John Curl's Blowtorch preamplifier part III

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I avoid Amazon where possible out of personal choice so use ebay. Warning to UK shoppers. Avoid the music magpie store!


Reminds me, time for another soundcloud evening...

In the US Amazon is massive. I prefer to use it as a wish list and search engine, then order from anyone that doesn’t use “Ontrac” shipping where meth heads throw your 2 day shipping package at someone else’s house 2 weeks after it’s shipped.... (and maybe in the lawn while it rains)

Ontrac is another mechanism to insure slave/wealthfare state. It’s a 1099 (contractor) that doesn’t negotiate their wage (federally illegal), and has no real standards or pay. Where as I know UPS drivers that raised families, had benefits, and were able to retire.
 
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The Kemet (formerly NEC) EA2/EB2/EC2/EE2 relays appear to be essentially distortionless for line level stuff. They are often seen in gear that measures well and I believe AP uses them, or did.

These are real nice and AP did use them in the system One and two. I don't hear relays in the new 525 system but don't know. They are audible for phono switching at MC level. I wish they were not but I couldn't fool the test listeners.
 
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Whereas I would worry about it on a Shalco switch because Ed showed that there is micro-diode action on tarnished surfaces and you would therefore lose the 'air' in the top octave :p

Then again, JC of course has the solution. Just whip the top cover off and give the contacts a polish once a month the way they did back in the 1960's :p


:D
 
Whereas I would worry about it on a Shalco switch because Ed showed that there is micro-diode action on tarnished surfaces and you would therefore lose the 'air' in the top octave :p

Then again, JC of course has the solution. Just whip the top cover off and give the contacts a polish once a month the way they did back in the 1960's :p


:D

No, deliberately oxidizing surfaces has clearly shown there is no microdiode effect. Silver oxidation also is not a concern.

However silver reacting with sulfur in the air is a real problem.

So when you get to your final destination the delicate contacts in your stereo system won't work well with all the brimstone smells.
 
The Panasonic AGN series are a slightly larger version of the one I showed.

The Kemet series are intended to be used in the same application and have the same electrical ratings, but the avoid silicone rubber gas warning leads me to believe they are not quad bifurcated crossbar contacts. (Also lack of palladium on the data sheet I looked and along with lack of a mention!)
 
No, deliberately oxidizing surfaces has clearly shown there is no microdiode effect. Silver oxidation also is not a concern.

However silver reacting with sulfur in the air is a real problem.

So when you get to your final destination the delicate contacts in your stereo system won't work well with all the brimstone smells.


At least is is cooler down there, if you are boiled in sulpher it must be below the triple point, ~440C, the alternative location is ~7x7x1.2.kw per sq m, so about 760C...
 
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One thing to remember about JBL M2 is the stock configuration uses two Crown class-D power amps with internal DSP. The DSP handles crossover and speaker FR corrections. It also digitizes analog inputs to the DSP, then converts the digital back to analog before sending it to the power amp stage. So, everything that comes out of it is played back through its DAC, and possibly gone through ASRC if it were digitally input at the wrong sample rate. Listening tests with test subjects sitting in the middle of some room perhaps with curtains hanging in front of the speakers may not be the same thing someone would hear in the near field and lower volume levels. Also, the horns do have a sound, IMHO, but it is pretty neutral, nothing to complain about.

Yes, it is not a near field monitor. The drivers centers are too far apart for that.... you would have to very carefully sit at the exact acoustic cross over center.... which is at the JBL badge location.


THx-RNMarsh
 
Why not use a mix of very low frequency (for the boomer) at higher level,
and a 20KHz for the tweeter ? Just to break the suspensions and avoid neighbors complains ?
At my age, it seems not reasonable to wait one month ;-)

That might work, perhaps 100Hz or so, but I'd use a lower frequency for the tweeter,
maybe 3kHz. They do sound quite unpleasant until broken in, so you won't want to listen
to them. If you feed them mono out of phase, and place them face to face, you won't hear
very much sound.
 
Yes, it is not a near field monitor. The drivers centers are too far apart for that.... you would have to very carefully sit at the exact acoustic cross over center.... which is at the JBL badge location.
I usually set a equilateral triangle with speakers and listening position as the angles. But i cross the speakers in such a way that their axes crosses closer than the listening position. around 2/3 1/3 in front of the listening position.
It enlarge the lateral listening position, flatten a little the extreme trebles, erasing some unnatural excess (hifi effect) and produce a more natural restitution without loosing impacts on cymbals, as an example. Just try to orient them this way for the best result. I will be curious of your feedback.
 

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