Do not forget if you are using the power bricks for the ACAs that they are SMPS types and do not operate at 60Hz, but at very high frequencies...
There is very mixed opinion as to whether adding capacitance after the SMPS actually improves or makes their ripple worse.
Just try it a 6L6 says and have a read back through this thread.
Do you actually have a 60Hz issue?
If you are, a simply/easy thing to try is another power brick; they've been known to have quality issues although I've personally built 6 ACAs now from the kits and started with the bricks and had no issues. I have moved them all to dedicated linear power supplies after building them with my kids, and can say it does measurably improve things, so you might want to spend your efforts on building a quality, dedicated PSU instead. If you don't want to build one, there are a number of sources of nicely made and reasonably priced ones mentioned here on the forum or elsewhere.
What were the specific improvements after going from SMPS to linear PSUs? What were the "measurable" differences, and how did they sound differently?
I am asking because I recently went the other way. I tried an SMPS with my Aleph, and things seem to work well. However it somehow still feels like a sacrilege to use an SMPS where I (and many others) used big and heavy linear PSUs for decades.
i caused the build out of around 70 channels of the ACA....
i built around 12 channels of the ACA amps using only smps, my builds all turned out very quiet and i can not complain.....
I have built four different versions of the ACA, two with the kit SMPS and two with linear supplies based on 300VA transformers. The kit builds were the earlier ones where I refined some component selection, and are documented in ACA amp with premium parts. Those little amps sounded quite good, and were definitely best as a pair of monoblocks (parallel configuration) with my speakers.
The next two builds I did were housed in the old Hafler DH-220 chassis, and represented a set of experiments in CRC and CRCRC filtering using a new set of PCBs laid out by Rudi Ratios. Those builds are also documented later in the same thread as the ACA-220 v1 and ACA-220 v2. These both used higher supply voltages to get more power to my speakers. Except for trying a set of IRFP140 Mosfets in the v2 build, the boards used the same set of components for the amplifiers as in the SMPS versions. Each of the linear supply versions sounded better than the pair of monoblock ACAs with the SMPS bricks. The differences included improved dynamics and better sense of realism with acoustic instruments. Stereo separation and soundstaging remained comparable to the monoblocks, due to using separate secondary windings for each channel. This was impressive, as the ACA-220 builds were just used as stereo amps, not monoblocks.
I while ago I rebuilt v1 using a MeanWell RSP-150, 27V SMPS in place of the linear supply. (The 22V transformer ended up in my hotrod F6.) Making use of the PCBs' provision for on-board supply capacitance, I implemented a simple CRC network of 220 uF - 0.11 Ω - 4700 uF to filter the output of the SMPS. The result was not as satisfying as the amp with its linear supply. The big difference was in dynamic impact and lower frequency support for bass instruments. Lacking the support of the lower octaves, the midrange felt slightly diminished in transparency as well. On it's own the SMPS-modified ACA-220 v1 still sounded pretty good, and I imagine could work quite well with a set of smaller, high sensitivity speakers. My full-range Vandersteens, however, needed more support for the bottom octave.
I have some ideas for how to reuse the MeanWell RSP-150 power supplies (I have two), and those will be tested in a pair of forthcoming MoFo monoblocks. I intend to use some of what I learned with my F6, with a special variant of a Sziklai capacitance multiplier on the output of the SMPS. The main trick will be adding 24,000 uF of capacitance to the power rail.
The next two builds I did were housed in the old Hafler DH-220 chassis, and represented a set of experiments in CRC and CRCRC filtering using a new set of PCBs laid out by Rudi Ratios. Those builds are also documented later in the same thread as the ACA-220 v1 and ACA-220 v2. These both used higher supply voltages to get more power to my speakers. Except for trying a set of IRFP140 Mosfets in the v2 build, the boards used the same set of components for the amplifiers as in the SMPS versions. Each of the linear supply versions sounded better than the pair of monoblock ACAs with the SMPS bricks. The differences included improved dynamics and better sense of realism with acoustic instruments. Stereo separation and soundstaging remained comparable to the monoblocks, due to using separate secondary windings for each channel. This was impressive, as the ACA-220 builds were just used as stereo amps, not monoblocks.
I while ago I rebuilt v1 using a MeanWell RSP-150, 27V SMPS in place of the linear supply. (The 22V transformer ended up in my hotrod F6.) Making use of the PCBs' provision for on-board supply capacitance, I implemented a simple CRC network of 220 uF - 0.11 Ω - 4700 uF to filter the output of the SMPS. The result was not as satisfying as the amp with its linear supply. The big difference was in dynamic impact and lower frequency support for bass instruments. Lacking the support of the lower octaves, the midrange felt slightly diminished in transparency as well. On it's own the SMPS-modified ACA-220 v1 still sounded pretty good, and I imagine could work quite well with a set of smaller, high sensitivity speakers. My full-range Vandersteens, however, needed more support for the bottom octave.
I have some ideas for how to reuse the MeanWell RSP-150 power supplies (I have two), and those will be tested in a pair of forthcoming MoFo monoblocks. I intend to use some of what I learned with my F6, with a special variant of a Sziklai capacitance multiplier on the output of the SMPS. The main trick will be adding 24,000 uF of capacitance to the power rail.
