is it possible to run SDA 1C in bridge mode?

nhhiep

I put my HK Citation 7.1 4-channels amp in bridge mode for 400 WPC x2 to run my 1Cs and it goes into Protect mode instantly. Normal mode works fine.

is this the same for other amps? has anyone tried with your amp in bridge mode for any SDA speakers?

I know most SDA speakers can't run with mono amps, but this is not the case.

heiney9

Bridged is taking the 2 channels and summing them together making a single (mono) channel and making it non-common ground between the L & R output. No you can't and not you shouldn't even if you have the AI-1 cable. When you bridge a stereo amp you halve the impedance the load sees and since the SDA's tend to run closer to 4 ohms than 8 ohms a bridged channel will see a 2 ohm load and very few amps can handle a 2 ohm load. Bridging usually comes with a compromise in sound as well.

Short answer is no

H9

Joe08867

No, and its not advised to try it it unless you want to burn up that amp. H9 hit the nail on the head with his description of the issues inherent with bridging an amp.

Schurkey

A multi-channel amp system, bridged to two channels, may or may not have the problems described above. It all depends on the amplifier design and condition. Bridging can intensify some forms of distortion, but it reduces other forms. Done right, a bridged amp doesn't have to sound bad.

The Aragon Palladium- and the new Iridium-series amps are factory-bridged variations of their stereo amplifiers; and will drive a two-ohm load without problem. I bet a Hafler DH500 or XL600, or the Adcom 565se, bridged in the field will drive 1Cs, too.

From the Adcom GFA-565SE owners guide, downloaded from http://www.adcom-usa.com/gfa-565se-2

Although the GFA-565SE can generate a substantially greater amount of power in the
bridged mono mode than when it is in its normal stereo mode, it requires the use of
loudspeakers the nominal impedance of which does not drop below 4 ohms. lt is not
recommended that the GFA-565SE be used in the bridged mono mode into loudspeakers, or
multiple loudspeaker loads, which drop in value substantially below 4 ohms. Otherwise, you
may trigger the THERMAL PROTECTION 0 or blow one of the DC RAIL FUSES

I don't know about an HK Citation multichannel unit. Is your unit rated to drive a nominal-6-ohm speaker WHILE BRIDGED?
First Guess: No.

IF THE SDA SPEAKERS CAN USE THE AI-1 STYLE ISOLATION TRANSFORMER, bridged amps aren't an inherent problem for the SPEAKERS. Whether the bridged amp has the sound quality desired and current delivery needed is another story. It's not the bridging that's the problem...it's the amplifiers being bridged.

heiney9

Factory bridged designs that are "fixed" as in not switchable between stereo and bridged are a completely different animal and not really what the OP was asking. Great info, but not really at the crux of the matter. Essentially what you describe with Aragon "is" a mono block and was designed that way from start to finish. A mono block amp is rarely ever the same as a stereo amp with a bridging switch. Again two different animals.

The Op asked about bridging a stereo amp not using two mono block amps. Just trying to clarify further to create less confusion for the guys who are little behind the curve as far as electronics go.

As far as the last sentence, I have no idea what that means. If the impedance the amp sees is less that it can handle because it's bridged then in my mind it is a problem with bridging since the same amplifier won't have an issue in stereo.

H9

nhhiep

the HK citation can drive low ohm speakers w/o a problem. I bridged it before driving Lsi9s w/o any issues.

I am just wondering why it's not working with 1Cs or if anyone bridge their stereo amp to drive SDA speakers?

as far as SQ, I detect no differences in term of THD or ground noise. the user manual lists the same .003 THD in both normal and bridge mode. and yes, it even says it's OK to drive 4 ohms speakers in bridge mode.

http://audiojunkies.com/forum/blog/3704-zed-home-audio.html

heiney9

Like has been stated it doesn't work with SDA's because they need a common ground amp. A bridged stereo amp is NOT COMMON GROUND. That simple really!

H9

Schurkey

nhhiep wrote: »

the HK citation can drive low ohm speakers w/o a problem... and yes, it even says it's OK to drive 4 ohms speakers in bridge mode.

Do you have an isolation transformer in the SDA interconnect cable? The Polk-specified AI-1 is a functional unit, but the large-transformer aftermarket style (Search this site using "Dreadnought") is much, much preferred.

WITHOUT THE ISOLATION TRANSFORMER in the SDA interconnect cable, you'll have amplifier and/or speaker crossover problems--perhaps even failures.

OR, you can remove the SDA interconnect cable. You'd gain compatibility with bridged amps, but lose the SDA effect.

SDA 1Cs can use the AI-1-style isolation transformer. SDA 1Bs cannot. SOME (early production???) 1Cs may need a simple modification to make use of the isolation transformer; but the basic design is completely compatible.

http://www.polkaudio.com/forums/showthread.php?131691-2B-and-EARLY-1C-AI-1-modifications

heiney9

IMO, I would not run the HK bridged even with the AI-1. You won't gain much, if anything, and there most likely will be an issue with the load. It's an expense and some work to build the AI-1 but I don't think it would be worth it to see if it works for the amp you are using, if that's the only reason you would spend the $$$ and build one.

Only certain serail # 1C's can use the AI-1 with certain others needing further modifications to run the AI-1.

H9