John Curl's Blowtorch preamplifier part II

Status
Not open for further replies.
Disabled Account
Joined 2012
Nope, the disagreement is about testing listening perceptions. Require real controls ('ears only") and the hucksters and charlatans (and their marks) start squealing.

There are few controls needed nor a DBLT is needed to hear and perceive a center image in a 2 channel system. Just ask a lot of people with different 2channel systems etc etc and if they say they hear a center image then they Do hear a center image.

Whether it is a center image or any other perceptual description for what is being heard and described, there is a scientific explanation -- some times we know the scientific answer and sometimes we dont. When we dont... just do not be so quick to deny the commonly expressed perception, though.

This is where I say it is "as if" there was a center speaker/channel or what ever a particular description suggests.



THx-RNMarsh
 
Last edited:
Disabled Account
Joined 2010
No, not exactly the same, I was thinking more in terms of published specs by the manufacturer, in general terms only. Is say THD of say 0.04% really much better than say 0.05%?

OTH, if they use different internal topologies, than other, more subtle differences are only to be expected. It also depends how deep you go with measuruing - even relatively simple tests, like square wave full power drive into 8 Ohms at 10 kHz with 2 uF in parallel can show big differences between two nominaly similar amps. One might do a decent hob of it, while the other may do a terrible job of it, and even trigger the protection circuits.

Into real world speakers, you could get a very different sound from them. In my example, the Philips AH280 (rated at 60 WRMS into 8 Ohms) will deliver a clean but flat (strictly 2D, zero depth) sound, while the other will just sail through it smiling (Marantz 170D - 85 WRMS into 8 Ohms). Just a short look at 10 kHz//2uF nominally 8 Ohms square wave pattern will look completely different, the Philips will look really broken up, while the Marantz will sail through it withut breaking a sweat. Yet the published specs for the Philips are in fact a bit better thn those of Marantz, but listen to them and you'll understand why Philips bought Marantz in its day.

And if you really want to push it, throw in the H/K PA 2400. Rated at twice the power of the Marantz (170 WRMS into 8 Ohms), that is my defintion of being load tolerant, its 10 kHz/8 Ohms//2 uF at Marantz' full power (bat one half its own rated power), you need to look closely at the scope to even notice that it's drving reactive load. But then, it did cost quite a bit more than the otger two.

I agree that the "better looking" square response is an indication for a "technical better" amp considering stability issues. But I see strictly no evidence that the squareness of test signals must be the reason for you perceiving different sound quality. And by the way, these test conditions are far from being realistic.
 
There are few controls needed nor a DBLT is needed to hear and perceive a center image in a 2 channel system.

If you're trying to establish it as a fact (which in this case has already been done- this was just an example of a well-known and non-controversial example of the brain perceiving something that's not there), then yes, you absolutely need controls. Refusing to use basic controls is what separates the hucksters and charlatans from ethical and competent researchers.
 
Disabled Account
Joined 2012
If you're trying to establish it as a fact , then yes, you absolutely need controls. Refusing to use basic controls is what separates the hucksters and charlatans from ethical and competent researchers.

This may be where arguments begin...... Many people, who are not trying to establish fact, will just agree they hear no change or they do. And, from a consensus of opinion based upon the majority hearing IT (or not) the same described way... will accept THAT and move on. They dont need to know if it is because of material behavior or jitter or what ever. Nor a DBLT.

Sometimes, a correlation may exist between a test and listening descriptions which seems plausable. But if it is important enough to want to figure out why the 'as if' exists (and it does if a majority hear it), then by all means figure it out scientifically and add it to the explanation of what is heard. Though the 'center channel' affect heard isnt made more true by it.

Comment ,pls?


THx-RNMarsh
 
Last edited:
I understand that there is a minority of the population that doesn't perceive a phantom center

a 3rd center channel is invaluable for improved imaging/image stability over stereo - known very early on - Mercury "Living Presence" recordings were done 3 channel
but simple analog coding schemes for the 2 channels of stereo were cheap and easy for phono and radio which gave stereo the win commercially

and a lot of system have been proposed: Wendy Carlos Gosurround
 
Geez,
This is like the people who say we never went to the moon, how do you prove that? Of course I believe we did but so many think the whole thing was staged, what proof do you offer in that case? Many times we believe with no dblt or many other objective experiments, actual observation is all that is necessary many times but in many instances of course we need to do very well designed scientific studies, but not every time.
 
Different sorts of facts are demonstrated using different sorts of experimental methods. That seems like a trivial statement, but it's often not fully understood, especially in the fairy tale land of fashion audio.

DBTs are necessary for experiments involving human senses or other physiological responses. If no controls are used, what you've got is empty claims with no value other than to keep the true believers believing.

For info on verifying the moon landing, Google "retroreflector."
 
Disabled Account
Joined 2012
a 3rd center channel is invaluable for improved imaging/image stability over stereo - known very early on - Mercury "Living Presence" recordings were done 3 channel

I tried it back then and it works very well to keep the 'center' image centered when moving slightly to the left and right...... which isnt the case with just 2 channels. A simple sum and level blend into a center amp/speaker gives excellent result. Everyone should try it. You might just leave it in always.

Which moves the discussion needle to surround or multi-channel systems. That physical center channel can be very helpful in imaging placement.



THx-RNMarsh
 
Last edited:
Disabled Account
Joined 2012
You people have been busy overnight again! Talking about being sensitive in the hearing, I would find it a waste of time trying to find differences in sound - the only thing I'm interested in is whether it comes up to a certain standard; I have a selection of recordings which have certain attributes that cause systems with flaws to audibly misbehave in a prominent way, dramatically so sometimes, and using them the simple process is to determine which flaws a system has, and then eliminate those. When no audible flaws remain, then the system is up to scratch.
 
If you critically reflect on how you write these posts, you will notice that it flows from you and you don't exactly know what it is you are writing until after you wrote it!
So who's writing it, really??
It seems to me you're under the illusion that the 'I of the vortex' is you. It's self-evident that that's not the case. Libet's experiments bore this out.
 
Status
Not open for further replies.