Jump to content

Noob question - High current amplifiers


Recommended Posts

Hoping the brains trust can impart some knowledge...

 

I keep hearing about certain amps being better for high current applications or hard to drive speakers. 
 

How can I tell from amp specs that it is capable of high current applications?

 

On the flip side, how do I tell if my amp will drive low impedance speakers ok?

 

For reference I have a Vincent SV-227. 
specs below. 
 

Im considering some Monitor Audio Gold100’s which I know drop to quite low impedance. 
 

obviously I would trial prior to purchasing any speakers, but interested in thoughts on this. Happy to read any links if you have them. 
ta!
 

Technical Specifications

  • Frequency Response: 20 Hz – 20 kHz +/-0,5 dB; 20 Hz – 50 kHz +/-2 dB
  • Nominal Output Power RMS/8 Ohm: 2 x 100 Watt
  • Nominal Output Power RMS/4 Ohm: 2 x 196 Watt
  • T.H.D.: < 0.1 % (1 kHz, 1 Watt)
  • Input Sensitivity: 280 mV
  • Signal-Noise-Ratio: > 90 dB
  • Input Impedance: 47 kOhm
  • Max. Power Consumption: 320 Watt
  • Inputs: 4 x Stereo RCA, 1 x Optical, 1 x Coax
  • Outputs: 1 x Stereo RCA Rec Out, 1 x Stereo RCA Pre Out, 2 x Power Control, 4 x 2 Speaker Terminals
  • Playable Digital Formats: WAV, FLAC, APE, LPCM, MP3, ACC, AC3, WMA
  • Tubes: 3 x 12AX7
  • Colour: Black or Silver
  • Weight: 20 kg
  • Dimensions (WxHxD): 430x150x435 mm

 

Link to post
Share on other sites
  • Replies 170
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

You're being too modest there, Trev!     Why is the argument above focussing on how loud you can listen ... and not how the (dipping to low impedance) spkrs actually sound when driven by an

No it most definitely isn't.    Our hearing doesn't respond that way.    3dB doubles power and sound pressure level, but only a small increase in loudness.    I'm an acou

Yes!.... which is why it is essential that we consider "required SPL" in terms of "peak SPL" .... ie. already accounting for any possible "dynamics" in the music.   (ie. we can then ignore the dynamic

Better brains than mine will jump in but what you’re looking for in a high current amp is close to a doubling of watts as the impedance halves.
Ideally, though rarely in practice, something like:

100 watts into 8 ohms

200 watts into 4 ohms

400 watts into 2 ohms


The speakers have nominal impedance of 4 ohms and drop to 2.8. 

the amp doubles between 8 and 4 but doesn’t state what the amp outputs at 2 ohms, which I suppose is what you really want to know.


 

 

Edited by buddyev
  • Like 1
Link to post
Share on other sites
30 minutes ago, Kasman said:

 

 

 

Im considering some Monitor Audio Gold100’s which I know drop to quite low impedance. 
 

obviously I would trial prior to purchasing any speakers, but interested in thoughts on this. Happy to read any links if you have them. 
ta!

 

https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=2204:nrc-measurements-monitor-audio-gold-100-loudspeakers&catid=77&Itemid=153

Looks to be about 3ohms in the 4khz region. There is a bit of Electrical phase shift above that. A low impedance at very  low and /or high frequencies might give an amp' bigger issues but a decent amp' should be able to handle this load. 

1 minute ago, buddyev said:

Beat me by 10 seconds...

  • Like 1
Link to post
Share on other sites


I think that it's further complicated by the ability for some amps to deliver high "peak" current for short bursts- usually via banks of capacitors.  I think that the figures quoted above usually refer to constant watts delivered into a impedance of 8 and 4 ohms.  

  • Like 1
Link to post
Share on other sites
2 hours ago, Kasman said:

How can I tell from amp specs that it is capable of high current applications?

 

Most amplifier manufacturers do not really provide enough information for you to know.

 

Part of the reason for this, is that it's a very complex question.

 

 

Your speaker is nasty at ~4khz (low ohms, with a large negative phase angle) which will draw significant amounts of current (completely dependant on how loud you play).

 

 

So there are two questions.

 

Will the amp "fail" at such a load, most won't, some will  (eg. shutdown, or protection mode, etc)..... and when the amplifier clips, what is its performance like  (this is very varied).

