Cheap amp without load dependency.

[badspeakerdesigner]

Hey there guys. Some might know I've been dealing with a load dependency issue with some cheaper amplifiers I use and my speakers (Cnotes) that results in an excessively bright speaker. I tried borrowed some cheap-ish class a/b amplifiers to test and the issue went away with those. I was wondering if anyone knew of any Class D that don't exhibit the issue and are under say $200. I know about hypex modules but I'd rather not DIY and those appear to be beyond what I can afford. While I am a little burnt out on the DIY, the little wondom boards look intriguing as a way to just bypass the crossover network in my speakers all together.

The amp I tested that was fine was the audiosource amp 100, which looks like they currently still sell as an updated model in the form of the 100VS. So far that's the cheapest thing I can find. I used own one of these so it would be kind of funny to end up with another one. Was hoping to hear your ideas.

 

[Chrispy]

What amp(s) did you have issues with?

 

[Galliardist]

Might it be better to EQ than change the amp?

 

[badspeakerdesigner]

What amp(s) did you have issues with?

SMSL SA36 and Aiyima A07

I have EQ on them at the moment, but I would very much prefer to have as good of a base to work with as I can before applying EQ. It's probably in my head but I think the EQ'd speaker doesn't quite sound like it did with the Audiosource 100.

 

[Galliardist]

SMSL SA36 and Aiyima A07

I have EQ on them at the moment, but I would very much prefer to have as good of a base to work with as I can before applying EQ. It's probably in my head but I think the EQ'd speaker doesn't quite sound like it did with the Audiosource 100.

Sometimes it pays to go with what your head says.

In this case spending a bit more money may pay dividends - first a lower distortion class AB amp though I don’t know if the VS model is that amp - then a better speaker that will work with the new amp, though that can wait.

 

[Chrispy]

SMSL SA36 and Aiyima A07

I have EQ on them at the moment, but I would very much prefer to have as good of a base to work with as I can before applying EQ. It's probably in my head but I think the EQ'd speaker doesn't quite sound like it did with the Audiosource 100.

Interesting. I'd say its most likely in your head. I've not found any audible differences between my class d and ab (or other topology) amps. Did you do any comparisons blinded at all?

 

[RandomEar]

Interesting. I'd say its most likely in your head. I've not found any audible differences between my class d and ab (or other topology) amps. Did you do any comparisons blinded at all?

The Aiyima A07 has quite a bit of load dependency. I wouldn't be surprised if it sounds "wrong" with certain speakers. It being class D is not the problem, but the circuit design is. I agree that a well designed class D amp shouldn't be discernable from an equally well designed class AB specimen.

@badspeakerdesigner If you are looking purely for power amps, a used one based on the Hypex NC122MP or the older UcD180 module might fit the bill. If it has to be cheaper and/or new, the Topping PA3s doesn't seem to be load dependent, as far as I can see in the review. The SMSL A100 could work as well, but isn't quite as good spec-wise.

 

[badspeakerdesigner]

Interesting. I'd say its most likely in your head. I've not found any audible differences between my class d and ab (or other topology) amps. Did you do any comparisons blinded at all?

There's definitely an issue with the amps I've used, proof is in the data.


Orange audiosource, green aiyima a07

 

[Joe Smith]

Interesting difference. What is the measured impedance of your speakers? I didn't notice any extra brightness with my A07 with most of my speakers, which are in the 6 to 8 ohm range...

 

[badspeakerdesigner]

They are C-notes, can see impedance in the review for them here. That one is actually with my friends A07, mine seems to fair much worse in general.

This is how my A07 can look. The speaker is unlistenable at that point.

I even took the speaker crossover apart and added each component one by one, and you can see the point at which the speaker starts to present a load the amp doesn't play well with. Dark green is raw then the rest are components added one at a time. Something goes wrong when the cap is added and it stays wrong with the rest of the parts. I don't want to delve into this too much, just looking for amp recommendations.

 

[Chrispy]

There's definitely an issue with the amps I've used, proof is in the data.


