Power Amp specs and recommendations

Salonchi

Active Member
I am considering separating out my home cinema from stereo music setup, which would leave me needing a stereo power amp. I’ve always been a bit of a bigger is better thinker, but it has been dawning on me, after many years, that there might be some science in play!

The stereo components I have in place are Lumin T2 streaming Dac, and Amphion 3LS speakers. Current sharing an Anthem 525 Gen 2 (225W per channel) power amp with the home cinema setup. I use tidal and qobuz through roon for almost all of my music listening.

Lumin recommend is using the balanced XLR out, which provides 6Vrms. (RCA is available at 2Vrms)

The Amphion 3LS spec sheet on the web states, 50-150w recommended and the sticker on the speaker itself states 200W max. The speakers have a reasonably low sensitivity at 85db.

I generally listen at 75db max and often closer to 70db. If I started looking at some online calculators, it seems that a 50watt amplifier would would blast my head off with >93db.

So, it’s got me thinking that I shouldn’t be looking at 200w amps because they would hardly need to come out of standby mode, but I’ve always had in my head that watts equals quality, not volume necessarily, and headroom is good.

I am also pretty sure that I don’t want integrated. I like the ease of using roon with the leedh volume control. Though I did briefly consider the Lyngdorf for room perfect, but that definitely seem to defeat the of having such an expensive DAC.

I’m interested in people’s thoughts and to be educated on buying power amps. Usually I try to narrow my options based on specs and second values and then let my ears make the decision, but it feels that I am limiting my options if I start with a premise of >175watts. At the same time, I don’t want to get an amp that doesn’t make the most of the entry and exit points of the system.
 

Ugg10

Distinguished Member
Jut a small comment - if you listen at 75dB average (i.e. on an SPL meter using A weighing) then you need an amp that will provide swings of 20dB more so specing the amp for 95dB is where I would be at as a minimum. Remembering every 3dB double the power requirement, so your 93dB at 50w need 100W to get to 96dB. Irrespective of the power of the amp, volume is always in the control of the user.

Depending on your budget and listening styles, for a power amp that is pretty much invisible i.e. what goes in comes out the other end only louder, you can't go wrong with the new generation of Class D amps. These start wit the ICEPower derived XTZ A2-300 and then onto the Nord acoustics Hypex MP series (stereo integrated boards), NC500 and Purifi amps, that is typically the gerenal view on soud quality - Icepower - Hypex - Purfi. The nord amps typically come in mono block, dual mono or stereo and on some with a choice of op amp buffers to marginally tailor the sound. Given you have a £3k streamer/dac and £3k speakers the Nord Purifi SE mkII dual Mono would be my choice at £2k or the mono blocs with the same insides for a little more.


For Class AB amps the yard stick is a doubling of power between 8ohm and 4ohm load and a damping factor of over 150. if you can check the service manuals a beefy transformer rated at 4 or 5 times the power output and lots of capacitance (10k uF per channel +) is always a good thing. Rotel and Nad usually fair well in these stakes as do Bryston.

For pure Class A (e.g. Pass Labs) then the requirement for a good power supply increases even more as the efficiency of theseamps are around the 20% mark, the rest turn in into heat.

Just few thought but of you have a budget then that would help narrow things down.
 

Salonchi

Active Member
Jut a small comment - if you listen at 75dB average (i.e. on an SPL meter using A weighing) then you need an amp that will provide swings of 20dB more so specing the amp for 95dB is where I would be at as a minimum. Remembering every 3dB double the power requirement, so your 93dB at 50w need 100W to get to 96dB. Irrespective of the power of the amp, volume is always in the control of the user.

Depending on your budget and listening styles, for a power amp that is pretty much invisible i.e. what goes in comes out the other end only louder, you can't go wrong with the new generation of Class D amps. These start wit the ICEPower derived XTZ A2-300 and then onto the Nord acoustics Hypex MP series (stereo integrated boards), NC500 and Purifi amps, that is typically the gerenal view on soud quality - Icepower - Hypex - Purfi. The nord amps typically come in mono block, dual mono or stereo and on some with a choice of op amp buffers to marginally tailor the sound. Given you have a £3k streamer/dac and £3k speakers the Nord Purifi SE mkII dual Mono would be my choice at £2k or the mono blocs with the same insides for a little more.


For Class AB amps the yard stick is a doubling of power between 8ohm and 4ohm load and a damping factor of over 150. if you can check the service manuals a beefy transformer rated at 4 or 5 times the power output and lots of capacitance (10k uF per channel +) is always a good thing. Rotel and Nad usually fair well in these stakes as do Bryston.

For pure Class A (e.g. Pass Labs) then the requirement for a good power supply increases even more as the efficiency of theseamps are around the 20% mark, the rest turn in into heat.

Just few thought but of you have a budget then that would help narrow things down.
Thanks for the information in your ‘small comment’ The specs of the Nord Purifi look great, I’ve just not heard one before, but of the specs are to be believed then they are adding gain and nothing else, so doing their job very well.

I was thinking around a £2k budget, so the exact model Nord Purifi you mentioned with sonic imagery and upgraded binding posts hits right on the money. I’m not opposed to open boxed or even used though. Only concern with Nord is the used market if I keep tinkering and want to trade-in in the future. Parasound, Nad, Cyrus, Hegel etc all seem to have good resale value.

