I'm going to need an amp for my AsciLab C6B speakers.

[Ronald Z]

Every in-depth discussion of the C6B indicates that the speaker load can drop to 2 ohms which is almost no resistance at all. (Sometimes even lower momentary resistance can reportedly occur with a sharp bass spike in the source music). A polite 4 ohm amp (like the Topping LA90 I was initially considering) apparently either won't work or won't bring out the potential of these speakers.

The C6Bs are my first foray into the expensive realm of "near audiophile" speakers. I want to maximize their potential with a high quality, no frills amp, staying within the ethic of excellence within a budget. I am trying to say under $800 but will consider a little higher for exactly the right amp.

My wish list:
- No distortion at listening levels. (A "reference grade" amplifier)
- Post Filter Feedback (PFFB) is a must
- I would prefer a volume control; amps that constantly run at max volume make me nervous. (Once my Wiim Ultra did not function properly and the volume kept climbing until it reached maximum). I don't want to risk a high volume spike, especially with some of the more powerful amps that are out there, risking my speakers and my eardrums.
- A price that is not stratospheric

Suggestions will be greatly appreciated!

 

[staticV3]

The C6B has a minimum impedance of 2.6Ω:



To drive it, I'd buy a 3e Audio A5 or A7.

 

[YouDontHaveEnoughBass]

I power my Ascilabs with a pair of Fosi V3 monos and a Fosi P4 preamp; if I bought today I’d be tempted by the BT20 Max which wasn’t out at the time and has some nice looking features like a high pass filter and volume control etc built in so no need for a preamp

 

[Cote Dazur]

Suggestions will be greatly appreciated

Their is nothing in the spec of those speakers indicating that it can’t be efficiently driven by virtually any functioning amplifier rating at 50 watts. If worried about the drop at 200hz, get a 100 watt amp and you are all set.

• Design: 2-Way Bookshelf
• Tweeter: 1" Aluminium Ceramic Dome Tweeter
• Woofer: 6" Aluminium Ceramic Cone with cast Aluminium Chassis
• Enclosure: Passive Radiator
• Enclosure Finish:
  • Matte Paint Finish
  • Gloss Paint Finish (optional)
• Crossover Frequency: 1.1kHz
• Sensitivity: 85dB @ 2.83V / 1M
• Max SPL (IEC 60268 Full-Bandwidth): 99 dB SPL
• Max SPL (>100Hz): 105 dB SPL
• Frequency Response: -3dB @ 50Hz / -6dB @ 41Hz
• Impedance: Nominal 4 Ohm (min 200Hz / 2.6 Ohm)
• Dimensions (H x W x D):
  • Metric: 40 x 20.3 x 26.5 cm
  • Imperial: 15.7 x 8 x 10.4 inches
• Weight: 8.4 kg / each
• Recommended Amplifier Power: 50 – 250W

 

[Redacted]

The speakers are moderately sensitive, so it depends how loud the OP wishes to play music.
I'd say 50W @8ohms, and presumably more at 4ohms, might well be plenty.
The speakers have low impedance at 90-600Hz, but more ohms at low bass where most energy would be needed - many modern amps will be fine with that, especially if not cranked too high.
The suggestion of 3e Audio A5 seems fine to me. Other amps are available, with similar tech & spec.. Both the A5 & A7 are specced to run 2 ohm loads:

A5x A7x Series Next-Gen PFFB Amplifier | 3e Audio

www.3e-audio.com

 

[YouDontHaveEnoughBass]

I just spotted you’ll be running these on a desk, in that case don’t get the fosi monos there’s no need for that much power the A5 will do perfectly

 

[Ronald Z]

To drive it, I'd buy a 3e Audio A5 or A7.

Static V3: Seems we are in the golden age of clean amplification at modest prices!

Both the A5 and A7 are very inexpensive for such clean amplified sound. For near-field desktop use either of these little amps would be more than sufficient. The C6B speakers are far less daunting to amplify (with clean, distortion-free sound at moderate volumes) than I had imagined.

I am really appreciating these forums and all of your replies. When doing my own C6B research I ran across a number of Chicken-Little "the sky is falling" scenarios filled with overheated amps and self-protecting power downs. I will be offloading my deepest bass to a subwoofer, at least at higher volumes, so the power requirements to power the C6Bs should be rather modest.

I am still considering the Topping LA 90 Discrete with with Amir's review of 0.00 distortion. But it is only rated down to 4Ω. Ignoring for a moment that the LA 90 is probably overkill, does the 4Ω rating disqualify it for use with a speaker that dips to 2.4Ω of impedance?