Orange audiosource, green aiyima a07
View attachment 272829

Yeah that looks to be quite audible. I've got one little chip amp (different one, tho) like that but never used it all that much, was more curious about it than had a real use for it, but seemed fine with the speakers I tried it with. The class d I've used more regularly are Crown XLS amps.

 

[Joe Smith]

SMSL A300 might be a good fit...worth a try? About $200, uses Infineon amp chip, has digital volume control. I wonder if something's not optimal with you speaker crossover though...or it could be that Aiyima is changing its builds arround so much that it's affecting the sound...as I said, my A07 does not sound overly bright or unpleasant, but it's about a year and a half old.

 

[Galliardist]

The Aiyima A07 has quite a bit of load dependency. I wouldn't be surprised if it sounds "wrong" with certain speakers. It being class D is not the problem, but the circuit design is. I agree that a well designed class D amp shouldn't be discernable from an equally well designed class AB specimen.

@badspeakerdesigner If you are looking purely for power amps, a used one based on the Hypex NC122MP or the older UcD180 module might fit the bill. If it has to be cheaper and/or new, the Topping PA3s doesn't seem to be load dependent, as far as I can see in the review. The SMSL A100 could work as well, but isn't quite as good spec-wise.

The UcD module would work. I’m not sure that a PFFB amp like the Topping is the solution in this perticular case (hence the suggestion of an AB amp) but I’m going from a subjective report where a problem in the treble persisted. You could always try one and return it if it doesn’t work though.

 

[DanielT]

But why the fixation on a cheap class D amp when it apparently worked well with a class AB amp? Do you not have physical space with a class AB amp?

Used, you can imagine, so why not, for example, a class AB, which is proven to be perfectly fine. Within your price range, this:

Review and Measurements of NAD C 320BEE PWR Amplifier

This is a review and detailed measurements of the NAD C 320BEE power (speaker) amplifier. It is on kind loan. The C 320BEE is a vintage product, dating back to 2003 I think. The BEE designation is apparently a reference to Bjorn Erik Edvardsen who was one of their designers. Can't tell if he...

audiosciencereview.com

Edit:
I've tested them both with different speakers,...the NAD every day of the week. I even still have the NAD amp (or the receiver model in my case).
Class D amp absolutely, but then some good Hypex for example. It needs to come up a bit in price over $200.

 

[Kimbrough Xu]

What's load dependancy issuse?

 

[Deleted member 48726]

What's load dependancy issuse?

Some amplifiers doesn't like certain speaker loads, a combination of phase shifts and or low impedances at certain frequencies. It is up to debate from time to time because amplifiers aren't tested with complex loads and thus doesn't show issues in the data. You will see some stating that it's all imaginary while others state that they hear differences between amps on the same set of speakers. First mentioned will dismiss the issue because of lack of data and refer to measurements that doesn't show issues and will ask for AB blind testing. This is not a trivial task for the usual listener to do exact though.

 

[Talisman]

In reality the dependence on the load refers to a frequency response which changes according to the impedance of the loudspeaker, it can also be clearly seen in the frequency response test at 4 and 8 ohms which present two curves which tend to move away at the extremes of band.
For example

 

[Joe Smith]

But as per the above curve, if one's hearing tops out at about 12 or 13kHz as true for many of us older gents, net effect would be a slight treble brightness with 8 ohm speakers in the above example - up between .5 and 1 dB - right?

 

[Deleted member 48726]

But as per the above curve, if one's hearing tops out at about 12 or 13kHz as true for many of us older gents, net effect would be a slight treble brightness with 8 ohm speakers in the above example - up between .5 and 1 dB - right?

That last curve doesn't show much of an issue. The curves in OP show changes in the audible range. Last one doesn't really.

 

[NTK]

Below is the impedance curve of OP's speakers (C-Note). The impedance magnitude of his speaker is 15 - 36 ohms from ~6 to 17 kHz, which is much higher than the 8 ohm dummy load Amir used. This will raise the response at the higher frequencies more than what is shown in the 8 ohm graph.