Copper®Harmony RCA Plug - a new breed

I was contacted by KLE Innovations recently to review their entry level RCA connector (plug).

I have no idea why - Maybe due to a blog that I maintain?

Anyhow - I was a little skeptical that the Copper Harmony RCA Plug could significantly better my existing Silver Bullet RCA's, since they share (i.e. visually) very similar design principals.

So I set about planning a testing strategy based on about 30 tracks that, over the years, I have used for auditioning various audio components, who's purchase I was considering.

Well, I didn't even have to wait for the Copper Harmony RCA Plug to burn-in to realize they are something extremely special.

Anyhow - to cut to the chase - the Copper Harmony RCA Plug delivers an exceptional performance which improved upon details, dynamics, imaging, etc... of the Silver Bullet RCA's that I own.

Now, I have not compared the Copper Harmony RCA Plug directly to RCA's that conform to a more "conventional" RCA design, mainly because my Silver Bullet RCA's had already demonstrated their superiority.

So - the Copper®Harmony RCA Plug resolves to a very high level of performance and it is very very quick - perfect for just about any duty in the realm of audio - including their use on digital cables!

Because of their ability to allow the flow of extremely small "micro details" in an audio signal, I believe they would also be ideally suited for use on those turntables that employ a one piece wiring harness - especially when using moving coil cart's.

So if you are interested in the complete review please go to

If you would like more information from KLE Innovations then use the following

o Website – (nearly ready)

o Email -

Please note - I have no affiliation with KLE Innovations and was not paid to participate in the review.

I am just very impressed with what I consider to be a stellar product and feel it would be beneficial to share my experience with the members.

Sorry - the link to my blog should have been...

Copper®Harmony RCA Plug

Shouldn't the copper RCA's need to be 75ohm to be suitable for digital cable?
From what I understand - to guarantee true 75 ohm cables you should use
a BNC connector I believe.

I've used standard rca's without a problem on cable designated as
"digital" and they worked very well.

"The NAME" from Van den Hul is sold as an analogue
interconnect with standard rca's - but the say they can be used for digital -
I tried them also and they sound great.

Some sites I checked (diy audio and blue jeans cable) says there is no such
thing - but they could be mistaken :-)

Pasternack advertises a 75 ohm RCA

Then I saw a digital cable with an XLR connector - are XLR 75 ohm?

Can anyone else clarify this point please

Many thanks
The impedance of a XLR Connector is 110 Ohms

Good Listening

I asked KLE Innovations

Could the Copper Harmony be used for Digital ICs (interconnects)?
Is impedance an issue? ·
Steve, the Copper®Harmony and Silver®Harmony will
both be excellent for Analogue and Digital cables - the Harmony plugs are
very linear even beyond 150 KHz and the their impedance will easily match
a 50ohm, 75ohm, or even a 110ohm cable.

From the review it appears that KLE has a nice sounding plug, but I find their response to Steve's inquiry about their impedance very puzzling to say the least. Regardless of their linearity at high frequencies, how can a single plug design "easily match" three different impedance values? A given plug has only one characteristic impedance.
Bill - since I'm no expert I cannot readily address your concerns. I have
however passed on your post to KLEI for comment.

From what I have read in various articles on the subject, there is an issue of
internal cable "reflections" that can arise in digital cable use,
when the impedance of the connector is lower than that of the cable. This
can degrade transmission.

KLEI did share the findings of one reviewer that specifically tried them on a
75ohm cable as a digital interconnect and found them superior to a very
good interconnect purpose built for digital applications.

One key design point of the Copper Harmony is their small neutral
conductor, which contributes greatly to their enhanced performance (at
least in analogue applications).

Perhaps this also is responsible for their very good performance as a
connector in digital applications, in that the small neutral pin may reduce
those internal reflections to levels that are no longer an issue, which might
make them well suited for use with 50, 75 and 110 ohm cables?

