Question Amp under-power?? Marantz PM-47 amplifier (40w) + JPW P1 speakers (70w)

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mrlawrencelam

Well-known member
Mar 25, 2022
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Hi,
Did you pay a lot for the speaker cable ?

Regards,
Shadders.
US$1 per meter. Why? Your question sounds like bad news.

The speakers now locate next to the amplifier. So I purchased only 4m (two meters for each side).

What is the purpose of using two different materials anyway?
 

shadders

Well-known member
Nov 19, 2009
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US$1 per meter. Why? Your question sounds like bad news.

The speakers now locate next to the amplifier. So I purchased only 4m (two meters for each side).

What is the purpose of using two different materials anyway?
Hi,
Not bad news unless you paid an awful lot for the cable.

There is no electrical difference that could ever be heard. I expect that they used clear plastic insulation and tinned copper one side as you have indicated, to assist in the correct polarity connection at both the amplifier and speaker.

You wouldn't believe it, but some people believe speaker cables are directional, despite the signal that they carry is AC.

Regards,
Shadders.
 

mrlawrencelam

Well-known member
Mar 25, 2022
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@shadders The speakers are now located immediately next to my amplifier. We are not talking about an extended length of 30ft or more. Although I am not an experienced audiophile, as an enginneer my common sense tells me I don't need an expensive wire for such a short distance.

These wires will run near the CD player, amplifier and TV along with other wires. So I am thinking to add another plastic tube (from the aquarium shop) and shield off any possible electromagnetic interference.
 

shadders

Well-known member
Nov 19, 2009
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@shadders The speakers are now located immediately next to my amplifier. We are not talking about an extended length of 30ft or more. Although I am not an experienced audiophile, as an enginneer my common sense tells me I don't need an expensive wire for such a short distance.

These wires will run near the CD player, amplifier and TV along with other wires. So I am thinking to add another plastic tube (from the aquarium shop) and shield off any possible electromagnetic interference.
Hi,
EM waves can only be suppressed by metal, so plastic pipe will not assist. The magnetic field given off by the speaker cable is relatively low, and follows the 1/r^2 law - the further away from the cable, the magnetic field drops off very fast.

I would not worry about it, as RCA cables (phono plugged ones) are shielded, as are any aerial cable (coaxial). The plastic tube may force a distance between cables, which is not a bad thing, but may be unnecessary. Also, it is cables that run in parallel that can be an issue, but again, i don't think you will have a problem.

In my experience, and from engineering, the cable you have is more than adequate.

Now you have the speakers a few metres apart facing you, the sound should be considerably better.

Regards,
Shadders.
 
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mrlawrencelam

Well-known member
Mar 25, 2022
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I am curious why one side is tinned copper (copper coated with a thin layer of tin) while the other side is bare copper. I googled and the nearest answer is to prevent corrosion. But if it's for preventing corrosion, why tinned only one side?

I doubt it has anything to do with conductivity since copper is far more superior than tin as an electric conductor.
 
I am curious why one side is tinned copper (copper coated with a thin layer of tin) while the other side is bare copper. I googled and the nearest answer is to prevent corrosion. But if it's for preventing corrosion, why tinned only one side?

I doubt it has anything to do with conductivity since copper is far more superior than tin as an electric conductor.
It's simply to differentiate the wire, if they were both the same colour it would lead to confusion on plug attachments
 
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mrlawrencelam

Well-known member
Mar 25, 2022
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It's simply to differentiate the wire, if they were both the same colour it would lead to confusion on plug attachments
Possible. I also noticed only the tinned copper side has printing "Choseal High Quality Speaker Cable + Manufacture date". The printing is also an indicator.
 
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shadders

Well-known member
Nov 19, 2009
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Hi,
The thickness of the tin plating is so thin that the extra resistance will be in terms of less than 1 mill-ohm. It is so negligible, that for the same length, copper and tinned copper, the extra could not be measured (multimeter), unless using a special setup such as a whetstone bridge.

People use banana connectors, and their surface area for contact with the speaker terminal hole is much less than when using bare wires under the screw terminal of the speaker connector. No one complains about that, so it is not an issue.

