dual3255evm strange problem
or maybe its obvious:
ive got a pair of 3255 evms running from a single psu.
ive just done my first power-up with both amps connected, and my homebuilt timer which controls the reset on both boards, via a relay connected to gnd.
power up and the timer kicks out the reset as expected.
i get the fault LED on both boards flashing faintly (not a listed error) , and no output from either amp.
disconnected my timer circuit and manually triggered reset, same problem.
disconnected the wire connecting the reset pins on both boards together, problem goes away.
i cannot see why connecting the two reset triggers together should be an issue? they are directly connected to ground when the error is present, after all. any suggestions?
or maybe its obvious:
ive got a pair of 3255 evms running from a single psu.
ive just done my first power-up with both amps connected, and my homebuilt timer which controls the reset on both boards, via a relay connected to gnd.
power up and the timer kicks out the reset as expected.
i get the fault LED on both boards flashing faintly (not a listed error) , and no output from either amp.
disconnected my timer circuit and manually triggered reset, same problem.
disconnected the wire connecting the reset pins on both boards together, problem goes away.
i cannot see why connecting the two reset triggers together should be an issue? they are directly connected to ground when the error is present, after all. any suggestions?
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I am still impressed with the sound quality of the TI TPA3255EVM. I am back to using my Altec Peerless 15335A bridging transformers on the inputs. The greater transparency, overall smoothness, the tonality and soundstage depth are really great.
I finally got my analog playback system set up, and I can just play album after album. Even with a pair of KEF LS50 monitors, I can get a lively, big sound with an incredible bass response and sweet midrange. The music floats in my living room like I have a powerful tube amp. It’s a great match with my Audio Research LS7 tube line stage preamp and Audio Research PH5 tube phono stage. The sound has been so clear, I was able to use my system effectively for adjusting the lateral and vertical tonearm bearings, and vertical tracking angle by ear.
I am going to build an unregulated power supply to power two of these amps in PBTL mode. It might not make a difference versus running one amp in BTL (stereo) mode, but it’s worth investigating.
I finally got my analog playback system set up, and I can just play album after album. Even with a pair of KEF LS50 monitors, I can get a lively, big sound with an incredible bass response and sweet midrange. The music floats in my living room like I have a powerful tube amp. It’s a great match with my Audio Research LS7 tube line stage preamp and Audio Research PH5 tube phono stage. The sound has been so clear, I was able to use my system effectively for adjusting the lateral and vertical tonearm bearings, and vertical tracking angle by ear.
I am going to build an unregulated power supply to power two of these amps in PBTL mode. It might not make a difference versus running one amp in BTL (stereo) mode, but it’s worth investigating.
So far I am very impressed by these amps. I am using them as monoblocks (PBTL mode). Two SE-600-48 driving two of these amps. Because of space and height constraints, I have yet to find a case I can fit in everything, so I have made a makeshift case using a newegg shipping box.
I have put 2 120mm fans in the case, right now just resting on the amp. These are running of a USB 5V 1A power supply, so very low speed, but enough CFM air movement to keep the "case" cool even after hours of play. I don't turn off the "case" since the no load power usage is very low. The fans are totally silent so there is no noise coming from the amps.
My system - Pioneer Elite VSX-23TXH using a preamp, source is Flac music over HDMI to Pioneer. From Pioneer to TI 3255 EVM to Maggies 1.6QR. Earlier I had Crown Amp (high current Class A/B 450W/ch).
Regarding the sound, since each amp is now delivering upto 600W (upto 200W+ at less than 0.01% THD), the sound and the bass is very very clean and detailed. Hearing notes in songs which were never heard before. Some string held for a little long, some note reverberating noticeably, a guitar strum more prominent, fingers hitting the fret. I think it's a total experience, really hard to describe, just need to be there to feel it. I don't have much experience with a tube amp, so I can't compare to any tube amp sound. I am glad I went this route vs buying Hypex based amp (about 1500$ or so).
I have put 2 120mm fans in the case, right now just resting on the amp. These are running of a USB 5V 1A power supply, so very low speed, but enough CFM air movement to keep the "case" cool even after hours of play. I don't turn off the "case" since the no load power usage is very low. The fans are totally silent so there is no noise coming from the amps.
My system - Pioneer Elite VSX-23TXH using a preamp, source is Flac music over HDMI to Pioneer. From Pioneer to TI 3255 EVM to Maggies 1.6QR. Earlier I had Crown Amp (high current Class A/B 450W/ch).
Regarding the sound, since each amp is now delivering upto 600W (upto 200W+ at less than 0.01% THD), the sound and the bass is very very clean and detailed. Hearing notes in songs which were never heard before. Some string held for a little long, some note reverberating noticeably, a guitar strum more prominent, fingers hitting the fret. I think it's a total experience, really hard to describe, just need to be there to feel it. I don't have much experience with a tube amp, so I can't compare to any tube amp sound. I am glad I went this route vs buying Hypex based amp (about 1500$ or so).
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I did ask the same question in an earlier thread. The answers were kinda mixed. Anyway, no harm in very low RPM fan circulating air in the case.
