Give me an Amp Crash Course

[killdozzer]

It would be like asking me, 'just what is cancer anyway?', in 10 words or less .

So you're an MD in MD?

People, I'm really not happy with this Yamaha, I have to tell you. It is so god damn warm all the time. Warm, warm, warm... I keep checking what effect I left turned on and there are none, but still it plays like a freakin' SONY.

So far the external decoder input (main) comes closest to the direct path, but with this there's no middles. I doubt I can use it.

CD IN was luke warm, unberable, I don't know why but... I can't play it as loud as with NAD it just seems like they will start screeching. And this is so obvious and audible, it is not just a tiny difference, I'm telling you, I have a feeling if I turn up the volume it will start distorting.

I'm still digging around to see what else I can do to get a cleaner sound. Will let you know if I succeed.

killdozzer

 

[slipperybidness]

Concerning impedance vs. load--just remember that the lower the impedance, the more difficult the load is for the amp. Yes, it is counter-intuitive.

For defining impedance, Wiki is our friend. The key to understanding impedance is that it has a frequency dependent nature, while resistance is frequency independent. When we start looking at impedance, we have to start including the capacitance/inductance terms in the equations. When they start talking about "imaginary" and "real" part, these are simply mathematical concepts using the Sqaure Root (-1) that readily apply to the equations for AC.

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.


In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current (AC) circuit. Impedance extends the concept of resistance to AC circuits, and possesses both magnitude and phase, unlike resistance, which has only magnitude. When a circuit is driven with direct current (DC), there is no distinction between impedance and resistance; the latter can be thought of as impedance with zero phase angle.


It is necessary to introduce the concept of impedance in AC circuits because there are two additional mechanisms to be taken into account: voltages in conductors self-induced by the magnetic fields of currents (inductance), and electrostatic storage of charge induced by voltages between conductors (capacitance). The impedance caused by these two effects is collectively referred to as reactance and forms the imaginary part of complex impedance whereas resistance forms the real part.

 

[killdozzer]

I'm still digging around to see what else I can do to get a cleaner sound. Will let you know if I succeed.

killdozzer

a, it could be some of the DSP, I have to check whether "effect off" means all DSP off.
I found this in a review:
Mike found guitar and bass on the Doors song to be a bit thuddy, the overall sound a bit thin, and the high frequencies a bit crispy. Jim Morrison and co. seemed bottom-heavy to me, with a murky bass that overpowered some of the subtler notes. To Mike's ears, the Keith Richards track demonstrated slightly slow bass but a good midrange attack. I noted excellent separation as on the Doors track, and the drums displayed a nice kick, again at the cost of some subtlety.

I agree with many of the observations and would add some.
Also, I see the Dolby light coming on only when I switch to TAPE/MD input. I have to see is it on when I play over CD in.

External decoder bypasses Dolby as well, but my laptop has Dolby. I hope it will suffice.

 

[killdozzer]

May have figured it out. EXT. decoder suits me best as it seems to bypass everything in the amp. There's still some difference. I had both NAD and Yamaha at my home for some time and I was switching cables like crazy. There was some sort of 'warmth' to Yamaha which I generally dislike as a feature of equipment. I took to some reading and what I found in the manual didn't really sound comforting.

Now, this may be the wording of the text. Perhaps it's just semantics. If it's not, it's not good. You get the feeling that there's no true stereo in this particular model. It is 5.1 and all the channels get 'created even if you turn off the B speakers. In this case it simply redirects the signal into main L + R.

This all redirecting business doesn't sound good to me.

 

[killdozzer]

This is what it says:

Number 8 and 0 concern this.

killdozzer

 

[lovinthehd]

Then don't feed it a 5.1 signal if you don't want it downmixed to stereo....

 

[killdozzer]

Then don't feed it a 5.1 signal if you don't want it downmixed to stereo....

Thank you. I see what you mean. However, I never feed it 5.1, don't really like it, and still there's this strange warmth when compared to NAD. Which leads me to believe it's not the input. The input (and all the rest: laptop, digital archive, placement in the living room, all the cables (not that they should matter)) is the same.

And then there's the same power output for both 2.0 and 5.1. Now, what I wanted to propose, no matter how improbable, is that the signal is always redirected. Let's look at it this way; if you feed it 2.0 and turn on the 'effect' / 'surround' speakers you hear the sound. It is not genuine 5.1 as it is not being divided accordingly but still it is being created and you can hear it. If this receiver really doesn't have the genuine 2.0 stereo sound, then those created 'effect' / 'surround' speaker signals would simply be redirected to the mains.

