Sakura Systems OTA Cable Kit

Sorry for the lack of contribution to the discussion for some time but it was impossible for me due to an increased workload.

To understand why there might be problem with making contact, one must look into the design of female RCA connectors (the ones on the chasis), particularly the inner, signal "lip" that makes contact.

Some female RCA connectors have round lips that make full 360 degree contact. With these an OTA RCA will make an instant contact however you plug it in. 47Labs chasis RCA connectors are made this way.

Other types may have either single or double "strip" contact surface and with these, you need to align the spiral that you make with OTA cable bare ends over the plug that cable makes contact to it. Sometimes several tries may be needed but once you have the contact, problem solved. With ground cable plugs in place, it should be safe to make this adjustment with gear turned on (volume on lower value, however, is better). If no contact, unplug completely the signal only plug, rotate a bit and plug in again, repeating this until there is a solid contact.

These differences in construction does not mean that one female RCA connector is better than the other.

I am confused, however, how Dekay has managed to break even five of inner plugs (Dekay, if that means anything, I think I have one extra and could send to you, for more I would have to ask Japan)... Delrin is pretty elastic material.

Ultrakaz, your friend is right about Delrin static properties but that is only one part of the story about this material and why it is used in this design - on the other hand, your friend is wrong if he says OTA is a telephone cable. It's starting design premisse was based on a telephone cable design and that is where the similarity ends.

Best,
Sead

Hi Sead:

The ones that break the most are the ones connected to hot tube gear and/or a SS amp which runs predominantly in class "A" (also quite "hot" @ the RCA's). I assume that it is the heat that weakens them (as these female RCA's are not on the "tight" side) and/or thermal cycling as I do not leave the tube amps on all of the time. One of the center shafts, however, was broken due to my error when not maintaining a 90% angle when removing it from a Bel Canto DAC (which has very tight fitting female RCA's on it). Once again, all of the posts failed at the "cross hole" section which is without a doubt a structural weakness in the design. I realize that tooling expenses are quite high, but would suggest eliminating the "cross hole" entirely and instead using an "outer ring", which would slip over the shaft, for this locking purpose, if retooling ever comes up. This should not effect the sound (it may even improve it as it would eliminate the haphazard "loop" which most likely occurs when threading the wire through the "cross hole") and it would make this part a great deal stronger (both by eliminating the "cross hole" and by adding the "ring" surround to the section which is subjected to the greatest amount of stress when installing/uninstalling the RCA's.

As far as Matching RCA's with the OTA counterpart, I have never seen the "strip" example of these type of connectors but recently became aware that the OTA RCA's are not compatible with vintage type RCA's (the ones currently on a Pilot 240 amp that I am using). The easy solution to this is to replace the female RCA's on the vintage piece (as they are garbage anyway:-).

On another note, someone once mentioned to me that OTA "banana" plugs (for attaching the cable to speakers) would be an interesting addition to the kit. This may have been RedKiwi's suggestion, but I cannot remember for sure, and am unable to locate the old email.

I will add that I have probably installed/uninstalled the connectors a great deal more than what I would consider the "norm" due to experimenting with different cable configurations over the past 8 months. I also never asked for replacements outright, though did make it clear as to why additional ones were required (but @ that point I had only broken 1 or two of them as I recall).

I do not wish to detract from what I consider to be a truly high end but affordable (to many of us) product, just to detail my experiences with it in which the positive's far outweigh the negatives (that is if sound is one's main priority).

Good to see you back in the forums again.

Dekay,

»…. Once again, all of the posts failed at the "cross hole" section which is without a doubt a structural weakness in the design. I realize that tooling expenses are quite high, but would suggest eliminating the "cross hole" entirely and instead using an "outer ring", which would slip over the shaft, for this locking purpose, if retooling ever comes up.«

If I am picturing it right in my head, the outer ring can't make a solid spiral that would withstand even three unplugging, thus would make life even harder and the spiral pretty loose. The entire purpose of the cross hole is to ensure for a neat yet firm spiral.

Sure, this hole makes the plug less strong at this point but, nobody really thought of torsion force taking place there, and it should not be subject to torsion under the normal operation, therefore everyone should avoid twisting and rotating the shaft while plugged in, if nothing, it screws up the spiral aesthetics and also can lead to breakage of the wire. :-)

I hear you mentioning the heat and, that could explain it in your case. Heat, plus a bit of a twist and off the plug goes. Really, to my knowledge, you are the first one to break it… :-(

»This should not effect the sound (it may even improve it as it would eliminate the haphazard "loop" which most likely occurs when threading the wire through the "cross hole")….«

Theoretically, yes. Practically, I am not sure as the loop is there also in the signal return plug and I am failing to find something sonically wrong here. It sure would make things stronger but I really have no negative experience with this.

