Layout Question
I am thinking about the layout of the FE amp that I am working on and would appreciate some input from you guys.
The place where the amp will sit is short on surface area, so I have decided to minimize the footprint of the amp by stacking the amplifier boards and mounting the transformers to the sides. This will result in an amp that is taller, but has a smaller footprint.
The question I have is regarding the mains power inlet. The width of the enclosure is only a little more than the FE boards. If I build the traditional layout with the amp boards at the back and the transformers at the front, then the mains power line coming from the back panel will have to pass within about 25 mm of the edge of the bottom FE board. Even though the FE amp has good PSRR and it's the power supply side of the board, it seems risky to run that much current so close.
I could shield the power inlet and mains wires by building a conductive enclosure as it runs past the amp board and ground that enclosure to safety ground at the power inlet. That configuration would be my plan with Layout A.
Less convenient for using the space and less attractive looking would be Layout B. In this case, I turn the enclosure sideways and bring the mains power in from the other end of the enclosure. It is clearly ideal from a noise standpoint, but less attractive from a package standpoint.
Can anyone comment on running mains power that close to a My_Ref or other amp board? Also comments on experience with a shield enclosure for mains power would be great. I could make the shield enclosure out of either aluminum or copper. The idea of the copper would be a better conductor and not as good at sustaining eddy currents.
Thanks in advance for your thoughts.
Jac
I am thinking about the layout of the FE amp that I am working on and would appreciate some input from you guys.
The place where the amp will sit is short on surface area, so I have decided to minimize the footprint of the amp by stacking the amplifier boards and mounting the transformers to the sides. This will result in an amp that is taller, but has a smaller footprint.
The question I have is regarding the mains power inlet. The width of the enclosure is only a little more than the FE boards. If I build the traditional layout with the amp boards at the back and the transformers at the front, then the mains power line coming from the back panel will have to pass within about 25 mm of the edge of the bottom FE board. Even though the FE amp has good PSRR and it's the power supply side of the board, it seems risky to run that much current so close.
I could shield the power inlet and mains wires by building a conductive enclosure as it runs past the amp board and ground that enclosure to safety ground at the power inlet. That configuration would be my plan with Layout A.
Less convenient for using the space and less attractive looking would be Layout B. In this case, I turn the enclosure sideways and bring the mains power in from the other end of the enclosure. It is clearly ideal from a noise standpoint, but less attractive from a package standpoint.
Can anyone comment on running mains power that close to a My_Ref or other amp board? Also comments on experience with a shield enclosure for mains power would be great. I could make the shield enclosure out of either aluminum or copper. The idea of the copper would be a better conductor and not as good at sustaining eddy currents.
Thanks in advance for your thoughts.
Jac
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Thanks
That second build is within site now, just the Mundorf AG caps and some Neotech OCC wire (to satisfy my OCD) left to order and I'm good to go
Congrats.
I never made the comparison myself, but Bob said that the Mundorf caps really helped the bass. They are pricey though. I guess that's just the price of our obsession.
Jac
Jac you could always use one of these and mount a switched IEC inlet in the front base of your amp so that you can mount things in the usual? way.
PX0588 - BULGIN - SOCKET, IEC, SIDE ENTRY, FREE | Farnell element14 UK
PX0588 - BULGIN - SOCKET, IEC, SIDE ENTRY, FREE | Farnell element14 UK
Thanks for the encouragement Jac. It will be interesting to see what improvement the new boards with upgrade components make and i'll still have my original boards for backup if I screw up
Next year I intend to finish the job by fitting better hardware, sockets etc. Oh and R core transformers to replace the toroidal ones which produce a bit of mechanical noise.
As to your build, I'd go with layout B myself. I prefer to keep mains wiring as far away from the boards as possible. Why build in a known potential problem which could be difficult to solve once the amps finished is my take on it.
Next year I intend to finish the job by fitting better hardware, sockets etc. Oh and R core transformers to replace the toroidal ones which produce a bit of mechanical noise.
As to your build, I'd go with layout B myself. I prefer to keep mains wiring as far away from the boards as possible. Why build in a known potential problem which could be difficult to solve once the amps finished is my take on it.
If you strictly follow pairs of close coupled wires for EVERY circuit, then you will find that interference effects are very much reduced.
Close coupling the mains wiring and the terminations reduce emitted interference.
Close coupling the input wiring and the terminations reduces the sensitivity to picking up interference.
When you do this, you will find that mains to low level interference virtually disappears.
Try it without the chassis.
Move temporary wiring around. Place it alongside the FE PCB. Does it create any noise change at the output?
Place it under the PCB, then over the PCB.
Are there any locations where you can hear, or measure, an increase in output noise?
Once you have found the "no go" areas, then you can layout your Chassis/modules.
Thanks Andrew. I should have thought of that and tried already. I will give it a go.
Also, I like Marra's idea in either layout. Not running the mains power inside of the chassis and using a "stealth" 90 degree inlet plug both keeps the power isolated from the boards and allows the chassis to be a little narrower.
Thanks all.
Jac
Wish I had just bought Amtrans AMGR from hifi collective now instead of ordering Caddock MK132 from parts connexion, they charged me over 10 dollars postage for 6 tiny resistors a week and a half ago, still not arrived.
Components did arrive (free post) from HK and somewhere in Taiwan on Friday last week, I ordered everything at the same time!
