Parasound A21 vs Sanders Magtech (or clipping for dummies)

[Darren69]

Happy Easter,

Guys and lurking girls, as you may know, I am thinking of some monos or the Sanders Magtech in the near future, teamed up with a DEQX Pre Mate.

Listening to my A21 the other night however, I did wonder if what I was doing was academic (amp wise, I mean).Maybe I should just put the money into room treatment and then the DEQX, retaining the Parasound?

I understand the theory (Sanders, Musical Fidelity et al)that big 'power' equals no clipping but am I considering something academic? The A21 is no slouch, would I notice the extra grunt at the levels I listen at? Very seldom do I shake the plates in the cupboard as, at the least, one will kill their ear-balls. I do regularly listen at level where you need to raise your voice to speak to someone next to you.

Is this the part where one sighs and tells me to bugger off and listen to some stuff myself?

As always, all constructive comments are appreciated.

[betty boop]

room, treatments and setup (ie speaker position, listening position - this is free costs nothing) first....and then anything else equipment wise(including deqx) will only bring more gains on top of that.

 

things like deqx I wouldnt see as a silver bullet, many in the professional game (and am talking people whom do room treatment etc for a living) will tell you they should be seen as icing or even cherry on top. they'll make the best of a bad situation...but it is much better to just make the bad situation better in the first place pretty sure you said in an another thread bill mcclean who sells the deqx told you pretty much the same things as well ?

 

re things like mono blocs etc, yes will bring some gains...but you'll enjoy them even more with the speakers, room and setup optimised the best you can

[Luc]

Sanders, it's the final port of call for some Darren. Room treatments are nice though, they've crtainly improved my listening exp' and SQ of my low end system.

[Darren69]

Sorry, I am being ambiguous as usual and giving out too much info. Don't you guys know what I am thinking?? haha.

I will be doing the room treatments for sure. Ceiling, walls, floors and some absorption under the dining table.

How would I know I was sending my A21 into clipping? If I am not, then I don't need to budget for a bigger amp.

[Gordon Macfarlane]

The most obvious sign of prolonged clipping is dead tweeters

This from the net : "Clipping will usually affect the HF drivers rather that the woofers. Clipping will sound more like metalic excessive noise on top of the HF passages."

I have Gale 401's which require heaps of quality current amplification , I use a Rotel Michi RHB 10 which according to the specs is capable of 150 amps peak. The A21 does 60 amps peak but the JC1 is 135 amps peak.

See if you can borrow a pair of JC1's for a direct comparo to the A21.

[aechmea]

If you aren't driving your SPL to high levels and your speakers are relatively efficient, then you probably aren't clipping.  You will clip when you switch on 'party mode'.

If your speakers are low impedance, then that could be another consideration.

 

I am an unashamed 'no clipping under any circumstances' type. The Parasound A21 (which I had) is 250wpc and the Magtech (which I have) is 500wpc.  The doubling of wattage adds a little headroom - but not enough to really worry about.  3dB (= double) is nothing really.  

 

The advantage in my opinion of the Magtech is that it performs into low impedance speakers, has a regulated power supply (which is supposed to be good) and has no protection circuitry at all (to get in the way).  It does it all without raising a sweat.  And, most importantly, it sounds better.  The Parasound was good , but the sound was a bit fragile/crystalline to me.

[Darren69]

Ozzy, I might be able to get some second hand JC1's in the coming months for a decent price. I don't know where I could 'borrow' some from.

I might have to load my rig into my car and come to the Hunter Aechmea, haha.

[Zaphod Beeblebrox]

I believe I already directed you to the most significant upgrade you have yet heard. Why not head along that path? I also advised you to address room issues, before anything else. Room treatments can be, far and away, the most cost-effective and easy to implement upgrades possible. Depending on your ambition, the cost of room treatments can be less than a couple of hundred Dollars.

Edited April 20, 2014 by Zaphod Beeblebrox

[sir sanders zingmore]

I'm a great believer in headroom and if you read Roger sanders thoughts on the matter he holds that most 'normal' efficiency speakers need far more power than most people think.

An easy way to check if your amp is clipping is to connect a CRO across your speaker terminals and play music. If there is clipping you'll see the waveform run into a brick wall. It will not last long and you may have to adjust the timescale on the CRO in order to see it. You probably won't even hear it as clipping (ie distortion) but it will correspond to a sense of the amp 'running out of puff', or 'losing coherence'

Or not, ymmv

[Darren69]

Am definitely doing room treatments Zaph, will be spending around $3k methinks. In my OP I should have said 'maybe I should put MORE money into rom treatments instaed of the oomphier amp'.

SSZ, what is a CRO?

Edited April 20, 2014 by Darren69

[sir sanders zingmore]

CRO = cathode ray oscilloscope

[Catostylus]

CRO = cathode ray oscilloscope

 

As an OT aside, do they have LED oscilloscopes these days?

[davewantsmoore]

Happy Easter

 

The generalisation that a bigger amplifier is better is not a good one.

 

A bigger amplifier will only help you if your existing one is not big enough.

 

 

Using an amplifier which is bigger than you need, actually has drawbacks in SQ as it requires sending a smaller input signal (than the smaller amplifier would need) to get the same output power.

 

If you need a 1000w amp... then get one.    If you need a 150w amplifier, then getting a 500w one will not (necessarily) improve SQ.

Edited April 21, 2014 by davewantsmoore

[andyr]

The generalisation that a bigger amplifier is better is not a good one.

