Ideas on Internal Wiring for Saburo

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Hi there. Managed to build my Saburo cabinets at long last. Now wondering how to wire them up - before glueing the lids on. Clearly it would be a good idea to allow for the possible replacement of drivers. So what is the best way to facilitate this? One problem is that the terminals on the Fostex FE126En are not very robust and not suitable for directly attaching to any thick or stiff cable. Should I be thinking about laying permanent internal wiring leading to screw terminals located somewhere in the compression chamber, these connected to the driver with a short length of thinner, flexible wire?

Is it an idea to use solid copper busbar rather than wire?

Any ideas for a good solution most welcome. I guess you've all thought about this before.

[Incidentally, I used two-part epoxy resin plus microfibres for my adhesive. It's the only thing that definitely doesn't shrink or creep and it's great for filling any gaps. Much loved by boatbuilders.]
 
In my opinion, solid buss bar would be overkill for this application, and require an extraneous mechanical/solder connection. I've built a couple of pairs of double mouth horns ( Aiko and Valiant), and installed a recessed terminal cup at the vertical center of back panel, and ran wires straight through the internal panels, sealing with hot melt glue.

If the internal panels are already glued in place you can easily drill the required holes though all panels with a bellhanger drill bit.

I've been almost exclusively using single strand of #24 wire on all FR builds for years now, and considering the very short length of direct path to the driver in these particular designs, I honestly don't see any advantage of heavier wire/cable. The lighter wire certainly makes for much easier (solder) connection to the speaker terminals.
 
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You surprise me. 24AWG is thin for an 8 ohm circuit path. Have you actually tried anything fatter? I've never failed to hear an improvement in sound when increasing the thickness of amplifier or speaker cables. An 18 inch length is not insignificant. In my amps I use 16SWG (15AWG) if I can fit it in. And I'm also surprised that you use solder. I've always found that tightly screwed terminations sound better. Have you tried that?
 
frugal-phile™
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Have you actually tried anything fatter? I've never failed to hear an improvement in sound when increasing the thickness of amplifier or speaker cables.

Oh yes. I have 10 & 12 g (and more stored downstairs). With FRs things kept better & better as cable got thinner (and solid better than stranded). Thinner than CAT5 gets impractical.

Speaker cable is very system dependent.

BTW. Do make sure that the terminals are arranged so that you can change wire.

Don't take our word for it. Try it yourself.

dave
 
You surprise me. 24AWG is thin for an 8 ohm circuit path. Have you actually tried anything fatter? I've never failed to hear an improvement in sound when increasing the thickness of amplifier or speaker cables. An 18 inch length is not insignificant. In my amps I use 16SWG (15AWG) if I can fit it in. And I'm also surprised that you use solder. I've always found that tightly screwed terminations sound better. Have you tried that?


to echo what Dave noted, a brief personal anecdote:

Over 20 yrs ago I owned a small Linn based system that included Kheilidh speakers bi-wired with 10ft of K400 cable. Approx 10 yrs later, in my early days of DIY craziness, I read about Chris Van Haus' magic recipe for DIY with CAT5 cable;
DIY Cat5 Speaker Cables

After spending quite a few hours stripping and braiding cable and terminating with 4mm banana plugs, my first impression upon plugging in the completely fresh wire was - "Holy crap, that (tight / articulate bass, soundstage dimension/depth, midrange clarity) was missing before?" Even though 10yrs old at the time, I was able to trade the cable back in for credit on other used gear.

It gets better

Once you trip down the rabbit hole of internet / DIY audio forums and start trying some of the tricks that conventional wisdom suggests "can't work / make a difference .. " or have the opportunity to hear things at get togethers like VSAC, RMAF,, it becomes far easier to take leaps of faith that have low cost of admittance.

After reading some real lunatics waxing rhapsodically over connecting their flea watt SET amps and FR drivers with wire as thin as #32 magnet wire, it didn't take long to try a single pair of CAT5 conductors for both UTP interconnects and speaker cables.