Don't think i'll use PCX again, not impressed.
Components did arrive (free post) from HK and somewhere in Taiwan on Friday last week, I ordered everything at the same time!
Don't think i'll use PCX again, not impressed.
I think it may have more to do with the Atlantic Ocean and the repective Post Offices. My HiFiCollective orders, coming to the US, have taken 2 to 3 weeks. They were no faster than an ebay purchase from Russia. Go figure.
Overall, PCX has given me good customer service, although they are not as automated as many others. Sometimes the prices are better there than HiFiCollective (not comparing shipping) and sometimes not. One thing that I really like about HiFiCollective is that the list how many they have in stock where PCX doesn't and will send you an email next business day to tell you they are out of stock.
I understand your frustration and would order from HiFiCollective whenever feasible if I lived in Scotland. Overall, I think both companies try hard and offer things that we can't get elsewhere, so I will give them the benefit of the doubt.
Here's hoping your MK132s arrive soon.
Jac
Hi Jac,
since I've already used it with succes, with both the TP My_Ref and the FE I would go for layout A, simply run power wires (twisted, as Andrew suggested) between modules.
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I was thinking about C15, in fact... C15 have some effect on sound.
C16 and C14 are FG or FW caps mainly for aesthetic reasons and just for the sake of...
Agree, but since FW costs not much more than good quality standard caps and looks good... why not?
Think I need more than a nice looking cap today, an Arctic survival suit might do
Solved my attenuation issue. I got two 10K Tocos pots from Taiwan last week. Measured them today, one was miles out but the other had almost perfect channel matching
It's now doing very well in my passive pre. I worked out how to install ASIO4all in foobar, bypassing the windows mixer makes a big improvement, windows volume slider no longer works (which is nice) but foobar's control still works and as far as I can tell does no harm to sound quality. Used this way foobar does sound a bit better than Jriver.
Anyway i'm now using foobar's volume control to reduce system gain instead of resistors on top of the pot.
I have ditched my turntable and DCB1 for a far simpler set-up consisting of, 250Gb netbook - USB-DAC - Pot in a box (no input selector) - My-Ref-FE monoblocks - Rega R3 speakers. Wish I had done this a year ago but I now know more about impedance and computer audio. Thanks for all your kind patience and help people
Just need that PCX order to turn up now and I can finally build my premium spec FE's
Solved my attenuation issue. I got two 10K Tocos pots from Taiwan last week. Measured them today, one was miles out but the other had almost perfect channel matching
It's now doing very well in my passive pre. I worked out how to install ASIO4all in foobar, bypassing the windows mixer makes a big improvement, windows volume slider no longer works (which is nice) but foobar's control still works and as far as I can tell does no harm to sound quality. Used this way foobar does sound a bit better than Jriver.Anyway i'm now using foobar's volume control to reduce system gain instead of resistors on top of the pot.
I have ditched my turntable and DCB1 for a far simpler set-up consisting of, 250Gb netbook - USB-DAC - Pot in a box (no input selector) - My-Ref-FE monoblocks - Rega R3 speakers. Wish I had done this a year ago but I now know more about impedance and computer audio. Thanks for all your kind patience and help people
Just need that PCX order to turn up now and I can finally build my premium spec FE's
Hey Jac,
FIY - The version I shipped around (still never got full reviews
) is only 10.5" W (w/.5" wood sides) - 7.5" D - 5.5" H. The board mounting style has worked great with both a MR V1.2 and the FE. In fact the "mini" is all I have used for the past several months. You can see the AC path in the photos starting at post #1315 - 1317. No special metal for shielding was needed and the amp is hum free. Might just work for your limited space.
Hey Jac,
FIY - The version I shipped around (still never got full reviews
Hi Bob,
Good to hear from you. Thank you for this. I don't expect to be shipping mine around the country, but it is a good idea. I had completely forgotten about your "back to back" approach. Very nice.
Jac
Mains Power Wires Close to FE boards - Noise
I took Andrew's advice and did a little test to see if I got any noise when the mains power wires ran close to the boards. Of course, twisted wire would be the best, but as a first try I just moved an extra long mains cable everywhere I could reach that was close to the boards. As Dario reported, no noise issues. YEAH!
That said, my thinking on where to place the amp enclosure has evolved and I will probably build it in Layout B, with the mains power coming in at the other end.
Jac
I took Andrew's advice and did a little test to see if I got any noise when the mains power wires ran close to the boards. Of course, twisted wire would be the best, but as a first try I just moved an extra long mains cable everywhere I could reach that was close to the boards. As Dario reported, no noise issues. YEAH!
That said, my thinking on where to place the amp enclosure has evolved and I will probably build it in Layout B, with the mains power coming in at the other end.
Jac
Opps!
My Parts Connexion order arrived. Yeah!
Unfortunately, I realized that I ordered too many of the R13 (100k) Caddock MK132. So the result is that I have 4 extra Caddock R13 that I don't really need. Not a big deal, but if there is an FE builder, especially one in the US, that wants them, I'll make you a good deal. Send me a PM.
Jac
My Parts Connexion order arrived. Yeah!
Unfortunately, I realized that I ordered too many of the R13 (100k) Caddock MK132. So the result is that I have 4 extra Caddock R13 that I don't really need. Not a big deal, but if there is an FE builder, especially one in the US, that wants them, I'll make you a good deal. Send me a PM.
Jac