Hi X, Thanks for looking into this. I watched NP's 2012 burning amp vid on the F6. He briefly goes into the differences between the two. Its still fuzzy, but I came to the conclusion that it wasn't likely to be simple. If he'd done one on the M2, I'd probably understand better. I'm still learning. 
The F6 is supposed to be a really sweet sounding amp, so for now I'll complete it as designed. Just need finish the wiring, and set the bias.
If Huge has an elegant solution to use the DB's in the F6, it's another option for all these DB's you guys keep coming up with.
Next up will be the M2X, and a HPA Yarra, 15v tranfo's. I just gotta finish my speaker build first. My unheated shop is just starting to warm up.
The F6 is supposed to be a really sweet sounding amp, so for now I'll complete it as designed. Just need finish the wiring, and set the bias.
If Huge has an elegant solution to use the DB's in the F6, it's another option for all these DB's you guys keep coming up with.
Next up will be the M2X, and a HPA Yarra, 15v tranfo's. I just gotta finish my speaker build first. My unheated shop is just starting to warm up.
I was, and still am, slightly nervous about that circuit. It might not be able to drive an M2x to full volume. M2x needs 3V RMS at the daughterboard output bolt, to produce full rated output power. However the First Watt article about the H2 circuit, shows an output voltage plot which only goes up to 2V RMS:
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On top of that, one must include the signal attenuation created by the voltage divider in the new circuit, where R105 drives the 600 ohm input impedance of the Edcor transformer.
Mark I read the F6 manual and I think I see what you are getting at. I compared the M2 to the F6 specs, assuming the M2X is the same. The F6 input sensitivity is .17v less than the M2. If I found the right calculator, 2.83v is a shade over 9dB of gain. The M2 @ 3v gives me 9.54dB. But thats not that big of a difference. So it should work... But be mindful of the different DB gains so you don't over drive the amp. I'm taking big leap here, it's probably more complicated than that.
The Pass H2 board has been verrified to work. It sounds quite nice. I tested it using my Hakuin amp on a plank.
So to keep busy during this spare time, I went to work on the Hakuin M2x boards. I used the exact Mouser cart from post# 1224. Since these Hakuin modules will be used strictly for preamp duty in the Yarra, I eliminated a few redundant components the main board already has. I used the adjusted resistor values for an all ‘Vintage’ Toshiba edition. (Right on GaryS
Yarra rail voltage is 28.5vdc feeding the Hakuin, after its onboard CRCRC the voltage drops to 24.5vdc. Voltage across R112 is 11.9v, that’s good for a tick under 80mA bias. I strategically placed a few components on the underside of the pcb to allow clearance for the 2SA1837 heatsinking and to give R121 room to breath, it gets a bit warm.
C113 and C114 were not populated at first because the Yarra main board is cap coupled. But, I noticed a slight DC spike when powered on and off. Installing a 5uF film cap in C114 totally eliminated the DC spike and offset is now rock solid hovering at 0mV.
First listening impression is this circuit is extremely quiet with a deep black background. The Yarra/Hakuin preamp combo is now in my main system so it will be getting a heavy workout in the coming weeks
Hi Vunce,
Do you have any further impressions to share of the Hakuin / Yarra combo (particularly in comparison to the Melbourne) now that you've had it in your system for a bit?
Thanks
Hi Aljordan,
There have been many changes since my last post, I just have not gotten back to update everything. I will very soon though.
Teaser pic
Attachments
Sorry I wasn't more clear.
It would be nice to have a blank, perf board, daughter board. Same form factor with power, input, output and ground. It would also be nice to have the power supply decoupling filter caps incorporated on the daughter board.
I already did a perf board version, but it wasn't too pretty so I thought I would see if there might be some interest in some blank boards.
I do like having these boards to swap in and out and still have a decent preamp case, volume and input selector.
It would be nice to have a blank, perf board, daughter board. Same form factor with power, input, output and ground. It would also be nice to have the power supply decoupling filter caps incorporated on the daughter board.
I already did a perf board version, but it wasn't too pretty so I thought I would see if there might be some interest in some blank boards.
I do like having these boards to swap in and out and still have a decent preamp case, volume and input selector.
You mean literally make vero-board perf boards with thousands of 0.100 in x 0.100 in centered holes and with the 5 Yarra0-format holes so that you can whip up your own amp and have ready access to the PSU and audio in and out? That's an interesting idea - I am sure it would take JPS64 no time at all to make such a board layout.
Are you thinking of something totally diffferent than the 6 or 7 different amps we already have currently?
1. Melbourne
2. DCA
3. WB18
4. Korg 6P1
5. Hakuin
6. Pass H2
7. ACP+ (to be released pending approval from Mr. Pass)
Are you thinking of something totally diffferent than the 6 or 7 different amps we already have currently?
1. Melbourne
2. DCA
3. WB18
4. Korg 6P1
5. Hakuin
6. Pass H2
7. ACP+ (to be released pending approval from Mr. Pass)
ACP+ design is awaiting for Mr Pass to give his blessings.
Amp Camp Pre+Headphone Amp - ACP+
The matched set of LSJ74 will be the bottle neck for most. I happen to have a matched pair from DIYA Store - cost about $55 IIRC.
Amp Camp Pre+Headphone Amp - ACP+
The matched set of LSJ74 will be the bottle neck for most. I happen to have a matched pair from DIYA Store - cost about $55 IIRC.
This may be a good candidate for inversion to use n-channel jfets (parallel 2SK209GR are cheap, and reportedly work as good replacements for 2SK170s) and p-channel outputs. The ACP is very similar to the J2, so EUVL’s work will probably be helpful: UDNeSS, or You don't need Semisouth's
I have covered a few variations of the M2x compliant input stage in the main M2x thread. I have built several sets of input stages using Veroboards or strip boards, including an ACP+. These include both unity gain buffers and low gain (~ 6dB) preamp stages. Search the M2x thread for my handle and you will find what I did.Yes,
But if you keep going you might cover everything?
I do like to experiment. That's why I built the YARRA.
Getting the M3 mounting holes and connections located properly can be tricky and requires some patience. In my opinion, the mounting hole connecting scheme was both a benefit and a weakness of this concept. Nevertheless, there are a variety of ways of making input stages, and it is fun to explore different circuits.