I think you need to solder these two operational amplifiers. I will do that
https://www.diyaudio.com/community/...post-filter-feedback-pffb.390701/post-7269917
https://www.diyaudio.com/community/...post-filter-feedback-pffb.390701/post-7269917
I understand but I need a factual reason. I’m not one to embark on a delicate circuit modification without an understandable reason. But thank you for replying.
"please note, if you are talking about the not-PFFB AMP,you don't need modify, but if PFFB-AMP, then you need modify(see user manual) " This is a quote from the manufacturer and designer of this amplifier
I would love to see a full schematic! @bloqhed I agree with you that there is a reason I’m just not smart enough to intuit what that reason is. As I said, I hooked it up based on the printed info on the board, “short in- to GND at SE Mode”. That seems pretty clear to me and it sounds as good as my Pass Zen V9 Jfet class A amp. I have an email in to 3e Audio ‘French connection’ asking for clarification but so far no response. Meanwhile it’s been making beautiful Sounds 6-16 hrs/ day no problem for over 2 weeks.
Attachments
I believe someone did a teardown of the input stage of the Topping PA5 over on ASR, you'd have to check the thread there. I'm with you where it goes above me. What little I know is that the input stage has to do with getting better performance via PFFB.
Thanks bloqhed, I suspect it does have something to do with the max power out, just not sure what other than the potential input amplitude that some balanced commercial gear can put out.
@3eaudio
I ordered two 480-1-29A (mono version) from your shop, which I am powering with a Meanwell 48VDC / 10A Power supply.
As my source is SE, I am using a pair of Lundahl LL1540 to do the conversion from SE to PP. The primaries and secondaries are in series, for a 1:1 ratio. At the secondary side, I connected the output of the LL1540 to the +in and -in (red and black of the supplied cable), leaving the yellow wire (gnd of the amp board) unconnected. As the input impedance of the board is 20k, I have not added any more resistors or zobel to the LL1540. I made a drawing of the connection.
I listened to it, sounded nice, everything seems to work. Yesterday I wanted to confirm gain and phase, I put it at the testbench with 8R as load. I measured 0,18V at the secondary of the input transformer (so also 0,18V between the red and black wire going to the board), and 2V at the output. The gain is therefore a bit more than 10x, while the manual says it should be 20x. Any idea why that could be the case? Shall I connect the yellow wire to the center tap formed at the secondary of the input transformer?
I used a Fluke 17B to measure at 1kHz.
I ordered two 480-1-29A (mono version) from your shop, which I am powering with a Meanwell 48VDC / 10A Power supply.
As my source is SE, I am using a pair of Lundahl LL1540 to do the conversion from SE to PP. The primaries and secondaries are in series, for a 1:1 ratio. At the secondary side, I connected the output of the LL1540 to the +in and -in (red and black of the supplied cable), leaving the yellow wire (gnd of the amp board) unconnected. As the input impedance of the board is 20k, I have not added any more resistors or zobel to the LL1540. I made a drawing of the connection.
I listened to it, sounded nice, everything seems to work. Yesterday I wanted to confirm gain and phase, I put it at the testbench with 8R as load. I measured 0,18V at the secondary of the input transformer (so also 0,18V between the red and black wire going to the board), and 2V at the output. The gain is therefore a bit more than 10x, while the manual says it should be 20x. Any idea why that could be the case? Shall I connect the yellow wire to the center tap formed at the secondary of the input transformer?
I used a Fluke 17B to measure at 1kHz.
Attachments
In the manual, it says gain of 20.5 for the TPA3255. There is no mention if the gain is in dB, but if it is indeed 20.5dB, then the measured 10x voltage gain would agree with my measurements. https://www.3e-audio.com/wp-content/uploads/2023/03/DS_EAUMT-0xx0-x-FB_Rev1.1.pdf
I wanted a bit more... configuring the input transformer to 1:2 would give that, but then only 5k input impedance.
I wanted a bit more... configuring the input transformer to 1:2 would give that, but then only 5k input impedance.
Hi all, I have the 3E Audio 2ch amp with PFFB. I'm trying to team it with an Arylic Up2Stream Pro wireless receiver but I'm having some trouble - lots of noise comming through. In troubleshooting I can confirm the amp sounds fine fed from a signal generator, and that the Arylic sounds fine feeding a deskptop amp. The problem is when the two of them are connected together. I've made the mods to the 3E for Single ended input. The noise is not hum, it's more like loud static and unstable.
Does anybody have any suggestions?
Does anybody have any suggestions?
Hi 3eaudio, thanks for responding - I made the mods as specified in the manual. I used NE5532 Op amp. I've traced the circuit and it's as shown in the manual.
Hi, yes, black and yellow wires are connected to signal ground. However I have found that leaving the yellow ground connection floating is lower distortion - but sill very noticeable.