B22 Question

Yes, the grey looking stickers are Thermasil pads and the brown plastic shouldered washers should be put on the MOSFETs mounting holes to provide isolation.

I suppose any SIP sockets would suit your purpose.

I haven't encountered any ß22 build with socketed resistors/caps - most builders just select a gain and stick with it (or do surgery to change it) but it's not as simple as switching between two sets of resistors, as it is in many tube designs.

Unless you're planning on driving K1000s or some other equally inefficient headphone, a gain of 5 should be good.

The link you provided for the Millet MAX heatsink mounting is correct. The gray pad is item 1, the shoulder washer is item 2.

The ED7064 is what I always order for SIP sockets. I've tried others, but like these the best.

I built the last four B22s with the gain positions socketed. Doesn't take much more work than installing the parts permanently and makes it a whole lot easier to change down the line.

Hello,

 

I have some b22 question and I do not really know where to post it.

 

First, how it sounds like ? I found a lot of people ranking it to top headphone amp, but I cound not find how ?

 

I like the single ended class A triode power amps, because of the great balance between detailes and easy listening (2A3 PSE now). Before I had transistor based amps which delivered great deal of detailes, but after one hour it was a pain. Also tried really sweet (I mean too sweet) puch pull amp with tubes, I liked it, but single ended class A with triodes delivers great detailes with relaxing listening for as much time I have. Also the band ends differs.

 

So, how the b22 performs in bass, miderange ? Easy listening more or detailed ? Good for listening for hours ? Tight bass ? Owerflowing bass ? Less, but accurate bass (what I prefer) ?

 

Also, I found posts that the question of active ground vs. 2 channel is discussed deadly. Where ? I would be really interested why the 3 channel is better. Is it really ? Also, I would consider 4x 12V 2Ah SLA battery for powering it. I do not really understand why the g22 makes it better. Is it really makes a difference ? I really believe sometimes less is more.

 

This amp come to my roadmap because I plan to buy some low ohm closed headphones, which is hard to drive with tubes. When I saw the schematics, I did not like it because the global negative feedback, but than I read the material and less concerned about the feedback. Would it work open loop ?

 

My signal source is now a TC Electronic konnekt 8, but CD also, and just finishing a tube riaa for my turntable.

 

Thanks a lot for any answer, thought, advise on the above.

 

JG

1) How : people compare high-end amps in terms of noise measurements, ability to drive different loads and simply comparing it to other high end amps by ear.

2) Beta22 performance : good all-round.

3) Batteries : you'll have lots of fun trying to run such a huge amp from batteries.

4) Topology : it's designed this way for a lot of reasons, could read amb's site for details.

Open loop gain is about 56dB or 631x.

 

 

Hello,Thanks for the reply.Maybe there is a misunderstanding. I do not plan to run speakers on it at all. Without that, 200mA is not huge, but rather small. Standard and cheap 7Ah SLAs (4x) will do it fine. If I calculate that I take out half the capacity by 3 boards, that is still nearly 6 hours. That is plenty for me, usually 2 hours is enough.I see now the open loop gain, which is not small at all. In the other hand, I saw a statement somewhere that the negative feedback is very weak, just a small amount of negative feedback applied.I could devide back the input signal with 5xdB, but than there would be noise problems, so open loop use is not an option than LOn sound, I do not think there is a perfect amp, but I could not find the weaknesses anywhere. Every article just describe how good it is. I believe it is the top solid state amp, probably better than most tube amp, but I still want to position it somehow. Of course to hear it would be the best, but I do not know any in my area. Before building it, I want to look around as much as I can.Another important question, I found independent articles on b22s, which describe the sound well, but does not mention which config it is. Can I assume that if it not mentioned other way, it is probably the active ground, 3 channel version ?So far I did not found anybody who wrote down experience on comparison of a 2 board and a 3 board amp. Thanks,JG

"3-channel" or "active gnd/supply splitter" doubles your current draw - to keep the "gnd channel" in Class A while sinking both R,L amp currents it needs to be biased at 2x the R,L channel amp's - particularly costly for battery operation

 

cheaper, better is a passive gnd in a "correct" hierarchical star gnd, if you are really concerned use 16 oz roofing copper sheet for the gnd "wire" - properly done it will measure better than AMB "3-channel" on the gnd contamination/crosstalk issue

 

the biggest gnd contamination/crosstalk issue is the contact resistance of the shared gnd of the standard TRS connector with the "single point" contact - can be ~10 mOhm in 1/4", many times higher in 1/8" TRS

 

replacing the TRS connector with 4 wire "balanced" output multicontact pin/socket connectors is the most effective way of eliminating this bigger gnd contamination/crosstalk issue

 

 

battery power for the B22 seems really excessive when its design with cascodes, C-multiplier input circuit PS filtering give it a exceptionally high immunity to pwer supply variations already

 

Edited by jcx - 9/27/11 at 7:47am

I would agree in theory but if I would believe measurements and theories only, I would just make a strong opamp amp :-)

Yet I did not found anybody who compared 2 and 3 channel version. All post I found so far just believe active ground is better.

 

Also, If the amp has so good immunity to PSU noise etc. what is the reason for the complicated PSU (for headphones, full A class operation) ? An LM317/337 pair would do the job easy.

 

In the other hand, I made a CK2III before, I think it is a nice little amp, class A also. The bad thing is that I can hear (and prefer) when I run it from my large bench dc power supply, or I run it on its onw PSU. I can not esplain it, but makes significant difference.

 

Regards,

JG

subjective opinions here are fairly worthless due to the ignorance of, outright hostility to learning, applying well established psychoacoustic and perceptual testing controls, standards - discussion of Blinding is in fact prohibited over most of the site's forums

 

when does anyone describe their level matching (to 0.1 dB, 1% Vrms) technique, instrumentation, how many offer opinions of equipment they have never been in the same room with at the same time, claim "I heard it at a meet xx weeks/mo/yrs ago...", or has any ever admitted - "I thought I heard a difference but the statistics when I scored aganist the Blinding protocol session key it was my imagination"??

 

favorable comments of any discrete, Class A, physically massive pile of parts can be due to deeply entrenched preconceptions coloring the opinion - how long was Single Power successful - how harsh are the comments now that he's burned people by not delivering - after years of accolades his circuit designs/implementation are now condemned as unsafe, shoddy

 

 

given these entrenched failings of "opinion" in these forums I much prefer to point out engineering circuit principles, analysis, predictions, test measurements and take my circuit design, performance goal as technical accuracy - "3-channel" fails in technical analysis and measurement

 

except for input noise I can beat the B22 with my composite op amp designs on any distortion measurement at audio frequencies within the (CFA DSL driver +/-14 V, 400 mA) op amp V,I drive capabilities - double both # with bridge/parallel and even HE-5/6, LCD orthos can be adequately driven with op amps

Edited by jcx - 9/27/11 at 2:48pm