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This was still using the Hafler chassis, I simply removed the linear supply and replaced it with the SMPS. The power supply caps on the amplifier boards were also reduced to be compatible with the SMPS. My inclination is to return to a linear supply, but with my spare 24V transformer. That will place the ACA-220 v1 and v2 on equal footing, except for the power Mosfets.
The CRCrC configuration that I'm using for the linear supply is 36,000 uF - 1.0 Ω - 15,000 uF - 0.11 Ω - 15,000 uF.
The CRCrC configuration that I'm using for the linear supply is 36,000 uF - 1.0 Ω - 15,000 uF - 0.11 Ω - 15,000 uF.
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One more thing - I didn't try running the SMPS without any filtering on the channel boards. I wanted to provide some independent power (to the extent possible) for each board. My thoughts were that I already knew what a 'bare' SMPS powering two channels sounded like, and wanted to try a simple filter per channel.
If I were to repeat that experiment, I would build independent cap multipliers for each channel, and have 15,000 uF or more local bulk capacitance after those. This experiment will actually be carried out with my MoFo amps.
If I were to repeat that experiment, I would build independent cap multipliers for each channel, and have 15,000 uF or more local bulk capacitance after those. This experiment will actually be carried out with my MoFo amps.
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Linear PSUs usually have a lot more filtering / smoothing than a SMPS/brick power supply. Is this a "fair" comparison?
I used a RCLC filter for the SMPS with my Aleph, with the first R = 0.7 Ohm. This large resistor makes sure the SMPS does not go into protection mode even with large capacitors. The voltage drop across the resistor is compensated by using an SMPS with a higher DC voltage (27 V), and I get 24 V after RCLC filter.
I used a RCLC filter for the SMPS with my Aleph, with the first R = 0.7 Ohm. This large resistor makes sure the SMPS does not go into protection mode even with large capacitors. The voltage drop across the resistor is compensated by using an SMPS with a higher DC voltage (27 V), and I get 24 V after RCLC filter.
I have seen good and bad examples on both types of supply. There is alot of high end gears with smps that sounds better than linear.. Vice versa so it highly depends on how its design around it..
I have tried things like lucent. Vicor. Tyco switching DC to DC bricks... It's very good even if it's switching.. No prob with it even for dac.... Tried capacitance multiplier..also very decent especially if the transformer have hum issues
All have advantages and weakness... Sound wise and how to apply. That's why diy is fun as we can explore
Bob Cordell power supply thread is worth a read. Alot of myth and tips there. Especially on how to make a good crc clc.. It works for me. His baf videos on how to filter lt 317.. All worth the time to look at it..
I have tried things like lucent. Vicor. Tyco switching DC to DC bricks... It's very good even if it's switching.. No prob with it even for dac.... Tried capacitance multiplier..also very decent especially if the transformer have hum issues
All have advantages and weakness... Sound wise and how to apply. That's why diy is fun as we can explore
Bob Cordell power supply thread is worth a read. Alot of myth and tips there. Especially on how to make a good crc clc.. It works for me. His baf videos on how to filter lt 317.. All worth the time to look at it..
Do you have a kink to, or the title of this thread? Thanks for the recommendation.
ripple voltage is a function of load current and C, being directly proportional to load current and inversely proportional to C, the difference is in the factor 6.28F, where is either 60 or 50hz for linear power supplies, and for smps minimum of 20khz, so the ratio is 20000/50 or 400, but 30 to 70 khz for smps is not unheard of...
i have used smps for the last two years and the thing i like with the smps is the ease of use and the very low noise compared to linear, really diyer friendly...
but the very low cost compared to linears is the thing i like most..
i have used smps for the last two years and the thing i like with the smps is the ease of use and the very low noise compared to linear, really diyer friendly...
but the very low cost compared to linears is the thing i like most..
Look at sticky in the power supply section.. Favorite threads.. There is a Bob Cordell thread listed
DIY speaker for ACA suggestion?
Hello diyAudio community -
I hope you're all staying safe and LISTENING in place!
I have two ACA kits, and am looking for basic guidance / suggestions for DIY speakers to pair with the amps. I would appreciate both specific suggestions, and also general guidance (made up example: "stay away from three driver speakers").
Thank you!
Hello diyAudio community -
I hope you're all staying safe and LISTENING in place!
I have two ACA kits, and am looking for basic guidance / suggestions for DIY speakers to pair with the amps. I would appreciate both specific suggestions, and also general guidance (made up example: "stay away from three driver speakers").
Thank you!
I just found this. My vote would be for a full range driver design (in the spirit of keeping things simple!).
ACA Speaker short list
I’m sure this has been asked, done before... Can I put a B1 Korg in the same enclosure as a pair of ACAs all using the same 24V SMPS to make a simple integrated amp?
ACA Speaker short list
I’m sure this has been asked, done before... Can I put a B1 Korg in the same enclosure as a pair of ACAs all using the same 24V SMPS to make a simple integrated amp?
There might be a way to make it fit, but it would be a tight squeeze in the little kit chassis (Mini Dissipante 2U).
There are also a few reasons why it might be best to keep the B1 Korg and ACA in separate chassis. Among them are vibration dampening / control needed for the Korg NuTube, heat generated by the power amp adversely affecting the pre, and power supply interactions; though the B1 Korg PCB is pretty well filtered. Maybe give it a go with the 3U Mini Dissipante. Then there might be room for RCA jacks on the back panel.