 

[staticV3]

I am still considering the Topping LA 90 Discrete with with Amir's review of 0.00 distortion. But it is only rated down to 4Ω. Ignoring for a moment that the LA 90 is probably overkill, does the 4Ω rating disqualify it for use with a speaker that dips to 2.4Ω of impedance?

The LA90D goes into protection below 4Ω, so yes.

 

[Ronald Z]

At $270 (Amazon), the 3E Audio A7 looks to be well suited to run the C6B. It has more power than the A5 and the distortion is still low. (The A5 would clearly have worked well also). I am really pleased to find such a clean amp at such a low price! Thank you all for your advice.

The C6Bs have just arrived and I will be opening the box this afternoon.
The Audio A7 has been ordered.

 

[Ronald Z]

The effort to adequately provide clean amplification to the C6B speakers continues.

The 3E Audio A7 arrived from Amazon and after some use, I have come to the conclusion that I don't like it. The bottom gets hot to the touch after awhile when I am powering my C6B AsciLabs at medium volume.

I bought the A7 with the 5amp 48volt power brick (240 watts). It is supposed to support up to a 10amp 48volt power brick (480 watts)! I wanted the 480 watt transformer brick in the future. But that's a lot of power going into the A7's very small chassis. If it is already running hot, I don't see how you can get full power out of it without eventually baking the chips or other components until they throw in the towel. In short, I believe the A7 to not be robustly engineered enough for long term use.

My Possible Alternative Solution:
I am considering the Buckeye Hypex NCx252MP priced at $625. It has an internal power supply (no clunky brick needed) and appears that it will not run nearly so hot. Amir reviewed its predecessor (the NC252MP) and it was "recommended."

The Buckeye NCx252MP with upgraded circuitry has recently replaced it:

https://www.audiosciencereview.com/...-hypex-ncx252mp-amplifiers.68761/post-2492362

The Buckeye is rated at 4Ω, but I believe it should dip to 2Ω on a very temporary basis (as in during a sharp bass transient spike). I think it will fit the bill, but I wanted to get an opinion from someone familiar with the product or with enough knowledge to present any downsides that I should consider.

 

[Mark609]

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

 

[Ronald Z]

The A

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

The speakers are reported, by one reviewer, I can't recall where I saw it, as having an occasional "brutal" instantaneous impedance drop to just under 2Ω during a sharp transient in the 200hz range. I'm guessing that is not as scary as it sounds -- my $150 Fosi ZA3 handles them just fine. The Fosi does not have a PFFB circuit so I wanted to upgrade. The C6B are premium speakers (at least for me they are!) and I want a rock-solid amplifier that will power them cleanly.

 

[thunderchicken]

Honestly, a Wiim amp pro would fit the bill here. It has the added benefits of proper bass control and room correction. They run about $400. Love mine, use it with KEF Q1 metas and an RSL 10S mkII. I just cross to the sub a bit higher than usual to get extra headroom on the speakers. Works really well, sounds incredible.

 

[Chrispy]

A power amp would not have a volume control, sounds like you need a pre-amp as well as amp (assuming amp means power amp). An integrated amp might be another consideration, the Wiim mentioned is a good choice depending what your sources might be.

 

[Ruediger]

The 3E Audio A7 arrived from Amazon and after some use, I have come to the conclusion that I don't like it. The bottom gets hot to the touch after awhile when I am powering my C6B AsciLabs at medium volume.

I bought the A7 with the 5amp 48volt power brick (240 watts). It is supposed to support up to a 10amp 48volt power brick (480 watts)! I wanted the 480 watt transformer brick in the future. But that's a lot of power going into the A7's very small chassis. If it is already running hot, I don't see how you can get full power out of it without eventually baking the chips or other components until they throw in the towel. In short, I believe the A7 to not be robustly engineered enough for long term use.

The 3e amp case works with air convection. I wouldn't say they get too hot, but I don't know your placement and SPL. You can easily change the temperature by raising the box from the floor and not surrounding with other hot stuff. Consider the feet on them a basic suggestion, fine in many cases. But if you draw a lot of power a little change there works wonders. My experience with 3e A7 stereo and mono is that they can easily be made to work in demanding scenarios. Whereas just powering the C6Bs is not that big a pair of speakers. I would consider the A5 for them.

If you want something just above handwarm when driving the C6Bs also consider the WiiM Vibelink. Or any other of the top WiiM amps. Bigger case, different cooling concept, works nice.

Moving up to bigger boxes like the Buckeye obviously will work.

 

[Ronald Z]

I am really appreciating the replies!

