Cheap amp without load dependency.

[CDMC]

Look for something with Hypex UcD (there was a Niles model tested here; ProJect Amp Box SE/DS are also UcD180), Icepower ASX2 (but make sure it’s properly buffered!), or Anaview (Parasound Zonemaster 250/450).

That said, at relatively low power I’m not sure D saves much over a small AB amp (e.g. Parasound Zamp) and the latter can be found at great prices.

There is one for sale in the classifieds. Full disclosure, it is mine.

 

[Deleted member 48726]

Hey good news, I went and grabbed that crown XLI800 for sale locally. It was in immaculate condition, apparently used for only a few hours. I was concerned about noise/hiss but I hear none at my listening position. The fans are nearly dead silent thankfully.

But here's the final result, no load dependency issues! Look at that lovely normal top end. I'm so relieved that my problems are over. Time to enjoy the speakers.

View attachment 273493

That's what people usually experience with pro amplifiers if they "dare" to try them.
And they come with power galore so no worries about headroom or blasting tweeters because of clipping.
Only caveat may or may not be the cooling fans' noise. Most of the time it's not a problem because we actually do not drive them hard enough in the listening space to have them spin up much.

Have a nice one

 

[JSmith]

Are these TI chip always implemented filter free ? Most applications ?

It depends on what model chip is being used... some are, some aren't;

Two types of class-D amplifiers exist: traditional class-D that requires a low-pass LC filter to produce an analog output, and TI’s new filter-free class-D which does not require a low-pass output filter for normal operation because the speaker provides the inductance necessary to achieve high efficiency. Two families of class-D APAs (TPA032D0x, TPA005Dxx) use the traditional modulation scheme that requires the LC filter for proper operation. The data sheets, EVM manuals, and application notes (References 2 and 3) provide more information about this filter. The filter-free class-D APA families (TPA2000Dx and TPA2001Dx) use a modulation scheme that does not require an output filter for operation, but they do sometimes require an RC low-pass filter when making measurements. This is because some analyzer inputs cannot accurately process the rapidly changing square-wave output and therefore record an extremely high level of distortion. The RC low-pass measurement filter is used to remove the modulated waveforms so the analyzer can measure the output sine wave. Additionally, the class-D APA outputs can be also connected to optional electromagnetic interference filters (EMI filters). These filters are normally suggested for applications with output power around 5 W, and sensitivity to external electromagnetic signals. These filters are normally used in TI's digital input Class-D audio amplifiers with output sense (TAS2770 and TAS2562 are examples of these families).

https://www.ti.com/lit/an/sloa068a/sloa068a.pdf

TPA3255 which the Aiyima A07 uses for example is not filter-free, but thought it was worth a mention in general.


JSmith

 

[Kimbrough Xu]

Class D amps needs an output filter to remove the carrier frequency from the switching, this output filter has a rising impedance with frequency thus treble response can vary depending on speakers .

Better class D amps has the filter inside the feedback loop and this solves the problem.

But on a tight budget a used old AB amp in good condition is also a possibility.

Thank you for your explanation. So if the class d amps have an output filter, does it mean the amp can vary depends on the speaker so that the system can be constant?

 

[Mnyb]

Thank you for your explanation. So if the class d amps have an output filter, does it mean the amp can vary depends on the speaker so that the system can be constant?

The system can vary a lot if the output filter is not inside the feedback loop se NTK’s simulations in this tread.
The filter works as an impedance in series with the loudspeaker.

When you put the filter inside the feedback loop the very high negative feedback class D amps uses removes this effect inside the the audible band and a bit more ( where the feedback loop is effective ).
In practice it effectively lower the amps output impedance.

 

[Mnyb]

It depends on what model chip is being used... some are, some aren't;

https://www.ti.com/lit/an/sloa068a/sloa068a.pdf

TPA3255 which the Aiyima A07 uses for example is not filter-free, but thought it was worth a mention in general.


JSmith

It’s worth mentioning it expended my knowledge a bit

I remain a bit sceptical I would personally prefer an class D amp with filter and post filter feedback .

 

[DanielT]

Hey good news, I went and grabbed that crown XLI800 for sale locally. It was in immaculate condition, apparently used for only a few hours. I was concerned about noise/hiss but I hear none at my listening position. The fans are nearly dead silent thankfully.

But here's the final result, no load dependency issues! Look at that lovely normal top end. I'm so relieved that my problems are over. Time to enjoy the speakers.

View attachment 273493

Congratulations! The Crown XLI800 seems to have no problem whatsoever keeping your C-note speakers under full control.

Good that you told us about this with the fans. That you experience them as quiet on the Crown XLI800. Temperature-controlled fans perhaps? Considering how little power you will use for your home HiFi and your C-notes, the fans hardly ever turn on that often, right?