Regards,
Shadders.
 

mrlawrencelam

Well-known member
Mar 25, 2022
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Finally got my speaker stands. Very nice quality and firm. Paid about US$40 for a pair. Columns 80% filled with sand. Speakers are secured with Fiber-Castell Tack-It (similar to BluTack). Will test sound quality shortly.

Question: Do I need to put foam dampeners below the spikes (between floor and spikes)?

847B87CB-C880-47E9-8A5D-BA69C0177A7B.pngBE045BC2-4338-463C-982B-9671945D5057.png8DA7C8C7-508C-458B-B75B-0C0BA09A59AE.png311DD293-256C-47CB-9057-C12CEDAE8225.pngC91188C2-931E-4DEE-BE1C-BA0DDAA1BA0B.png
 
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plastic penguin

Well-known member
Finally got my speaker stands. Very nice quality and firm. Paid about US$40 for a pair. Columns 80% filled with sand. Speakers are secured with Fiber-Castell Tack-It (similar to BluTack). Will test sound quality shortly.

Question: Do I need to put foam dampeners below the spikes (between floor and spikes)?

View attachment 3429View attachment 3430View attachment 3431View attachment 3432View attachment 3433
See how they sound as is (with the spikes first).
Don't get too hung up on soft pads, spikes, elephants legs blah blah blah...

Just enjoy your new stands. If they are worth their sorts, should be audibly better than sitting speakers on a cabinet.
 

mrlawrencelam

Well-known member
Mar 25, 2022
30
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I am not an audiophile. I don't have trained ears. I would be pretending to be an expert if I say the sound has improved.

But at least psychologically it feels better. Anyway, I think the sound is perfect for me now. Compared to when they were wall-mounted near ceiling, the difference is heaven and earth.

92F88ABA-51E6-4689-92CF-BC38F4D9B164.png
 
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plastic penguin

Well-known member
I am not an audiophile. I don't have trained ears. I would be pretending to be an expert if I say the sound has improved.

But at least psychologically it feels better. Anyway, I think the sound is perfect for me now. Compared to when they were wall-mounted near ceiling, the difference is heaven and earth.

View attachment 3434
I'm not an audiophile (whatever that means). I'm a music first person.

I know that they've said on the Wam, but they are different in that most have either high end gear or multiple systems. They serve their purpose but rarely relate to people like you and I.

Give yourself a few days and then tweak your speakers or stands as required, if necessary.
 
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camcroft

Well-known member
Jan 12, 2012
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I am not an audiophile. I don't have trained ears. I would be pretending to be an expert if I say the sound has improved.

But at least psychologically it feels better. Anyway, I think the sound is perfect for me now. Compared to when they were wall-mounted near ceiling, the difference is heaven and earth.

View attachment 3434
Yes they are nice stands. But for g.d's sake you can now put some clothes on ;)
 
Last edited:

Edbostan

Well-known member
Aug 5, 2021
212
103
970
This is my first post here.

I have an Marantz PM-47 amplifier from 1996. The label behind the case showing 8~16 ohm.

Online information shows:

Power output: 40 watts per channel into 8 ohm (stereo)
Frequency response: 10Hz to 50kHz
Total harmonic distortion: 0.008%
Damping factor: 60
Input sensitivity: 2.5mV (MM), 150mV (line)
Signal to noise ratio: 86dB (MM), 96dB (line)
Channel separation: 80dB (line)
Dimensions: 439 × 103 × 340mm
Weight: 5.4kg
Year: 1996

The two speakers are 2-way JPW P1:

Nominal impedance: 8 ohms
Power handling: 70 watts
Sensitivity at 1w/1m: 89dB

Is the Marantz amp (40w) too weak to handle the JPW speakers (70)? I see people recommending the power of amp should be 50%-100% more than the speakers. In my case, my amp should be 60~80w, right?

I find the sound quality of the speakers to be less satisfying although almost everybody from different online forums are praising the these speakers. I wonder if it is the undersizing of my amp?
I had Cyrus One rated at 25W which drove a pair of JPW AP2s which were basically P1s and the amp powered the JPWs fine.
 

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