Almost 3000 pages 😱 not really a hand-sized handbook 😀
Thanks for sharing, looks like a great reference!
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If you don't mind having to source some NOS JFETs which are becoming scarce, I have a super-symmetric project which fits your criteria. It is based on Nelson Pass' super-symmetry, so is sort of a very small Pass Labs X-amp. My build gives the first few watts in Class A, but operates Class AB above that to around 25W maximum output. With larger heatsinks, you can scale up the Class A envelope. The harmonic spectrum is highly adjustable, so you can make it sound "forward" and "solid-state-like" or very "laid-back" and "tubey" (whatever these things mean 🙄). I have extra boards, if you are interested.
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@ needtubes
with you try the pcb in both modes (stereo and symetric)
and what is the difference in listening between stereo and symmetrical mode?
with you try the pcb in both modes (stereo and symetric)
and what is the difference in listening between stereo and symmetrical mode?
I previously built a single-ended (not super-symmetric) version of this circuit using larger IXYS MOSFETs on the output. It sounds very nice and exerts great control over my speakers, as does the super-symmetric version. The main difference is the sound signature from the differing distortion spectra. The super-symmetric version is a bit more forward and focused (likely due to the fact that the even harmonics are largely cancelled), while the single-ended version is a tad more open. Both are very detailed and 'musical', and I enjoy them both. It has been fun so far trying different ways to "unbalance" the super-symmetry in order to get a bit of warmth and space back from the increased second harmonic.
Juma’s cubie amps (particularly cubie 2 and 3) might be worth a look.
Cubie - small F5 variant with GR grade JFETs and LatFETs
I use the front end as a preamp, sounds very good. Very similar the pass 25w susy amp but not balanced and uses lateral mosfets. Also, I would look at the VSSA amp, basically an f5 with bjt input and lay fets and lower bias.
Iam not sure I would do class a in that small of a chassis. My experience is that small chassis class a amps don’t allow enough bias to make it worthwhile. And there is not enough room in the chassis for enough capacitance. This is especially true if you have speakers that drop below 4 ohm...
Cubie - small F5 variant with GR grade JFETs and LatFETs
I use the front end as a preamp, sounds very good. Very similar the pass 25w susy amp but not balanced and uses lateral mosfets. Also, I would look at the VSSA amp, basically an f5 with bjt input and lay fets and lower bias.
Iam not sure I would do class a in that small of a chassis. My experience is that small chassis class a amps don’t allow enough bias to make it worthwhile. And there is not enough room in the chassis for enough capacitance. This is especially true if you have speakers that drop below 4 ohm...
Thank you everyone... You are terrible!
I'm going to build an ACA to start with, if I run it at 24v it stands a fighting chance of being loud enough.
Then if it's not loud enough it becomes my desk amp for work... Or I build some more efficient floorstanders from my jbl 2118s.
And I build juma's cubie3 for home, which allows me to stick with my small form factor. The heavy biased AB should still work very well for me.
In reality my room acoustics are more limiting than the difference between a good and great amp. So this should keep me happy for now.
I think I have a suitable heatsink and I have a 24v smps. so I need a single sided pcb design to etch and buy a bag of bits from RS to fill it!
I'm going to build an ACA to start with, if I run it at 24v it stands a fighting chance of being loud enough.
Then if it's not loud enough it becomes my desk amp for work... Or I build some more efficient floorstanders from my jbl 2118s.
And I build juma's cubie3 for home, which allows me to stick with my small form factor. The heavy biased AB should still work very well for me.
In reality my room acoustics are more limiting than the difference between a good and great amp. So this should keep me happy for now.
I think I have a suitable heatsink and I have a 24v smps. so I need a single sided pcb design to etch and buy a bag of bits from RS to fill it!
I also forgot to mention the MoFo, which IMHO, sounds better than the ACA, and easier to build. For same 24v smps it will deliver 11wrms. Needs a preamp though - if you have a headphone amp, that is a pretty good start.
Here is how to use a 24v SMPS with a MoFo:
https://www.diyaudio.com/forums/pow...er-supply-integrated-aca-amp.html#post5549139
Here is how to use a 24v SMPS with a MoFo:
https://www.diyaudio.com/forums/pow...er-supply-integrated-aca-amp.html#post5549139
See... I try and make a decision... And you throw more options at me to try and sway me.
Interesting thread though, i like the use of chokes as power storage.
Interesting thread though, i like the use of chokes as power storage.
The USSA-5 is a highly regarded amp and on my to-build list. I have all the parts in fact, but I am not sure it’s appropriate project for the OP who said this is his first step up from a TPA3116 class D amp. I would say it’s an amp for a seasoned builder with at least a couple of discrete Class A or AB amps under his/her belt. The power supply is much more than SMPS brick and a cap Mx, then there are the parts costs (the actives alone run circa $175 IIRC), and there is setup adjustment to zero offset and set bias. This is where the Alpha is a bit better. Same PSU and chassis requirement but inexpensive easy to find actives and no setup adjustments.
Or with class AB amp that operates in class A most of the time. This saves a lot of the heat/size issue. The Honey Badger is great.
To be fair, I'm new to scratch building amps, but I do build satellites from build manuals and spent 7 years teching in a studio repairing quad 405s, studer tape machines and endlessly recapping a large neve mixing desk. So I'm not a noob from the build/assembly point of view, just new to the plethora of amp designs available. Neither am I particularly knowledgeable about amp design which is why I want to start with a simple class a, half the point of this is to get a better understanding of discrete electronics, the nice amp at the end is a well engineered byproduct!
I've dug out a heatsink, 350mm long 95mm tall (once I've faced the cut edge off) with 50mm long combined fins and base. I hope to cut this into two to make a stereo (ACA) amp.
I've dug out a heatsink, 350mm long 95mm tall (once I've faced the cut edge off) with 50mm long combined fins and base. I hope to cut this into two to make a stereo (ACA) amp.
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