 

Very true!   An amp which put out 100s of watts rms, typically need multiple output devices to do this ... and the amp designer has to get these multiple parallel devices working in exact synch, to get it to sound good.  This is a much more difficult task than with a smaller amp - say, a 50w amp - which has only one output device (or a PNP/NPN pair) on each channel.... however, if the amp designer has done it right then a 'big' amp can sound just as good as a 'little' amp.

 

IE. it is the sonic equivalent of the 'little' amp but just delivers many times the power.  As such, it has much more headroom ... and will sound better as it can deliver transients better.

 

 

 

you can calculate the power required, and then double it (to tack on 3dB headroom).

 

Reading some of the late great Allen Wright's white papers, I would suggest you need to add a minimum of 10dB headroom.

 

 

Regards,

 

Andy

[davewantsmoore]

How would I know I was sending my A21 into clipping?

 

• An amplifier of this type will exhibit obvious distortion when clipping.   You should hear it  
• You can take a SPL reading with a meter, and then work backwards to see what watts would produce that.
• You can take an electrical measurement of the output waveform of the amplifier to see that it is not being clipped.

 

You will be in most danger of clipping your amplifier at the impedance peak that your speaker presents between 1-4khz and at 20hz, as your amp is only capable of delivering 100w into this load.

 

This is still quite loud for a 93dB/w/m speaker though.

 

Knowing actually how loud you listen is the key to working anything out on paper.    People throw around all sorts of "I listen at"  80dB or 100dB or 60dB .... but with every 3dB being a doubling of power requirements, you can see we need to be pretty accurate to zone in on the amplifier requirements.

 

 

 

All of this ignores the elephant in the room, which is that amplifier size does not (necessarily) correlate to the quality of the design/manufacturing....   and when it does it is not necessarily in a specifi direction  

[davewantsmoore]

As such, it has much more headroom ... and will sound better as it can deliver transients better.

 

My point is that many people seem to run with this idea all the way to the horizon.    The "transients" are only so big.... hence you only need so much power.

 

The concept that more power will always be better and better and better, is wrong.

 

 

Of course, we don't need to guess these things either way.   It can all be calculated and measured quite simply.

[Zaphod Beeblebrox]

As an OT aside, do they have LED oscilloscopes these days?

I have yet to see an OLED oscilloscope, but I guess they're not far away. OTOH, LCD oscilloscopes are very common. I use an LCD oscilloscope, but still like to use one of my cathode ray tube jobbies often. CRT oscilloscopes respond faster and deliver cleaner traces, unless one is prepared spend mega-Bucks (well, about $20k).

Edited April 21, 2014 by Zaphod Beeblebrox

[Gordon Macfarlane]

My point is that many people seem to run with this idea all the way to the horizon.    The "transients" are only so big.... hence you only need so much power.

 

The concept that more power will always be better and better and better, is wrong.

 

 

Of course, we don't need to guess these things either way.   It can all be calculated and measured quite simply.

Yes , wasn't trying to suggest that more power will always be better but rather adequate power is a must.

[Catostylus]

I have yet to see an OLED oscilloscope, but I guess they're not far away. OTOH, LCD oscilloscopes are very common. I use an LCD oscilloscope, but still like to use one of my cathode ray tube jobbies oftne. CRT oscilloscopes respond faster and deliver cleaner traces, unless one is prepared spend mega-Bucks (well, about $20k).

 

Thanks for your answer, ZB. Rereading my post I realise I actually meant LCD, so thanks for answering the question I meant to ask. I was never expecting OLED ones to be about yet.

[Zaphod Beeblebrox]

Thanks for your answer, ZB. Rereading my post I realise I actually meant LCD, so thanks for answering the question I meant to ask. I was never expecting OLED ones to be about yet.

It shouldn't long. OLED screens will sweep LCD from all segments of the market. Eventually.

[betty boop]

Yes , wasn't trying to suggest that more power will always be better but rather adequate power is a must.

 

by adequate I would say also its the quality of the power thats important...not the quantity per say...otherwise we would all be using high powered PA amps...

[andyr]

Yes , wasn't trying to suggest that more power will always be better but rather adequate power is a must.

 

However, the issue is, Gordon ...what is "adequate" power?

 

Dave would say it's whatever you are using to drive your speakers to your desired listening level ... plus 3dB headroom.

 

Whereas, I would say it's whatever you are using to drive your speakers to your desired listening level ... plus 10dB headroom!

 

The two headroom allowances produce very different power outputs.

 

 

Regards,

 

Andy

[andyr]

by adequate I would say also its the quality of the power thats important...not the quantity per say...otherwise we would all be using high powered PA amps...

 

I think you've missed the point, Al.   We've taken "quality" for granted in this discussion.  The argument is ... how much extra do you need to allow, for faithful headroom, for transient delivery.

 

Andy

Edited April 21, 2014 by andyr

[betty boop]

I think you've missed the point, Al.   We've taken "quality" for granted in this discussion.  The argument is ... how much extra do you need to allow, for faithful headroom, for transient delivery.

 

Andy

 

I think you missed that I wasnt responding to you

 

as far as transients go its why good amps have massive power supplies with power reserves well in excess of output claims made. some miss the point that different makers spec amp power in different ways. it isnt actually the given you make out. personally rather than go on about specs I tend to find the proof is in the eating. if comparing amps from the same maker in the same range you could say a 500w amp likely have more in reserve than the one specd at 250w. but i wouldnt draw same line from one maker to another as in many cases its like comparing apples and watermelons. the quality of their power can be quite different.

[sir sanders zingmore]

• [*]An amplifier of this type will exhibit obvious distortion when clipping.   You should hear it  

 

I'm not sure I agree that clipping is always obvious as distortion. In my experience it can happen very quickly and it's effects are a bit more subtle.