I got this, my 100H LC meter is out of range for its claim 230H.
It's a bit more expensive and claim 80% permalloy.
https://item.taobao.com/item.htm?spm=a1z09.2.0.0.KvaKyt&id=39991111619&_u=85skkbbe486
Anyways, subjective listening sound fairly good and I couldnt tell much difference to my other Japanese Tamradio tranny.
80% nickel is making it more expensive methinks. 230H for a primary inductance is very impressive but with such a high value the self-resonance is going to be very low, perhaps below 1kHz. Meaning the impedance is dominated by the self-capacitance over most of the band. I might order a pair for a tryout.
Also due to the output inductor, according to TI note slaa701. The Wurth 7443630700 inductor significantly reduces this rise.
Cheers,
Mike
Hi,
I got my evm - sounds good but I'm having this problem with a linear 19V 4A linear supply and 4 ohm speakers. The regulator is AMB sigma11 from an 80VA talema toroid, and doesn't drop out of regulation, so I guess the amp is current starved ? If so, a bigger transformer ? It's surprising that this amp is so hungry. My experience is that class-D sound great until they suddenly start distorting but this amp shuts down? Weird.
Forgive me joining in, but I received my 3250 EVM board on Friday, connected it to my Pi and a 36v 10A supply, without issue. I don't think 4A is sufficient.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Or combination of psu-voltage used and bulk capacitance as mentioned in evm userguide ? The AMB supply is small though and wasn't there an overlooked cap multiplier problem with them ?
NOTE: The performance of the TPA3251D2EVM/TPA3251D2DDV is dependent on the powersupply. Design the power supply with margins that can deliver the needed power. In lowfrequency applications additional bulk capacitance may be needed. Replacing the bulk capacitors on the TPA3251D2EVM with 3300 µF or more capacitance may be necessary, depending on the power supply used.
NOTE: The performance of the TPA3251D2EVM/TPA3251D2DDV is dependent on the powersupply. Design the power supply with margins that can deliver the needed power. In lowfrequency applications additional bulk capacitance may be needed. Replacing the bulk capacitors on the TPA3251D2EVM with 3300 µF or more capacitance may be necessary, depending on the power supply used.
Have you tried power in in shutdown-mode or did you wired a short somewhere?
(I once accidentally powered a 3255 with the power plug connected into OUTA/OUTB, fault-led went on, nothing failed)
Uhm, "TPA3255 Device Setup Guide & Configuration Tool" will give the answer..
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3151 can deliver 1 second 150watt into impedance minimum of a 4 ohm speaker. Powersupply s11 is standard 1A continuous (20 watt), maybe 2A continuous (35 watt) here (heatsinking), with lot of headroom for peaks.
TI config tool estimates 6.3A and 7A needed for 3 ohm/19V, maybe the 20 or 35 watt powersupply can deliver that for 1 second ?
TI config tool estimates 6.3A and 7A needed for 3 ohm/19V, maybe the 20 or 35 watt powersupply can deliver that for 1 second ?
Hi,
Thanks for the replies! That 3250 looks good - nice! Are you pleased with the sound?
I switched transformer today to a 150VA 30VAC. The amp no longer shuts down. Running music full volume from my phone, the clipping light stops flashing at a regulated 24V.
When I switched to a 2v rms DAC as the source, I can get to -2dB from full volume without the clipping light coming on by turning up the regulated voltage to 32V. Above -2dB the light occasionally flashes regardless of voltage (tested up to 37V, board max is 38V) but the sound is just too loud for me to care whether it's clipping peaks or not. My normal listening volume is around -24 to -20.
The S11 with 2.5"on board heatsinks doesn't get hot with 32V output and full volume - just warm, and it has 39V minimum after the bridge rectifier so it won't drop out of regulation.
So I guess 5A, 24V is about the minimum for this amp and ideally it wants around 36V 7.5A for my speakers and ear-bleeding "fun". I guess a 32VAC 250VA transformer would be enough to make sure it never goes into clipping at full volume. However, I'll never listen at that volume so it's just a case of whether a lower power source impedance would matter. Given the S11 has a very low output impedance, I'm not sure it does and I will probably stick with the 150VA 30VAC and spend the money elsewhere.
Quick pic attached. I'm waiting on my Taobao transformers now... and thinking about changing the onboard regs - LM338 for 15V (2x LM329 at the base - click this link for an explainer) and TPS7A4700EVM for 12V. Has anyone tried changing regs?
Thanks for the replies! That 3250 looks good - nice! Are you pleased with the sound?
