[rklein]

I have roped another DSD fan.     YES!

Yes...yes you have.... (Sorry  Jason...no more DSD talk in the NCore thread...  )

Randy

[barrows]

http://www.audiocircle.com/index.php?topic=110782.msg1144617#msg1144617

Thanks jt, I have seen Ric's mod.  He removes the terminal, to make room for his cap mod.  I was just wondering if anyone has soldered speaker wiring directly to the existing terminals: removing the screw and compression nut, sticking the wire through the hole in the terminal, and then soldering down to the surface of the terminal.  From looking at it, it appears that this would make a good connection.  Just have to be careful to not overheat surrounding components, but the wire itself would act as a pretty good heat sink.

[jtwrace]

Thanks jt, I have seen Ric's mod.  He removes the terminal, to make room for his cap mod.  I was just wondering if anyone has soldered speaker wiring directly to the existing terminals: removing the screw and compression nut, sticking the wire through the hole in the terminal, and then soldering down to the surface of the terminal.  From looking at it, it appears that this would make a good connection.  Just have to be careful to not overheat surrounding components, but the wire itself would act as a pretty good heat sink.

I see.  At that point why not just use bare wire?  That's what I do and it works very well and you don't make a mess of the terminal.  Some DeoxIT and you're good to go. 

[Speedskater]

How could you possibly use "Constrained Layer Damping" on an already built chassis?  As CLD requires two of the same sized panels with the damping compound in between.

[turbogti]

Are you suggesting removing the fuse from the power supply?

replace it with a solid silver or copper or silver/gold. 

[brj]

How could you possibly use "Constrained Layer Damping" on an already built chassis?  As CLD requires two of the same sized panels with the damping compound in between.

The constraining panel does not have to be the same size as the structural panel you're trying to damp.  What was described earlier, however, was not constrained layer damping, but rather free-layer damping.  This paper provides a nice overview of the two methods and relative effectiveness, but does not address the impact on resonant frequency.  This paper addressed the frequency shift in one plot and covers several other damping methods besides, although not likely to be employed in audio.

Sticking rope caulk to the inside of chassis panels provides one of the simplest means of free-layer damping.  I'd be curious to see how well green glue sticks to metal, as green glue coupled with some vinyl tile or another high density (but non-resonant) tile would make for a rather simple CLD system.

[Speedskater]

"brj" your second link seems to have gone missing.

Two things about "green-glue":
a] It's not glue.
2] It starts out life with a texture much like peanut butter and it remains that way.

I'd be curious to see how well green glue sticks to metal, as green glue coupled with some vinyl tile or another high density (but non-resonant) tile would make for a rather simple CLD system.

That's not a CLD system.

[brj]

Link corrected.

I don't wish to divert this thread, but a CLD system has a constraining layer and a viscoelastic layer mounted to whatever surface you're trying to damp.  Green glue is a viscoelastic polymer with sufficient adhesive qualities to permanently attach 2 layers of drywall together in its usual application, which leaves me comfortable with their description of it being a "glue".  Thus, in my example, Green Glue forms the viscoelastic later and the vinyl tile forms the constraining layer (reacting mass).  This forms a CLD system.

Again, the Sound Coat that rklein used is an example of free-layer damping.  I haven't tried Sound Coat, but I've used rope caulk in a similar application, the very "ringy" steel chassis of an external power supply.  I actually have enough space in that chassis that I may eventually get around to trying a CLD solution on the inside of the upper surface, though the rope caulk was an obvious improvement.  (An improvement based on the knuckle test, at least.  If I make the CLD change later, I'll use the accelerometer app in my phone to get better feedback, if still far from precise.)

[turbogti]

are you referring to this http://www.greengluecompany.com ?

I have two layers of green glue sandwiched in my bedroom, and, it doesn't really help. I could feel the wall shaking even music was just played at moderate volume (sound was also leaked from that wall). I personally believe concrete walls work much better, or thick metal layers at your ncore case. 

recently I have suspended the amps with magnetic levitation and it works very well! 

[Speedskater]

In the home theater forums I have read countless threads and many, many posts from Ted White about Green Glue.  These threads make it very clear the Green Glue is NOT an adhesive and the drywall(sheet-rock) must be joined by screws.  A good CLD systems requires that both outer panels by of the same size shape and material construction.  That is two 1/2 inch drywall panels are better than one 1/2 & one 5/8 panel.

If you are going to do a project like this, I suggest using Liquid Nails- Sub Flooring Adhesive, which is an adhesive and is more readily available in small quantities.

I don't believe that this project will make any different with any stock Ncore product.

[barrows]

I see.  At that point why not just use bare wire?  That's what I do and it works very well and you don't make a mess of the terminal.  Some DeoxIT and you're good to go.

JT: here is why: 1. I would like to avoid a steel screw in close proximity to the wiring.  Any steel will develop a magnetic field due to the AC current, and this magnetic filed could produce distortion.  Many high end companies go to great length to avoid additional magnetics, especially directly in the signal path.
2. A screw terminal connection is never perfect, the only pressure connection which can be perfect is one where the connection is crimped by a hydraulic press, actually producing a cold weld between the materials.  If one can have a true hydraulic crimp and cold weld, that is the best connection, next best is a pressure crimp followed by solder (to fill in gaps and eliminate gas penetration).  Any air gaps in a connection will induce some noise/distortion, as electrons in their chaotic ways will jump the gaps, with noise caused by the jump.
3. I would prefer not to use non-insulated, stranded wire, as the same electron jump noise will happen as electrons move across the gap from strand to strand.  Large gauge solid core is out because of skin effect problems.  I prefer to use litz wire (Cardas) to avoid these problems.  Litz wire is best terminated by solder, as it has to be tinned anyway to use, and the tinned wire end will not make a great connection with the stock nCore screw terminal.