 

The simplistic answer is you need an amplifier which can operate safely with 2ohm, and if you want to play loud, significant amounts of power.  (eg. >>> 100w)

Link to post
Share on other sites

denon-pma-2500ne-hifi-news-2016.pdf (novial.sk)

 

This test swayed me to the 2500 as, 1. Always admired the premium gear, 2. Engineered and Made in Japan. 3. Build quality, and 4. Sounds terrific paired with my Legend speakers(which dip into 4ohm or lower) and that HIFi News are a credible magazine to obtain info.

Had considered Musical Fidelity M6si and Rega Elicit R. 

Others know more than me on this forum, however i took into account its "dynamic" power at low impedance, instead of dropping off, it increases. Also its maximum current is reasonably impressive.

Granted it wont likely go as loud as a Musical Fidelity, Rotel Michi, Parasound, to name a few, or separates.

For me, depending on the production of a recording, i rarely go past 10 o'clock on the volume when i want to crank it up. Also having recently acquired new speaker cable (Purist Audio Design Musaeus), the signal is getting to the speakers far more efficiently than my previous cable.

Others here will give good advice.

my 2c

 

Edited by mattd2308
grammar
  • Like 1
Link to post
Share on other sites
3 hours ago, Kasman said:

 

I keep hearing about certain amps being better for high current applications or hard to drive speakers. 
 

How can I tell from amp specs that it is capable of high current applications?

 

On the flip side, how do I tell if my amp will drive low impedance speakers ok?

 

 

4 minutes ago, davewantsmoore said:

 

The simplistic answer is you need an amplifier which can operate safely with 2ohm, and if you want to play loud, significant amounts of power.  (eg. >>> 100w)

 

 

^  ^  ^ what the man said ... so your Vincent SV-227 may not do them justice.  :(

 

Unless:

a. you ears are only a couple of metres from your spkrs, or

b. you don't listen very loudly.

 

Andy

 

Link to post
Share on other sites


 

Monitor audio claim these as being 86dB, the measurements show them almost 3dB less efficient.

 

3dB Doesn't sound like a lot but it actually requires double the power

Link to post
Share on other sites
1 minute ago, sir sanders zingmore said:

 

Monitor audio claim these as being 86dB, the measurements show them almost 3dB less efficient.

 

3dB Doesn't sound like a lot but it actually requires double the power

Indeed.

It is a really big and widespread problem with almost all speaker manufacturers significantly over stating the sensitivity of their speakers when compared to actual and properly conducted measurements.

  • Like 1
Link to post
Share on other sites
15 minutes ago, sir sanders zingmore said:

 

Monitor audio claim these as being 86dB, the measurements show them almost 3dB less efficient.

 

3dB Doesn't sound like a lot but it actually requires double the power

 

Although in the scheme of things you need around 10 times the power to get twice as loud. 

 

So being 3dB quieter may not be as bigger issue, about a 20% difference. 

Link to post
Share on other sites


18 minutes ago, sir sanders zingmore said:

Monitor audio claim these as being 86dB, the measurements show them almost 3dB less efficient.

 

Why isn't that fraud and prosecutable under consumer protection laws as misleading advertising?

  • Like 1
Link to post
Share on other sites
On 10/03/2021 at 5:16 PM, DrSK said:

 

Although in the scheme of things you need around 10 times the power to get twice as loud. 

 

So being 3dB quieter may not be as bigger issue, about a 20% difference. 

3 dB sound increase or decrease is twice as loud or half as loud.

10 dB electrical increase or decrease is twice as loud or half as loud.

 

Please note, this is incorrect, I confused the issue and I apologise.

Edited by pwstereo
I was wrong
  • Like 1
Link to post
Share on other sites
25 minutes ago, DrSK said:

 

Although in the scheme of things you need around 10 times the power to get twice as loud. 

 

So being 3dB quieter may not be as bigger issue, about a 20% difference. 

 

I get what you're saying but I think it still matters.

As an example of why I think this

 

Let's say you usually listen at 86db but sometimes crank it up to twice as loud (~96db)

Let's say you require 50w of power to 86db (due to listening room/distance from speakers etc) 

You'll need 500w to get to 96db (ten times the power as you say)

 

But now you plug in your monitor audio speakers that claim to be 86db but are only 83db

Suddenly you need 100w of power to get your 86dB and 1kw when you want to crank it up

 

So that 3dB misstatement actually means that to get "like for like" volume, you need double the power at all listening levels

 

EDIT: Just saw @pwstereo's reply, so maybe I'm talking out of my hat as usual (although I thibnk I end up at the same spot which is the 3dB difference means you need double the power)

Edited by sir sanders zingmore
Link to post
Share on other sites

Thanks for all your comments. Yes most of what your all saying is what I suspected. 

