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Can anyone please help me!
I recently made a directional interconnect with RCA plugs using Connectronics Musiflex microphone balanced type cable. This cable consists of two insulated inner wires and a bare copper drain wire which contacts a plastic shield.
I used a wiring regime suggested to me by someone here. That is connecting one insulated wire to the centre pins of the RCA plugs and the other insulated wire to the RCA collars. Finally at the source end I also soldered the drain wire to the collar (but not at the destiniation end).
Problem is it sounds cold/clinical/hard and lean, compared to the way I had it wired originally. Then is sounded rich smooth, full and relaxed. Beforehand I had connected the cable in a way which was supposed to be wrong. I had twisted the two insulated wires together and connected them to the centre RCA pins and connected the copper drain wire only to the RCA collars.
My question what are the other "proper" ways to connect up the plugs. Can you for example not connect the copper drain wire/shield at all or connect it at both ends instead of one? or something else? I need to get some richness back.
The cables I made today are much better than before.
The straightforward interconnect I made is miles better than the last one I did. I tried SF Tech's suggestion to stip away cable casing, shield and drain wire and use the unshielded twisted pair of insulated inner wires. That is very good, - confirmed when using CD with the cable as well. The glassiness/glare/coldness (which I experienced when using the full cable with the shield connected to the source end) is gone, leaving a nice clear transparent sound. Detail is much better. The bass is definitely also a bit fuller and less lean than with the shielded cable. The balance is a bit wamer than before though I could maybe do with a bit more warmth and richness. It is also still a touch bright, but less so than before. But in general I'm very impressed and I'm definitely going make some more straight interconnects like this. It was quite time consuming and fiddly to cut the outer casing off, but well worth it. I made 1 metre leads. I might try a 1.5 metre leads next as I could do with that length. I guess you can't go too long without any shielding though.
The step up cable to phono stage cable (with flying leads) is also great. It produces less hum than my last wiring effort, or any other wiring config I did before. Thanks very much for those photos Jeff, they really helped. I still get a bit of hum when I connect resistors in parallel to the secondary side of the step up using Y connectors (i.e. Y-connectors plugged into the phono stage with one input on each having the RCA input and the other a RCA socket with a resistor soldered onto it.) Is there anything I can do about this hum? I suppose Its because this small part is not shielded? When you put your hand closer and closer to the resistor the hum gets louder. When you take out the Y-connect/resistor and plug in the cable straight there is virtually no hum so it definitely is coming from either the resistors or Y-connectors or both?
But anyway, thanks a lot guys. I am smiling now!
...every phono cable I've seen has been terminated with "flying" leads that are terminated at the grounding screw on the preamp.
Your "twin-ax" design is fine and is usually recommended over coax cables for phono IC purposes. Also, you may be able to get away with unshielded cables for your other source components, but not for phono interconnects.
Ok, back to the flying leads: the idea is NOT to have the drain wires connected to the RCA's. Rather, the drain on each channel should be connected to some grounding wire which is terminated together with an alligator clip or spade. Just be sure to have enough of the grounding wire so that it will reach from the preamp input to the grounding screw.
Below are some photos that might help. Ignore the fact that there are 4 conducting wires instead of 2, like yours. Also, do not connect the drain wire at the TT end.
Hope this helps. If you have any questions, e-mail me.
Many thanks for that. I actually want to make 2 sets of leads: -
1. One is a straight 2 RCA to 2 RCA interconnect for connecting my phono stage to my preamp.
Lets forget this lead for the time being
and concentrate on this other lead:
2. The other is a cable from my step up transformer bare wires to RCA sockets which will be connected to my phono stage. My turntable lead (LP12) has 2 RCA's which I connect to the primary side of the step up transformer and a ground lead which I connect to the step up grounding screw. I also run a separate cable from the step up grounding screw to the phono stage grounding screw.
Bearing this in mind do your instructions still apply? Do I have the following right: - I solder one end of my musiflex cable (using the insulated wires) to the secondary side of the step up transformers leads, then at the other end of the musiflex I solder RCA sockets on - with respective insulated wires connected. The drain wire at the RCA end (phonostage end) is then soldered to a separate wire (as per your nice pictures) and run to the phono stage grounding screw. At the other (source) end of the musiflex is the drain wire left unconnected?