Less can be more - even more transparent than a braided 12 conductor snake, not much more than pennies a foot, and easy to solder. Since most of the small full range drivers and all the speaker terminals that I tend to use have small contact points best suited to either solder or crimps (that actually entail an extra physical connection), the soldering makes most sense. If it (solder) is good enough for PTP wiring of a tube amp with well over +400V DC B+, I figure it's good enough for the 3 or 4 watts average power going into the speaker.



Yes, I've listened to $200,000 systems ( Linn / AudioNote / and too much crazy stuff at shows) in which the sales tax for a bi-wire set alone costs more than my entire current system ( AudioNote Sogon), but I'd be hard pressed to attribute the cabling's contribution to what I can hear but never afford.
 
This is very interesting. I suspect the reason why thinner wires could sound better is the same reason that a lower damping factor can sound better. I understand the Fostex FE126 benefits from having an amp with a lower damping factor (though as an electronics engineer I would prefer to refer to this as a higher output impedance) so it is perhaps no surprise that additional resistance in series with the speaker can improve the sound. Has anyone actually tried using a more substantial additional series resistance, such as 1 ohm resistor? That would be interesting. The idea is that it would let the speaker cone move more easily in the way that it wants to, absorbing the back emf produced by the coil in a way that has less effect on its motion. The science sounds plausible but has anyone tried it?
 
John, back emf is a jolly good thing! Your amp´s damping factor = amp´s output impedance divided by the driver impedance, and that damping keeps the cone from overswinging. By adding resistance to the driver impedance you get less damping - akin to a car with completely knackered shock absorbers. Feels like more bass, but in reality all you get is some muddy booming without any control. Run a formula and see how much one or two additional ohms will raise the Qtc.:eek:
 
Dave - horses for courses, as usual. With the drivers we use for horns a bit of fine tuning can be beneficial, drivers with Qtc off the scale used to imitate bass in tiny boomboxes (I hate them) become sheer horror.
And as to using solid core (CAT5 or the wunderwaffe Scott and I use when nobody is looking - humble doorbell wire)...the effect is not in bass. It´s some magic somewhere in the highs, nobody has yet been able to find an explanation about the why and how. But with a very good recording and when you have had a quiet day that hasn´t overstressed your hearing - something is there. Somewhere.
 
FWIW, assuming we don't want the wire to act as some kind of filter, we need to ensure L&C are controlled to sensible levels, and voltage drop is minimised. Internal wire runs are generally quite short, so voltage drop is usually something of a non-issue. Using the FE126En's published spec. as a baseline, & assuming a 6ft total run (3ft each leg) you're looking at a fraction over 0.3V drop in a 24ga conductor, translating into roughly 0.36dB loss. Not something to loose a great deal of sleep over; we're well into reasonable zones there, the maximum acceptable loss generally being assumed as 1v (if you're happy with that, then a 27ga conductor should be sufficient).
 
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May I question this, Pit?

amp´s damping factor = amp´s output impedance divided by the driver impedance, and that damping keeps the cone from overswinging. By adding resistance to the driver impedance you get less damping

Are you sure? Wikipedia has it the other way round: Damping factor - Wikipedia, the free encyclopedia It also states that the additional impedance of cabling is part of the source's (amplifier's) output impedance, not part of the load, which sounds more likely to me.

On this basis, increasing cable resistance will decrease the damping factor, which will decrease the accuracy of control of the voice coil. Which is why it is interesting that some speaker/amp combinations seem to benefit from thinner cables. It remains a mystery.
 
Come on, Dave.

Using ohm's law, back emf drops to zero when the amp's output impedance is infinite.

Have you never tried connecting a relay or some other coil across a battery and then felt the electric shock as you disconnect it? If the source impedance is infinite, the back emf will try to be infinite (hence the electric shock).

Pit, I can't see how back emf can be a good thing - it would be much easier to drive a straightforward resistive load.
 
voltage drop is usually something of a non-issue

I couldn't agree more. The question is more about using additional resistance to tailor the damping factor to suit the speaker/amp combination. If, as some people claim, the damping factor can be too high (I still have doubts) then it could easily by reduced by inserting a small resistor in series with the speaker. It possibly only need be of the order of 0.05ohm. Consider an amp with o/p impedance of 0.01ohm (quite reasonable for a good, high-feedback design), this would change the damping factor from 800 to 160.
 
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