Cat 5 question

Bob Brines

Member
2003-01-31 10:11 pm
That cable is breath-taking! I use 4 Cat5 WIRES rather than 4 Cat5 CABLES.

Most 206E implementations, including mine, wind up with a rising frequency response. The simplest solution, although not necessarily the best, is to add series resistance. Running large gauge cables with essentially zero resistance exacerbates the problem. Thin wires is generally the way to go. Some folks use as small as 30ga wires with good results.

Hey, if it works for you, use it. That's not the way I'd do it.

Bob
 
Agreed. Thin / high resistance wire is a simple & elegant way of adding series resistance to a driver. Better than using a separate resistor IMO -the fewer connections the better. Connections are always trouble.

I'm one of the insane people Bob mentioned who've used 30ga in the past, although that really was extreme -FF165K in pipe-horns with Audiolab monoblocks. It actually worked rather well, so long as you went easy with the old volume knob. 20 - 24ga is usually a decent compromise for FR units with a sensitivity of ~92db or greater.

There is a price to thin wire that needs to be kept in mind though, and that is that you limit the dynamic bandwidth -there's only so much current the wire can handle. Within reason, that's less of an issue with FR drivers though, because unsupported, they can't handle the huge LF transient swings of some recordings (say, Pink Floyd's Live at Pompii) anyway.
 

Bob Brines

Member
2003-01-31 10:11 pm
FYI my 4-strand cable is star wound -- on end it looks like this:

..+..
-...-
..+..

(disregard the ".." -- ascii art is near impossible when the editor insists on eating leading spaces!)

The cable is twisted about once an inch. This gives the cable a modicum of RF cancellation. I don't live in an RF dirty area, so this is not really a problem.

If you think that 24ga is too small, you can get 18ga 4-wire cable at HD, etc. It's used for HVAC and irrigation control applications.

Bob
 

OzMikeH

Member
2007-03-18 9:22 am
I just made a set of speakers cables using old telephone wire (for fixed installation behind the wall), it's 24 AWG solid just like cat5 but much easier to untwist.

I untwisted 4m of wire, one pair for each speaker. I stretched it out and sticky taped the ends to a linoleum floor an inch apart and ran over the top with packaging tape, then peeled it off the floor foot by foot and folded the edges of the tape over the wires. I stuck it down again with the sticky side up and repeated the taping process from the other side. The tape does make a mess of the polish on the floor but that's a minor issue compared to She Who Must Be Acknowledged's reaction to crinkly bits of old packaging tape draped across the living room floor.

My big ugly amp has a huge damping factor, I think I need still more resistance to bring the bass up. But these 20 minute cables make it much more enjoyable to listen to.

I didn't bother twisting it, I dont have any RF issues.
 

Hotsauce

Member
2006-06-26 12:54 am
My experience with cat5E wire is that for Fostex drivers I prefer a single twisted pair of wires, although I haven't ever used as long a run as you need.

Cat5E initially sounds very thin, with no bass and brittle highs. After 50-100 hours playing it breaks in some and smooths out a bit.

John C.
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
The right combination of CAT 5 will appropiately damp low requency harmonics probably caused by back EMF. This gives the true performance of the speakers and not the blown up bass which generally is not coherent with the image of the initial onset of the initiating musical instrument..
 
Hi,
adding resistance between the amplifier and the speaker will raise speaker Q.

A long single pair will have more resistance than a long dual or multiple pair.
The speaker Q will be higher with the single pair than with a multiple pair of the same length.
Some speakers suit a slight raising of Q to tune them to their environment.
Most speakers tend towards a prominent bass peak when additional resistance is put into the feed.
Try your speakers and find which suits you and your room.

One thing added resistance does not do is add damping. Additional resistance reduces damping.
 
I can't imagine the little T amp is happy driving that much capacitance. Does it have a zoble network on the outputs? My old SI sounded awful driving my much slimmer, tightly braided, plenum (teflon insulated) Cat5 cables. It was much happier with a single twisted pair of 18g rat shack hook up wire. My old Marantz integrated sounded better with the braided Cat5. I'd try one twisted pair of wire stripped from one of those Cat5 bunches. Then I'd try three braided together and pick my favorite.

pj
 
At the moment i'm thinking of going for 4 twisted Cat5e wires, unless anyone can suggest otherwise.

Someone elsewhere suggested Kimber 4TC works very well with full range speakers. Anyone had any experience with the Kimber 4TC? Very pricey though.

Also, as I want to improve the bass as much as possible, am I to understand that the thinner the wire, the higher the resistance and the more bass?
 

OzMikeH

Member
2007-03-18 9:22 am
Just to claify:
I wanted to REDUCE the damping of my amp, It's capable of shoving 18 amps at difficult speakers to keep them "in control"
My speakers sounded wonderfully balanced with a tube amp, with this SS amp there was very little bass (same with my Trends TA10.1, no bass). More resistance = more bass with my speakers. I only need about 1.5m of speaker cable, I made 4m for the extra resistance, I think I need more. For comparison reasons my old cables were 20AWG PVC quad flex wired as Bob Brines has done his.

If the wires are left twisted or tightly braided you might get capacitance problems. If they are separated by 1 inch by the sticky tape there is much less capacitance. In the interests of domestic harmony I strongly recommend the use of clear tape, the brown stuff is very ugly.

I made this cable because I remember reading a post about it about 6 months ago, I went to the shop and looked for some 300 ohm ribbon cable as used in old TV antennas, I think that stuff would make excellent speaker cable for Fostex FR drivers.

If you do want them twisted then one twist per foot should be enough. Most cat5 looks like about 25 twists per foot.
Old telephone cable is much easier to work with than cat5.
 
As yet I haven't gone ahead with the wire change, today though I have finally gotten my *** into gear and began untwisting the individual cat5 strands.

I'm still a bit unclear though on what is the best way of using cat5 cable in my situation. My speaker drivers are Fostex FE206E's in a back loaded horn and the cables would be about 3.5m (11.5 foot) long. My amp is a KingRex T20 (i.e. a T-Amp).

I just wanted to get some more thoughts from people on:

- How many strands to use?
- What pattern of twisting to use?
 
Old telephone cable is much easier to work with than cat5.

Without getting into the whole 'what cable is best' issue again, IME, telephone cable sounds horrible.
I spent a couple of hours making up a pair of Cat5 style braided leads using phone cable, and they sounded so bad I threw them away as soon as I'd tried them! Cat 5 in the same application was fine.
 
wixy said:
I'm still a bit unclear though on what is the best way of using cat5 cable in my situation. My speaker drivers are Fostex FE206E's in a back loaded horn and the cables would be about 3.5m (11.5 foot) long. My amp is a KingRex T20 (i.e. a T-Amp).

With the efficiency of the 206 you can get away with a single pair... split them up, sandwich with packing tape... example picture attached...

dave
 

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wixy said:
As yet I haven't gone ahead with the wire change, today though I have finally gotten my *** into gear and began untwisting the individual cat5 strands.

I'm still a bit unclear though on what is the best way of using cat5 cable in my situation. My speaker drivers are Fostex FE206E's in a back loaded horn and the cables would be about 3.5m (11.5 foot) long. My amp is a KingRex T20 (i.e. a T-Amp).

I just wanted to get some more thoughts from people on:

- How many strands to use?
- What pattern of twisting to use?

In my application using it as internal wiring for a wide range driver, 6 strands each way works the best. Just pull two out. The same for hot and return.