Hi BK,
Mundorf MCap EVO Oil 10uF 450VDC, Sonic Craft
Or just use the Silmic II 10uF in the meantime. Then swap out to a “fancier” cap whenever your ready.
Ah, I see - very flexible board design!
BK
Thanks TboneAK!
The tba parts should be fine. Since I won’t be using headphones, I’m building the Yarra/Melbs to give the most oomph possible, hence the 22v trafo.
This looks simply amazing and the work done is first class professional!
Congrats JP and xrk!.
Regards
Prasi
Just wanted to give an update on the Yarra PCB. I ran into a couple of delays with the production because it is such a complex layout with lots of vias and cutouts for sub boards. The fab house had many questions and emails back and forth before production actually started. The 12 hr time difference sort of added a delay to emails back and forth. The PCB is now truly in production. Hopefully will be done in 2-4 days.
So.. let's see if I understand this correctly (have been jumping across a few threads to try and work out what this one is about)
1) This is a mainboard to use the melbourne daughterboards from another project, and it's essentially a PSU and input/output caps?
2) The melbourne board schematic in post 1 looks very similar (identical?) to Aksa Lender preamp/hpa except its running of dual rails? [and the HPA uses a current transistor rather than the discontinued part]
If that's correct... then.... what's the difference between this and the aksa lender preamp/hpa (more interested in the hpa aspect)? Or is this just a slightly different take on the same thing?
Would this work with the PSU from the Simple DC Coupled HPA?
(Simple High Performance DC Coupled Class A HPA with sub PPM THD)
Just trying to gauge if I should jump on this as well haha
1) This is a mainboard to use the melbourne daughterboards from another project, and it's essentially a PSU and input/output caps?
2) The melbourne board schematic in post 1 looks very similar (identical?) to Aksa Lender preamp/hpa except its running of dual rails? [and the HPA uses a current transistor rather than the discontinued part]
If that's correct... then.... what's the difference between this and the aksa lender preamp/hpa (more interested in the hpa aspect)? Or is this just a slightly different take on the same thing?
Would this work with the PSU from the Simple DC Coupled HPA?
(Simple High Performance DC Coupled Class A HPA with sub PPM THD)
Just trying to gauge if I should jump on this as well haha
Haha, the Aksa fan club returns!
Hi YOB,
Glad you found this in your perusals.
The Melbourne is indeed similar to Aksa Lender Preamp but dual rail, more importantly, is DC coupled, if you wish. It also has a topology tweak on the output - it has a mu-follower which enables it to drive lower impedance loads at lower distortion. This was needed since the 600ohm Edcor on M2x was quite a difficult load for the regular Aksa Lender. Maybe the HPA version would have faired better - but I needed dual rail to be compatible with M2X.
You can indeed use same awesome PSU from the ppm distortion HPA project. However that’s a 18v supply and the Melbourne likes 24v to 30v dual rail.
It’s got a lot of SMT though so the YARRA is pretty much all TH, which works well for a lot of folks. The use of linear trafos and cap multipliers also makes this PSU one of the best around. It can handle loads in excess of 1A depending on your trafo and diodes.
Jump on in if you want. Get the Melbournes at least and play with them.
Glad you found this in your perusals.
The Melbourne is indeed similar to Aksa Lender Preamp but dual rail, more importantly, is DC coupled, if you wish. It also has a topology tweak on the output - it has a mu-follower which enables it to drive lower impedance loads at lower distortion. This was needed since the 600ohm Edcor on M2x was quite a difficult load for the regular Aksa Lender. Maybe the HPA version would have faired better - but I needed dual rail to be compatible with M2X.
You can indeed use same awesome PSU from the ppm distortion HPA project. However that’s a 18v supply and the Melbourne likes 24v to 30v dual rail.
It’s got a lot of SMT though so the YARRA is pretty much all TH, which works well for a lot of folks. The use of linear trafos and cap multipliers also makes this PSU one of the best around. It can handle loads in excess of 1A depending on your trafo and diodes.
Jump on in if you want. Get the Melbournes at least and play with them.
I won't pretend to understand what a mu follower is but I'm on board with the improvements you say it brings
I'm just mainly interested in using it as a hpa, the hpa schematic on first post had +/- 15v? or is 24-30V still the preferred voltage?
Would prefer to stick with that PSU if it works since it's a handy get out of jail card for avoiding mains wiring
Will the boards work without a mainboard / would I lose anything (aside from tidiness haha) from just wiring it up like you did with the wooden board prototype I saw on one of the threads?
My initial trepidation of soldering SMD when I started with the PCA has passed after making several PCAs and the ppm hpa
I'm just mainly interested in using it as a hpa, the hpa schematic on first post had +/- 15v? or is 24-30V still the preferred voltage?
Would prefer to stick with that PSU if it works since it's a handy get out of jail card for avoiding mains wiring
Will the boards work without a mainboard / would I lose anything (aside from tidiness haha) from just wiring it up like you did with the wooden board prototype I saw on one of the threads?
My initial trepidation of soldering SMD when I started with the PCA has passed after making several PCAs and the ppm hpa
It will work fine without the Yarra (but kind of messy), and you will need a clean dual rail PSU. 18v should be ok for a HPA - you will need to adjust the resistors on the CCS to get the current up to, say 80mA to 100mA for driving lower impedance phones. I used mine with only 42mA bias and they worked surprisningly well on 55ohm headphones.
Maybe just get a set of Melbournes to play with? They are TH.
Maybe just get a set of Melbournes to play with? They are TH.
This is going to be a sweet preamplifier. Can't wait to see the case in real life. JPS64 made this look probably as good or better than many big name professional products. Vunce tells me the populated PSU board alone weighs 3.1 lbs. Still waiting to hear from JPS64 regarding manufacturer's quote.
I have made SW assemblies before, but never anything with this many parts - it is an incredible amount of work to see that it all fits a-priori. I think we also have JPS64's significant other to thank for the SW model. What a lucky guy. I do not know another guy on DIYA whose spouse does audio with him on the same projects!
Hi JPS64,
Any news on the quotation for the custom case yet? These HiFi2000 guys take their time!
Cheers,
X