Probably resulting in an impression of 'warmth' although output levels of the main R and L speakers won't mismatch as proposed in the manual, since the redirected signals are the same as those going to the L and R in the first place.

If there really are 5 separate amps working inside this unit (.1 being the active sub and thus not powered), the result is something like a strange form of bi-amping where both drivers in the speakers are receiving the same signal more than once.

Or would you say I have a lot of time on my hands?

Believe me, I don't. I'm just desperate to find a source to this difference in sound between these two amps, since I took the ideas on this forums to be true and thought no difference should be heard, since both NAD and Yamaha are suppose to be sufficiently well constructed.

 

[slipperybidness]

I don't think any "redirecting" is at play here.

What that means is that if you only have 2 speakers hooked up, and you feed it 5.1, then the other 3.1 channel info will get sent to the 2 speakers that are hooked up--that's the classic definition of "redirected" audio.

If you feed it 2 channels of input, and have 2 speakers hooked up, then there is no possible way to have the info redirected.

Now, if you have some silly DSP engaged, that could be the problem. You need to figure out how to defeat all DSP, this is typically accomplished with a "Direct" or "Pure Direct" mode, or look for some other similar feature.

 

[lovinthehd]

If your sources are not 5.1, I wouldn't worry about it....but as slipperybidness says, you may have to play with the settings....they're tools to shape sound to your liking. As to differences, which is one actually better/worse? Pick the one you like better in that regard and don't look back.

 

[killdozzer]

Almost like they were reading my posts here

Check this out: DAC/intgr.amp/subout/bassmanagement/100aWpc/8ohm (and from ELAC)

ELAC DebutSeries DA101EQ

Absolute Sound is mentioning 599$ ??? (fingers crossed). This could hold me all the way to Luxman.

Only one question remains, for the love of me, I couldn't find is it a 'memory stick' USB-IN or is it a 'PC' USB-IN?

BTW, it is a looker; notice how the fascia and (well... I guess rearia) make up feet of this component. This was thought over through and through!

killdozzer

 

[killdozzer]

What precious information I found!! I downloaded a service manual for my Yamaha rcvr. It has tons of interesting things about the unit. Sub out cut off frequency is 90Hz, which will be high enough (I hope) to integrate with LS50 and bass/treble knobs affect main channels only. So only main left and main right will lose i.e. bass when I turn it down. There’s even info about db ratio for the knob, but I have to read more to understand this.

It will be tapping in the dark, but good enough for starters. I think I’ll be able to get a more or less clear picture on whether I want the sub. Then the next amp will be slightly more serious in this ‘sub-out’ department.

P.S.: there’s also a great deal on how to program the channels and how to turn off effects for each separate channel. Also, instructions for taking it apart, and you don’t really own an amp until you take it apart.



killdozzer

 

[slipperybidness]

What precious information I found!! I downloaded a service manual for my Yamaha rcvr. It has tons of interesting things about the unit. Sub out cut off frequency is 90Hz, which will be high enough (I hope) to integrate with LS50 and bass/treble knobs affect main channels only. So only main left and main right will lose i.e. bass when I turn it down. There’s even info about db ratio for the knob, but I have to read more to understand this.

It will be tapping in the dark, but good enough for starters. I think I’ll be able to get a more or less clear picture on whether I want the sub. Then the next amp will be slightly more serious in this ‘sub-out’ department.

P.S.: there’s also a great deal on how to program the channels and how to turn off effects for each separate channel. Also, instructions for taking it apart, and you don’t really own an amp until you take it apart.



killdozzer

Just a note for you, when you see "cutoff frequency", that is typically the -3dB point by definition.

A cutoff frequency is not a "brick wall" cutoff.

 

[slipperybidness]

Almost like they were reading my posts here

Check this out: DAC/intgr.amp/subout/bassmanagement/100aWpc/8ohm (and from ELAC)

ELAC DebutSeries DA101EQ

Absolute Sound is mentioning 599$ ??? (fingers crossed). This could hold me all the way to Luxman.

Only one question remains, for the love of me, I couldn't find is it a 'memory stick' USB-IN or is it a 'PC' USB-IN?

BTW, it is a looker; notice how the fascia and (well... I guess rearia) make up feet of this component. This was thought over through and through!

killdozzer

I like it!

 

[killdozzer]

Just a note for you, when you see "cutoff frequency", that is typically the -3dB point by definition.