No audible noise/lift at your listening position you say. Good to know. Good to know for everyone to know this with fan noise and level of noise/elevator, thus the Crown XLI800 could possibly be a choice also for others for their home HiFi. With the addition that what is experienced as annoying in terms of sound, fan noise and noise/elevator is of course individual, but still.

What input sensitivity have you chosen? You can choose between 0.775V or 1.4V.
Here is a shorter video showing the setting options Crown XLI800 for those curious to see it:

Edit:
Of course with the Crown XLI800 you don't have to worry about it being driven into clipping, as Holdt in #42 pointed out. A big (the biggest?) advantage of using these PA amps for home Hifi. They are real powerhouses, plenty of power if you need it.

 

[badspeakerdesigner]

Congratulations! The Crown XLI800 seems to have no problem whatsoever keeping your C-note speakers under full control.

Good that you told us about this with the fans. That you experience them as quiet on the Crown XLI800. Temperature-controlled fans perhaps? Considering how little power you will use for your home HiFi and your C-notes, the fans hardly ever turn on that often, right?

No audible noise/lift at your listening position you say. Good to know. Good to know for everyone to know this with fan noise and level of noise/elevator, thus the Crown XLI800 could possibly be a choice also for others for their home HiFi. With the addition that what is experienced as annoying in terms of sound, fan noise and noise/elevator is of course individual, but still.

What input sensitivity have you chosen? You can choose between 0.775V or 1.4V.
Here is a shorter video showing the setting options Crown XLI800 for those curious to see it:

Edit:
Of course with the Crown XLI800 you don't have to worry about it being driven into clipping, as Holdt in #42 pointed out. A big (the biggest?) advantage of using these PA amps for home Hifi. They are real powerhouses, plenty of power if you need it.

Thanks for the info, looks like it's on 0.775 for now. 1.4v just made the signal louder, surprisingly at no change to the noise floor.

I'm curious what sinad actually means on an amplifier. This one seems to be nearly 30db worse in performance there than the A07 but it sounds totally fine to me? Even if the amp wasn't going to work out, I couldn't pass it up as it was just $100 and I could always use it for PA. But I guess I lucked out here. It's also nice to be back to balanced xlr cables, rca is just a junk connector to my live sound workin' self.

 

[RandomEar]

I'm curious what sinad actually means on an amplifier. This one seems to be nearly 30db worse in performance there than the A07 but it sounds totally fine to me? Even if the amp wasn't going to work out, I couldn't pass it up as it was just $100 and I could always use it for PA. But I guess I lucked out here. It's also nice to be back to balanced xlr cables, rca is just a junk connector to my live sound workin' self.

SINAD relates the signal to the noise and distortion levels. In case of the Crown, it looks to be heavily distortion-limited. The graphs in the reviews are somewhat misleading, because they misrepresent the actual noise level of the device due to a phenomenon called FFT gain. But even being generous and adding 30 dB to the noise floor, it would end up somewhere around -85 dB, which is still far off from the highest distortion peaks around -63 dB.

In a very discerning test scenario and with quick and well setup A/B switching you might actually be able to tell the Crown apart from a significantly better amp by its distortion. In any real listening scenario with actual music and not test tones, the vast majority of people won't be able to recognise distortion below -40 dB. You can test it yourself

 

[badspeakerdesigner]

SINAD relates the signal to the noise and distortion levels. In case of the Crown, it looks to be heavily distortion-limited. The graphs in the reviews are somewhat misleading, because they misrepresent the actual noise level of the device due to a phenomenon called FFT gain. But even being generous and adding 30 dB to the noise floor, it would end up somewhere around -85 dB, which is still far off from the highest distortion peaks around -63 dB.

In a very discerning test scenario and with quick and well setup A/B switching you might actually be able to tell the Crown apart from a significantly better amp by its distortion. In any real listening scenario with actual music and not test tones, the vast majority of people won't be able to recognise distortion below -40 dB. You can test it yourself

I've done that test before, with music I get to -18, with tones -30. Hows that for golden ears lol.

 

[RandomEar]

I've done that test before, with music I get to -18, with tones -30. Hows that for golden ears lol.

Yeah, in the end, aiming for maxmimum SINAD is often more about peace of mind and somewhat about principle. For me, especially the "noise" part in "signal to noise" is important as I'm running a near field setup and loathe tweeter hiss. And to mitigate that to an acceptable degree, SINAD values over 90 dB are actually useful with sensitive speakers. Therefore, there is a meaning to and a practical difference between a SINAD of 75 dB and a SINAD of 90 dB in some cases.