I will post their response as soon as I have it
I got the opportunity to hear the new Copper Harmony RCA ends myself this past week, in comparison to the standard copper Bullet connectors. Your review is spot on, and I agree with you all around on your assesment. Much faster, more attack, better extension and energy in the upper highs, and tighter bass. Midrange is a bit more open as well, in comparison to the copper Bullets. Still retains the same excellent focus as Mr. Eichmann's previous Bullet ends. Keith has a real winner with these, and the price is extremely reasonable.
BigS - it's always nice to hear someone else had a similar experience :-)

Bill - I received a reply from KLEI that contained the following explanation..

- The overall impedance of a "digital path" (e.g. the digital devices + the cable + the connectors) is determined by whichever of those individual components has the lowest impedance.

- if the overall impedance is lower than the value that the "digital path" is specifically designed for (i.e. 50, 75 or 100 ohms) the signal can become degraded

- Conventional RCA's often have an impedance less than the cable or the component - which reduces the overall impedance of the "digital path" to that of the RCA, often resulting in transmission issues

- Due to it's advanced design, the Copper Harmony has an impedance greater than 100 ohms, making it a very good choice for use on digital cables having an impedance of 50, 75 or 100 ohms, since it will not reduce the overall impedance within that "digital path" to a value less than the cable it is attached to.

Also, due to the high conductivity rating of the materials used for the conductors in the Copper Harmony, jitter will be significantly reduced.

This makes the Copper Harmony RCA an excellent choice for digital applications.

I did find other RCA`s that are designed specifically for use on 75 ohm cable, but none for 50 or 100 ohm.

I hope this answers your question
The Canare RCAP-C series RCA connectors are supposedly designed for 75ohm spec.
According to BJC, "These Canare plugs are designed for the best possible impedance match with 75 ohm video coax"
Williewonka, thanks for posting the response from KLEI. While I understand their thought process and belief that their design is an excellent choice for digital applications, their plug still has one specific characteristic impedance and cannot therefore 'match' other different impedance designs. It may however still sound fine in such applications.
Bill - I think that is a very fair assessment!

Dragon - I also found 50 and 75 ohm RCA's from Pasternack

Cheers guys :-)
Ooops - in the posts above the impedance numbers should have read ...
50, 75 and 110 ohms - my mistake - hate these virtual keyboards.

KLEI web site is now up and running

Mr Eichmann has an Interesting approach to cables as well as RCA plugs

Take a look :-)
I have just completed a review of their Silver®Harmony RCA Plug - the next level up in their line. See my blog for the full review

It has...
- significantly better imaging
- slightly better dynamics
- much deeper low end
- extended top-end details
- and very transparent

I also tried the Copper®Harmony RCA Plug on a Van den Hul "The Name" 70 ohm Interconnect bridgeing from my Pionner Elite DV-45A DVD players s/pdif output to my Schiit Bifrost and it performed very well - better than the original Van den Hul RCA's that came on the cable.

Personally - for the $30 extra I would go for the Silver®Harmony RCA Plug.

Ooops that would be a 75ohm cable :-)

Hi Williewonka,
Can you tell me if the harmony silver plugs midrange is full sounding with nice tonal density or thinner sounding then harmony copper plugs?
Snopro - I found that the answer to your question is dependent on the track

For example: I have some tracks that appear to have less bass, but it was actually due to the deeper image - the bass had moved further back and was therefore lower in volume. Some might interpret that as less bass.

I didn't find the Silver Harmony sounded any thinner - just all around better
- better image and more focussed witn more "space"
- faster dynamics
- finer details

The bass was significantly deeper on tracks with really deep bass - like R&B and pipe organ music

Both Harmony RCA's were warmer than the Eichman Silver Bullets I originally had

The Silver Harmony are well worth the extra $30

Having said that their performance is very dependent on the wire you are attaching them to.