Without fans, the air gets kinda warm, since I have power supplies stacked on top of each other next to the amps. I have replaced fans in the power supplies to Noctura running at lowest RPM. Then I took 120mm 12V quiet case fans, stripped off the +/- connectors, took a USB cable, cut the small end, connected the fan's +/- to USB cable +/- (ignoring the datalines), used some electrician tape, since these wires are very very thin. So, that's how I made my makeshift USB fans. Connected both fans to a 2USB port power plug. Since USB is only 5V, and the amp these fans are pulling is about 0.2A or so, total wattage is less than 2W for both fans, and whisper quiet unless you put your ears in the case.
The next project will be to either make a wood or acrylic case for the entire setup since I know how I want to place the thing inside.
Without fans, the air gets kinda warm, since I have power supplies stacked on top of each other next to the amps. I have replaced fans in the power supplies to Noctura running at lowest RPM. Then I took 120mm 12V quiet case fans, stripped off the +/- connectors, took a USB cable, cut the small end, connected the fan's +/- to USB cable +/- (ignoring the datalines), used some electrician tape, since these wires are very very thin. So, that's how I made my makeshift USB fans. Connected both fans to a 2USB port power plug. Since USB is only 5V, and the amp these fans are pulling is about 0.2A or so, total wattage is less than 2W for both fans, and whisper quiet unless you put your ears in the case.
The next project will be to either make a wood or acrylic case for the entire setup since I know how I want to place the thing inside.
Am looking wonderful TPA32xx series as well, notice you are supplying it with Meanwell SE-600-48 (specs reads 200mv ripple noise).
Any likelyhood of 200mv ripple noise will an impact of EVM's PreAmp & 3255 Amplifier SQ?
I did read about the 200mv ripple noise but then I also read that the effect is only measured in measuring instruments (not in the ears -- atleast I know not in my ears for sure). My requirement was a 600W power supply. The low ripple switched 600W PS was 3 times the cost I think and I had two buy 2 of them. So, economically it didn't make sense (atleast not to me). So far the net cost for 2PS and 2EVMs is about 300$ or so. Throw in case and some other stuff, and it will be even 400$ or so, and if you splurge on connectors, make it $500.
The SQ of these monoblocks exceed amps which cost 5x the cost. I have heard lots of low (under 1k), medium (1-5k) and high priced amps (>5k) and these monoblocks in current state are somewhere in middle to high priced amps in SQ.
The SQ of these monoblocks exceed amps which cost 5x the cost. I have heard lots of low (under 1k), medium (1-5k) and high priced amps (>5k) and these monoblocks in current state are somewhere in middle to high priced amps in SQ.
Thanks mwahal, these are valuable information which really helps my decision to building amps.
Another remotely related questions:
What you use to connect the AC mains to the 600W PS, and also what you use to connect for DC output supply to TI 3255 EVM.
For me, I have AC mains/DC output wires attached to connectors, then screw down the connector to PS's AC, DC poles; I am not sure should I crimp wires or solder the wires to connectors to get the lowest contact resistance (which affects SQ)?
As I am using 16AWG wires as DC output supply on 14AWG connectors,
which I will fill-up the excess gaps in inserts holes with solder on 16AWG wires, does this increase contact resistance? I read some recommends crimp down the connectors to wires as the lowest contact resistance?
How do you rate the SQ of NE5532 op-amp use in TI 3255 EVM, what would be a better/best drop-in replacement op-amp for this EVM, say towards medium to high priced amps?
Another remotely related questions:
What you use to connect the AC mains to the 600W PS, and also what you use to connect for DC output supply to TI 3255 EVM.
For me, I have AC mains/DC output wires attached to connectors, then screw down the connector to PS's AC, DC poles; I am not sure should I crimp wires or solder the wires to connectors to get the lowest contact resistance (which affects SQ)?
As I am using 16AWG wires as DC output supply on 14AWG connectors,
which I will fill-up the excess gaps in inserts holes with solder on 16AWG wires, does this increase contact resistance? I read some recommends crimp down the connectors to wires as the lowest contact resistance?
How do you rate the SQ of NE5532 op-amp use in TI 3255 EVM, what would be a better/best drop-in replacement op-amp for this EVM, say towards medium to high priced amps?
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I am using 14AWG to connect everything directly, without using any connectors. The wires are all screwed in the amp and the PS. The only connector is banana plugs out from the speaker out to the back of the speaker plate.
For my ears (and my wallet), I really like the amp in its current state. The details are very rich and bass is deeper than what I had before. For 300$ for a pair of monoblocks, you cant beat the price/performance ratio!
I am loving my TI TPA3255EVM amp so far (low hours)!Using the MeanWell LRS 350-48 SMPS with it.
Quick question: On your first pic, the red/blue wire is connected to +V on the PSU. It appears reversed in the second picture. Can you please clarify? I am ordering the same PSU, want to be sure how to connect this properly.
Thanks
I agree. The NE5532 op amps are fine. If you haven’t heard the amp yet, give it a try in stock form.
Nice catch! I switched around the wires from one picture to the other because one of them was a little short to reach the power input to the board. Just connect VDC + output from the SMPS to red terminal input on the board and you will be good. Sorry for the confusion
I am using TPA3250 EVM (less a quarter output power of TI 3255EVM), thus am using 16AWG should be enough.
For your speaker, do you just screw the bare wires, crimp it, or solder it to the banana plugs ?