»As far as Matching RCA's with the OTA counterpart, I have never seen the "strip" example….«

Theta had these on some equipment, Marantz has them and lots of others do as well. Hm, maybe I have not found the right word, that is also possible (but I think you know what I mean anyway). Again, this means nothing in terms of quality of a connector.

»On another note, someone once mentioned to me that OTA "banana" plugs (for attaching the cable to speakers) would be an interesting addition to the kit….«

Banana plug makes a subtle but noticeable improvement in terms of further reduction of sonic glare and even better palpability. That is, in speakers that have standard banana binding posts. I think the reason bananas are not part of the OTA kit in US is the fact that most of customers wants to use the kit in the most rational way, thus replacing bananas in favour of two additional RCA plugs (to make for 3 sets of interconnects) should be looked at in this sense. In Europe, we normally supply bananas with the kit but we have two RCA connectors less in the kit.

I dunno if Ivo is following the discussion but he may be able to fill in with his impressions about bananas, as he has done a thorough testing with and without. Also, after some burn in time, I hope that James will share his impressions with us as well, since he's got bananas in with his kit.

The best thing, however, is to avoid 5 way binding posts in general as it presents (IMO, as I don't want to get into discussion with anyone dissagreeing on this) such a waste of material in order to fascinate an average consumer.

»I will add that I have probably installed/uninstalled the connectors a great deal more than what I would consider the "norm" ….«

It should be no big deal to have the broken ones replaced.

»I do not wish to detract from what I consider to be a truly high end but affordable (to many of us) product, …«

No need to mention this. I uderstand perfectly well.

»Good to see you back in the forums again.«

Thanks.

Best regards,
Sead

I just finished using some smaller pieces of OTA as jumpers from some female rca's (to PCB) that I replaced on an amp that Dekay very kindly sent me. If anyone out there has any leftover wire that they would consider selling, please e-mail me. I'm thinking of enough to do a half-metre interconnect, and if I'm not mistaken, I would need about 2 metres (or 6 feet) to do that. I'm also thinking of a little experiment with an ungrounded power cord which would require about another 8 or 10 feet, but that is not critical. So if anyone has either 6 feet or 14-16 feet that they'd sell me, please let me know. Just bare wire, no connectors required.

Hi Sead:

Now that you brought it up, I may experiment with separate entrance and return holes/channels on the outer (neutral) portion of the RCA connectors. These will, of course be DIY "jobs", but the "loop", again haphazard in this application, (as it may or may not occur depending on the position of the wire) is something that does not "jive" with the reduced metal mass philosophy of the overall design, as this would add up to approx. 33% more metal mass to the connector (granted that a "loop" does occur), plus the uncertainty of the effect of the "loop" itself. I have noticed a substantial difference in the sound by how the cable is attached to the speakers/amp in that looping the wire around a binding post does some strange things to the LF response (a smaller contact area, sans loop, is my much preferred method). I now wonder if eliminating the possibility of a loop occurring (in any instance) in the IC's would also have beneficial results?

I do not quite understand your comments on the "outer ring" suggestion as this is by far the greatest stress point on the middle post of the RCA's (both when installing and uninstalling the RCA). The outer ring (plus...sans the second hole in the post) would significantly reinforce this specific area and would only be compromised by the tightness of the fit (on the post) and the single strand of 26 gage "bare" wire which would be forced under and held by the ring. These compromises are in comparison to engineering the concepts into a "one piece" unit. Maybe what I am envisioning is not made very clear by my wording as this is a difficult area for me?

I realize that the people who do not have these materials @ hand do not have a clue as to what we are talking about, so will end this discussion here.

Please feel free to email me directly with further thoughts/info and if we come up with anything that makes sense it can then be added to the thread. Now that you have sparked my interest, I will certainly play around with this as time and energy permits.

Unfortunately I just sold my SET amp, which was my favorite "window into the music" and super for testing gear (now using a push/pull amp in pinch). But fortunately I today purchased a vintage stereo SET console (complete with light weight paper drivers) that I hope to "part out" and have up and running in the next couple of months, granted that I can figure it out with the help of a few "web friends". It was $20 if I can get it out of the shop by tomorrow morning, so it is time to hit the hay right now.

As always, I look forward to further dialog.

Best regards,

David