I should add that each step up has an extra wire on its secondary side called a "electromagnectic shield". I was told by the manufacturer (Sowter) to connect this to the -ve terminal to go to the phono stage. Is this right?
If I did all this would I have two many ground wires? There would be two connected to the phono stage (from step up grounding and from drain wire).
I see that I have basically the same set-up as you do.
From the phono stage to the preamp, I use a 4 condutor DIY microphone cable that's unshielded, similar to the one in the photos but without the flying leads. From the step-up to the preamp, I use a DIY 2 conductor microphone wire.
"The other is a cable from my step up transformer bare wires to RCA sockets which will be connected to my phono stage. My turntable lead (LP12) has 2 RCA's which I connect to the primary side of the step up transformer and a ground lead which I connect to the step up grounding screw. I also run a separate cable from the step up grounding screw to the phono stage grounding screw."
Yes, that is correct.
"Bearing this in mind do your instructions still apply? Do I have the following right: - I solder one end of my musiflex cable (using the insulated wires) to the secondary side of the step up transformers leads, then at the other end of the musiflex I solder RCA sockets on - with respective insulated wires connected. The drain wire at the RCA end (phonostage end) is then soldered to a separate wire (as per your nice pictures) and run to the phono stage grounding screw. At the other (source) end of the musiflex is the drain wire left unconnected?"
Yes, that's correct. You must be sure not to have the drain wire touch the RCA plugs. And yes, the source end (step-up) drain wire
should not be connected.
"If I did all this would I have two many ground wires? There would be two connected to the phono stage (from step up grounding and from drain wire)."
Yes, that's exacly how I have it...a seperate grounding wire from the step-up to the phono stage and the flying grounding wires from the Musiflex (those 2 wires will be connected with a clip or spade) to the phono stage. So you'll have just 2 physical connections to the preamp ground.
"I should add that each step up has an extra wire on its secondary side called a "electromagnectic shield". I was told by the manufacturer (Sowter) to connect this to the -ve terminal to go to the phono stage. Is this right?"
I have only 2 wires coming from the secondary side...one+ and one-, so I'm not familiar with your third wire.
Hope this helps,
Many thanks for all your help Jeff. I will try all that out tomorrow and see how I get on. I understand your instructions exactly now. thanks for going into so much detail. It was lucky you had a similar set up. Someone on the Vinyl Asylum recommended this way of wiring Step up to Phono Stage to me as well but I didn't understand it properly until now.
The other thing now is: How should I configure the cable from the phono stage to preamp?
1. Should I try to use Musiflex cable in the way that it is configured in the picture Duster posted? If so which end should have the drain wire(connect to shield) soldered to the RCA collar.
2. As per 1. but shield connected to both collars?
3. Should I try the way SF TECH suggested and use the 2 bare twisted insulated wires from my Musiflex cable after carefully cutting off outer casing/shielding/drain wire
3. Other? Why and how do you use a microphone cable with four insulated wires for the phono stage to preamp cable?!!!!
"1. Should I try to use Musiflex cable in the way that it is configured in the picture Duster posted? If so which end should have the drain wire(connect to shield) soldered to the RCA collar.
2. As per 1. but shield connected to both collars?"
If you have no RFI problems, you can try it as per Duster's post, but leave the drain unconnected at either end. I've read that an unshieded cable will sound better, but I have no personal knowledge of that. OR...
You may want to take a short length of drain wire on one end of the cable, as in my picture #1, and tuck it under some heatshrink without having it touch the RCA. You can try the cable like that and if you have some RFI problems, then conect it to the ground on the RCA. That's how I configured my cables. So far, I found that they work fine without any shielding. OR...
Connect the drain at one end only. I did that on a long run of cable (20') from my preamp to my amps. I happened to plug the shielded end to the source (the preamp), but others do it the opposite way.
"3. Should I try the way SF TECH suggested and use the 2 bare twisted insulated wires from my Musiflex cable after carefully cutting off outer casing/shielding/drain wire?"
"3. Other? Why and how do you use a microphone cable with four insulated wires for the phono stage to preamp cable?!!!!"
