Knowing what an Amplifier's current is?

[Witterings]

I often see posts in forums saying Amps with high current will drive speakers better at low volume but how do you know what amps have a high current as it's not something that's generally listed and what would a low current vs a high current be?

I currently have an Arcam SA30 with ProAc D20R speakers, a lot of my listening is at low volume when everyone else is asleep or sitting chatting over a drink with the Mrs and playing background music quietly.
I think it's widely accepted it doesn't get the best out of a system so am looking at what might mitigate as much as possible without using EQ to emulate a loudness button.

Specific things I notice are: If listening the radio quietly, male DJ's voices can be hard to distinguish what they're saying and poorer recordings become very muffled on the low end and "too rich" to listen to.

I have a small Denon M39 with Elac B5.2 bookshelf speakers in my kitchen and whilst it's also affected, overall it doesn't seem to "lose" quite so much at lower volumes.

Amps I'm considering looking at as alternatives are:
Atoll IN300
Marantz Model 30
Exposure 3510
Rega Aethos
Hegel H190

Interested to see what people's opinions are and if any of those would make a noticeable difference to the SA30 ... mainly at lower volume as that'd be my main target to improve if I were to actually change.

 

[Gza]

I'm in the similar situation as you, live in a terraced house so mainly listen at lower volumes. My speakers are proac d2 and I auditioned several amps and settled on a sugden a21se. It sounded the best with my speakers at lowish volumes. So another amp to consider if you can get an audition. The only other one I listened to on your list was the rega which i thought was good as well.

 

[Witterings]

I'm in the similar situation as you, live in a terraced house so mainly listen at lower volumes. My speakers are proac d2 and I auditioned several amps and settled on a sugden a21se. It sounded the best with my speakers at lowish volumes. So another amp to consider if you can get an audition. The only other one I listened to on your list was the rega which i thought was good as well.

I've so often heard the synergy between the Sugden and ProAc is meant to be amazing, my biggest concern is the total power as it's quite a large open plan area and whilst I didn't mention it I have a HT setup and all the amps I listed have that option but don't belive the Sugden does.

Would love to hear them with a Sugden though!

 

[chris geary]

one good way to see if an amp has high current, if it is not in the specs, is to see if the amp power is rated into 8 ohms/4ohms/2ohms. A higher current amp will put out X watts into 8 ohms, and double that into 4 ohms.

 

[RICHARD1111]

I've so often heard the synergy between the Sugden and ProAc is meant to be amazing, my biggest concern is the total power as it's quite a large open plan area and whilst I didn't mention it I have a HT setup and all the amps I listed have that option but don't belive the Sugden does.

Would love to hear them with a Sugden though!

I had some D20R speakers and was using a Musical Fidelity M8 Pre and Power amps (500w!). I found Inwas only listening to music for the sake of it and didn't really enjoy it so decided to sell the M8 amps and bought and old Sugden A21a. The first day I listened I just thought "this sounds OK, at least I've free up loads of cash" the second day I started to get a warm feeling inside my chest when listening ing to music. I would then stay up for hours and hours listening to music every night. My biggest recommendation to anyone regarding HIFI is to try a Sugden a21. Not only is the music wonderful, but a certain smugness from having a (relatively) cheap amp that sounds so amazing. It's only due to going "down the valve rabbit hole" that I sold it....but now my amp is 5 times the cost of an A21!

The A21 should have been my last forever amp!

After the A21, I bought an IA4 (surely if the A21 is great, this will be amazing) but I genuinely preferred the a21.

 

[irb]

I don't know where you've seen it said that amps with high current will help at low volumes. Honestly, that's incorrect. It's when you turn the volume up that an amplifier has to supply more current! The speaker's impedance determines how much current is required.
From what i can tell, I don't think that the Proacs are a particularly tough load, requiring very beefy amps with lots of current capability. And the Sugden A21 is not a high current amp.
So my advice would be not to worry about current. Maybe a Sugden amp would sound better. (They are lovely.) But at low volumes you're fighting against the human ear's equal loudness contours. (Often referred to in the past as the Fletcher Munson curves.) The overall system frequency response is the most important thing, and a different amp won't make much, if any, difference. Proacs in general are known for having quite a warm sound I think? If things sound too muffled and rich, is it possible you need leaner or brighter sounding speakers?

 

[Martin 52]

I have the model 30 marantz drives my b&w with ease . States 100 wpc but double at 4ohms . I often listen early on a morning and is perfectly fine . Also they can be picked up for a reasonable price. Definitely worth a listen

 

[Amormusic]

I've so often heard the synergy between the Sugden and ProAc is meant to be amazing, my biggest concern is the total power as it's quite a large open plan area and whilst I didn't mention it I have a HT setup and all the amps I listed have that option but don't belive the Sugden does.

Would love to hear them with a Sugden though!

I too have had a Sugden A21a Signature.

They are fantastic amps and unless you want to shake the walls are plenty loud enough. You really don't need many Watts.

They are fantastic at all volumes, including low, so fit your bill.

Additionally, the marriage between Sugden and ProAc is amazing.

You should definitely add one to your "must listen" list as they are superb amps.

 

[Pressure23]

One of the best hifi experiences I’ve ever had was at Sevenoaks in Bristol listening to ATC SCM40s driven by a very expensive 20 watt valve amp. It was sublime. The salesman reported that the ATC rep had said that while ATCs need lots of power, the watts weren’t as important as the current delivery for peaks. Intuitively this makes sense, and I think there’s a really important insight here.

But I got an E in physics and I have no real idea what I’m talking about. I’d love it if someone with more technical knowledge could explain whether current really is more important than wattage.

 

[irb]

Well, as usual in life, there's no simple answer.

Looking at the physics first, the power/current required depends on the sensitivity of the speakers (i.e. the sound pressure level you get out for a given voltage input), and on the impedance of the speakers (impedance is like resistance for AC signals, so if you have low impedance, then for a given voltage level, you'll draw more current.)

But the specifications you get from manufacturers are only a tiny snapshot of what's going on, because SPL varies with frequency, as does impedance. And with impedance you also have to consider phase angle. Sensitivity is usually quoted at 2.83 volts, measuring at 1m. The ATC SCM40 speakers are quoted as putting out 85dB, which is a bit below average. The impedance is quoted as 8 ohms nominal, but that might hide a multitude of sins. (There is an IEC spec for this, which says that minimum impedance should be no less than 80% of nominal, which is 6.4 ohms for an 8 ohm nominal speaker. But most manufacturers ignore this, nowadays.)

I mentioned phase angle, above. Without going into this in detail, real world speakers draw more current than you'd expect, because of the phase angle of the impedance. Anyway, ATC recommend 75 watts RMS as a minimum for the SCM40. That ought to get you about 104dB, which is a sensible figure to aim at for peaks, bearing in mind that you will be listening from further away than 1m.

There are other factors to think about, though. A smaller room and/or shorter listening distance will mean that less power will be fine. Preferred listening levels make a huge difference, as does preferred style of music.

And then there's the subjective side of it. Amp/speaker matching is unpredictable, in practice. Sometimes an amplifier that shouldn't work does, and vice versa. Yes, the amplifier's ability to deliver current is part of the picture, but specifications are no guarantee. Sometimes a big amp that's supposed to have plenty of current available doesn't bring a particular speaker alive, while a smaller amp that shouldn't work on paper does.