Link on That Auction Site

Finally managed to find another pair of Coda 8's after three years of searching, at a price even I can afford.

8.5/10 condition (a few scratches) but the cabinets are solid, the grilles have no tears or punctures, the surrounds are in perfect shape.

And you know what? Stacked, they sound magnificent.

Yes, in parallel. That means a 3 ohm load. But considering how quietly I play my music, I really am not going to worry about this!

At the price, not a score, but definitely worth four dancing bananas.

Nice!

That's a decent price. Consider what you'd get new for that, or heck, even all the lesser used and vintage.

congrats!

thats a pretty good deal.

how about wiring them in series? also, does the stack give you more than the sum of the parts? i found that stacking Large Advents gives a more balanced sound than a single pair will, the mid's in particular are greatly improved. for the Coda's i would expect the low end to improve somewhat.

I've got my fingers crossed they survive shipping. The seller's f/b is not very good...

Sam: The speaks were stuffed into an Altec Lansing box, with tons of peanuts, and individually wrapped in bubblewrap. One front baffle had popped off, but a well-placed thump with my fist fixed it. When I bought 'em, her feedback was 100%. That negative hit happened while my box was in transit.

Scott: I will be trying them in series as soon as I hit RatShack later today for some new banana plugs; right now I'm just using some scrap wire to make sure they work. So far, so good... but I will have to eventually make a series vs. parallel decision! I'm hoping to find my SPL meter to make some -*test*-('")s.

When I was using just two speakers, I had standing waves which made the bass really good in just two spots in the room. Now, it's good everywhere, and there's a lot less treble beaming. I'd say that's an improvement.

Paul: I think I made out pretty darn good. In 1997 these had an MSRP of $300 a pair ($390 today), and I'd paid $190 at a Tweeter closeout then. $87... man, I'm still giggling over that.

Of course, now this means I have to build new shorter stands. A pair of these on one single upright 2x4 is not exactly great. 4x4s are called for!

I think you did very well Tom.

I´ve always found stacking small speakers makes a lot more sense than stacking large ones. The improvement in the bass department was to be expected. I believe you will find that particularly true at low listening levels.

May I make a suggestion? Rather than stacking the speakers in an upright position, try to turn them 90º and stack them on their sides, with the tweeters on the outside. It will likely improve your imaging even further.

You waited for 3 yers right? I can see the reason for your ebay handle, then.

Jorge

P.S. - Here´s a pic from the actual speakers for future reference.

Ha! I'm neither patient, nor an artist! So, in a way, the name's my alter ego.
Right now, they're stacked (from top to bottom)
woofer - tweeter - tweeter - woofer, a sort of quasi-D'appollito array.
I have never considered stacking them sideways because I've never heard of this.

Food for thought, Jorge.

Hm...

Like Jorge once said, i'm a sucker for small speakers. That Kef coda 8's are classics.
Congrats.

Tom,

Speaking about parallel vs. series connection I remember reading something about being alright connecting drivers in series, but being an unknow value regarding speakers, i.e. with crossover and all.

I wonder if a connection in series is appropriate for speakers in a hifi context. I´m aware this kind of connection is often used in sound distribution systems in hotels, churches, conference rooms and the like, where the concerns are totally different.

Looking forward to your conclusions.

Jorge

Well, I tried the speakers in series.

Awful. The bass was rather on the "tubby" side, and treble suffered. I really think this is a result of the crossovers. Being a nominal 12 Ohm load, they were much quieter as well.

I haven't found my SPL meter yet, but going by my ears, I can't tell any difference in loudness between one pair playing and two pair in parallel.

So for now, they're in parallel. I am thinking of adding a 1 Ohm sandbar resistor in series with each side to bring the load to the amplifier up to 4 Ohms. I've got some in my parts box, so I will let you know how that goes. I know that's not recommended by some, but I really don't like running a 3 Ohm load. :worry:

Test material: Sarah McLachlan - Surfacing (CD)
and
various Cowboy Junkies CDs
and
Elton John - Captain Fantastic and the Brown Dirt Cowboy (LP)

A resistor in series, ehm? Interesting.