I use solid silver interconnects, which are extremely detailed and I find very neutral. Both the Copper and Silver Harmony RCA's brought out the best in the interconnects

Hope this helps
I plan on having some cables made up using Mogami 2549 and the Copper Harmony RCA plugs with the ground floated on one end of the cable run. Since Mogami 2549 is all copper, would it be wasted money to get the Silver Harmony plugs instead?
And has anyone found cable manufacturers doing builds similar to the build I want? Thanks...
I plan on having some cables made up using Mogami 2549 and the Copper Harmony RCA plugs with the ground floated on one end of the cable run. Since Mogami 2549 is all copper, would it be wasted money to get the Silver Harmony plugs instead?
I have found the Silver Harmony plugs to be better than the Copper Harmony plugs, even with copper wire, so it is probably not a waste of money :)
I DIYed my own set of cables using a the exact same design as yours, Sbrownnw. But I used a set of VALAB Rhodium Plated Carbon Fiber RCAs though instead of the KLE. I finished them off with a nice sheath of Nylon Multifilament. I don't know if they are world beaters because I really can't tell a difference among cables.
@Yping, what differences did you notice with the silver vs the copper harmony with copper cable? TIA
Got the KLE Copper Harmony RCAs with Mogami cable (ground floated at one end) in my home system and they sound great!

I have my older Mogami with Pro-Fi RCAs (still a great sounding cable) for sale here if anyone is interested in a value priced well performing interconnect set:
Sbrownnw - if you think the Copper Haermony are good as an analogue link try them on a digital cable.

They will surprise you :-)
@Williewonka, thanks for the recommendation, but I do not have any digital cables in my audio system (tried to keep everything analog). Only two components with DACs are the Bluray / CD player and my Motorola / Comcast cable box and they are internal and use stereo analog on both. I do have HDMI cables but they carry video only and I use a passive switchbox separate from my audio 2 channel gear.

I hope to upgrade the Rega RCA plugs on my RP6 to the KLE Copper Harmony next.

Oh, the older set of my Mogami cables with the Pro-Fi RCAs sold over the weekend.
Sbrownnw - Yping is suggesting a better RCA, but that really depends on the tone-arm/harness combination...

If you are using the standard Rega Arm without any mods - then go for the Silver Harmony or Pure Harmony

if the internal wiring has been upgraded then go for the Pure harmony or even the Absolute Harmony

For something like the Audiomods Arm - Absolute Harmony - nothing less

But one thing for sure - the improvements will amaze you :-)

And just for fun - checkout

The Mogami / KLE Copper Harmony cable combo seems to be really breaking in and almost sounds too good if that is possible? Incredible soundstage width and depth, with great mid and bass punch with overall amazing clarity, especially with my vinyl source. My system has never sounded better.

With this said, I wonder if the KLE Silver Harmony is the correct path for my Rega RP6 RCAs? Could they be too responsive or upset the copper mojo of my current setup?
Sbrownnw - my observations with the Harmony line is that they simply enhance the performance of the cables they are attached to without adding "colour".

Adding them to my silver IC's actually improved their warmth and fullness.

Food for thought - the metals used in these RCA's are actually proprietary alloys that perform "as good as" pure silver and pure copper.

So, how much better is each model than the next ...
- If I were to rate the Silver Harmony as 50% better than the Copper Harmony
- then I would rate the Pure Harmony as 40% better than the Silver Harmony
- and the Absolute Harmony only being 25% better than the Pure Harmony.

Yes - diminishing returns!

For me (and my budget), the Pure Harmony is the best "value" or "bang for the buck" because the level of improvement they brought to the performance on my silver IC's was extremely good. They are noticeably better than both Copper and Silver Harmony.

I have Absolute Harmony on my analogue rig, which I believe will augment the resolution capability of a cartridge upgrade I am planning.

The Pure Harmony are on my digital rig because I think they compliment the resolution capability of the DAC - if I upgrade the DAC then I will consider upgrading those to the Absolute Harmony also.

In short - I try to match the resolution of the RCA to my cables and to the components they will be used on and within my system

You may find the Silver Harmony to be the best "value" on an all-copper cable, but the Pure Harmony may also provide enough of an improvement to warrent that additional expense.

It's your budget, your choice!

