AIYIMA A70 Mono Amplifier Review

[EddNog]

My feeling is this is an amp for those that like to tinker. The dual sub filters will likely be may be redundant with the subs filters, but will let folks listen to both filters, and may actually prefer say the amps to the subs.

One filter (front dial) is for the active speaker output and the other filter (rear dial) is for the RCA line level output.

-Ed

 

[EJ3]

One filter (front dial) is for the active speaker output and the other filter (rear dial) is for the RCA line level output.

-Ed

Ah, an answer to a key question about this unit at last! Thank you!

 

[EddNog]

Ah, an answer to a key question about this unit at last! Thank you!

Ironically this is the third time I’ve said this in this review thread LOL!!!

 

[ampguy]

One filter (front dial) is for the active speaker output and the other filter (rear dial) is for the RCA line level output.

-Ed

I'm confused!! So lets say I want to use both, one for L full range, one for R full range, plus a powered sub. I have a single sub using both RCA's to powered sub. Are you saying I don't have dual high pass filters, one on my sub, and one on the back of the amp? With the Left knobs on front handling high pass of the full range L/R speakers (and if so, what setting do I want to use on the bottom)?

The SMSL A100s have about 4x the power and do have high pass full range filtering (abeit fixed at ~100Hz or so). Otherwise I'm not sure of many amps that have this adjustable, Parasound HINTs did.

 

[EddNog]

I'm confused!! So lets say I want to use both, one for L full range, one for R full range, plus a powered sub. I have a single sub using both RCA's to powered sub. Are you saying I don't have dual high pass filters, one on my sub, and one on the back of the amp? With the Left knobs on front handling high pass of the full range L/R speakers (and if so, what setting do I want to use on the bottom)?

The SMSL A100s have about 4x the power and do have high pass full range filtering (abeit fixed at ~100Hz or so). Otherwise I'm not sure of many amps that have this adjustable, Parasound HINTs did.

This amp doesn’t do high-pass filtering (which is incredibly stupid—this is the single feature we all want more than anything!); the front dial controls LOW-pass filter of the speaker level output (binding terminals) in the back—this is literally only of any use as an amplifier for a PASSIVE subwoofer. The small dial on the back controls the LOW-pass filtering setting of the RCA (mono, line-level) output on the back, and this thing is basically useless because almost all powered/active subwoofers already have their own low-pass filters.

-Ed

 

[ampguy]

This amp doesn’t do high-pass filtering (which is incredibly stupid—this is the single feature we all want more than anything!); the front dial controls LOW-pass filter of the speaker level output (binding terminals) in the back—this is literally only of any use as an amplifier for a PASSIVE subwoofer. The small dial on the back controls the LOW-pass filtering setting of the RCA (mono, line-level) output on the back, and this thing is basically useless because almost all powered/active subwoofers already have their own low-pass filters.

-Ed

Thanks Ed, I get it now. So the redundant low pass on amp, and on most powered subs is fine, I mean, not all filters are the same 12db/oct, 24db/oct, parts, etc. So I'm fine with this redundancy. (Preferably bypassable on the amp, or at least adjustable to 200Hz or more).

Some sub vendors recommend using the high level amp outputs for sub input vs RCA, so I can also see where the line level control can be handy for some, but such a big knob in front is odd.

Regarding high pass filltering on the mains, many here like that kind of bass management, and I will just state that sometimes good combos of mains and subs don't have a problem with the full range going to L/R mains that say cutoff at 80 to 120Hz, with a well setup sub that covers below that, IMHO.

 

[EddNog]

Thanks Ed, I get it now. So the redundant low pass on amp, and on most powered subs is fine, I mean, not all filters are the same 12db/oct, 24db/oct, parts, etc. So I'm fine with this redundancy. (Preferably bypassable on the amp, or at least adjustable to 200Hz or more).

Some sub vendors recommend using the high level amp outputs for sub input vs RCA, so I can also see where the line level control can be handy for some, but such a big knob in front is odd.

Regarding high pass filltering on the mains, many here like that kind of bass management, and I will just state that sometimes good combos of mains and subs don't have a problem with the full range going to L/R mains that say cutoff at 80 to 120Hz, with a well setup sub that covers below that, IMHO.

Right. I don’t rely on any high-pass filtering for my LS50 Metas and am more than pleased with how well I’ve been able to integrate my SVS SB-3000 subwoofer with them going full range.

-Ed

 

[EJ3]

Ironically this is the third time I’ve said this in this review thread LOL!!!

ADHD: Skimming down the threads, I don't always see the answers the first time they appear.

 

[EddNog]

ADHD: Skimming down the threads, I don't always see the answers the first time they appear.

Frankly everyone is missing them, so don’t feel bad about it. Happens frequently on threads like this where there’s so much activity that posts flip a new page out.

-Ed

 

[ampguy]

Right. I don’t rely on any high-pass filtering for my LS50 Metas and am more than pleased with how well I’ve been able to integrate my SVS SB-3000 subwoofer with them going full range.

-Ed

LS-50s here, have used high pass at variable 100-200Hz, and turned off, they simply don't need them. My sub with these are a REL HT-1205. Various Kefs, Harmans, with other amps in other rooms, also did not benefit from high passing the mains either, in my environments. I get that some setups probably do, and save wattage, etc. from duplicating some low end overlap. Am glad my systems don't need that management.

