Funny you should mention the weather Bob, as we are about receive some freezing rain followed by several inches of snow this afternoon. So my plan is to do some more work on my amp while we are stuck inside. Over the last couple of days after confirming the hum in my amp is not in the amp but somewhere ahead in the chain I have been taking the amp apart to finalize construction. I pulled out my c 13 jumpers and soldered the jantzen caps directly to the boards, and did a few nonessential tweaks. Once back together I am going to nail down exactly what external component is causing hum. One thing I have been noticing about the simple pots people are using as a volume control is that the grounds for channels are connected whether it be by wire or ground plane on pot pcb. I have mine separated. I noticed on your volume control it looks like your simple pre has the pot mounted to a pcb. Does the pcb your using share a common ground? Does isolating them cause hum? Very curious.....
Not sure which you are talking about. I have both a JC-2 with a pot and a home-brew shielded Alps. JC-2 has a common ground plane. All the grounds (4) on the alps connect at a central star. At one time I was convinced the JC-2 common was the problem but that was not the case.
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Hello Dario,
I have not still build the FE, it's matter of time and money... but I also would like first to listen for a while the C version. As you know I have listened to My-ref A for about two years and I like it very much. Then, a month ago, I changed A into C version and I still think that My-ref C it's a bit fatiguing for my ears... so I will listen to C version until the next summer, just changing (if I find a free afternoon to do this) the C13 cap. But if My-ref C will remain a bit fatiguing also with a paper-oil cap K75, I don't know if I will go on building FE... I fear it will be too detailed for me. With all the very good reviews I have read about FE, I have no doubt at all about the quality of this amp, it's just a question of taste/ears/speakers... and of course money 😱
Does anybody here has listened to My-ref A ?
Yes it is, but in my case, functions more to facilitate connecting wires than any real circuit change. As I remember, having all socket grounds plus the case as a single element was essential to interference rejection. The PCB may yield different results in another application.
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I got in at V1.2 C so have no reference for tha A version. I'll just report my general view on upgrading. The progression through the C range, and I'm including individual component upgrades within each version, were primarily subtractive. More music got through with fewer distracting artifacts. When that happens the apparent impact is increased due to better clarity and definition.
Though maybe a little dramatic, my first comment on the FE was a quantum separation from it's predecessors. That was still related to refinement more than additional power and/or SPL. You are correct that some/many improvements require spending a little more. I'm sure Dario agrees as he purposesly published two versions of the Fremen Edition - economy and full.
So my best answer is any flavor of MyRef, probably including the A that I didn't hear, is a cut above many DIY and most commercial amps in a wide price range. A builder can stop anywhere along the development path and be more that pleased with the performance. Time and cash investment are personal choices, but I haven't heard anyone say they regretted the increase in either. I suggest you trust the often posted comment "The best sounding amp I have ever owned", or what's that other one?? - Gobsmacking 😀
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Weather seems an issue these days, hellish storm here last night and this morning followed by snow. Just got the internet back.
SoIL4x4 - You need to connect all signal returns together in your passive pre then connect them to chassis ground to avoid a pin 1 problem.
Also connect signal return to chassis ground in your My-Ref, same reason.
Kreisky - The FE mono blocks I built are the best amps I've owned by a fair measure and I've had quite a few over the years. I just used the mouser BOM listed in the build guide so there is scope for even further improvement but for now I'm enjoying them so much, I'm tempted to just leave them as they are. My speakers can be bright with some amps but they just sound extremely open and detailed with the FE's, the bass is stunning too, WAY better than I expected for a chip based amp.
SoIL4x4 - You need to connect all signal returns together in your passive pre then connect them to chassis ground to avoid a pin 1 problem.
Also connect signal return to chassis ground in your My-Ref, same reason.
Kreisky - The FE mono blocks I built are the best amps I've owned by a fair measure and I've had quite a few over the years. I just used the mouser BOM listed in the build guide so there is scope for even further improvement but for now I'm enjoying them so much, I'm tempted to just leave them as they are. My speakers can be bright with some amps but they just sound extremely open and detailed with the FE's, the bass is stunning too, WAY better than I expected for a chip based amp.
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I have been trying different schemes for about three hours with no success...davy can you elaborate, what do you mean by pin 1 problem?
It's a term for an incorrectly connected signal return originally referring to a balanced connector (pin 1 is the signal ground in a balanced connector) but it's equally valid in a single ended connection (RCA). Have a read through the excellent article posted on here about system grounding, there's a lot of info but not all will be relevant to your setup.
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html
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No, while in other designs it's so, this is not the case... the MyRef signal return should not be connected to the chassis.
When PGND is connected to the chassis also signal return is, via the 1R resistor.
No, while in other designs it's so, this is not the case... the MyRef signal return should not be connected to the chassis.
When PGND is connected to the chassis also signal return is, via the 1R resistor.
Will, as you built your amps was there a point the FEs were mounted on something non metalic - like the betas in post #1259. If so, was the hum present there also?
No, they have always been mounted to the metal enclosure. I am going to redo the passive with better isolated rcas tonight and some better wire. I think my grounding scheme is good at the passive. The hum is barely present, and that is with no pgnd connection in the amp. I think I am close. I have tried a different pot and cables...trying to rule out one element at a time. Looking at the cheap rcas I used in the passive I am a little suspicious. I have a few pairs of well insulated rcas to try. The good news is the amp is dead silent with my phone as the source, so I should be close.
Ah, got you!
So it needs to be one or the other to comply with the grounding regulations.
Cheers Dario.
Pin1 is the Screen to Chassis connection.
It is NOT connected to Signal.
Pin 1 effectively extends the Chassis enclosure to include the Screen as part of the enclosure.
A system connected with RCA plugs & sockets can also have what is termed a pin 1 problem, that's what I was trying to infer.
Is that a better description?
Is that a better description?
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It obviously pays to read back over what you post. I knew fine well that pin 1 connects the screen to chassis but I still somehow managed to mess it up when I posted signal ground instead.
Probably because when it comes to balanced connections I think in terms of - Signal hot - Signal return - and lastly - Signal ground (instead of screen)
Yesterday on another forum I typed MM instead of MC when discussing a cartridge, I noticed it today and corrected it. No one said anything, probably because very few people take part in that forum compared to this one 😀
Probably because when it comes to balanced connections I think in terms of - Signal hot - Signal return - and lastly - Signal ground (instead of screen)
Yesterday on another forum I typed MM instead of MC when discussing a cartridge, I noticed it today and corrected it. No one said anything, probably because very few people take part in that forum compared to this one 😀