Idea was to build a very good low power amplifier, so bootstrapping was not required.
It is under question if I would be able to achieve more power with similar performance, with that approach.
As for wider power supply range with the same output power and without any components adjustment, it would be simple but I didn’t think that far.
It is under question if I would be able to achieve more power with similar performance, with that approach.
As for wider power supply range with the same output power and without any components adjustment, it would be simple but I didn’t think that far.
Think there will be another of tombos amps built. Albeit not soon! I need another amplifier project like another hole in my back side but I feel the need to build this one! Also have the R21 project on the production line. Seems rude not to! I also have a small ish chassis. Maybe a bit like manniraj so I'm hopeful I can cool it nicely in a compact enclosure.
I also have those same PSU PCB as Vunce and manniraj and they seem to have good space for the R21..... winner!
Currently have Aksa AN39 in the system which I am enjoying.
Thanks for everyone's input and experiences.
I also have those same PSU PCB as Vunce and manniraj and they seem to have good space for the R21..... winner!
Currently have Aksa AN39 in the system which I am enjoying.
Thanks for everyone's input and experiences.
Such regulators would limit max. power to 8W/8Ω and 4W/4Ω. We have to consider peak currents and those would be over 3A for 4Ω load. Anyway, regulated power supply is not required for this amplifier. It has about 100 dB PSRR in the whole audio band, so there will be no hum or noise.
Regulated PS provides better performance at high power output, especially with low impedance loads. I’ve tested amplifier with full power into 1.7 Ω (over 40 W). With unregulated PS and such low load impedance, depending on PS quality, it would max-out at 20 – 30 W.
I'm still wanting to spice up the psu some.
I'll be using the same prasi CRC PSU as manniraj and others, but possibly two of them.
Post 35 recommends 120 to 150 va for dual transformer builds.
I use very sensitive (120+db) 8ohm speakers.
would two 100va transformers https://www.antekinc.com/as-1212-100va-12v-transformer/ be okay?
I'll be using the same prasi CRC PSU as manniraj and others, but possibly two of them.
Post 35 recommends 120 to 150 va for dual transformer builds.
I use very sensitive (120+db) 8ohm speakers.
would two 100va transformers https://www.antekinc.com/as-1212-100va-12v-transformer/ be okay?
Wow, 120 dB/1W. Is this only for mid to treble range? I can’t imagine such efficient horn loudspeakers for low frequency that would be smaller than a house.
In your case, 100 VA transformers are fine. You don’t need high bias and every W that can be squeezed out of amplifier. 12V secondaries are OK for unregulated power supplies. If you intend to build R21 modules, then higher secondary voltage is required.
In your case, 100 VA transformers are fine. You don’t need high bias and every W that can be squeezed out of amplifier. 12V secondaries are OK for unregulated power supplies. If you intend to build R21 modules, then higher secondary voltage is required.
Bridged (BTL) operation should be no problem. Output MOSFETs are adequate for much higher output power. As is, bias is adjustable from 0.7 to 1.4 A, with 1 A being recommended value. Amplifier maintains the same harmonics distortion profile even in the class AB operation.
Max. output power should be 30 W/8Ω and 60 W/4Ω.
What happens to the harmonics profile in real life is hard to say. Usually, some H2 cancellation is expected. But, it shouldn’t matter at all as distortion is extremely low.
For bridged operation, output zobel values of 100 nF/10 Ω are a better choice.
Max. output power should be 30 W/8Ω and 60 W/4Ω.
What happens to the harmonics profile in real life is hard to say. Usually, some H2 cancellation is expected. But, it shouldn’t matter at all as distortion is extremely low.
For bridged operation, output zobel values of 100 nF/10 Ω are a better choice.
Well, not hard at all as it is easy to drive stereo amplifier as a bridged monoblock.
Here are distortion measurements for 1 W, 30 W, 60 W and IMD distortion, with the same conditions as at post #149. As expected, there is an overall distortion rise and H2 level drop. Measurement at 1W contains signal source distortion close to 0.0001 %. For this I had to use DAC as a signal source.
Attachments
I wonder what is a usual ratio between number of acquired project files and actually built ones?
There is over 500 PCB downloads and over 400 BOM downloads. So far, I know of only two completed builds (manniraj and Vunce).
So, if there is someone that has quietly finished project, chime in please. Your experience could help and speed up other builds or, if negative, spare other members from an unnecessary effort.
There is over 500 PCB downloads and over 400 BOM downloads. So far, I know of only two completed builds (manniraj and Vunce).
So, if there is someone that has quietly finished project, chime in please. Your experience could help and speed up other builds or, if negative, spare other members from an unnecessary effort.
There are many irresistible candies in the “shop window”.
I know this amplifier is not the right choice for everyone, so if there is any experience from other builds to be shared, it can be helpful for those intending to build it. Judging by number of project downloads, there could be few.