A cutoff frequency is not a "brick wall" cutoff.

This is a very welcome piece of information. You've hit spot on what I need to know.

I found a basic secondhand sub from KEF for 230$, I thought it's a good place to start with the same brand like the mains. It says the sub goes down to 30Hz, which makes it a real 'music sub woofer' and that is exactly what I'm aiming for.

Thanks!

killdozzer

 

[herbu]

It says the sub goes down to 30Hz, which makes it a real 'music sub woofer'

Are you sure? What does, "goes down to", mean? -3dB? -6dB? -12dB? What kind of music do you listen to? A piano goes down to 27.5Hz. A bass guitar 30.8Hz. Tuba and most large pipe organs 16.35Hz. A bass drum 60Hz. As an instrument approaches the max capability of your speaker, when does it start to become muddy/distorted?

My point: Don't think that "goes down to" means "plays well and accurately down to".

 

[killdozzer]

You don't have to get mad immediately!



You know, I’ve been thinking about that very same thing the other day, perhaps for slightly different reasons. I listen to a lot of contemporary pop and indie and since a lot of machines are being used as instruments these days, music goes as deep as movies. No real difference there.

If you’re interested, play the song ‘Ur’ by SZA from her album ‘Z’ (and play it loud). It is full of sounds and effects that resembles earthquake and go very deep. Even my LS50’s start shaking the entire loft, you can feel through your bottom if you’re sitting down or feet if you’re standing up.

I guess people could stop making the difference between ‘movie’ and ‘music’ subwoofers altogether.

My main concern is money really and as soon as you start looking for something bellow 30Hz price goes up steeply. If it’s some SVS, REL or Velodyne… you can spend a fortune.

The reason I’m thinking of a second hand is because I have to determine whether I want to have a sub or not. I don’t want to buy new and expensive and realise I’m not satisfied. The reason I got my eyes stuck on this one is because it is KEF (I’m hoping for a smoother match, although I know it’s not a rule written in stone). I’ll sell it if I’m not happy and want lose much. (Actually, I’ll sell it even if I’m happy and buy something more serious).

This is what the home page says: Frequency response: 30Hz to 150Hz +/-3.0dB

And the manual says this: Frequency range: 15Hz - 140Hz at a rate of 12dB/24dB

I must admit I don’t know what this i.e. -6dB means in reality… Is it audible or not?

 

[herbu]

I must admit I don’t know what this i.e. -6dB means in reality… Is it audible or not?

Play something. Turn your volume up 6dB and down 6dB. Then you tell me.

 

[killdozzer]

It is not that easy. I have a feeling it's difficult for you to put yourself in the shoes of someone who knows far less and then explain something to that person so that he gets it. You know, like good professors do.

You said turn volume up and down, but in relation to what? What is the reference point?

Furthermore, when I try to make sense out of your two posts together it only gets messier. You've asked is it -12dB, so I suppose there is a reference point, otherwise the question doesn't make sense. And if most tables state that 80 - 85dB is the loudness of human speech, shouldn't -12dB be totally silent? 0dB is suppose to be a quiet room with nothing but hum in your ears.

Then again, there's a threshold of what's audible for human hearing, so bellow that it shouldn't matter whether it's -100dB or -200dB, right? If you can't hear it, you can't hear it.

If I play something with the volume knob positioned in the middle and then go 6dB louder and then quieter, how does this help me answer your first question? How will I know when is it -12dB, or 6dB? I don't have a precise meter.

To make things more complicated for someone like me, the volume knob on my Yamaha says '0' is all the way up. And as if that's not enough, numbers up to that zero don't have a 'minus' attached to them. So tables state that 0dB is a quiet room, but my rcvr says that the point where my speaker would probably burst is '0'.

I can only guess that what you're asking is at what volume level will the sub get activated? But I can't answer this. I hoped it would be visible from the links I provided.

P.S.: to think that the active sub has it's own volume level only makes my head hurt. Am I suppose to adjust the volume on my sub every time I turn on the volume on my amp? If not, why is it there? If I turn it all the way up, shouldn't there be to much bass for low level listening?

 

[lovinthehd]

It is not that easy. I have a feeling it's difficult for you to put yourself in the shoes of someone who knows far less and then explain something to that person so that he gets it. You know, like good professors do.

You said turn volume up and down, but in relation to what? What is the reference point?