That should lower overall loudness a wee bit, but nothing very noticeable, I´d guess.

...or you could make a series/parallel speaker circuit.

But, for calculating the total resistance of a combination series/parallel circuit it has to be taken in steps.

If you have a circuit with 2 parallel components in series with a third resistive component (we're going to consider the 4 ohm speaker to be purely resistive), first you have to calculate the total resistance of the parallel section. Then the total resistance is equal to the series component plus the total of the parallel components.

For example:

Parallel components:

Total parallel resistance = (R1*R2)/(R1+R2)
Total parallel resistance = (4*8)/(4+8)
Total parallel resistance = 32/12
Total parallel resistance = 2.67 ohms

Total parallel plus Series:

Total resistance = R1 + R2
Total resistance = 4 + 2.67
Total resistance = 6.67 ohms total

Not to bad for amp load.

Argh. This is where I start to get confused, Alvaro.

The KEFs are 6 Ohm speakersso I used the formula:

1
------------ =
1/R1 + 1/R2


1
----------- =
1/6 + 1/6


1
------------- =
.0167 + .0167


1
----------- =
.0334


2.99999... Ohms


Then 2.99999 + 1.0 Ohm in series = 3.99999 Ohms total.

I'm very sorry for the confusion. If my math is wrong, please tell me.

******************

Jorge: I did try a 1 Ohm, 10 Watt resistor in series and I couldn't tell any difference at all in the sound, so now I have to figure out a way to put them in the speaker line that's neat and semi-permanent.

Well, the right formula for parallel impedance (resistance) circuits is :

Rt= (R1xR2)/(R1+R2)

Rt= (6x6)/(6+6)

Rt= 36/12

Rt = 3 Ohms.

In your case it will be ; Total parallel plus Series

RT = Rt (total parallel) + Rs (serie resistance)

RT = 3 + 1

RT = 4 Ohms.

Now this is in theory.

In the audio world, simple spec numbers rarely adequately describe real-world performance. When a speaker is specified as being "6-Ohms," that is really an oversimplification of a complex issue. A speaker's impedance is different at different frequencies!
But Impedance is not resistance.
Impedance is the combination of the resistance of a speaker plus its reactance. (Reactance describes the electrical effect of the inductors and capacitors . The drive elements themselves also have a "reactive" element.)
if you put a ohmimeter in your speakers you have multiple readings. They are constantly changing...from 3 to 6 to 8 to 3 and 6 ....

Well, enough bla, bla, bla...
IMHO you shoul try to put two resistances or four (between the two speakers) in parallel also, instead of one only in serie. IMO, it will be a more stable circuit.

If you put a 6 Ohms resistance in parallel the formula goes like this:

1/Rt = 1/R1 + 1/R2 + 1/R3

1/Rt = 1/6 + 1/6 +1/6

1/Rt = 3/18

Rt = 18/3

Rt = 6 Ohms

not bad...

at least in theory......

BTW, Tom i forgot to mention another important issue here. A very tricky part indeed.

First keep in mind that it only takes 1 watt to push your speakers to their rated sensitivity. Typically sensitivity rating are in the form 90db at 1 watt at 1 meter.

Two speakers in Parallel receive the same voltage, but the total current is divided between them. Two speakers in Series divide the total voltage, but they both get the same amount of current.

When you turn the Volume Control, you are not applying watts to the speaker, you are applying signal or voltage, and the resulting watts are what ever they are based on the load.

If you apply 16 volts signal to 8 ohms, the resulting power is:

P = (E^2)/R
P = (16^2)/8
P = 256/8 = 32 watts


16v to 4 ohms

P = 256/4 = 64 watts

Notice that while each example above consumes a different amount of power, they all have the same signal voltage applied to them.

So power and perceived sound are not linear. One nudge upward of the volume control does not result in one nudge upward of the power.

When you turn your Volume Control up one very very small amount, just enough to hear a change in the sound level, that is about 3 db. Three DB represents a doubling of applied power.

All that said, I still say your amp shouldn't have a problem with 4 or 6 ohms, but obviously, I can't actually promise that.

Sorry, this was probably a lot of talking that adds up to not much help....