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Old 19th April 2012, 11:41 PM   #4501
a.wayne is offline a.wayne  United States
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Not sure if i do or not, so best to read it up fast ... It was on an Open forum, A letter to the editor , credits were given ...
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Old 19th April 2012, 11:44 PM   #4502
tvrgeek is offline tvrgeek  United States
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OK, .001 W is at least above typical DC offset. I am not buying a millionth of a watt for a second. We are talking a signal delivered to a speaker at that level, not the difference between signals or some ultra cold sensor output.

Brad, I had not heard that description of noise in a tube amp, and maybe it is the tube amps I have, but have not heard the effect either.
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Old 19th April 2012, 11:45 PM   #4503
bcarso is offline bcarso  United States
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Even with the bit of detail the results stated are absurd on the face of it. 1 mW referred to an 8 ohm load is still quite a healthy voltage (about 89.4mV rms), yet the claim is made that the Halcro has 8.9% distortion at this output power. Based on the noise levels measured for the amplifier, this would be very easy to see on an oscilloscope, without any need for signal averaging!

Either there are some serious typos or something very strange is going on. I disbelieve those results.

Another thing that smacks of marketing: the expressions in the form of fractions: "1/1000" and so forth. Reminds me of the soap ads that touted "Ninety-nine and forty-four one-hundredths percent pure" (Gee! Isn't that pure enough for just about ANYONE???)
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Old 19th April 2012, 11:47 PM   #4504
bcarso is offline bcarso  United States
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Quote:
Originally Posted by tvrgeek View Post
Brad, I had not heard that description of noise in a tube amp, and maybe it is the tube amps I have, but have not heard the effect either.
I seem to recall it was in an interview of Keith Johnson in The Abso!ute Sound, many years ago, but I could be mistaken. I do recall he remarked about the large number of charge carriers involved in a tube versus silicon devices.
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Old 19th April 2012, 11:49 PM   #4505
a.wayne is offline a.wayne  United States
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Steve may respond . i sent him an email , so less be friendly , err. ahh, Best to warn T, Huh ...
I had a similar conversation with Mr Audio Note some 15 + yrs ago and he was of the same mindset , that first watt got all of his focus ...

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Old 20th April 2012, 12:01 AM   #4506
bcarso is offline bcarso  United States
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Originally Posted by tvrgeek View Post
OK, .001 W is at least above typical DC offset. I am not buying a millionth of a watt for a second. We are talking a signal delivered to a speaker at that level, not the difference between signals or some ultra cold sensor output.
As to the microwatt claim: JA states that for the DM58 he saw 82.8dB signal-to-noise ratio at 2.83V rms out, "unweighted", which I've concluded over the years means in an 80kHz bandwidth. The A-weighted number given is 96.8dB below the same signal.

82.8dB below 2.83V is 205uV. A microwatt referred to 8 ohms is 2.83mV. Although signal averaging would be helpful here, with just a little lowpass filtering I'll bet one could still easily see 8.9% distortion in a 1kHz sinusoid on a 'scope. And his discussion implies that the distortion would be expected to be still worse, due to whatever curious phenomena are accounting for the extraordinary rise going to a milliwatt.

Piscine in the extreme.
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Old 20th April 2012, 12:06 AM   #4507
bcarso is offline bcarso  United States
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Originally Posted by a.wayne View Post
Steve may respond . i sent him an email , so less be friendly , err. ahh, Best to warn T, Huh ...
I had a similar conversation with Mr Audio Note some 15 + yrs ago and he was of the same mindset , that first watt got all of his focus ...

If it's the B&K test equipment I remember, some of it used to be quite decent and very utilitarian, as if designed by working technicians, and as well affordable for the most part. I'm sorry to hear they went out of biz.

PS: In fact come to think of it, I still use a BK Precision 875A LCR meter, and it's been quite adequate. I preferred the model that had a zero adjust but I think I gave that up when the family biz went broke.

Last edited by bcarso; 20th April 2012 at 12:08 AM. Reason: afterthought
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Old 20th April 2012, 12:07 AM   #4508
a.wayne is offline a.wayne  United States
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Not Following you Brad, 2.83 V @ * is 1 watt ... No ..?
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Old 20th April 2012, 12:08 AM   #4509
a.wayne is offline a.wayne  United States
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Originally Posted by bcarso View Post
If it's the B&K test equipment I remember, some of it used to be quite decent and very utilitarian, as if designed by working technicians, and as well affordable for the most part. I'm sorry to hear they went out of biz.
NO , it's B&K audio .... They made amplifiers , et al .......
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Old 20th April 2012, 12:29 AM   #4510
bcarso is offline bcarso  United States
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Not Following you Brad, 2.83 V @ * is 1 watt ... No ..?
Yep ---what do you find discrepant? The claim is 8.9% distortion (excluding noise as I read him) at a milliwatt, unspecified (but presumably larger) at 1 uW, again excluding noise.
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