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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 27th March 2013, 03:08 PM   #37381
Max Headroom is offline Max Headroom  Australia
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Default When A 5534 Is Not A 5534....

Quote:
Originally Posted by qusp View Post
....nobody ever said that all opamps of all types sound/function the same in every situation, or did they?
There is considerable discussion in pro-sound/recording circles of 5534 op-amps of differing manufacture and/or age and/or encapsulation materials sounding different.....for example !.

Dan.
 
Old 27th March 2013, 03:23 PM   #37382
Kindhornman is offline Kindhornman  United States
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John Curl's Blowtorch preamplifier part II
Sy and John,
Here I have to agree with you and at the same time point out that on this site there are really two camps. Those that use engineering and design and those who I was just informed the other day tweak and nothing more. I tried to point out to someone the other day that just rolling op-amps in a circuit made no sense as none of them had been optimized for their particular use and was told that they didn't care. If a particular op-amp sounded different in a particular application that was reported as either meaning a device was good or bad and that was all they cared about whether this was all subjective or not did not phase them. The same with those changing capacitors at will and never checking the actual value besides on the wrapper and saying one was better than another based on cost and fancy marketing.

In this thread I do expect better, and I expect to see a reasoned explanation of why and how something is used in a particular way. I tried to point at some details about speaker design to a purveyor of high dollar speakers on this site and was told why would I care what was happening on a macro level, I only care what I can measure in the far field and damn what happens before that! This same designer said that all compression drivers are the same, they are only commodity devices and can be interchanged at will. Some don't even want to look for the forest let alone the trees........
 
Old 27th March 2013, 03:44 PM   #37383
Steve Eddy is offline Steve Eddy  United States
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Quote:
Originally Posted by SY View Post
Do you have that in log frequency? (I know, I'm a pain)

I'm not sure of the relevance of crosstalk- after all, phono cartridges rarely have more than 20dB or so and their imaging isn't terribly compromised. Is there data showing audibility of, say, 40dB of crosstalk?
What's the crosstalk of a pair of loudspeakers in a listening room without a dividing panel between them?

se
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Old 27th March 2013, 03:49 PM   #37384
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
I dunno, why don't you tell me, Mr. Headphone Guy?
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Old 27th March 2013, 03:53 PM   #37385
Nelson Pass is offline Nelson Pass  United States
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John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by godfrey View Post
Ditto, looks like a typo.


Funny, I thought I got that idea from Nelson, but I can't find the source now.

Maybe I just extrapolated from the inverting version, which he showed here in the "7 Easy Pieces" thread.
Not a typo, just a variation of another schematic in "& Easy Pieces"

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Old 27th March 2013, 04:05 PM   #37386
Steve Eddy is offline Steve Eddy  United States
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Quote:
Originally Posted by SY View Post
I dunno, why don't you tell me, Mr. Headphone Guy?
But you see, I'm not Mr. Headphone Guy. I'm a speaker guy. Headphones run a distant second.

se
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Old 27th March 2013, 05:19 PM   #37387
1audio is offline 1audio  United States
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John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by Steve Eddy View Post
But you see, I'm not Mr. Headphone Guy. I'm a speaker guy. Headphones run a distant second.

se
Most headphones don't have even 40 dB of separation. Simple arithmetic- driver is 32 Ohms, common ground lead is 1/2 Ohm at best (people really don't like stiff wire on headphones), usually more like 1 Ohm.
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Old 27th March 2013, 06:04 PM   #37388
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
OK, then we're all screwed.
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Old 27th March 2013, 06:11 PM   #37389
Mooly is offline Mooly  United Kingdom
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John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by john curl View Post
It appears that you guys can't even agree on how to make a buffer. '-)
That's why I'm personally fishing for info on the noise gain technique, I'm not going discrete on this, to many stages.

Quote:
Originally Posted by john curl View Post
A note on IC op amps:
It is almost impossible to effectively recommend a specific op amp, unless you know the conditions that it is being used.
For example:
Is the drive Z low, medium, or high?
Well, if your interested...all opamps driven from a very low impedance.

Quote:
Originally Posted by john curl View Post
Is the output load resistance low, medium or high?
Lets say its for a low impedance version. Peak opamp currents could reach around 27ma at full output swing worst case (but see below)

Quote:
Originally Posted by john curl View Post
What is the output swing that is necessary, and what are the available power supply voltages?
Is this application for battery operation?
I know it sounds simple, but nobody here DEFINED the problem, before entering their choices, AND your choices are all over the map. '-)
Required swing is much below rail voltage. Put it this way... the power amp considered has a sensitivity of around 200mv RMS for full output. Supplies for opamps either -/+15 or 18v

Quote:
Originally Posted by Nelson Pass View Post
Not a typo, just a variation of another schematic in "& Easy Pieces"

Thanks for clarifying
 
Old 27th March 2013, 06:22 PM   #37390
Max Headroom is offline Max Headroom  Australia
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Default Not All Headphones Are Junk...

Quote:
Originally Posted by 1audio View Post
Most headphones don't have even 40 dB of separation. Simple arithmetic- driver is 32 Ohms, common ground lead is 1/2 Ohm at best (people really don't like stiff wire on headphones), usually more like 1 Ohm.
Not all headphones run common ground....most better quality headphones run a Y-lead with 4 conductors.....Dr Dre Beats headphones run common ground...

Dan.

Last edited by Max Headroom; 27th March 2013 at 06:25 PM.
 

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