1 hour ago, davewantsmoore said:

Most amplifier manufacturers do not really provide enough information for you to know.

I suspect this is why I was a little confused. 

 

22 minutes ago, Hifiplus said:

Choose other speakers.

Yes it’s feeling a little this way, hence why I posed the initial question I suppose. 
I don’t however want to end up with a combo that’ll struggle if I want to turn things up a little. 

Link to post
Share on other sites


6 minutes ago, Kasman said:

Thanks for all your comments. Yes most of what your all saying is what I suspected. 

I suspect this is why I was a little confused. 

 

Yes it’s feeling a little this way, hence why I posed the initial question I suppose. 
I don’t however want to end up with a combo that’ll struggle if I want to turn things up a little. 

 

It's a balance. I've always felt you should first choose the speakers you love and then choose an amp to drive them.

Of course, if your speaker choice puts suitable amps out of your price range then you need to rethink

  • Like 1
Link to post
Share on other sites
4 minutes ago, sir sanders zingmore said:

 

I get what you're saying but I think it still matters.

As an example of why I think this

 

Let's say you usually listen at 86db but sometimes crank it up to twice as loud (~96db)

Let's say you require 50w of power to 86db (due to listening room/distance from speakers etc) 

You'll need 500w to get to 96db (ten times the power as you say)

 

But now you plug in your monitor audio speakers that claim to be 86db but are only 83db

Suddenly you need 100w of power to get your 86dB and 1kw when you want to crank it up

 

So that 3dB misstatement actually means that to get "like for like" volume, you need double the power at all listening levels

Yep, you'd get 93dB instead of 96dB out of 500W.

 

The difference is always around 20% and 3dB.  Whether that makes a significant difference, guess it depends. 

 

Although I'm fairly certain the rating is at 1W at 1m. So 100W goes a long way if its RMS. 

 

I normally keep an eye on peak power and current and how quickly it can deliver it. Not all 100W RMS amps are equal. 

Link to post
Share on other sites

Turn things up a bit?  How loud do you need to go to get that 'loudness' hit?

If you believe that oodles of power on tap is what you want then you'll be worshipping at the alter of Roger Sanders and his Magtech amps.

Plenty of fanboi's here have them and swear by them. They have difficult systems (apparently) that need to have instant grunt when a track requires it and their speaker selection requires it.  Not many amps can do what the Magtech's do when they are called upon to use all their grunt to keep a hold of a speaker dropping down into 4 ohm purgatory or worse 2 ohm hell.

 

How deeps your wallet btw?

Link to post
Share on other sites
16 minutes ago, pwstereo said:

3 dB sound increase or decrease is twice as loud or half as loud.

10 dB electrical increase or decrease is twice as loud or half as loud.

 

No it most definitely isn't. 

 

Our hearing doesn't respond that way. 

 

3dB doubles power and sound pressure level, but only a small increase in loudness. 

 

I'm an acoustic engineer with 20 years experience, which includes research and development of algorithms in hearing perception. 

 

10dBA for doubling is a rule of thumb that holds reasonably well. Actual doubling of loudness really requires Phon instead of SPL. 

Edited by DrSK
  • Like 3
Link to post
Share on other sites
2 minutes ago, DrSK said:

 

No it most definitely isn't. 

 

Our hearing doesn't respond that way. 

 

3dB doubles power and sound pressure level, but only a small increase in loudness.

That's my misunderstanding then, I think I'd equated a doubling of SPL with a doubling of loudness. Sorry for the goof.

Link to post
Share on other sites
19 minutes ago, sir sanders zingmore said:

EDIT: Just saw @pwstereo's reply, so maybe I'm talking out of my hat as usual (although I thibnk I end up at the same spot which is the 3dB difference means you need double the power)

And I may have confused a doubling of SPL with a doubling of loudness apparently ?

Link to post
Share on other sites
Just now, pwstereo said:

That's my misunderstanding then, I think I'd equated a doubling of SPL with a doubling of loudness. Sorry for the goof.

 

All good, doubling of SPL is usually just 3dB as with doubling of power. Not loudness. 

 

It gets a bit more fun if you have coherent addition of SPL, interaction between waves of similar frequency say. You might then get 6dB.

Link to post
Share on other sites
1 minute ago, pwstereo said:

And I may have confused a doubling of SPL with a doubling of loudness apparently ?

Sorry, my response was a bit abrupt! 

 

Just gave up on working for the day after a 4am start to catch up on reports and analysis, a bit grumpy.

Link to post
Share on other sites
6 minutes ago, DrSK said:

Sorry, my response was a bit abrupt! 

