of the IEC metal housing. I prefered this rather than using a metal standoff connecting the MB to chassis.
 
K

karucho

Member
Joined 2012
Yes X, I think what you explain is correct according to regulations. But since the aluminum creaked, when the hex standoff dug in, I don't think we need to worry about that connection failing. It is true that if I had to do it again, I would surely include it in the initial construction approach (according to regulations) :nod:
 
N

Nikodemuzz

Member
Joined 2018
Nikodemuzz said:
Hello! I am looking for a preamplifier to fit my needs, possibly Yarra could be the one? In all honesty, with my limited expertise I have a bit of a hard time judging whether I am in the right place. Perhaps you could help?

  • The idea is to have a fixed gain, single input preamp in a system where inputs and volume attenuation (*) are handled by MiniDSP Flex, and Firstwatt F4 being the power amp, driving FHXL's with sensitivity of 88 dB.
  • Since neither of the Flex or the F4 provide voltage gain, that would be the main function of the Yarra preamp. About 15 dB of gain should do it.

My expertise level is such that I have built several amps and projects and trust my soldering. What I don't trust is my capability of modifying circuits or independently choosing components to fit the purpose. Which is why I'm sort of doubting whether the modularity of the Yarra concept is a bit more than I can handle. All projects I have done so far have had building instructions to go with them.

What do you think? Am I in over my head on this one? Is Yarra a good fit for my use case in the first place?

(*) This is something that I still have to think about. I hate the idea of having several volume controllers in my system, but on the other hand, I want to do it the best way. I would have a good-quality remote controlled stepped attenuator available for the project.
Click to expand...
I can see that perhaps my questions were a bit too simple. I went through the entire thread, and I have more or less found the answers to my original questions. I'm still not quite sure if I'm able to take into account the adaptation of some of the components for each individual setup. I'll have to try and figure those out as I go. I might end up building several DB's, but I was intrigued by the description of the Hakuin, particularly regarding the soundstage and imaging. The Melbourne was recommended for 0dB amps but I'm thinking ~15db of gain should suffice.

I still have a few questions:

  • Somewhere in the thread there was a mention that there is a 12V outlet to power auxiliary stuff, did I understand correctly?
  • Is there a possibility to provide 5V DC as well (USB-C)?
  • The availability of those voltages would be huge as it would open up an avenue to integrate the Yarra with a DAC and a Bluetooth receiver on the input side, and a MiniDSP unit on the output side. It would be a very capable unit indeed. Simply put, I would love to get rid of all the individual devices and especially all the interconnecting cabling and power supplies. Do you see any problem preventing a concept like this from working?
 
N

Nikodemuzz

Member
Joined 2018
xrk971 said:
The new Mk I PSU board has a AC/DC that makes 12v for auxiliary stuff.
Click to expand...
Thanks @xrk971! If I understand correctly the Yarra preamp still comes with the PSU board? Would it perhaps make more sense to build an Aksa Lender then with the Mk1 PSU, so that I don't end up with an extra PSU board? Not the end of the world really, but it would seem like an unnecessary waste of a perfectly good board.
 
K

karucho

Member
Joined 2012
Hello,

This paragraph is taken from the F4 manual

"1) You can drive it directly with a line source such as a preamp.
Using this amplifier presupposes that you have a preamplifier or other source with adequate voltage and/or loudspeakers sufficiently sensitive to be able to work with the voltage and gain you have.
You would think offhand that this might be a real problem, but it is my experience that this is often not the case.
First, you will find that the more sensitive drivers deliver good volume levels
at quite low wattage. My Lowther DX55’s (93 dB/watt) mounted in Alerion enclosures adequately fill my 11,000 cubic foot listening room with about 5 volts (the equivalent of a 4 watt amplifier). I can achieve good levels with headroom to spare with my phono stage or DAC feeding an X1 preamp, which has a maximum of 14 dB gain.
If I lived in an apartment, I could get complaints from my neighbors.
Thanks to the dutiful efforts of John Atkinson at Stereophile, I have been able
to examine the maximum gain and output voltage of the tube and solid state preamps he has measured over the last 20 years or so ( www.stereophile.com ).
Virtually all active line stages achieve adequate gain and voltage swing to drive the above combination. Basically you need a linestage with about 12+ dB gain and 10+ volt maximum output.
This includes tube products from VTL, Hovland, ARC, Cary, McIntosh, CJ, EAR, MF, BAT, Lamm, and Rogue. It includes solid state preamps from Pass Labs, Krell, McIntosh, Levinson, Halcro, Naim, Boulder, Ayre, Bryston, Threshold, McCormack, Linn, Sutherland, and on and on.
If your loudspeaker is less efficient, then you need more gain from your source and/or more gain and voltage swing from your linestage. As you go in sensitivity below 87 dB, you will want to consider 100 watt balanced mono-block use, with a preamp capable of swinging 14 volts per balanced output and having a gain of 20+ dB.
As your loudspeaker increases in sensitivity, you need less gain and voltage swing."

The Yarra/Melbourne, I think it would fit perfectly.
 
W

wcwc

Member
Joined 2011
Couldn't you just add a 12V meanwell brick in the Yarra enclosure to do the same thing and use the original PSU? That is what I would probably do, but then I would be using powercons instead of an IEC in a slightly deeper enclosure. I need the 12V power supply for a BTSB may also add a muses volume control which also needs power.
 
N

Nikodemuzz

Member
Joined 2018
wcwc said:
Couldn't you just add a 12V meanwell brick in the Yarra enclosure to do the same thing and use the original PSU? That is what I would probably do, but then I would be using powercons instead of an IEC in a slightly deeper enclosure. I need the 12V power supply for a BTSB may also add a muses volume control which also needs power.
Click to expand...
Yes, this is also a possibility. Just a matter of real estate in the end I suppose. Killing several birds with one stone would always be nice. How would you go about providing the 5V in this scenario? I could use something like DC3N-1205S for voltage step-down but I'm not sure how reliable solution that is long term.
 
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