Should all interconnects and speaker cable be from same manufacturer?

[barrows]

My understanding has always been that the wide bandwidth undamped circuits of Spectral gear required the damping networks in the cables for the circuitry to stay stable. I thought current Spectral warranty requires the use of MIT or Spectral cables with damping networks?

Are you sure the output stages were not oscillating when used with other cables and a reactive speaker load?

In any case, Spectral gear is a special situation. I have not heard of another audio manufacturer ever recommending a specific brand of cables to be used with their gear.

I am now curious as to my understanding of the Spectral situation and will try and look up the details.

 

 

[Jud]

...may have it right on this one. While Spectral does say MIT cables are required with amps not designated "Universal" or the warranty will be void, and they give a technical reason for it similar to what you describe, I think the out of control situation is something Spectral says *can* happen if you use other cables (and thus they won't extend the warranty to cover such situations), rather than that their amps *will* inevitably go out of control without MIT cables.

 

[barrows]

I found this on their site:

 

"MH-750 Ultralinear CVTerminator Series II Speaker Interface • This specialized interface includes MIT Terminator technology optimized for the ultralinear, high-speed requirements of Spectral components, and provides increased clarity, more natural image focus and improved low-frequency weight and extension. Spectral amplifiers are not warranted for use with speaker cables other than MIT. The 750 Ultralinear CVTerminator Series II represents the basic speaker cable requirement for Spectral amplifiers."

 

Whether or not an amplifier will fail running in an underdamped condition will be highly dependent on the speaker load as well. So some cables may work fine with some speakers, and some cables may allow oscillations with some speakers. And some cable and speaker combinations may cause the amp to fail.

I would be wary of operating an expensive amplifier under conditions which are not covered by the warranty personally. Most amplifiers are damped on their outputs as necessary to be compatible with all/most cables and speakers, Spectral does not do this.

 

[esldude]

With earlier Spectral gear I have used or owned they also had similar warnings. I have used a number of non-approved items with never a problem. At first I checked it with an O-scope, but never saw anything amiss in the resulting output.

 

This does sound similar to an interview with someone from Spectral who said they preferred to let the cables provide or control the roll off of the system response. Though Demian Martin who designed those electronics for Spectral wrote that wasn't in his mind when designing them. Perhaps he can weigh in on this.

 

I always had the idea MIT cables had high capacitance. I did use the Spectral into an ESL which itself is somewhat a capacitive load so maybe my results would have been different with other speakers.

 

The description of the approved cables at MIT says the network gives multiple poles for extended frequency response. That doesn't really jibe with extra capacitance. Might be shunt peaking coils that Mr. Martin mentioned. Or it could be little more than marketing speak to make you think something wonderful is in those boxes. At one time were some views inside the boxes and there were I believe a cap, resistor and coil. MIT has at times called them a low pass filtered cable. Which also doesn't jibe so well with extending the frequency response. Does sound like having at least two poles of roll off so the cable determines roll off and not the wide bandwidth Spectral amp.

 

Given the wide impedance variation in speakers such terminating networks would really need to be adapted for each speaker to be fully effective. But in marketing that would be a much nastier sales job versus magic wonder boxes other cables don't have. I don't have any on hand, it would be fairly trivial to measure what is in the thing and what it does electrically.

 

[barrows]

inside of MIT boxes, as I recall they were mostly RC networks, but maybe some of the higher end ones also had inductors. I always thought it was a weird thing to do, as these networks should be tuned for the entire circuit to make sense at all (circuit: amp output, cable parameters, and speaker load). Applying them universally to all possible amp/speaker combinations did not make any sense to me... Now, at least some of MITs designs have adjustable networks, perhaps switching different combinations of damping circuits in and out to tune the "cable" to the entire circuit.

 

[esldude]

http://www.6moons.com/audioreviews/mit2/shotgun_2.html

 

http://www.mitcables.com/reference-library/mit-cables-technical-whitepapers.html

 

This is the middle of a 6 moons review. Has a picture of what is inside their cables along with something of an explanation. Second link is to white papers they have explaining their approach.

 

Yeah, since my last post I looked over some info which they are more forthcoming with than they once were. I paid little attention to MIT since years ago I thought the several times I heard their IC or speaker cable it made a clear difference. Unfortunately it seemed a negative one in each instance.

 

Apparently Bruce Brisson is attempting to create a low pass Bessel Filter to minimize group delay in the audio band. As time went on he apparently attempts to create multiple roll off poles to create an even group delay and impedance over the audio band. Saying that other cables have too little impedance as frequency goes down. Resulting in highlighting of various frequency bands in the audible range and light weight sound. I did always think their products sounded warmer though in the sense of lost speed and drooping subjective treble response. Such an effect would work to make sure wide band amps don't oscillate or use up power out of the audio band by controlling those out of band loads potentially.

 

He claims cables with over a 100 response poles. Roughly the higher priced their cable the more poles and the better the result. Some are switchable as you mention Barrows. I think they also have SS and Tube versions of the cables. Still such a complex network without taking into account the speakers seems like a crap shoot at best. I do note they once made a complete system of cables meant for use with Avalon Speakers and all Spectral electronics. That seems the way to go if these filtering techniques are truly beneficial.

 

At least their claims are somewhat technically understandable vs the we do magic marketing ploy commonly employed by others. Or the quantum physics explanation of one filter company and maybe a couple cable companies.