 

Just gave up on working for the day after a 4am start to catch up on reports and analysis, a bit grumpy.

Not at all, you were just correcting a factual error. I'm sure we're all grateful to have it quickly corrected and from a credible source.

  • Like 1
Link to post
Share on other sites
55 minutes ago, allthumbs said:

 

Why isn't that fraud and prosecutable under consumer protection laws as misleading advertising?

Because almost every company does it and there is the difficulty in knowing (or discovering ) their methods of measurement, notwithstanding the fact that our consumer laws really lack the teeth to pursue it since this isn't an area where a majority of the population dwell.

 

97% of people couldn't give a schit about claimed specifications for audiophile speakers.

Link to post
Share on other sites
2 hours ago, sir sanders zingmore said:

Monitor audio claim these as being 86dB, the measurements show them almost 3dB less efficient.

 

In this case the measurements are dB/2.83V ... and monitor audio state their specs in dB/w.    For a 4ohm speaker this gives 3dB difference.

 

Are they taking advantage of "people who don't know the difference" by using watts?..... to get a bigger number.    We could debate that all day.   I don't think so, but the IEC says they should use 2.83V .... but I've never been an establishment type of guy (and think it's kinda quirky).

 

Quote

almost every company does it

 

I think you've just overstated a tiny bit here.  LOL.

Edited by davewantsmoore
Link to post
Share on other sites

 

 

 

 

1 hour ago, sir sanders zingmore said:

It's a balance. I've always felt you should first choose the speakers you love and then choose an amp to drive them.

10,000%

Link to post
Share on other sites
2 hours ago, allthumbs said:

Why isn't that fraud and prosecutable under consumer protection laws as misleading advertising?

 

It could / would be ..... but they didn't claim what he said (he just didn't read it right)  ?

Link to post
Share on other sites
2 hours ago, allthumbs said:

 

Why isn't that fraud and prosecutable under consumer protection laws as misleading advertising?

Something something cable claims

  • Like 1
  • Haha 2
Link to post
Share on other sites

Let's settle down guys.

Monitor Audio state 86db 1w/1m.  Soundstage Network quotes 2.83V/1m. That gives different results especially in lower impedance speakers. It's not false advertising. 

 

 

19 minutes ago, Ittaku said:

Something something cable claims

Can't resist any opportunity to have a dig about cables. Obviously.

  • Like 2
Link to post
Share on other sites
41 minutes ago, deepthought said:

Let's settle down guys.

Monitor Audio state 86db 1w/1m.  Soundstage Network quotes 2.83V/1m. That gives different results especially in lower impedance speakers. It's not false advertising. 

 

 

 

 

Yep, @davewantsmoore pointed that out. So most of what I wrote can as usual, be safely ignored ?

  • Haha 1
Link to post
Share on other sites
7 minutes ago, sir sanders zingmore said:

 

Yep, @davewantsmoore pointed that out. So most of what I wrote can as usual, be safely ignored ?

Just like your Podcast then!

Edited by deepthought
  • Like 1
  • Haha 1
Link to post
Share on other sites
1 hour ago, deepthought said:

Just like your Podcast then!

 

58 minutes ago, sir sanders zingmore said:

spot on :)

 

You're being too modest there, Trev!  :thumb:

 

Why is the argument above focussing on how loud you can listen ... and not how the (dipping to low impedance) spkrs actually sound when driven by an amp which is built to handle low impedance loads - which often, yes (but not always), means more powerful?

 

A few of us listened to Russ's B&Ws the other day - driven by his recently-acquired Magtech amp (500w into 8 ohms, 900w into 4 ohms ... and stable into 2 ohms).  We didn't listen any louder than we did the previous time - when he had them powered by his 250w Elektra HD.  But - with the Magtech - they sounded much better.  Then we listened to them with a software tweak (on Russ's Mac) which Con implemented - which rolled off the B&Ws to complement the entry of his subs - which, because the spkrs and the amp had less 'heavy lifting' to do ... improved them even more!  :thumb:

 

Andy

 

  • Like 3
Link to post
Share on other sites

  Note to one's self.

 

Sarcasm should always be appended with emoticon preferably with winking or sunglasses or both.

 

Industry standards for audiophiles pfft! ??

Link to post
Share on other sites
9 hours ago, andyr said:

 

 

You're being too modest there, Trev!  :thumb:

 

Why is the argument above focussing on how loud you can listen ... and not how the (dipping to low impedance) spkrs actually sound when driven by an amp which is built to handle low impedance loads - which often, yes (but not always), means more powerful?