I tied 2 of the wires (red and pink)to the positive and 2 (white and yellow)to the ground of the plugs. See link...ignore the XLR wiring diagram. These are the cables I used for all the IC's except for the step-up to the preamp. For that, I used a 2-conductor version of the GAC-4/1's. My tonearm cable was a custom-made Incognito wire.
Good luck. Let us know how it goes.
Many thanks for all the help Jeff,
My options are clear now. Before I was very confused. I was getting the options for the two different types of cable I wanted to make mixed up. Was my own fault as I didn't explain I wanted to make two different cables in the first place in my original post last week!! I didn't initially realise the options would be different for each of the two applications! Thank God for this forum and its helpful members!
I'm going to try the options out today and see how it sounds. Will post my results.
Many thanks again,
Carefully strip off the outer jacket, shield foil, and and any internal binding. Remove the drain wire. Make a pair of interconnects using just the twisted pair... I've made cables like this before, and they can sound very good. As always, YMMV!
from 5 Easy Pieces. Why not just use some Teflon cat 5 wire? I have found that very low capacitance cables work best for phono IC's. If you have to shield, keep the shield as far from the IC as possible. I found that about 1/2 inch minimum is necessary for no increase in C.
He could certainly try the cat5 wire... didn't know whether he had access to any. I have tried the "stripped" twisted pair from high quality mic cable, and had good results.
Many thanks for the advice,
Sound a bit tricky but interesting (stripping everything off and using the two insulated inner wires only.) But what is the difference between this and using the cable with the casing etc, connecting the two insulated wires to RCA pin and RCA collar respectively and cutting the drain wire very close to the main plastic insulation housing and taping to make sure it doesn't contact the RCA plug at all? Does having the drain wire and plastic shield present put not connected harm anything? Am I missing something?!
My practice is to ground the shield at the load end, not the source end, of all cables.
I meant to direct Davy to ping you, but typed Abe Collins instead of Al Sekela! Whoops! Anyhoo... cool that you jumped in here. I was assuming that he was trying to make garden-variety line level interconnects. If I had known this was a TT to preamp or step-up xformer setup, I would not have offered the same advice! I stand by my recommendation to try unshielded twisted pair for line level, although it may not be the right configuration for everyone.
Sorry SF Tech,
Should have originally explained I wanted to make two different cables. Thats partly why I was getting confused with all the conflicting advice. It is becoming clearer now!!
The cable you describe is a shielded twisted pair aka "shielded twin core cable" that can be wired for use as a balanced XLR cable, or (in your case) wired as an rca interconnect cable aka "unbalanced single-ended cable". The only thing "balanced" about a single-ended cable such as this is the fact that a dedicated conductor is used for the return path (twisted around the signal path conductor) rather than relying on a shield for the return as in the case of coaxial cables.
When the cable is wired as an rca interconnect cable, the twisted pair is intended to be wired with one conductor for positve (+) aka signal, and the other conductor used for negative (-) aka return or ground. The fact that the + and - are twisted together is an important geometry that's beneficial towards noise rejection (so don't wire both twisted conductors for + and wire the shield's drain wire for - ).
As I recall, the cable you built is intended for a phono-level application. I suggest that you keep the cable wired as-is with the + and - twisted together, then try connecting the mylar/foil shield's drain wire at the phono preamplifier end of the cable rather than at the TT end of the cable (opposite of the diagram). While the TT is considered the source component, the cartridge is a passive device so grounding the shield at the phono preamplifier end is prefered in some cases. Also, you can try the cable wired as-is (with the + and - twisted together) but connect the mylar/foil shield's drain wire at both ends of the cable as another option. One way or the other should solve the problem (I hope)...
The "problem" per se, is that you you are using a cable for something other than its intended purpose... ie it is a balanced audio cable, intended to make balanced connections, and may not be the best choice for unbalanced interconnects. That is not to say that it shouldn't be done, but it may not get you to where you want to go (sonically speaking). You have to figure out what to do with the "extra" conductor. Some people think that extra conductor will compromise the design regardless of how you deal with it. Technically speaking, the only "proper" way to terminate the cable is the way that I described to you. That does not mean that you cannot terminate it in another way that sounds better to you! Using the twisted pair together as your signal conductor won't harm anything as long as the shield is connected at both ends. Try to ping Jon Risch or Abe Collins if you don't get a satisfactory response in this thread.
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