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Post by DaveC on Apr 6, 2018 17:06:55 GMT
the information already having been made available to you. See my previous post. |
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Post by TheMooN on Apr 6, 2018 17:31:18 GMT
the information already having been made available to you. See my previous post. I fail to see why my somewhat Heath Robinson, by your standards, methodology should deter you from your intention to perform an instrument level diagnostic test, of your choosing, on an item of pre or power equipment again of your choosing ? As I am confident that any results that you may wish to publish here will be far more accurate than mine. Surely your intention was to test for any measurable variance between....say a standard Bussman fuse and an SR Blue, rather than an intention to replicate and verify my results obtained on my equipment within my own room ? |
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Post by julesd68 on Apr 6, 2018 18:04:41 GMT
That seems an eminently sensible approach at this stage ...
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Post by Deleted on Apr 6, 2018 18:24:48 GMT
8% is not subtle. . . . Obviously I only need the internal 5 x 20mm fuses, but I think it will be expensive, as I need 5 for my power and pre amps if my memory serves me correctly. 8%? I have never given a quantitative improvement figure and wouldn't even be able to. Why not just buy the fuses you need for your power amplifier only? They should give you the most improvement and you haven't spent as much if you don't like the results. No Martin, you did not. I am going to do my best to ignore this thread now. I won’t be fitting my mo o blocks with SR Blues. |
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Post by DaveC on Apr 6, 2018 21:40:00 GMT
Surely your intention was to test for any measurable variance between....say a standard Bussman fuse and an SR Blue, No it was not. If your read what I said, although this is now the second time you have misquoted me; my offer was only to validate your claimed "measurements and calculations". At the time you were serious, defensive and did not hint at any of the Heath Robinson you now admit to. But here is a new offer, if anyone thinks it can be measured, and what they want measuring, then send me the equipment in question, both fuses and I will measure it. But this has to be a serious and professional offer. Before doing so read my comments about the Bristol Show again ? Dave |
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Post by TheMooN on Apr 7, 2018 11:17:29 GMT
Why would I feel the need for you to validate anything that I have conducted and written about here Dave ? I am neither the manufacturer or retailer of this product, nor Mr Atkinson.
My query remains, why not acquire an SR Blue and conduct an instrument level suite of tests yourself ? At the same time you might as well listen to some music and pen your considerations here, I am sure that there are many here interested in your results from both.
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Post by DaveC on Apr 7, 2018 11:28:42 GMT
Why would I feel the need for you to validate anything ? As I have said before, see my previous posts ? |
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Post by Deleted on Apr 7, 2018 12:14:36 GMT
I recently popped in four Synergistic Research blue fuses into the system:
1x mains conditioner
1x pc psu
2x dac
Made a nice uptick in the sound. More organic and relaxed.
The first I put in the mains conditioner, it didn’t sound right, so out it came and I swapped it’s direction round, plugged it all back in and hey presto, sounded much better. Odd.
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Post by MikeMusic on Apr 7, 2018 12:37:20 GMT
Directionality seems to be common to us all.
Bonkers to me at least, but always worth swapping around to check
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Post by Deleted on Apr 7, 2018 12:44:33 GMT
Directionality seems to be common to us all. Bonkers to me at least, but always worth swapping around to check Amen. I’m very glad I put them in one at a time and made the necessary adjustments then, or I’d have driven myself mad with the guess work! I could replace the four fuses in my amp with these bad boys too, but they’re not cheap... |
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Post by MikeMusic on Apr 7, 2018 13:26:00 GMT
Directionality seems to be common to us all. Bonkers to me at least, but always worth swapping around to check Amen. I’m very glad I put them in one at a time and made the necessary adjustments then, or I’d have driven myself mad with the guess work! I could replace the four fuses in my amp with these bad boys too, but they’re not cheap... Four in your amp ! Ouch. Try a 30 day trial ? |
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Post by Deleted on Apr 7, 2018 13:52:38 GMT
This is where the plot thickens; there’s no dealer in Australia and tbh I just can’t afford them right now, what with the new cables and custom made hi fi rack incoming. Of course at a later date though, I’m sold on the benefits.
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Post by TheMooN on Apr 8, 2018 11:11:49 GMT
W Directionality seems to be common to us all. Bonkers to me at least, but always worth swapping around to check Amen. I’m very glad I put them in one at a time and made the necessary adjustments then, or I’d have driven myself mad with the guess work! I could replace the four fuses in my amp with these bad boys too, but they’re not cheap... As a much less spendy option I would recommend swapping out just the master fuse on the mains current rail, an easy task should your amp sport an rear plate mounted fuse holder? MOD: not necessary, let's leave the personalities out of it. You have each given as good as you got. |
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Post by Deleted on Apr 8, 2018 11:23:21 GMT
Amen. I’m very glad I put them in one at a time and made the necessary adjustments then, or I’d have driven myself mad with the guess work! I could replace the four fuses in my amp with these bad boys too, but they’re not cheap... As a much less spendy option I would recommend swapping out just the master fuse on the mains current rail, an easy task should your amp sport an rear plate mounted fuse holder? Fair suggestion, but the Magtech is slightly unusual in that there are two fuses per side, accessible on the back of the amp (one for left and likewise right). I’m assuming that this is because it’s so powerful an amp (500W RMS). What I might do is leave it alone (it’s already decked out with hifi tuning supreme - so not shabby already!) because I know it’s not my ‘amp for life’. |
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Post by TheMooN on Apr 8, 2018 11:39:38 GMT
Ahhhhhh. However you could conduct an quick n dirty subjective test by temporarily Blueing up one Chanel ? Even easier to make a comparison should your pre sport a Chanel balance facility.
