[dflee]

Have an interesting situation and would like some guidance.
For a number of years I have been running a Coda 4,3,2 amp into a bi-connection pair
of speakers (two sets of cables). I had 225 watts to each half of the speaker using the four channels. This sound to
me was pretty good. I got a pair of Pete's American cable and jumpers. Using my old cable on the lf and the
American on the hf, the sound was pretty good. Used the jumpers and bridged the amp and things got quite better.
Not sure if it was the bridging or the jumper that made the improvement but using the previous cable, going from just using two channels and jumper to
four made an improvement. Anyway, using the amp in bridged mode blew channel 4. Went back to stereo mode and the sound has dropped off significantly.
Do I get the amp repaired (Coda said $300 for channel 4 + $ for any leaking caps or other things) and get another set of cables (looking at $600)
or put 1K or abouts in a new amp. I will stay with sand cause glass is not an option.

Confused
Don

[rollo]

   As good as the TWL cables are my guess was the change in amplification method used.If you like the amp and $300 is a non issue do it. Would need a working amp to keep or sell.
   Trying another amp is always fun. But now which one ? Find one that offers the same power as the coda in bridged mode. have fun.


charles

[richidoo]

It's interesting that the sound of the amp changed so much when in bridged mode.  Bridged more than doubles the power and doubles the load, so the safe operating area of a transistor was probably exceeded in bridge mode due to designers error. If you are bit by the bug now, and want that better sound you heard, then start looking for another amp cuz this one can't handle bridged mode. Since you only need stereo amp now, you will find a lot of options. Probably not for $300 though... The bridging probably lowered the output impedance of the amp and made the bass more firm and punchy, and other drivers more vivid. Class D usually has the lowest impedance of any topology, but some of them are less listenable than class AB. I just heard a great class D, Classe Sigma stereo. oolala 

A tip: You can get some of the benefits of biwiring by crossing the leads at the speakers. Install the jumpers as normal. Then attach -SC lead to the -bass, and the +SC to +treble. This puts the low impedance SC connections around the whole crossover, not just on the bass. You can also cross it the other way with + on the bass. The jumpers bond the treble and bass so it doesn't matter, except that it does...     If you have a single ended amp you can put the +SC lead on whichever you want to emphasize a little more, be that treble or bass. This made a big improvement for me over the normal connection to just the bass end. Thanks to ecramer for this tip!

[Freo-1]

Have an interesting situation and would like some guidance.
For a number of years I have been running a Coda 4,3,2 amp into a bi-connection pair
of speakers (two sets of cables). I had 225 watts to each half of the speaker using the four channels. This sound to
me was pretty good. I got a pair of Pete's American cable and jumpers. Using my old cable on the lf and the
American on the hf, the sound was pretty good. Used the jumpers and bridged the amp and things got quite better.
Not sure if it was the bridging or the jumper that made the improvement but using the previous cable, going from just using two channels and jumper to
four made an improvement. Anyway, using the amp in bridged mode blew channel 4. Went back to stereo mode and the sound has dropped off significantly.
Do I get the amp repaired (Coda said $300 for channel 4 + $ for any leaking caps or other things) and get another set of cables (looking at $600)
or put 1K or abouts in a new amp. I will stay with sand cause glass is not an option.

Confused
Don

Perhaps you should do both.  Get the Coda fixed, sell it, and get another amp.

[RDavidson]

Bridging doubles the wattage but halves the current, so that may have something to do with it.....unless the Coda is somehow designed to use all output stages in bridged mode, which I don't recall seeing done in any bridgable amp......but, that doesn't mean something like this doesn't exist.

Everything probably sounded great until your speakers demanded some major current, which the amp couldn't deliver bridged.

[Quiet Earth]

Bridging doubles the wattage but halves the current

Do you mean doubles the voltage? I don't think you can double wattage and halve the current simultaneously. (P=IV)

It sounds like the amp wasn't made to be bridged or something was hooked up wrong. If it were me and I really liked the amp I would fix it and bi-wire.

I like richidoo's pseudo bi-wire trick too.

[RDavidson]

Do you mean doubles the voltage? I don't think you can double wattage and halve the current simultaneously. (P=IV)

It sounds like the amp wasn't made to be bridged or something was hooked up wrong. If it were me and I really liked the amp I would fix it and bi-wire.

I like richidoo's pseudo bi-wire trick too.

Yes, you're correct. I was trying to say that you double the output power (but mistakenly used the word wattage) from a single channel, but halve resistance (halve current). Knew what I was trying to say. It just came out wrong. That's what I get for not double checking my info. Hey, it's casual Friday.

[Quiet Earth]

Anyway, using the amp in bridged mode blew channel 4. Went back to stereo mode and the sound has dropped off significantly.

Did you pop the cover off to see if you blew a fuse? I don't know exactly which version of the amp you have, but I think there might be 4 more fuses inside of the amp, one for each channel. So that would be 4 fuses inside the amp plus the main fuse on the back panel. Just a thought.

[dflee]

Quiet:
Thanks for not being. Your thought is very insightful and I will look at it today. One can
only hope it is something that simple. Can't figure out why I didn't think of that since
everyone says I'm simple minded

Don

[opnly bafld]

Legacy Classics* and a bridged 4 ch amp not rated for 2 ohms stereo (4 ohms bridged). 
I'm surprised it lasted long enough for you to notice anything other than smoke (sorry about your amp  ).

A 2 ch Legacy/Coda or a rebuilt Electron Kinetics Eagle 2 will get the    back.




*had Bill D's personal pair for 5 years, they were tweaked and even harder to drive than stock versions. 

[jackman]

I have that Legacy amp and it's not happy with loads much lower than 8 ohms. It's a good sounding amp but I always thought it sounded MUCH better in un-bridged mode. Bridged was more powerful but not as refined as standard mode.

I'm not a fan of amps running in bridged mode. Mono amps are a different matter but amps like the coda-Legacy never sounded right in bridged mode on my system. 

[dflee]

With my wife having two eye surgeries (Nov. 20th was right eye cornea replacement and Wed she has retina operation on the left)
and major dollars deductible and copay, it will be a while before I can venture into new amp. Thankfully I do have two operational
channels but will be looking into another amp in the future. Question now is where should I put the money. Do I try to get the
most watts for the dollar or can a lower wattage amp provide better sound? I know this is kind of a loaded question but putting it
out there. Does quality surpass quantity in the 1 to 1.2k category?

Thanks
Don

[dlaloum]

Check out the Crown XLS series of amps - there is a thread about them at the moment...

My speakers (Gallo) needed an amp that could supply more W as well as Amps... the Crowns did the magic.... and they are (relatively) dirt cheap.