Need a little advice on some AR Mono Block Amplifiers...and Speaker wires

Mikado463

Mikado463

Audioholic Spartan
So separate phono pre vs RIAA stages? Weird.
no, the phono 'input' is just that, an input. RIAA staging, loading, etc is all accomplished within the phono-pre. This allows for much greater flexibility than what would be accomplished in 'one box'. As MC cartridges have become the popular choice over the past 20-30 years this makes total sense.
 
lovinthehd

lovinthehd

Audioholic Jedi
no, the phono 'input' is just that, an input. RIAA staging, loading, etc is all accomplished within the phono-pre. This allows for much greater flexibility than what would be accomplished in 'one box'. As MC cartridges have become the popular choice over the past 20-30 years this makes total sense.
Some of the fancier pre amps also accommodated both MM and MC cartridges, or you could use an external stage. Just to have an input labeled phono and it being a line input doesn't make a lot of sense to me, but much vinylphilia escapes me :)
 
-Jim-

-Jim-

Audioholic Field Marshall
Gents, when reviewing your comments above I started reviewing the Audio Research Reference Phono Preamplifier Manual (see previous link if you want to read it in your spare time :rolleyes: ).

It advises setting inputs based on the mv output of the Phono Cartridge (rather than Phono Cartridge type?) and offers 3 settings for Gain starting with:

Lowest Gain 42dB-optional factory wiring when the Phono Cartridge Output is 4.0 -6.0 mv
Low Gain 48 dB- when the Phono Cartridge Output is 0.4 -3.0 mv
Highest Gain 69dB- when the Phono Cartridge Output is 0.05 - 0.3 mv

As I was typing the details above from the manual into this post, I realized the 3rd column directs those who own the "Ref 1" (which I assume is the Audio Research Reference 1 Preamplifier) to use the Aux 1 input on it has 3dB attenuation when compared to the other ARC Ref 1 inputs.

AR REF Phono Preamp Settings.jpg


This solves the mystery as to why the Phono Preamp is connected to the Aux 1 inputs on the Reference 1 Preamplifier. I am at a loss as to why AR would design the output of the Phono Preamp to be so "hot" it needs 3dB attenuation when plugged into their Ref 1 Preamp but not their other preamplifiers.

Is this weird or is it just me...
 
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Mikado463

Mikado463

Audioholic Spartan
Jim, my take is and I'm assuming there is a switch on the back so as to set one of the three 'gain settings' ? If so it would be to correlate with output of cartridge. Moving Magnet/Iron having the highest output and Moving Coil typically being either low output(.5 mv or less) or high output(.9 mv or greater). Cartridge loading would be a fixed value I presume.

Regardless, as I said prior an outboard phono-pre offers far greater flexibility to optimize ones cartridge set up
 
-Jim-

-Jim-

Audioholic Field Marshall
Mikado, yes there's a combination of switches and different RCA inputs. They also offer the ability to fine tune Input Impedance by soldering in supplied precision "audiophile grade" load resistors into the chassis. Non-standard load resistor values are also offer upon request for a US $10.00 fee. They also have instruction on how adjust the capacitance if 180 picofarads in unsuitable for your moving magnet cartridge.

Certainly the separate phono preamp give lots of flexibility for those with Turntables. I still don't get the Aux 1 input concept though. :confused:
 
-Jim-

-Jim-

Audioholic Field Marshall
lovinthehd, as I stated in post #83 above (without the chart this time):

"As I was typing the details above from the manual into this post, I realized the 3rd column directs those who own the "Ref 1" (which I assume is the Audio Research Reference 1 Preamplifier) to use the Aux 1 input on it has 3dB attenuation when compared to the other ARC Ref 1 inputs.

This solves the mystery as to why the Phono Preamp is connected to the Aux 1 inputs on the Reference 1 Preamplifier. I am at a loss as to why AR would design the output of the Phono Preamp to be so "hot" it needs 3dB attenuation when plugged into their Ref 1 Preamp but not their other preamplifiers.

Is this weird or is it just me... "
 
lovinthehd

lovinthehd

Audioholic Jedi
lovinthehd, as I stated in post #83 above (without the chart this time):

"As I was typing the details above from the manual into this post, I realized the 3rd column directs those who own the "Ref 1" (which I assume is the Audio Research Reference 1 Preamplifier) to use the Aux 1 input on it has 3dB attenuation when compared to the other ARC Ref 1 inputs.