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Post by MartinT on Apr 8, 2018 12:18:51 GMT
I’m assuming that this is because it’s so powerful an amp (500W RMS). Not really, it's more a case of how much damage does the designer want down the line if the customer short-circuits an output or an output transistor fails while it's under warranty. Fuses blow slowly so they'll only do it to stop the whole thing from smoking. On the other hand, fuses in power rails will slightly limit dynamics under big current swings. I remember the Magtech being slightly limited dynamically when I compared it to the Chord some years ago. No shortage of power, though. |
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Post by TheMooN on Apr 8, 2018 15:55:40 GMT
A little lite reading...
"At low frequencies the audio signal can heat up and cool down the fuse element within a single cycle, causing the resistance of the fuse to vary as a function of the signal amplitude. This leads to distortion because the attenuation of the fuse resistance against the load impedance changes as a function of signal swing [5]. Fuses are often undersized with respect to the peak audio current they may be called on to pass, recognizing that a smaller fuse will provide relatively more protection and that with normal audio signals, such high currents are brief events much shorter than the time constant of the fuse element. The cold resistance of a 2-A 3AG fuse was measured to be 78 mΩ, while its resistance when passing 2-A DC was 113 mΩ. This represents a 45% increase in fuse resistance.
The distortion of a fuse can be measured by looking at the voltage across the fuse with a sinusoidal signal current passing through it. The fuse under test is put in the ground leg of an 8-Ω load resistor so that the signal voltage across the fuse can be easily analyzed. This technique largely takes the distortion of the driving source out of the picture. Figure 13.4a is a plot of fuse distortion versus frequency when a 2-A fast-blow 3AG fuse is passing a 2-A RMS sine wave signal. As expected, fuse distortion increases dramatically at low frequencies. Signal voltage across the fuse was 250 mV. Amplifier THD (due to the fuse) is calculated by normalizing the fuse distortion voltage to the amplifier output voltage. The resulting amplifier distortion is shown in Figure 13.4b. Amplifier distortion is lower than fuse distortion by a factor of 64 because of the small voltage across the fuse compared to the total signal voltage. At 20 Hz, amplifier distortion due to the fuse is calculated to be 0.0033%."
Other relevant papers:
Amplifier-Loudspeaker Interfacing
Author: Greiner, Richard A.
Affiliation: Department of Electrical Engineering, University of Wisconsin, Madison, WI,
JAES Volume 28 Issue 5 pp. 310-315; May 1980
Publication Date: May 1, 1980
"Ideally the fuses used in the output current circuit would be linear resistors as well. However, since Fig. 4. Reproduction of an oscilloscope trace showing that they have to get hot (and melt) to burn out, they are actually out cycle for a fuse with a 20-Hz signal large enough to cause nonlinear elements in the output circuit. If fuses are to be burnout in about 0.8 s.
The substantial change in the slope of the V-I curve shown indicates a large resistance change with heating useful, they must blow out when the system is used at some of the fuse element. specified power level over the maximum desired. Typically, a fuse will increase in resistance to about 3 or 4 times its cold value just short of burnout. At 60% of full load it bursts just short of fuse burnout.
Typical measured modulawill increase to about twice its cold value. A typical fuse tion of a high-frequency signal when pulsed with tone blow-out cycle is shown in Fig. 4. The resistance change bursts that are set at 60% of burnout are shown in Fig. 5. per cycle is clearly evident. The calculations and measure- This figure shows the oscilloscope trace of a 5-kHz signal merits of this section show some possible problems with modulated by 20-Hz tone bursts. The tone bursts have been distortion caused by these changes in the fuse during normal filtered out to show only the 5-kHz modulated signal.
The program reproduction, heating and cooling cycle of the fuse is clearly visible. The Using the simple circuit of Fig. 3, it can be shown that for time constants of typical fuses are such that this heat, and a typical regular speed fuse, of the tubular type, the distortion- consequently resistance, cycling can take place for normal distortion produced could reach the values shown in Table 6. musical beats at low frequencies. To minimize interaction These figures represent intermodulation distortion for any of this type across the frequency spectrum, it would seem frequency when the output circuit is pulsed with power wise to provide separate fuses for each frequency range of a multiway system.
Fast blow fuses are worse than regular fuses since they change temperature 10 times more quickly. There is no solution to this problem except over fusing or putting inside of a feedback loop. This can be done, of course, by putting the using fuses at all, unless the fuses are included within the fuses in the power supply bus or even within the normal -- feedback loop."
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Post by MartinT on Apr 8, 2018 17:18:53 GMT
I've been saying that fuses are non-linear thermal resistors for a long time.
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Post by DaveC on Apr 8, 2018 21:51:05 GMT
I can't find the original source to the top citation, but I do have the AES paper on the second. It relates to putting fuses in series with the loudspeaker !!! Yes really ! And the actual words are :
There is no solution to this problem except overfusing or not using fuses at all, unless the fuses are included within the feedback loop. This can be done of course by putting the fuse in the power supply bus......
Which of course is exactly where they are, no one would be stupid enough to consider putting a fuse in series with the loudspeaker !!
The diagram showing the non-linearity of fuses, is though fascinating, and was alluded to recently by Nick Gorman.
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Post by nrg on Apr 9, 2018 7:51:32 GMT
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