I switched transformer today to a 150VA 30VAC. The amp no longer shuts down. Running music full volume from my phone, the clipping light stops flashing at a regulated 24V.
When I switched to a 2v rms DAC as the source, I can get to -2dB from full volume without the clipping light coming on by turning up the regulated voltage to 32V. Above -2dB the light occasionally flashes regardless of voltage (tested up to 37V, board max is 38V) but the sound is just too loud for me to care whether it's clipping peaks or not. My normal listening volume is around -24 to -20.
The S11 with 2.5"on board heatsinks doesn't get hot with 32V output and full volume - just warm, and it has 39V minimum after the bridge rectifier so it won't drop out of regulation.
So I guess 5A, 24V is about the minimum for this amp and ideally it wants around 36V 7.5A for my speakers and ear-bleeding "fun". I guess a 32VAC 250VA transformer would be enough to make sure it never goes into clipping at full volume. However, I'll never listen at that volume so it's just a case of whether a lower power source impedance would matter. Given the S11 has a very low output impedance, I'm not sure it does and I will probably stick with the 150VA 30VAC and spend the money elsewhere.
Quick pic attached. I'm waiting on my Taobao transformers now... and thinking about changing the onboard regs - LM338 for 15V (2x LM329 at the base - click this link for an explainer) and TPS7A4700EVM for 12V. Has anyone tried changing regs?
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I am very pleased with sound, at all volume levels, driving a set of Q Acoustics 2050i floor standers, fed by an RPi3 running Rune through a Kali and a Mamboberry LS+ DAC. Even though mine is effectively a lower power version of yours, it still goes too loud for my listening at full volume.
The amp is noise/hiss free (I'd expect nothing less), but I'll try a 'better' power supply.
Considering the physical quality of the board and components, and how it sounds, $249 is a reasonable price, but at $113, its a bargain...
Nanoloop, why would you change the regs? Are you going to change stuff on all your equipment just because you can?
I'm also very pleased and like you, very happy with the price. Might buy another and do bi-amping... 🙂 However, there are 2 sets of electro caps in the signal path so I'm interested to know if it can be better...
Why would you NOT change a low grade part for a better one if you can? 😀
A long time ago I built a Mini3 amp with some different 3 pin regs to try out how they sound. Worst one was LM2937/40 - and that's what Ti chose for this board when they make a decent UA7812. They chose a "bad" National Semi part. Clearing out inventory?
@Doctormord,
OT question, I remember that your website used to be (at least partially) in English, now all I see is German. Any idea what that happened? 🙂
OT question, I remember that your website used to be (at least partially) in English, now all I see is German. Any idea what that happened? 🙂
I'd guess the engineers who did those EVMs had absolutely no clue how to engineer a top notch system. That's why the audio/measured performance is that bad.
Maybe you'd seen the board made by 3audio? He isn't using an LDO at all, just feeding direct from the buck converter. His performance is at the same level as the EVM at minimum.
So yeah, i'd say, they needed to clean their stock of lm2940, yes.
If you can hear the sound of an LDO feeding an opamp with a PSRR of 100+dB, congrats to your golden ears. 😉
Im excited to hear if performance went up, really. I don't have this golden ears. 🙁 So i have to rely on measurements.
Cheers. 🙂
TI's engineers care about the numbers not particularly how it sounds. That's why they use NE5534 in some of their DAC reference schematics as I/V converters 😀 Now perhaps some of those were done by Burr-Brown engineers before the acquisition but there's no reason they should keep the reference schematics the same if they no longer approve of them is there?
Save
True.
(For reference systems they also choose the color of system decoupling caps according to the favors of the companies "golden ears" they want sell an audio system implementation to. Especially on the japanese market. True (internal) story.)
(For reference systems they also choose the color of system decoupling caps according to the favors of the companies "golden ears" they want sell an audio system implementation to. Especially on the japanese market. True (internal) story.)
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Do you have evidence that this "low grade part" is affecting the performance of the amp? If you do then absolutely. I guess the next thing to do after changing the part will be testing it to show that improvement has been made. I ask this question straight out of curiosity. I am thinking of getting this EVM (still have to decide on 3251 or 3255) and would like to know as much as possible about these boards from current users.
Regards,
The EVM's work.
They are well documented.
They are well-made.
They are in circulation.
They sound good.
They can be tested (test points included on the board.
They can be upgraded.
The manufacturer provides advice on how to upgrade them.
They are not expensive.
Delivery is quick.
What else do you need to know?
Cheers,
Mike