The layout does not follow that schematic. First off, the bridge only attaches to C4, R7 and R9. It does not connect to R10. Perhaps someone who knows the circuit could add the part numbers to the layout so it can be checked. I have the amp playing and it sounds wonderful. I would like to get the Zobels working as well.
One other thing, if you are pulling that 55vac from the main transformer, then the rails would be +-77v which is way too high for two pair of outputs.
The amp plays fine but with the trimmer set to 1R the most I can get is 9mA bias fully warmed up.
Thanks, Terry
One other thing, if you are pulling that 55vac from the main transformer, then the rails would be +-77v which is way too high for two pair of outputs.
The amp plays fine but with the trimmer set to 1R the most I can get is 9mA bias fully warmed up.
Thanks, Terry
Amp rail is +/-55vdc maximum (2x30-40vac transformer).
Replace 220R resistor in series with 1k trimmer... use 180R or 150R and set bias 30-50mA.
Regards
i think you should make both board because that is protection relay.when dc out it will off quickly and protect your speaker.if you are using other protection circuit than its ok.
My bad, sorry.
Great to hear your impressions. I need to build a two-pair output amp and am deciding which one to choose among so many options!
Great to hear your impressions. I need to build a two-pair output amp and am deciding which one to choose among so many options!
Mile, could you please show us where have you discussed about your protection system in this forum? I would like to know more about it. Does it provide power-on delay? Does it disconnect the speakers as soon as power switch is off? I guess it doesn't. TYVM.
Protect provide power-on delay, DC and overload protect, protect also disconnect the speakers as soon as power switch is of.
Regards
R.rel is a resistor with value same as relay coil resistance. i did that because i have found a good text in ESP33 Loudspeaker Protection and Muting
AC points on a PCB should be connected to the AC points of bridge rectifier,it has been done by the schematics in post http://www.diyaudio.com/forums/solid-state/173462-studio-reference-amplifier-190.html#post4296935 . i draw that schematics as reversed one that APEX has given earlier. i have drawn an amplifier PCB and have had left a lot of space on a right side of PCB where is negative rail-the original schematics was for positive rail (emiter resistor from positive rail) so i reversed it/mirrored it to use it as it was more convinient for me. that is how i got it done like this.
you should use any transistor that has hFe larger than 200-300 in a place of 2N5401 to get it´s Uce as low as possible. i used BC516 (darlington) and relays on both channels tourn on in a same time and i have under 1V of Uce.
560r is not fixed value and it depends on how high is transformer rail voltage and what is relay coil resistance and defined working voltage. 2W should be enough in most cases,and value of that resistor should be as high as needed to get relay voltage in proper value,signed on relay it self. it is about 700 Ohm in my case.
i am sorry that i haven´t seen those posts earlier and i am so glad that you did this amplifier. please tell me how it sounds to you,because i have a certain opinion about it but i would like to read your impressions first.
I have been playing the amplifier. I A/B'd it against my Symasym and it is cery similar. Good strong bass, big sound stage and clear mids and highs. I'm not sure it is any improvement of the SR100. I know it will handle a little more voltage but I'm not sure it is enough to notice.
I build the little Zobel boards but didn't install Rrel as I still don't quite understand how to determine the correct value. I have tried to match up the schematic with the board and I just can't get there. As you know, this will likely never find its way into case so the protection is not crucial to me but I do hope to understand how it works.
Blessings, Terry
I build the little Zobel boards but didn't install Rrel as I still don't quite understand how to determine the correct value. I have tried to match up the schematic with the board and I just can't get there. As you know, this will likely never find its way into case so the protection is not crucial to me but I do hope to understand how it works.
Blessings, Terry
not yet,i have etched pcb's for a smaller version but i just can't get enough time to finish it.
have you built A17 or A23? if you did,could you write a word or two for comparing those two amplifiers?
it is not necessary to use that large IRFP,you can use smaller one but also increase sors resistors value.
with H version the idea was to have A-class first watt of power to a loadspeaker with about 300mA (or more) of bias.
I know I built A23. I don't remember the A17. I will have to check on that one. I have a huge stack of boards now of the Apex variety. All work except A40. I never got the bugs worked out of that one. I will look for the A17 and see if I built it. For me it is all about enjoying the build and the challenge of getting it working. They all sound lovely. I will get the A23 and this SR150 hooked up to the A/B setup and see if I can hear much difference.
Keep the layouts coming.
😀
you are just like me - enjoying in building amplifiers,but those two amplifiers made me to listen them for months now. i can not decide wich one is better for my ears,loudspekaers and room. A23 sounds to me a bit more like a (recorning)studio-amplifier and it does not give or take anything from the input signal,it only amplifies it and deliveres to loudspeakers. it is clean sounding,it has everything that one amplifier should have but sr150 gives all that but a little more. i´d say that is reacher in bass and a bit more compatible with my loudspeakers and room. mostly i compare that two amplifiers like porshe panamera (A23) and ferarri ff (sr150),both great and unique sounding...
good luck and easy built for a23! 🙂
good luck and easy built for a23! 🙂
I dug through the stack and found I have built these Apex amps. A9, AX9, AX14, AX14 IPS, FX14, NX14, AX17, AX23, AX33, AX40, P30, SR100 & SR150. As I said my A40 is not working but the others all play perfectly. I can't say from memory which, if any, sound better than the others. If I get a chance in the near future I will try to do some close listening comparisons between them. That sounds like a fun way to spend a couple days. I do remember being quite impressed with the little A9. That one was a very pleasant surprise. I am pretty impressed with the P30 preamp that I just finished. It has good sound and a lot of output. It would be good for an amp that has low gain. The most impressing of all of these is the AX14 IPS driving the Slewmaster 5P OPS. A 250W CFA "Super pair" monster.
I'm attaching a pic of the collection so far.
Blessings, Terry
I'm attaching a pic of the collection so far.
Blessings, Terry
Attachments
AX-14 aka kelvin v2? hum, i wonder why? i should try to ltspice it up and see how it measures.
I was going through some of the threads, to figure out what is what 🙂
Terry did you ever see/build the complementary jfet or bjt pre-amp types?
sf3.1, sb3.1?
also, what tests are you running on these amps?
thx rick
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