[rklein]

How could you possibly use "Constrained Layer Damping" on an already built chassis?

Hmmmm... Well, I peeled off the thin layer of cellophane and applied with minimal pressure to the metal surface. 

Am I to expect a visit from the CLD police in the middle of the night for the perceived misuse of this product? 

Seriously... with all due respect, the damping material that I used certainly did not hurt my NCores.  And maybe, just maybe they might have helped.  As I stated earlier, for $12, I tried it.  I certainly did not expect 5 additional posts devoted to the pros/cons of this subject.

On another note, if someone has soldered their speaker wire and got rid of the screw as Barrows has posted about, I would like to know as well.  Especially, any technique you wish to share.

Regards,

Randy

[Speedskater]

JT: here is why: 1. I would like to avoid a steel screw in close proximity to the wiring.  Any steel will develop a magnetic field due to the AC current, and this magnetic filed could produce distortion.  Many high end companies go to great length to avoid additional magnetics, especially directly in the signal path.

The slight possibility of this happening is restricted to very sensitiy circuits with high impedance's and very low signal levels. Nothing like that in a power amplifier.

3. I would prefer not to use non-insulated, stranded wire, as the same electron jump noise will happen as electrons move across the gap from strand to strand.  Large gauge solid core is out because of skin effect problems.

While Class "D" amplifiers do have high switching frequencies where skin effect does come into play, the circuit designer does understand this and takes it into account.

I prefer to use litz wire (Cardas) to avoid these problems.

Skin effect is not a problem at speaker cable frequencies and sizes.

[Speedskater]

  I prefer to use litz wire (Cardas) to avoid these problems.  Litz wire is best terminated by solder, as it has to be tinned anyway to use, and the tinned wire end will not make a great connection with the stock nCore screw terminal.

Yes, never use solder-tinned stranded wire with a screw terminal.  With time the solder will cold-flow and the screw will loosen.

[brj]

In the home theater forums I have read countless threads and many, many posts from Ted White about Green Glue.  These threads make it very clear the Green Glue is NOT an adhesive and the drywall(sheet-rock) must be joined by screws.  A good CLD systems requires that both outer panels by of the same size shape and material construction.  That is two 1/2 inch drywall panels are better than one 1/2 & one 5/8 panel.

My reference to drywall was only made to mention Green Glue's most common application for those unfamiliar with it, not to suggest that how it is applied on drywall is how it should be used in any other potential application, whether CLD or otherwise. Certainly if you screw what would otherwise be your constraining layer to the layer to damped, through your viscoelastic layer, you've now coupled those layers and you no longer have as effective a CLD implementation.  (Many would argue that such a coupled system is no longer CLD implementation at all.)

For what it's worth, I double checked with one of the senior guys in our Loads and Dynamics group at work today to make sure I wasn't misspeaking.  Damping of acoustically induced bending modes relies more on a constraining layer that is very stiff (but can actually be very light and thin), whereas the damping of lateral modes can rely more directly on the mass of the constraining layer.  The degree of benefit realized by increasing the coverage area of your constraining layer relative to the surface to be damped will thus depend on which modes you're more concerned about, though CLD can be effective even with fairly minimal coverage.

rklein, my apologies.  Your free-layer damping approach is entirely effective, and I only sought to clarify why your approach was effective, if differently so, than a CLD based implementation.

Mods, please feel free to remove my posts if they are too distracting.  Thanks!

[Speedskater]

I just noticed that Green Glue should only be used in rooms below about 85°F,  so keep it away from vacuum tube amplifiers.

http://www.greengluecompany.com/faq

[rklein]

rklein, my apologies.  Your free-layer damping approach is entirely effective, and I only sought to clarify why your approach was effective, if differently so, than a CLD based implementation.

I appreciate it but no apology is needed.    I was just busting Speedskater's cajones a bit in good fun.

Randy

[barrows]

I ended up removing the speaker wire terminals entirely, as they are brass, and I do not want a low conductivity material like that for my speaker connections.  Now I can solder the output wiring directly into the PCB itself.

[srb]

I ended up removing the speaker wire terminals entirely, as they are brass, and I do not want a low conductivity material like that for my speaker connections.

What are you using for speaker binding posts at the amplifier rear panel and at the speaker enclosure input to avoid brass in the circuit?
 
Steve

[barrows]

Steve:  Amplifier binding posts are going to be Cardas copper with silver/rhodium plate.  My speakers are Focus Audio FS-888s with Cardas copper binding posts with gold plate.  I see lots of folks choosing nice copper binding posts in the nCore build thread, I just feel brass, at 28% the conductance of copper, seems like a bit of a compromise for such a low output impedance and low distortion amplifier.  Really is too bad that Hypex did not just use a copper terminal, or just some beefy plated through holes on the PCB for direct soldering.