Furthermore, when I try to make sense out of your two posts together it only gets messier. You've asked is it -12dB, so I suppose there is a reference point, otherwise the question doesn't make sense. And if most tables state that 80 - 85dB is the loudness of human speech, shouldn't -12dB be totally silent? 0dB is suppose to be a quiet room with nothing but hum in your ears.

Then again, there's a threshold of what's audible for human hearing, so bellow that it shouldn't matter whether it's -100dB or -200dB, right? If you can't hear it, you can't hear it.

If I play something with the volume knob positioned in the middle and then go 6dB louder and then quieter, how does this help me answer your first question? How will I know when is it -12dB, or 6dB? I don't have a precise meter.

To make things more complicated for someone like me, the volume knob on my Yamaha says '0' is all the way up. And as if that's not enough, numbers up to that zero don't have a 'minus' attached to them. So tables state that 0dB is a quiet room, but my rcvr says that the point where my speaker would probably burst is '0'.

I can only guess that what you're asking is at what volume level will the sub get activated? But I can't answer this. I hoped it would be visible from the links I provided.

P.S.: to think that the active sub has it's own volume level only makes my head hurt. Am I suppose to adjust the volume on my sub every time I turn on the volume on my amp? If not, why is it there? If I turn it all the way up, shouldn't there be to much bass for low level listening?

He's talking about the point at which its spl capability varies from the general +/- 3dB frequency response range of the speaker, the f3 is 3dB down (-3dB), f6 is 6dB down (-6dB) etc. It gives you a picture of how your speaker rolls off response at the lower end. Another consideration with a speaker is at what spl is this all being determined at, and why many don't try to "blend" speakers/subs at the spl levels they need...and cross them perhaps even at 100-120 even if their speakers have a -3dB point in the 30-40Hz range....at what spl can they do that?

 

[killdozzer]

Play something. Turn your volume up 6dB and down 6dB. Then you tell me.

He's talking about the point at which its spl capability varies from the general +/- 3dB frequency response range of the speaker, the f3 is 3dB down (-3dB), f6 is 6dB down (-6dB) etc. It gives you a picture of how your speaker rolls off response at the lower end. Another consideration with a speaker is at what spl is this all being determined at, and why many don't try to "blend" speakers/subs at the spl levels they need...and cross them perhaps even at 100-120 even if their speakers have a -3dB point in the 30-40Hz range....at what spl can they do that?

Thank you all for trying. However, I'm a literature/theory of cinema professor. The dB/Hz relation is still not fully clear to me (but I’m trying, honestly).

After all you said, it seems to me you could pose that exact same question Herb did on just about any subwoofer. I mean, if you can’t read needed info out of the manual, who can give you the answer. I can’t buy measuring equipment and go through 20 subs.

If you’re not happy with the spl at which your sub reproduces as low as 30Hz, couldn’t you just turn the volume up on your sub? (This is how little I know) I still can’t believe that if you put 1w into your speakers that you’ll hear the rated amount of dB at 1 meter distance. In all honesty, I still don’t understand why people (even here) say that you don’t need a sub in a small room. If your monitor doesn’t ‘make noise’ under, let’s say, 50Hz, what does it matter how big your room is? If it’s not there, it’s not there. (And please don’t tell me it starts reproducing bellow 50Hz only because the room is small or I will start pulling my hair out)

What Herb might have done is simply say; no, that sub is not good enough. I have no other choice but to trust what you say any way.

I am trying to determine (by ear) whether I’d be significantly more satisfied if I pair these monitors with a sub. During this process I’m trying not to lose too much money. Swerd already said that I could try with an ‘AE’ sub I mentioned in one of my posts, but that one I can only get new, which means that it is pricy to begin with and I will lose much when I try to sell it if I need to.

The easiest way I can think of is to borrow a sub, but I don’t know anyone who owns one. So the ‘second easiest way’ is to buy second hand. I figured that if I get it for 230$, I could sell it on for at least 200$ and this will not set me back too much.

The main problem, as I see it, by what you often write here, is that no one can tell me I would be satisfied even with a top SVS model. I have to listen to it and see for myself. And this was my initial logic: if I really like something that can ‘barely’ go down to 30Hz, there’s no reason not to be happy with something that easily goes down to 30Hz or 28Hz (given that other specs and conditions don’t change much, for example; if I like a cheaper model of KEF sub, I can aim for a solid medium model of KEF sub).



P.S.: (for the curious) I also intend to crossover main speakers a bit higher so that they don’t even bother with anything lower than cca. 70Hz. I expect they’ll do their job even better.