 

[EddNog]

LS-50s here, have used high pass at variable 100-200Hz, and turned off, they simply don't need them. My sub with these are a REL HT-1205. Various Kefs, Harmans, with other amps in other rooms, also did not benefit from high passing the mains either, in my environments. I get that some setups probably do, and save wattage, etc. from duplicating some low end overlap. Am glad my systems don't need that management.

I’ve tried it in the past myself with a DBX 234 active crossover. Really didn’t experience any benefit to cutting the LS50 Metas higher either.

-Ed

 

[totti1965]

I’ve tried it in the past myself with a DBX 234 active crossover. Really didn’t experience any benefit to cutting the LS50 Metas higher either.

-Ed

I’ve tried it in the past myself with a DBX 234 active crossover. Really didn’t experience any benefit to cutting the LS50 Metas higher either.

-Ed

But you should at least close the bass reflex port of your compact speakers, shouldn't you?

I was surprised when looking at Erin’s measurements, that Subwoofer support (high pass filtering) for most speakers doesn’t make so much positive effect in terms of distortion than I expected!

 

[EddNog]

But you should at least close the bass reflex port of your compact speakers, shouldn't you?

I was surprised when looking at Erin’s measurements, that Subwoofer support (high pass filtering) for most speakers doesn’t make so much positive effect in terms of distortion than I expected!

I’ve tried both, ports open, ports half closed, and ports fully closed (the foam plugs from KEF include a removable core). I got better results moving the speakers away from the wall and leaving the ports open than I did with the ports fully or partially closed at any distance from the wall. This even despite my multitude of DSP options in my subwoofer including crossover slope (6/12/18/24dB/octave) and degree-by-degree phase adjustability.

-Ed

 

[totti1965]

I’ve tried both, ports open, ports half closed, and ports fully closed (the foam plugs from KEF include a removable core). I got better results moving the speakers away from the wall and leaving the ports open than I did with the ports fully or partially closed at any distance from the wall. This even despite my multitude of DSP options in my subwoofer including crossover slope (6/12/18/24dB/octave) and degree-by-degree phase adjustability.

-Ed

Yes, maybe it is a Speziality of kef, which are not boomy at all in the bass. Most other speakers may sound better with closed ports in case of supporting them with a sub under 80 Hz.

 

[AudioKC]

Is the result of a multitone test with distortions/harmonics up to -60db a no-go for AMP? What do you think gens/ladies?

p.s. I voted "Not terrible (postman panther)"

 

[totti1965]

Your hearing is most sensible in the region between 2.000 Hz and 4.000 Hz, so it is quite o. k. and not a big audible concern. But proper engineering looks quite different imho.
I read something extremely interesting from Bruno Putzeys (the legendary Hypex / Nilai / Eigentakt / Purifi engineer) the day before yesterday:

Bruno Putzeys, Author at HomeTheaterHifi.com

hometheaterhifi.com

Bruno says that intermodulation distortion is more important (and more audible) than any other kind of distortion / noise, because the 32 Tone Test simulates music (and that is what we all wanted to listen!)

 

[ricaso79]

I connected the A70 mono to the SVS PB12, which has the amplifier working whenever it wants. I didn't feel like spending $350 on the SVS amplifier.

I liked the sound of the A70 mono. When calibrating using the Denon X3800h, the power was approximately 45% of the volume.

For the SVS PB12, I thought it was worth the savings compared to changing the SVS board.

 

[YesChickenNuggets]

Ok, I think I understand why 2 sub-knobs. They intend for people to use this in home theater. Passive sub isn't popular everywhere, but maybe there's more of a market in China for it.

I distinctly remember you guys complaining about the Tone-Knobs on Fosi's TB10. Then they were praised on the BT20 because they were defeatable. And now you guys HATE not having them again after they're not on the A70. It's pretty clear you guys don't even know what you want, LOL.

I wouldn't mind a highpass filter knob to cut out the bottom frequencies for the mains though. This would obviate the need for adding crossover in the majority of cases.

Right now I just use DSP to blend the sub. I've never found a sub that behaves in-room. It doesn't matter what their anechoic measurements are, without DSP in room subs are all over the place.

 

[EddNog]

…I wouldn't mind a highpass filter knob to cut out the bottom frequencies for the mains though. This would obviate the need for adding crossover in the majority of cases…

THIS is literally ALL we are asking for, @Fosi Audio @AIYIMA @Douk Audio

-Ed

 

[EJ3]

Ok, I think I understand why 2 sub-knobs. They intend for people to use this in home theater. Passive sub isn't popular everywhere, but maybe there's more of a market in China for it.

I distinctly remember you guys complaining about the Tone-Knobs on Fosi's TB10. Then they were praised on the BT20 because they were defeatable. And now you guys HATE not having them again after they're not on the A70. It's pretty clear you guys don't even know what you want, LOL.

I wouldn't mind a highpass filter knob to cut out the bottom frequencies for the mains though. This would obviate the need for adding crossover in the majority of cases.

Right now I just use DSP to blend the sub. I've never found a sub that behaves in-room. It doesn't matter what their anechoic measurements are, without DSP in room subs are all over the place.

I built & use my passive pair (run by a pair of bridged (mono [4 ohms]) NAD 2200's (1000+ watts RMS each) of 12" FR 20-80 Hz subs because I had the stuff sitting around to do it (and make it work).