 

A few of us listened to Russ's B&Ws the other day - driven by his recently-acquired Magtech amp (500w into 8 ohms, 900w into 4 ohms ... and stable into 2 ohms).  We didn't listen any louder than we did the previous time - when he had them powered by his 250w Elektra HD.  But - with the Magtech - they sounded much better.  Then we listened to them with a software tweak (on Russ's Mac) which Con implemented - which rolled off the B&Ws to complement the entry of his subs - which, because the spkrs and the amp had less 'heavy lifting' to do ... improved them even more!  :thumb:

 

Andy

 

It's the same here. My study system sounds much better powered with Russ's former Elektra HD than with the previous Quad 505. I don't play any louder (my study is not that big a room) but there is more dynamics, especially in the bottom end as the Elektra has far more headroom than the Quad.

Link to post
Share on other sites
20 hours ago, Kasman said:

Hoping the brains trust can impart some knowledge...

 

I keep hearing about certain amps being better for high current applications or hard to drive speakers. 
 

How can I tell from amp specs that it is capable of high current applications?

 

On the flip side, how do I tell if my amp will drive low impedance speakers ok?

 

For reference I have a Vincent SV-227. 
specs below. 
 

Im considering some Monitor Audio Gold100’s which I know drop to quite low impedance. 
 

obviously I would trial prior to purchasing any speakers, but interested in thoughts on this. Happy to read any links if you have them. 
ta!
 

Technical Specifications

  • Frequency Response: 20 Hz – 20 kHz +/-0,5 dB; 20 Hz – 50 kHz +/-2 dB
  • Nominal Output Power RMS/8 Ohm: 2 x 100 Watt
  • Nominal Output Power RMS/4 Ohm: 2 x 196 Watt
  • T.H.D.: < 0.1 % (1 kHz, 1 Watt)
  • Input Sensitivity: 280 mV
  • Signal-Noise-Ratio: > 90 dB
  • Input Impedance: 47 kOhm
  • Max. Power Consumption: 320 Watt
  • Inputs: 4 x Stereo RCA, 1 x Optical, 1 x Coax
  • Outputs: 1 x Stereo RCA Rec Out, 1 x Stereo RCA Pre Out, 2 x Power Control, 4 x 2 Speaker Terminals
  • Playable Digital Formats: WAV, FLAC, APE, LPCM, MP3, ACC, AC3, WMA
  • Tubes: 3 x 12AX7
  • Colour: Black or Silver
  • Weight: 20 kg
  • Dimensions (WxHxD): 430x150x435 mm

 

The specifications reveal your Vincent amp has correctly,  its input sensitivity almost identical to consumer line level ( nominally 310mv RMS ).  Internally this cleverly optimizes volume attenuation circuitry,  to preserve the real ability of your source components, which have similar line level output.  

 

 

Link to post
Share on other sites
8 minutes ago, stereo coffee said:

The specifications reveal your Vincent amp has correctly,  its input sensitivity almost identical to consumer line level ( nominally 310mv RMS ).  Internally this cleverly optimizes volume attenuation circuitry,  to preserve the real ability of your source components, which have similar line level output.  

 

 

 

all well and good but kind of irrelevant in the bigger picture here (that being that the amp is probably not a great match for the speakers)

  • Like 1
Link to post
Share on other sites
4 minutes ago, stereo coffee said:

The specifications reveal your Vincent amp has correctly,  its input sensitivity almost identical to consumer line level ( nominally 310mv RMS ).  Internally this cleverly optimizes volume attenuation circuitry,  to preserve the real ability of your source components, which have similar line level output.

Yes I googled that one and found a pretty good explanation of that. 
What’s your take on the THD? I looked at MF 5si as an example and they use a THD value of 0.01% which is 10x lower. I assume this is a case of manufacturers straying from an industry standard to make their product specs seem better. Is that the reason why the Vincent has almost a doubling of power when going from 8 to 4 ohms. I assume if you measured at 0.01%THD you wouldn’t quite see the doubling effect. 
 

Makes it hard to compare apples with apples. 
 

like what andyr said, before purchasing anything I’ll be auditioning and paying attention to how it sounds rather than just relying on how system specs align. 

11 hours ago, andyr said:

Why is the argument above focussing on how loud you can listen ... and not how the (dipping to low impedance) spkrs actually sound when driven by an amp which is built to handle low impedance loads - which often, yes (but not always), means more powerful?

 

Link to post
Share on other sites
  • Recently Browsing   0 members

    No registered users viewing this page.




×
×
  • Create New...