Hi Thimios,
You don't find that the PGA2311 has compression issues when dealing with complexe audio passages? I find it loses focus and you lose the air in between the instruments in those moments.
Let me know your thoughts
Do
Sorry for the late response
It is harder to measure with all the wires in the way but roughly
~4.25" (108mm) BJT to BJT and about the same measure for the other lenght of the PCB.
I have a 5.5" (140mm) internal chassis height and it fits well as you can see in the picture I posted earlier. So, 3U is 5.25" (133.4mm). It should fit well unless the internal height is much lower.
Ciao!
Do
This is a deliciously sounding amplifier! Soundstage is just breathtaking! Same impressions I had before listening to the one Fab had made but it had been so long since I last heard it that even though I knew it was a superb sounding amplifier, I just didn't remember 100% of it.
I'm really glad I finished the amplifier!
Andrew, big thank you for everything you do for the DIY community!! And btw, do you have PCBs of that Ovation Symphony line preamplifier of yours? I'm interested! 😀
Ciao!
Do
I'm really glad I finished the amplifier!
Andrew, big thank you for everything you do for the DIY community!! And btw, do you have PCBs of that Ovation Symphony line preamplifier of yours? I'm interested! 😀
Ciao!
Do
I believe that is a confusion here,as one guy speaking for sx amplifier and other for NX one.
SX is a class A amplifier when NX is a class AB one.
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Hi gaborbela,
I have the NX version biased at 55mV accross the 0.3 ohm emittor resistors. At +/-50V supply it does not give me much in Class A, maybe a few watts but it is enough. I feel like I can probably push it to 60-65mV accross the emittor resistors since I'm only at 45 Celcius on the heatsink, just warm!
I will attempt this on the weekend, although it does sound amazing just as is.
Ciao!
Do
leave the bias voltage as it is and reduce the emitter resistors slightly to get a bit more bias current and thus a bit more ClassA output before it transitions over to ClassAB.
Adding a 0r47 parallel to your existing 0r3 gives a net 0r183 for a 64% increase in bias current (and a 168% increase in ClassA power). You might be better reducing the bias voltage slightly to around 45mVre to 50mVre.
Adding a 0r47 parallel to your existing 0r3 gives a net 0r183 for a 64% increase in bias current (and a 168% increase in ClassA power). You might be better reducing the bias voltage slightly to around 45mVre to 50mVre.
Thanks AndrewT,
Good idea! I will try this instead. I'll just order some new resistors altogether or solder under the PCB.
Do
Thanks for your comments Pinocchio - very glad you like it!
Indeed if your heatsinks can take it, on the nx-Amplifier you can run the bias higher - just check that the bias setting is stable.
For the class A sx-Amplifier, I do not recommend you change the bias setting,which is currently at 700mA per transistor pair
Indeed if your heatsinks can take it, on the nx-Amplifier you can run the bias higher - just check that the bias setting is stable.
For the class A sx-Amplifier, I do not recommend you change the bias setting,which is currently at 700mA per transistor pair
Re symphony pre - very big project with lots of documentation. To release it will take a lot of effort. I really have to think about this.
I know it is off topic but last post on this... 😀
Maybe you could sell the PCBs and build in the price your R&D efforts and also make a poll of who would be interested to buy some PCBs?
Just a thought as it seems to be quite a nice gear to share with the world.
Do
It's not about the money.
I just don't want to put stuff out there that's half baked.
I'll have to think about it
🙂
I just don't want to put stuff out there that's half baked.
I'll have to think about it
🙂
I'm willing to take the plunge with some Ohmite Audio Gold 0R22 non-inductive resistors that I found in my stock, but not now... It is all tightly fit in the chassis and I'm feeling totally lazy at the moment, especially that it plays sooooo well! 😀
Ciao!
Do
I totally understand but think about all the nice people and how happier this world could be...
LOL! Just kidding!
Thanks for everything Andrew
Do
I'm planning to purchase, device below for Q-1,2 and 4,5 of PSU of NX amp
Looks same as 120PS127 except case is 12PAK-3 which looks like metal mounting back is omitted..
Please let me know if this part will be a problem?
PSMN4R3-100ES,127 NXP Semiconductors | Mouser
What is the complete meaning of 12PAK-3
Looks same as 120PS127 except case is 12PAK-3 which looks like metal mounting back is omitted..
Please let me know if this part will be a problem?
PSMN4R3-100ES,127 NXP Semiconductors | Mouser
What is the complete meaning of 12PAK-3
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Hi Pinnocchio,
Do you think it would be possible to fit in a HiFi2000 3U chassis? These chassis are 12cm high but the internal height is only 10cm (because of the heatsink fixings). Maybe bending the bjts legs?
Thank you.
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I just measured mine, and if you use NJW1302/3281 TO-3P outputs and bend the legs at 90deg it measures 10.15cm tip to tip. I suppose you could use tall standoffs so you could bend the legs at a more acute angle and make up that 15mm.