This solves the mystery as to why the Phono Preamp is connected to the Aux 1 inputs on the Reference 1 Preamplifier. I am at a loss as to why AR would design the output of the Phono Preamp to be so "hot" it needs 3dB attenuation when plugged into their Ref 1 Preamp but not their other preamplifiers.

Is this weird or is it just me... "
Ah, didn't see that copy of the manual page pop up before or I just clicked on last post instead of newest post....but don't see how that clears anything up myself. Just seems a bit confusing....
 
-Jim-

-Jim-

Audioholic Field Marshall
Well it told you to plug the phono preamp into the Aux 1 input in the preamp; which is the way my friends system was setup. The problem is it doesn't tell you why.
 
lovinthehd

lovinthehd

Audioholic Jedi
Well it told you to plug the phono preamp into the Aux 1 input in the preamp; which is the way my friends system was setup. The problem is it doesn't tell you why.
Well, if one would normally consider the use of the internal phono stage as the "phono" input and any other with an external phono stage via an aux input :) as is the general norm......but don't know about this AR outfit but haven't perused the manual for their pre-amp nor phono stage....
 
Mikado463

Mikado463

Audioholic Spartan
-Jim-

-Jim-

Audioholic Field Marshall
Yes, that was the conundrum.

One manual says the connection should go to Phono, and the other to Aux 1. But the table in the Phono Preamp manual explicitly directs the user to plug it into Aux 1 => if you are using the Audio Research Reference 1 Preamplifier regardless of Cartridge. So I'm interpreting that to override the direction given in the ARC Ref 1 Preamp manual.

It doesn't make a lot of sense to me to build an expensive system with a matching phono preamp with such a high output it needs to go into an attenuated input (Aux 1) in all cases regardless of the phono cartridge chosen. But it is what it is. And I guess more importantly it works. I'm suggesting my friend put a label over the Aux 1 so he & his wife won't get confused again.

By the way all of the AR manuals are available in the link in my post #75 above.
 
lovinthehd

lovinthehd

Audioholic Jedi
Yes, that was the conundrum.

One manual says the connection should go to Phono, and the other to Aux 1. But the table in the Phono Preamp manual explicitly directs the user to plug it into Aux 1 => if you are using the Audio Research Reference 1 Preamplifier regardless of Cartridge. So I'm interpreting that to override the direction given in the ARC Ref 1 Preamp manual.

It doesn't make a lot of sense to me to build an expensive system with a matching phono preamp with such a high output it needs to go into an attenuated input (Aux 1) in all cases regardless of the phono cartridge chosen. But it is what it is. And I guess more importantly it works. I'm suggesting my friend put a label over the Aux 1 so he & his wife won't get confused again.

By the way all of the AR manuals are available in the link in my post #75 above.
Are there specs listed in these manuals for the relative inputs/outputs?
 
-Jim-

-Jim-

Audioholic Field Marshall
On page 5 on the ARC Ref 1 Preamp manual there are limited specs but not broken down by output/input. Similarly data is on on page 6 of the ARC Phono Preamp manual but as it deals with only one signal it's more relevant.
 
Swerd

Swerd

Audioholic Warlord
I caught up with this thread this morning. My general response is EEEEK!!!

Recently, you mentioned that his amp failures seem to happen most often (90% of the time?) while playing vinyl records. Does he play records 90% of the total time he operates his system? As a result, this thread has moved on to talk about phono pre-amps and RIAA equalization for moving coil phono pickups. My question is does this really have anything to do with the frequent failure of a power amplifier?

What else has your friend modified, or done to alter his system from standard practices and principles? This is as bad as reading Dante's Inferno was for me as a freshman in college. How many Inner Circles of Hell do we have to discover before your friend's problem is solved?

First it was miserable speaker impedance. That seems to have been put aside now that those speakers were identified as X-1 Grand Slamm speakers, not Maxx speakers. However, I'm not yet confident that the X-1s are a benign load. Wilson Audio has a bad record on that. I also note that the review's measurements were signed by Martin Collums and not by John Atkinson. Atkinson has a long record of reliable measurements of speakers. If nothing else, they allow easy comparison among different speakers. Collums may be better known as long-winded reviewer, but I'm not familiar with his skills at measuring the performance of loud speakers. I don't know if his measurements can be compared with those of other speakers.