Hope that helps :-)
Sbrownnw - since you are into DIY I was wondering if you are up for an

I'm currently running an interconnect with a very different architecture. It's
similar "in principle" to the Anticables Interconnect, with a slight

For construction details see

I've used silver for the signal conductor, but you could simply use a single
strand of CAT6 in it's place.

For a 3ft IC you would need 9ft of CAT6, and 3ft of teflon tube - so it's pretty
cheap - a little more if you want to put a nylon sleeve on it.

They do require the KLEI rca's to perform their best.

I know the silver/copper version with the Absolute Harmony is exceptional
(close to the gZero6) and I think the "all copper" version would
provide some stunning details with that warmth of copper that everybody

The Copper Harmony would be a good match

Anyhow, if you are up for an adventure give them a whirl - you won't regret
it - I can pretty much guarantee it :-)

As a bonus - this design with the copper Harmony RCA's also perform
exceptionally well as a digital S/PDIF IC.

It's not for everybody, but those into DIY might find it worth while :-)
Thanks Williewonka.

I did not DIY my cables. I had Doug at make them for a reasonable price (cheaper than other Mogami RCAs listed on this site for sale but don't quote me since I am not affiliated). If people are interested I would contact Doug directly.

I am really enjoying my KLE Copper Harmony RCAs with Mogami 2549 wire. :)
Sbrownnw, the douglas connection link doesn't work...
The url was missing the protocol from the beginning. Here is the correct one:

I have an pair (1 each of left / right) extra unterminated KLE copper harmony RCA connectors after receiving my last shipment from Douglas Connection. Anyone want this extra pair for $28 including shipping and PayPal fees? PM me and we can work out the details.
Ok, as this site attempts to make itself better it actually makes things worse. Now posting a raw url without forum markup strips the protocol from the link. Here is the correct link with forum markup:

Douglas Connection
Sbrownnw, can you describe the sound of the KLEI Copper Harmony RCAs with Mogami 2549 wire...
@Yping, I think the Mogami 2549 for unblanaced RCA is a hard cable to beat. Very neutral and lets all the frequencies just flow. Many people like the 2549 and there are rumors that Linn uses this cable for some of their interconnects. And with Mogami used in many of the recording studios today I think it is a great all around cable. With the KLE Copper Harmony RCAs, I got a great soundstage with width and depth never before heard on my system with a nice air and tonality of the piece I was playing.
Sounds very nice... is it easy to get Mogami 2549 wire?
@Yping, I've seen the Mogami 2549 from for $.77 / foot.

@Yping / Williewonka, after my KLEI RCA cables broke in I experienced a very wide and tall sound stage. One I have experienced before. It almost seems like some sources are out of phase it is so wide and tall. Have you experienced this?

Sorry, the 3rd to last sentence should read:

One that I have never experienced before on my system.
Yes - I connected one pair of my DIY's out of phase - pretty strange results,but it was immediately noticeable.

You can tell just by removing the cover and looking at the connection.

The RCA's do present a much larger image though - very 3D

Hope that helps
Yes, the Copper Harmony RCA's present a much larger 3D image, very nice :) Are you not liking what you are hearing?
I really like what I'm hearing from my better sources (vinyl and CD). On my OK source (tuner) and my below average source (comcast cable box using their built-in DAC to stereo analog out) the KLEI Copper Harmony connectors seem to make a questionable source worse. I currently have the KLEI Copper Harmony connectors and Mogami 2549 throughout my system. I am going to try some older cables (Mogami 2549 without the KLEI Copper Harmony) between my comcast box and my Audio Refinement preamp and maybe between my tuner and my AR preamp.
Interesting and should be interesting feedback :)
Sbrownnw, the Copper Harmony RCA's present a much larger 3D image with excellent resolution...

Hmm, the Copper Harmony RCA's are reproducing a higher resolution, so perhaps the questionable sources are reproducing some this resolution as noise rather than resolved harmonics, maybe? That is the noise isn't smoothed like honey or fudge...

What do you think Williewonka? Am I thinking ok...
Actually, I am really not sure...

Williewonka, do you think you know what is happening...