Just to be clear - I am only recommending a bypass film cap across an electrolytic cap in the amplifier o/p signal path.
I would not recommend a film cap bypass on the power rail bypass caps unless the film cap has a small resistor in series with it. Without a series resistor it is all too easy to create a high Q resonant circuit which can ruin the subjective sound. This problem does not arise when the electrolytic cap is being used as an output cap driving into a relatively high impedance load.
The necessary size of this series resistor varies inversely according to the size of the film cap. For 100uF, 20-30m ohms might be OK
Actually it varies inversely with the square root of the film capacitor's value.
Rsnub =approx= 2 * SQRT( ESL_of_electrolytic / film_cap_value ) to reduce resonant Q below 1.0
where ESL is expressed in Henrys , cap_value is expressed in Farads , and Rsnub is expressed in Ohms.
Mikelm have you any shots showing your mounting technique for the film caps.? Assume you had to add wires?
Really liking my Mark Johnson Racam. Maybe my favourite amp at the moment. Bass is amazing. I have 3000uf output (2 X 1500//).
I've got some of Rudi's boards so I'm going to try another slightly different build.
Really liking my Mark Johnson Racam. Maybe my favourite amp at the moment. Bass is amazing. I have 3000uf output (2 X 1500//).
I've got some of Rudi's boards so I'm going to try another slightly different build.
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I just mounted the 100uF film cap to the casing close to the PCB and ran twisted pair to between them. If you're using the small casing from one of the diyaudio kits then space could be an issue so you might need to use smaller cap that fits inside the box - just use as large a power film cap as you can.
My work is getting rid of a ton of 19V Dell laptop chargers rated at 6.7 amps. I would love to use these in a few builds for a friend wanting a pair under a certain price range and understand this is what was used on the original Amp Camp single mono blocks.
Could I use these 19V ones and still make bridgeable amps that can also be wired like the 1.8 amps?
Also, I saw someone mention using a Step up DC-DC transformer. Could I use these with a step up to get 24V and also add some more filtering (CRCRC)???
Could I use these 19V ones and still make bridgeable amps that can also be wired like the 1.8 amps?
Also, I saw someone mention using a Step up DC-DC transformer. Could I use these with a step up to get 24V and also add some more filtering (CRCRC)???
19 volt for the ACA will just give a little less voltage swing on the output. So no issues using these PSU's in that area and yes, just build the ACA as per the V1.8 guide but use 19 volts rather than 24. Whether any filtering is needed (and whether it would make any difference) depends on the Dell PSU and how much noise/ripple it produces. Any filter will also reduce the 19v a little. So try without first.
Check the build guide for the V1.6 as I think that R15 is not fitted in these. This gives a slightly lower quiescent current because the lower supply voltage means the higher current is simply not needed.
I think you might be confusing DC/DC convertors rather than 'DC-DC transformers'. All transformers need AC, they do not work on DC at all. A DC/DC convertor uses an incoming DC supply to generate a high frequency AC waveform that is then applied to a transformer. The output of the transformer is then rectified back to DC again. So you get a DC voltage different to the applied input DC but there is a whole bunch of electronics in the middle.
Check the build guide for the V1.6 as I think that R15 is not fitted in these. This gives a slightly lower quiescent current because the lower supply voltage means the higher current is simply not needed.
I think you might be confusing DC/DC convertors rather than 'DC-DC transformers'. All transformers need AC, they do not work on DC at all. A DC/DC convertor uses an incoming DC supply to generate a high frequency AC waveform that is then applied to a transformer. The output of the transformer is then rectified back to DC again. So you get a DC voltage different to the applied input DC but there is a whole bunch of electronics in the middle.
got it. I will save the 19V supplies for when the Mofo boards are back in stock.
I am going to use the below CRC filter board for a pair of Amp Camp monoblocks but would like to use chokes instead of the resistors. Can someone point me in the right direction for choosing the correct choke?
The seller of the board recommended a 1mH airgap iron core choke but cannot find an exact one mouser.
Each ACA board draws 1A of current. You mentioned monoblocks. Would that be a single board drawing 1A or two boards drawing 2A total?
Your power supply board is capable of two CLC supplies so I assume each CLC section powers one monoblock.
If each monoblock has two amplifier boards drawing 2A total, either of these chokes would work:
Hammond 155B
Hammond 156B
If each monoblock has only one amplifier board drawing 1A, this choke would work:
Hammond 154B
Your power supply board is capable of two CLC supplies so I assume each CLC section powers one monoblock.
If each monoblock has two amplifier boards drawing 2A total, either of these chokes would work:
Hammond 155B
Hammond 156B
If each monoblock has only one amplifier board drawing 1A, this choke would work:
Hammond 154B
Sorry to confuse. I am building two separate amps.
It would be two amps, 4 total amp boards, with each amp using one of the above PSU boards and a dual secondary transformer for each amp.
So I would need 2 of the smaller chokes per amp. The board above is configured for Dual mono so one for each side.
It would be two amps, 4 total amp boards, with each amp using one of the above PSU boards and a dual secondary transformer for each amp.
So I would need 2 of the smaller chokes per amp. The board above is configured for Dual mono so one for each side.
I like the Hammond 154B. I used a set in the re-build of my M2x. Out of an abundance of caution, I added a 2.2 Ohm resistor in parallel with each choke. Helps bleed a small amount of Dc current from the choke and tames any incipient inductive ringing.
Something else to consider is adding a 1000uF cap in parallel with the second big cap. This will help lower the output impedance of the PSU at higher frequencies.
Something else to consider is adding a 1000uF cap in parallel with the second big cap. This will help lower the output impedance of the PSU at higher frequencies.
Awesome. Thank you! I’ll try both of these upgrades on the amp camps.
The M2x will actually be my next amp and it’s halfway done. Can you show me how you added in the 154bs? I also purchased the sellers dual mono dual rail board and was going to use 22,000uf caps and it would be cool to use 4 of these chokes ipo the resistors if they will also work..
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I am currently building a second ACA with a view to using both in bridged mode by way of XLRs. I intend to use the wiring shown in the ACA V1.6 guide (page 25 of 42). A Buss is connected between both RED speaker out binding posts and a connection made to it from Pin1 of the XLR (GRD/Shield) pins 2 & 3 are connected to the RCA - IN sockets. Would I be right in saying that if I want to use it in non-bridged mode I would have to desolder one side of the Buss from one of the RED posts?
No, the buss between the Red sockets and pin 1 (XLR) are the negative / GND connections. Leave them as they are and it will play as a stereo amp via the RCAs.