But reading this thread has revealed so much more.
  • 30 minute warm up for vacuum tubes? 3 minutes should be more than enough. Under 1 minute is probably just fine. I never heard of any electronic gear, audio or otherwise, that would blow-up if not warmed up enough. The voltage output of cool tubes might fluctuate a bit during that first minute, but that comes nowhere near causing total failure – 14 times!
  • Why in the world does your friend have 30' long cables between the pre-amp and the amplifier? That's much longer than from his amp to his speakers! If anything, it should be the other way around. The voltage between the amp and speakers is much higher than between the pre-amp and amp. I don't think that would cause the amp to fail, but I have to wonder what he was thinking.
  • All those MIT cables, with their mysteriously shrouded boxes, should be disconnected, dismembered, and burned.
  • RF from his multi-camera security system? Highly unlikely, as -Jim- said. But there's an easy test. Turn the security system off including all the cameras, and test the audio system. I'd bet there is no audible difference. I don't believe RF from remote wireless (?) cameras is related to the problem.
  • RF from passing boat's radios? Seriously? This is getting like worrying if your aluminum foil hat provides enough shielding for your brain. Does your friend also insist that you switch off your cell phone, and leave your car keys outside before you enter his house? (Do yourself a favor, and do not mention these RF emitters to him.)
@-Jim- You've been more than patient with your friend. He may have been a very good mechanical engineer, but he's in way over his head with his home audio system. I'm afraid he doesn't need an electronic repairman or diligent trouble shooter. He needs an intervention.
 
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-Jim-

-Jim-

Audioholic Field Marshall
I caught up with this thread this morning. My general response is EEEEK!!!

Recently, you mentioned that his amp failures seem to happen most often (90% of the time?) while playing vinyl records. Does he play records 90% of the total time he operates his system? As a result, this thread has moved on to talk about phono pre-amps and RIAA equalization for moving coil phono pickups. My question is does this really have anything to do with the frequent failure of a power amplifier?

What else has your friend modified, or done to alter his system from standard practices and principles? This is as bad as reading Dante's Inferno was for me as a freshman in college. How many Inner Circles of Hell do we have to discover before your friend's problem is solved?

First it was miserable speaker impedance. That seems to have been put aside now that those speakers were identified as X-1 Grand Slamm speakers, not Maxx speakers. However, I'm not yet confident that the X-1s are a benign load. Wilson Audio has a bad record on that. I also note that the review's measurements were signed by Martin Collums and not by John Atkinson. Atkinson has a long record of reliable measurements of speakers. If nothing else, they allow easy comparison among different speakers. Collums may be better known as long-winded reviewer, but I'm not familiar with his skills at measuring the performance of loud speakers. I don't know if his measurements can be compared with those of other speakers.

But reading this thread has revealed so much more.
  • 30 minute warm up for vacuum tubes? 3 minutes should be more than enough. Under 1 minute is probably just fine. I never heard of any electronic gear, audio or otherwise, that would blow-up if not warmed up enough. The voltage output of cool tubes might fluctuate a bit during that first minute, but that comes nowhere near causing total failure – 14 times!
  • Why in the world does your friend have 30' long cables between the pre-amp and the amplifier? That's much longer than from his amp to his speakers! If anything, it should be the other way around. The voltage between the amp and speakers is much higher than between the pre-amp and amp. I don't think that would cause the amp to fail, but I have to wonder what he was thinking.
  • All those MIT cables, with their mysteriously shrouded boxes, should be disconnected, dismembered, and burned.
  • RF from his multi-camera security system? Highly unlikely, as -Jim- said. But there's an easy test. Turn the security system off including all the cameras, and test the audio system. I'd bet there is no audible difference. I don't believe RF from remote wireless (?) cameras is related to the problem.
  • RF from passing boat's radios? Seriously? This is getting like worrying if your aluminum foil hat provides enough shielding for your brain. Does your friend also insist that you switch off your cell phone, and leave your car keys outside before you enter his house?
@-Jim- You've been more than patient with your friend. He may have been a very good mechanical engineer, but he's in way over his head with his home audio system. I'm afraid he doesn't need an electronic repairman or diligent trouble shooter. He needs an intervention.
Thanks for the post @Swerd .

