Aftermarket Powercords for Martin Logans

[enilsen]

I don't see what your objection to a transformer is.

I have no objection to the use of the transformer, only the fact that we open a can of worms when suggesting that power cords can make a difference. That would imply that there is a flaw with the current design and to improve on this by replacing the power cords will have a cascading interest into what is the source of the problem.

Why beat around the bush with subtle improvements when we can eliminate the problem once and for all. No power cord, No problem.

If I was to spend money on improving something that I though was flawed then I would back it up with a real tweak. Our speakers are voltage dependent and if the source of the current is not reliable then we need to address this thru other means.

I bet that most of us don't even have a constant feed of 110/220 volts and if that is true you speakers are not performing their best because they rely on a small transformer with no voltage regulator. Power cords won't fix this problem.

Here's a picture of a hv bias power supply that will take a 12 volt DC source and produce up to 1.5kv. Not too expensive and not impossible.

 

[Peter Hogan]

I have no objection to the use of the transformer, only the fact that we open a can of worms when suggesting that power cords can make a difference. That would imply that there is a flaw with the current design and to improve on this by replacing the power cords will have a cascading interest into what is the source of the problem.

Why beat around the bush with subtle improvements when we can eliminate the problem once and for all. No power cord, No problem.

If I was to spend money on improving something that I though was flawed then I would back it up with a real tweak. Our speakers are voltage dependent and if the source of the current is not reliable then we need to address this thru other means.

I bet that most of us don't even have a constant feed of 110/220 volts and if that is true you speakers are not performing their best because they rely on a small transformer with no voltage regulator. Power cords won't fix this problem.

Here's a picture of a hv bias power supply that will take a 12 volt DC source and produce up to 1.5kv. Not too expensive and not impossible.

How that circuit operates...If you look at the picture, you can see the two power input pins at the far left, then there are two input filter capacitors (small yellow ceramic one, and a large blue electrolytic one), that feeds the black 8 legged IC (and surrounding components), which will switch the DC to AC. That AC signal feeds the large power transistor (likely a MOSFET), which drives the primary of the large circular toroidal core transformer (green core w/copper wire wound around it). This steps up the voltage to a high AC voltage. Finally it goes through a voltage multiplier circuit (the grey/black diodes, and large blue disc capacitors at the far right), which rectifies and multiplies the AC to a higher voltage DC output. This is still an unregulated supply.

If you take just the transformer and the voltage multiplier portion of the circuit, it is very similar to the stock ML supply. Instead of the transformer being driven by the MOSFET, it gets driven by the AC from the wall. The multiplier circuit works very well as a filter for any spikes that may be on the AC line.

I have run my ML's from a variac, which allows me to vary the AC input, and therefore the bias voltage on the speaker. Even varying the input 30-40% made almost no difference in the speakers sound (although at very high voltages I did start to get arcing at the panel).

If you want to see if getting rid of the power cord will make an improvement in sound, there is an easy way to check. Play some music, and have somone else plug and unplug the speaker so that you cannot see them (i.e. you don't know if it is plugged in or not). The speaker will continue to operate from the stored charge on the panel for several minutes when unplugged. Plenty long enough to get a good listen. Then see if you can tell whether the speaker is plugged in or not by the sound. Record your answers, and I'll bet they are pretty close to 50% right, 50% wrong, i.e. random chance, or no difference.

Peter

 

[enilsen]

If you want to see if getting rid of the power cord will make an improvement in sound, there is an easy way to check. Play some music, and have somone else plug and unplug the speaker so that you cannot see them (i.e. you don't know if it is plugged in or not). The speaker will continue to operate from the stored charge on the panel for several minutes when unplugged. Plenty long enough to get a good listen. Then see if you can tell whether the speaker is plugged in or not by the sound. Record your answers, and I'll bet they are pretty close to 50% right, 50% wrong, i.e. random chance, or no difference.

No doubt you will get my vote following that test. I also have gut feeling us mortals will not do better than 50/50 with the listening test but I'm sure a few of the others that are better equipped will notice a difference.

I have run my ML's from a variac, which allows me to vary the AC input, and therefore the bias voltage on the speaker. Even varying the input 30-40% made almost no difference in the speakers sound (although at very high voltages I did start to get arcing at the panel).

That's good to know. I've always been curious if tweaking the hv bias can really make a difference (sound wise). Not a problem where I live, but I suspect others might encounter arcing at the panel when humidity levels change.
Hmm! The option to trim down the hv bias.

 

[Chuck Lee]

power cords

I have had good success with both the Foundation and Blue Circle power cords.At present because I don't have 2 spare LC2 for my double CLS system I am using Blue Circle 10 guage power cords (4) into two Blue circle 2 outlet power conditioning boxes.I have been told that Stats are prone to acting like large antena,so what ever you can do to filter the power to them the better.
I really like the Foundation and if I had just one pair of speakers these would be the prefered way to go.They filter in both directions.In any case anything is better than the stock IEC computer cords.

 

[Chuck Lee]

power cords

The trick of plugging and unplugging the electrical feed to the speaker will only be a display of the initial quality of the power that the speaker has seen.The old dirt in dirt out.Battery power would be nice,I have the Sutherland PHD phono and that solved the electrical problems there.I feel that with all the grunge on the line now and all the rf in the air that any kind of filtering is a must.Even a well shielded DIY power cable is an improvement over the stock power cable.I proved this to myself when I made upgraded power cords for a pair of Quad 63 speakers. I used Romex house wiring and cheap prong connector. The IEC was the stock Quad one. The guage of the Quad power cord was about 18 or higher.The subsequent owner purchased the home made power cords and paid extra for them because he could hear the difference they made to the Quads. So are Martin Logan speakers immune to power cable upgrades?My experience with the CLS for over 8 years says they are not.