 

[Harpy]

What about XLR balanced connections. Would they be superior to the more standard RCA inputs? Would balanced inputs make cables less important?

 

[esldude]

Balanced can help most with long cable runs and lowering common mode noise. In the typical home installation they usually aren't automatically better. Also some equipment makers implement their balanced input and output circuitry better than others. So like so many things, not a clear yes or no. Rather it depends. Though in my opinion it rarely will automatically be better in home audio use.

 

Now if computer equipment is spewing out as many awful EMI signals as some think, that may now make balanced a little better option. I haven't tried it both ways around a PC based audio system. What little I have done with PC based audio (my main source for the last year) I think too much is being made of EMI from the PC. Won't say PC emissions are non-existent or meaningless, I do think they are low down the list of problems. Others will surely disagree.

 

[crisnee]

I've not noticed differences in attack, nor have I listened for them. I'll have to give a listen for it as I'm trying out a few changes. Is it most noticeable in particular sounds/instruments?

 

As to your home made ICs; pretty cool. If your telephone cable wires are very thin like ours (you are in the U.K. right?) it seems like it must have been pretty tricky to terminate them. Did you shield them?

 

-Chris

 

 

 

[barrows]

Components allow for using balanced connections, and are truly balanced in topology, I highly recommend using balanced connections. If an audio designer goes to the trouble of implementing balanced circuitry, there is a good reason for it (performance improvement, lower noise/distortion) and you are not getting what you paid for running true balanced gear single ended.

Yes, the design of the interconnects still matters when running balanced. Remember, cables are lossy components-some are less lossy than others, but there is no perfect cable, and every cable will have some losses.

 

[Paul R]

I think you pegged it to be honest.

 

Perhaps two types of areas, one where there are "discussions" as such and one or more areas that are "publications" - such as FAQs or the blog areas.

 

I would avoid a Wiki like area though. Though Wikipedia is pretty cool, it is anything but definitive or reliable, at least, I don't think it is in my technical areas.

 

Also, it does not hurt to label off topic posts as such- easier to skip them then if someone really is determined to. If I purposely post something off topic, I label it with OT: .

 

-Paul

 

 

 

[esldude]

I wouldn't put too much faith in balanced inputs. I have seen many expensive high end brands implement it with a op-amps providing the extra balanced signal while running everything after in single ended mode. Others have fully balanced topology with those inputs. Using balanced with those is more direct into the amplifier circuit structure. Without knowing the particulars you cannot count on anything. It unfortunately is a case by case decision for one to make.

 

[Mark Powell]

Yes, they are very thin. You have to take care when stripping the insulation or you cut through the very thin strands of the wire. The insulation is fairly hard and tough to cut. They are not shielded, and I don't hear any hum with my ear to the speaker. Useless for the lead from pickup arm to phono amp though.

 

I use 'lightweight mainly plastic RCA connectors as I have a vague belief (and that is all it is) that lots of metal around the cable may be a 'bad' idea. To help prevent breakage with connecting/disconnecting I put heat shrink on each wire before soldering it. Then slide it up and shrink it of course. But they are still rather fragile.

 

I notice the effect most on drums and guitars. The opening guitar note on Johny Cash's 'San Quentin', after he has finished talking is very noticeable.

 

[crisnee]

Thanks for all the info Mark. I may eventually try to make a few ICs ala telephone wire. I like the idea of light flexible, made to length ICs.

 

-Chris

 

[ccclapp]

"Balanced can help most with long cable runs and lowering common mode noise"

 

Without debating the last .00001% of quality, realistically is it reasonable to run 50' balanced bnc between DAC and preamp/amp? I assume the cable selection matters due to length in question. If so, what would be a "reasonable" cable for such purpose.

 

Sorry, as I realize this is a bit off original topic.

 

Thanks

 

[Julf]

50' is not too bad. Of course shorter is better, but remember that the music was probably recorded through cables that long even for low-level mic signals - the line-level signal DAC and amp is less sensitive to noise, so you should be more than OK as long as you use balanced. But I would suggest you use pro studio cables, designed for longer lengths, rather than audiophile cables.

 

Julf

 

 

[barrows]

You will be OK running 50' cables if: The source impedance is low and the input impednace of the next component is high (like 150 ohms or less out to 50-100 Kohms or higher in) and the source component has a well designed output stage with lots of drive capability. You will want to use shielded balanced cables of low capacitance-most audiophile cables will be fine, but do pay some attention to capacitance specs (ask the manufacturer if they do not publish them) and you will probably want to avoid unshielded cables. Unshielded cables can sound better, so, if you want to try some, just make sure that you can return them if they pick up any noise (listen with your ear to the speaker cones).

 

I had a customer once who was running ~50' single ended cables to his amp, under the floor. His amp had single ended inputs only and he ended up picking up too much noise, radio stations, etc. As a last resort I recommended that he try running the cables through a grounded copper tube. He tried it, and the system went dead quiet.

 

[ccclapp]

"The source impedance is low and the input impednace of the next component is high"

 

Source will be balanced analog out from mytekstereo 192 either into lexicon mc12 proc in passthrough mode or directly into theta dreadnaught amp (wanting to serve two zones w caps>mytek)

 

Thanks for the wisdom!!