The 90% failure rate when listening to vinyl does seem to be the typical listening mix, so no smoking gun found there. I was looking to hear something like it always occurs when playing CDs, or Vinyl, etc., for guidance as to the root cause. (I only planned to replaced the MIT Cables in the phono pathway (including the speaker cables) to get proof of concept that the cables could be the source of the problem. When disconnecting those to get length measurements, my friend specifically asked me to replace the balanced interconnect between the Mark Levinson CD transport controller and the ARC Ref 1 Preamp as well - so I did that too.)

The issue with Phono Preamps has been resolved. Overall my friend's memory on how / why the stereo was installed isn't as good as it once was, so I've been trying to analyze and setup the system taking his verbal (non documented) input with a large grain of salt. Some of the problem is the poorly done manuals from AR, and some verbal input from those who sold him the system many moons ago, and his security system tech.

The only "mods" to the system were the installation of the MIT Cables (both interconnect & speaker) some time after the system was setup by the Sound Room and the X-1 Grand Slamm Speakers by Wilson. As best as I can tell the cables were installed by someone at the Sound Room after the Grand Slamms were field modified to Rev2 by Wilson. All of this was sometime about 20 years ago.

I have no knowledge how we got on the wrong track with the speaker model, and for that I've apologized. But at least that too is sorted now. And although the Grand Slamms aren't a perfect 8 ohm speaker by definition, they are no way are imperfect as the Maxxs' seem to be. All I can hope on the Stereophile reviews, is they peer review their articles before publishing the data. The verbal diarrhea by the author of the Grand Slamm review was far too "enhanced" for my liking. But maybe that was the accepted norm for same those many moons ago.

The 30 minute warm up was to please my friend. He actually wanted longer but I pointed out the AR Ref 600 Amp manual designates 5 minutes.

I originally thought the Balanced Cable length between the AR Ref 600 Amp and Preamp was excessive too, but the manual advises to keep your speaker cable runs as short as possible from the Amps. According to some photos of other Tube Systems I've seen this is a typical layout where the Amps reside between the speakers with the input equipment off to one side. I'd guess the speaker cables are 8 to 10 feet long max. Pro Audio equipment (real pro stuff) has no issue with 30 foot Balanced Cable lengths. Concerts often have multiple cables in giant reel boxes that weigh 250+ pounds that are on wheels for deployment for runs many times longer than 30 feet.

The MIT Cables were left on the floor for my friend to decide what he wants to do with them. He mumbled something about sending them to MIT for repair, but I gave him the evil eye when he said that. I said before you toss them out, I'd like to cut open one or two of the boxes to see what's really inside. I'm hoping the replacement cables I installed solve the problem and he no longer sees any value in any MIT Cables.

The RF concerns were folks grasping for anything they could think of as a possible cause. My friend did advise he's been removing the batteries from these sensors just in case. (There are about 30 around his house and I have no idea as to how many are still "active".) I didn't bother to comment back. I did point out to him the Cables I selected were all using Mogami 2534 cable which did address any RF & EM interference if those were contributing factors in addition to any component failures inside the boxes on the MIT Cables.

As per my post previously: "Mogami Neglex quad cable is perfect cable for home studios suffering from wiring and grounding problems. Mogami 2534 should also be used where intense RFI interference is a problem. Mogami 2534 provides an improvement in signal to noise of 10-20db over equivalent twisted pair cables. Double conductors quad cables are more effective in canceling noise that can get past even the best of shields and is critical in an environment of high RF and EM interference."

Actually my friend is very pleased with my efforts. He called me last night to see if I want to go salmon fishing sometime this week near Bowen Island. (He owns a 40 foot Cabo Sportsfisher which is down at the dock. - His house is seaside by Deep Cove.) I said yes, in part because it may be the last time I'll be on it fishing. He's been talking of it being too much for him to deal with these days (I agree). Another friend of his is talking about buying it soon.
 
Swerd

Swerd

Audioholic Warlord
All those seem like sensible things to do. Thanks for the update.
The 90% failure rate when listening to vinyl does seem to be the typical listening mix, so no smoking gun found there. I was looking to hear something like it always occurs when playing CDs, or Vinyl, etc., for guidance as to the root cause. (I only planned to replaced the MIT Cables in the phono pathway (including the speaker cables) to get proof of concept that the cables could be the source of the problem. When disconnecting those to get length measurements, my friend specifically asked me to replace the balanced interconnect between the Mark Levinson CD transport controller and the ARC Ref 1 Preamp as well - so I did that too.)
I have trouble imagining how a cable connecting any audio source to a pre-amp could cause such trouble as amp failure. In fact, I can't imagine how using balanced connections (assuming that the electronic items in question have the circuitry to make fully balanced connections possible) could matter. As far as I understand, fully balanced connections are needed for very low output items, such as microphones, where they will have long cables. The output for most microphones is in the range of 1.3-3.2 mV, whereas the output of most audio sources (line level), such as CD players, is in the range of 100-200 mV. Moving magnet record player pick ups do have a low voltage output of 4-5 mV, similar to microphones, and moving coil pick ups are even lower, as much as 10-fold lower. But I have never seen a turntable/pick up with a balanced connection. If I understand correctly, record player pick ups are not balanced sources. Just the same, I have much less trouble using relatively inexpensive 3-conductor balanced (XLR type) cables instead of those mysterious voodoo filled MIT cables.
I have no knowledge how we got on the wrong track with the speaker model, and for that I've apologized. But at least that too is sorted now. And although the Grand Slamms aren't a perfect 8 ohm speaker by definition, they are no way are imperfect as the Maxxs' seem to be. All I can hope on the Stereophile reviews, is they peer review their articles before publishing the data. The verbal diarrhea by the author of the Grand Slamm review was far too "enhanced" for my liking. But maybe that was the accepted norm for same those many moons ago.
Audio magazines or online publications often do submit their review articles to the manufacturers of the product before publishing. But, to my knowledge, no one sends their reviews out for independent peer review. The amount of verbal diarrhea in these reviews is usually directly proportional to the selling price of the item. Stereophile is among the worst in that regard. If I look at a Stereophile review, I skip the turgid prose, and go straight to the measurements. John Atkinson's measurements are reliable indicators of a speaker's sound quality, however his words accompaning those measurements tend to soft pedal any flaws in a speaker. The other source of reliably done speaker measurements is the Canadian National Research Council, published online as SoundStageNetwork!.
The 30 minute warm up was to please my friend. He actually wanted longer but I pointed out the AR Ref 600 Amp manual designates 5 minutes.
I can only offer this anecdote about tube warm up time. I worked many years in biochemistry labs. A common tool was a ultraviolet spectrophotometer. It uses a source of UV light, passes it through a narrow grating to get a very narrow range of wavelengths, and passes that light though a biochemical solution to see what wavelengths get absorbed and by how much. The source of UV light was a lot like a vacuum tube but it was filled with deuterium gas. When the filament gets hot, the gas emits UV light. So they have to warm up to work. Typically, we let it warm up about 10 minutes in the morning and left it on all day. Some perfectionists wouldn't use them until they warmed up as much as 30 minutes.

At one point, I got a new spectrophotometer that had lots of digital bells & whistles, but it still used a tube filled with deuterium as a light source. There was even a temperature sensor at the light source. The spectrophotometer sent out all it's measurements as data points in a spreadsheet file. If you wanted to look, you could monitor the light source's filament temperature as soon as you powered it up. I distinctly remember seeing how it finished warming up to a stable running temperature in less than a minute.
I originally thought the Balanced Cable length between the AR Ref 600 Amp and Preamp was excessive too, but the manual advises to keep your speaker cable runs as short as possible from the Amps. According to some photos of other Tube Systems I've seen this is a typical layout where the Amps reside between the speakers with the input equipment off to one side. I'd guess the speaker cables are 8 to 10 feet long max. Pro Audio equipment (real pro stuff) has no issue with 30 foot Balanced Cable lengths. Concerts often have multiple cables in giant reel boxes that weigh 250+ pounds that are on wheels for deployment for runs many times longer than 30 feet.
I've heard of those recommendations before, and I think they are worse than silly, they're backwards. It wouldn't be the first time that audiophiles (or other contrarians) oppose common sense in an effort to be noticed.

Let's go back to signal voltage levels in a typical audio system. If a typical sound source (line level) signal level is 100-200 mV, after a pre-amp (pre-amp level) those voltages are in the range of 0.1-10 V. After amplification those signal voltages are again increased by another 10-fold, or more. Those lower line level and pre-amp level voltages are much more prone to EMI/RFI interference than amp level voltages. That's why those interconnect cables (RCA or XLR) are shielded. To me, it makes much more sense if the low voltage signals go through short cables and the high voltage signals run through longer cables, as needed. I've never heard or read a reasonable justification for doing the opposite.
The MIT Cables were left on the floor for my friend to decide what he wants to do with them. He mumbled something about sending them to MIT for repair, but I gave him the evil eye when he said that. I said before you toss them out, I'd like to cut open one or two of the boxes to see what's really inside. I'm hoping the replacement cables I installed solve the problem and he no longer sees any value in any MIT Cables.
If you get a chance to look inside one of those MIT boxes, crack off all the gorp they slathered in it and take a photo. I've heard they're nothing but some caps and coils, and maybe a resistor. Why would an audio cable have passive filters? I and many others suspect that Wilson speakers suffer from poorly designed passive crossovers. How could adding more filters upstream improve them? These filters were MIT's one size fits all solution to an unknown problem. None of them are custom made for the owner's speakers. It's more likely a method of siphoning funds from purchasers.
The RF concerns were folks grasping for anything they could think of as a possible cause. My friend did advise he's been removing the batteries from these sensors just in case. (There are about 30 around his house and I have no idea as to how many are still "active".) I didn't bother to comment back. I did point out to him the Cables I selected were all using Mogami 2534 cable which did address any RF & EM interference if those were contributing factors in addition to any component failures inside the boxes on the MIT Cables.

As per my post previously: "Mogami Neglex quad cable is perfect cable for home studios suffering from wiring and grounding problems. Mogami 2534 should also be used where intense RFI interference is a problem. Mogami 2534 provides an improvement in signal to noise of 10-20db over equivalent twisted pair cables. Double conductors quad cables are more effective in canceling noise that can get past even the best of shields and is critical in an environment of high RF and EM interference."
If RFI or EMI is a problem in an audio system, it is easily heard. More often, it isn't a problem. As I mentioned earlier, all cables meant for low voltage signals, RCA or XLR interconnects, are shielded. Speaker cable, downstream from the amp, does not require it. Shielding shouldn't hurt anything, but I've never encountered a need for it in home audio.
 
Mikado463

Mikado463

Audioholic Spartan
Also in agreement with you guys on the exaggerated 'warm up' time for components, tube or SS. Some crazies believe 24 hrs for their SS amps, I don't get it ?? I do use a tube phono pre and a tube line stage with balanced XLR between line stage and my SS power amps. It's a run of about 12-13'.

By the time I've fired up my rig, poured a dram of my favorite whisky, lowered the tone arm, all is good !
 
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-Jim-

-Jim-

Audioholic Field Marshall
All those seem like sensible things to do. Thanks for the update.


I have trouble imagining how a cable connecting any audio source to a pre-amp could cause such trouble as amp failure. In fact, I can't imagine how using balanced connections (assuming that the electronic items in question have the circuitry to make fully balanced connections possible) could matter. As far as I understand, fully balanced connections are needed for very low output items, such as microphones, where they will have long cables. The output for most microphones is in the range of 1.3-3.2 mV, whereas the output of most audio sources (line level), such as CD players, is in the range of 100-200 mV. Moving magnet record player pick ups do have a low voltage output of 4-5 mV, similar to microphones, and moving coil pick ups are even lower, as much as 10-fold lower. But I have never seen a turntable/pick up with a balanced connection. If I understand correctly, record player pick ups are not balanced sources. Just the same, I have much less trouble using relatively inexpensive 3-conductor balanced (XLR type) cables instead of those mysterious voodoo filled MIT cables.


Audio magazines or online publications often do submit their review articles to the manufacturers of the product before publishing. But, to my knowledge, no one sends their reviews out for independent peer review. The amount of verbal diarrhea in these reviews is usually directly proportional to the selling price of the item. Stereophile is among the worst in that regard. If I look at a Stereophile review, I skip the turgid prose, and go straight to the measurements. John Atkinson's measurements are reliable indicators of a speaker's sound quality, however his words accompaning those measurements tend to soft pedal any flaws in a speaker. The other source of reliably done speaker measurements is the Canadian National Research Council, published online as SoundStageNetwork!.
I can only offer this anecdote about tube warm up time. I worked many years in biochemistry labs. A common tool was a ultraviolet spectrophotometer. It uses a source of UV light, passes it through a narrow grating to get a very narrow range of wavelengths, and passes that light though a biochemical solution to see what wavelengths get absorbed and by how much. The source of UV light was a lot like a vacuum tube but it was filled with deuterium gas. When the filament gets hot, the gas emits UV light. So they have to warm up to work. Typically, we let it warm up about 10 minutes in the morning and left it on all day. Some perfectionists wouldn't use them until they warmed up as much as 30 minutes.

At one point, I got a new spectrophotometer that had lots of digital bells & whistles, but it still used a tube filled with deuterium as a light source. There was even a temperature sensor at the light source. The spectrophotometer sent out all it's measurements as data points in a spreadsheet file. If you wanted to look, you could monitor the light source's filament temperature as soon as you powered it up. I distinctly remember seeing how it finished warming up to a stable running temperature in less than a minute.
I've heard of those recommendations before, and I think they are worse than silly, they're backwards. It wouldn't be the first time that audiophiles (or other contrarians) oppose common sense in an effort to be noticed.

Let's go back to signal voltage levels in a typical audio system. If a typical sound source (line level) signal level is 100-200 mV, after a pre-amp (pre-amp level) those voltages are in the range of 0.1-10 V. After amplification those signal voltages are again increased by another 10-fold, or more. Those lower line level and pre-amp level voltages are much more prone to EMI/RFI interference than amp level voltages. That's why those interconnect cables (RCA or XLR) are shielded. To me, it makes much more sense if the low voltage signals go through short cables and the high voltage signals run through longer cables, as needed. I've never heard or read a reasonable justification for doing the opposite.
If you get a chance to look inside one of those MIT boxes, crack off all the gorp they slathered in it and take a photo. I've heard they're nothing but some caps and coils, and maybe a resistor. Why would an audio cable have passive filters? I and many others suspect that Wilson speakers suffer from poorly designed passive crossovers. How could adding more filters upstream improve them? These filters were MIT's one size fits all solution to an unknown problem. None of them are custom made for the owner's speakers. It's more likely a method of siphoning funds from purchasers.
If RFI or EMI is a problem in an audio system, it is easily heard. More often, it isn't a problem. As I mentioned earlier, all cables meant for low voltage signals, RCA or XLR interconnects, are shielded. Speaker cable, downstream from the amp, does not require it. Shielding shouldn't hurt anything, but I've never encountered a need for it in home audio.
@Swerd I wasn't too concerned about the connection of components Preamp except if they were MIT Cables with Boxes on them. My premise is something in those Boxes could have failed, or intermittently fails during use. Remember I wanted a "clean" cable pathway from source to the Speakers. The Turntable output is via RCA Cables into the Phono Preamp. (No Balance Cable Option.) As found those MIT RCA Cables had Boxes on them - so I replaced them as I mentioned above.

By the way, a lot of high end Audio Equipment has both Balanced and Unbalanced (RCA) points for connection. (Nothing I own of course...)

As for the cable length, I too like to keep the interconnects short and have the amplifier feed longer speaker runs. But the AR manual states otherwise, and the original installation of the system, and speakers, was done by expensive labor from the Sound Room & Wilson. My friend and his wife like the layout (they had the room designed for this system and decorated specifically for it). They had special independent power circuits run during construction to feed each Amp, and other circuits pulled in just for the components. I was not going to challenge this over such a minor concern; especially after I found a decent Balanced Cable Spec that I think overcomes it.

I'm keeping my fingers crossed that I don't hear of any problems for a few years.
 
-Jim-

-Jim-

Audioholic Field Marshall
Hi Gents,

I just thought I'd update you on this project after almost 3 years of operation. My Buddy has not had any failures since my efforts to replace the MIT cables.

As my Grandfather used to say: "The proof is in the pudding". ;)
 

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