The 3e amp case works with air convection. I wouldn't say they get too hot, but I don't know your placement and SPL. You can easily change the temperature by raising the box from the floor and not surrounding with other hot stuff. Consider the feet on them a basic suggestion, fine in many cases. But if you draw a lot of power a little change there works wonders. My experience with 3e A7 stereo and mono ist that they can easily be made to work in demanding scenarios. Whereas just powering the C6Bs is not that big a pair of speakers. I would consider the A5 for them.

I am really appreciating the replies from everyone. Since I already have the Wiim Ultra, buying the the Wiim Amp Pro or Amp Ultra would probably not be the most efficient solution. (I think the Wiim products are extraordinary at just $300 to $550 and am a big fan.)

Perhaps I am being too hard on the 3e Audio A7. I expect I could manage the heat buildup by simply setting it on taller feet, providing more fresh air to the underside vents.

I do want a robust audio chain (streamer to speaker) underpinned by a highly stable amp with extra power on tap for those reported transients to the C6B in the 200hz region.

I was initially wary of any powerful amplifier with no volume control because I can easily envision an accident involving damaged speakers or injured hearing. (Once my Wiim digital volume control would not stop climbing until it reached max volume. It required a hard restart). I have heard of at least one solution (using a submenu in my Wiim Ultra to limit the maximum pre-amp output volume to wherever I would set it). That's why the $625 Buckeye Hypex is being considered even though it lacks the volume control knob. Buckeye offers an exceptional 3-year warranty. The 3e Audio A7, as far as I can tell, offers only a 30 day warranty.

 

[Ruediger]

I am really appreciating the replies from everyone. Since I already have the Wii Ultra, buying the the Wiim Amp Pro or Ultra would probably not be the most efficient solution. (I think the Wiim products are extraordinary at just $300 to $550 and am a big fan.)

If you already have the Ultra you just need a poweramp. Consider the Vibelink.

I currently use it every day with the C6Bs, but with a subwoofer from 80Hz down. Amp barely gets handwarm.

With the Vibelink you have a volume knob, 3 inputs and an upgraded DAC to the Ultra. If you want you can dial the volume down so you have a range of volume on the Ultra that never gets excessively loud. With other amps you could lower their gain. 3e has 3 options, high and low from RCA and even less when using XLR.

The creeping volume issue is unknown to me. What was that, software problem?

 

[YouDontHaveEnoughBass]

You can get a little usb fan to put under it, they don’t run fast enough to be audible but cool the amp down plenty

 

[Ronald Z]

If you already have the Ultra you just need a poweramp. Consider the Vibelink.

I currently use it every day with the C6Bs, but with a subwoofer from 80Hz down. Amp barely gets handwarm.

With the Vibelink you have a volume knob, 3 inputs and an upgraded DAC to the Ultra. If you want you can dial the volume down so you have a range of volume on the Ultra that never gets excessively loud. With other amps you could lower their gain. 3e has 3 options, high and low from RCA and even less when using XLR.

The creeping volume issue is unknown to me. What was that, software problem?

The creeping Wiim Ultra volume only happened once. I was adjusting the volume down using the Bluetooth based remote. I stopped clicking and the volume kept dropping. I wasn't paying much attention. But when the volume dropped to zero, there was no music. I started to click the remote again to increase the volume. I stopped clicking when the volume was a third of the way up, but the numbers kept climbing on the little Wiim Ultra screen, and soon reached full volume as if I had been holding down the volume up button (which I had not). I have a volume knob on my Fosi Za3 and immediately turned it down but my active subwoofer (also connected to the Wiim) was pounding the walls by then.

I believe what happened was an instruction-execution glitch (not a technical term, but something like that) or errant Bluetooth signal that set it off. The main reason it was concerning is that I am always careful to protect my speakers (and ears) from unmitigated high volumes.

For some reason, I overlooked the Vibelink and, given that I like the Wiim Ultra (and that you are successfully using it with C6B speakers), it looks like a reasonable solution. I offload my bass below 80hz as well to the subwoofer, so its amplification power looks more than adequate. As a bonus, the Vibelink is in my price range too!

 

[Mark609]

The A

The speakers are reported, by one reviewer, I can't recall where I saw it, as having an occasional "brutal" instantaneous impedance drop to just under 2Ω during a sharp transient in the 200hz range. I'm guessing that is not as scary as it sounds -- my $150 Fosi ZA3 handles them just fine. The Fosi does not have a PFFB circuit so I wanted to upgrade. The C6B are premium speakers (at least for me they are!) and I want a rock-solid amplifier that will power them cleanly.

Are you in the US? If so, write Dylan at Buckeye with your concerns. Being his amps ease thru 2 ohm loads I doubt if it would be a problem. Write owner Dylan at Buckeye. He's very responsive and thorough.

My "8 ohm" ELX (plugged) towers dip to about 3.2 ohms.. It's just what speakers do.