Once again, thanks for the insight. Really useful
 

3rdignis

Active Member
I set volume as high as I would listen, then measure in c weighting because you want to measure what the amp is being asked to produce not what you are hearing, as stated add 20db for peaks, (30 for the nth degree 15 min.)

This calculator airs on the side of caution

If a speaker has min ohms of 4 I would take amps 4 ohm rating and halve it because speaker are calculated with a double down amp. Speaker with 2 ohm min I would 1/4 the 2 ohm rating.

For your consideration class a/b amps may deliver 5% power fully class a.
 

gava

Active Member
Thanks for the information in your ‘small comment’ The specs of the Nord Purifi look great, I’ve just not heard one before, but of the specs are to be believed then they are adding gain and nothing else, so doing their job very well.

I was thinking around a £2k budget, so the exact model Nord Purifi you mentioned with sonic imagery and upgraded binding posts hits right on the money. I’m not opposed to open boxed or even used though. Only concern with Nord is the used market if I keep tinkering and want to trade-in in the future. Parasound, Nad, Cyrus, Hegel etc all seem to have good resale value.

Once again, thanks for the insight. Really useful
I don't know if you have seen this review on the Nord Purifi ?


Nord is a small company and I'd not heard of them until I read the ASR reviews.

If you want a better known manufacturer I think the only large company currently using the Purifi is NAD. The C298 (below 2k) also has Purifi inside and is a superb bargain - I don't think it's a dual-mono design, for that you will need the M28 which is a lot more expensive and doesn't measure as well as the Nord.

 

Salonchi

Active Member
I set volume as high as I would listen, then measure in c weighting because you want to measure what the amp is being asked to produce not what you are hearing, as stated add 20db for peaks, (30 for the nth degree 15 min.)

This calculator airs on the side of caution

If a speaker has min ohms of 4 I would take amps 4 ohm rating and halve it because speaker are calculated with a double down amp. Speaker with 2 ohm min I would 1/4 the 2 ohm rating.

For your consideration class a/b amps may deliver 5% power fully class a.
Thanks for this. The calculators are useful on that site
 

Salonchi

Active Member
I don't know if you have seen this review on the Nord Purifi ?


Nord is a small company and I'd not heard of them until I read the ASR reviews.

If you want a better known manufacturer I think the only large company currently using the Purifi is NAD. The C298 (below 2k) also has Purifi inside and is a superb bargain - I don't think it's a dual-mono design, for that you will need the M28 which is a lot more expensive and doesn't measure as well as the Nord.

I had seen the review on ASR. I don't often use the site other than to point me in the right direction sometimes. It feels like we can measure all sorts of metrics, but we aren't able to measure how something sounds, which is ultimately what we want to know.

I typed nad power amp in the browser and unfortunately, the C268 came up first at around £700. I thought, a bargain I'll get to and use mono, but then realised the wrong model number. Seems like it will be the NAD or Nord, I'll do my research whilst I wait to sell a few items to fund the purchase.
 

Mtache1212

Novice Member
Go for quality of parts and not rated wattage. A 200 Watt cheap receiver will have trouble driving a low sensitivity speaker that a high-end 70 Watt amp can do with a breeze. Get a toroidal transformer(s), big heat sinks, and Large caps. The heavier it is, is a good indication of quality.
 

larkone

Distinguished Member
Get a toroidal transformer(s), big heat sinks, and Large caps. The heavier it is, is a good indication of quality.
None of that is true for Class D based amps
 

butcherpete

Member
I have the same speakers, was in the same dilemma last year. All my listening was done with a new Anthem MRX 520, then decide to separate my A/V and PC steamed music, so I auditioned a Class D power amp by PS Audio (S 300), and never looked back S300 Amplifier – PS Audio
 

Salonchi

Active Member
I have the same speakers, was in the same dilemma last year. All my listening was done with a new Anthem MRX 520, then decide to separate my A/V and PC steamed music, so I auditioned a Class D power amp by PS Audio (S 300), and never looked back S300 Amplifier – PS Audio
Nice to meet a fellow Amphion owner.

I appreciate the specs of the Nord, but am still undecided about whether they’ll sound as good as the looks on paper. I’m swinging between these at the moment:

NAD C928
PS Audio S300 or Used M700 x 2
Used Hegel H20

Just waiting to see if I can shift some more hear. Trying to make this a no new cash leaving my wallet upgrade.

The Amphion speakers were a revelation. They really made me want to listen to a lot more music, and the Lumin does an amazing job too.
 

butcherpete

Member
Nice to meet a fellow Amphion owner.

I appreciate the specs of the Nord, but am still undecided about whether they’ll sound as good as the looks on paper. I’m swinging between these at the moment:

NAD C928
PS Audio S300 or Used M700 x 2
Used Hegel H20

Just waiting to see if I can shift some more hear. Trying to make this a no new cash leaving my wallet upgrade.

The Amphion speakers were a revelation. They really made me want to listen to a lot more music, and the Lumin does an amazing job too.
The Hegel are well known for matching Amphion speakers, as they often share a room at Hi Fi shows. I will be getting a pair of PS M700's to soon, I would have had them now, if I had not replaced my sub, from a BK to a Rel
 

Ugg10

Distinguished Member
PS Audio use Icepower amp boards, the S300 using the ICEpower 300AS1. The objective tests on these put them some way behind the NC500 and Purifi boards but whether this difference is audible and how well any buffers work is more subjective.
 

The latest video from AVForums

Oculus Quest 2 VR headset + Rotel A14 MkII Amp Reviews & Best of the Month
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom