Crimson Power amp distorting as part of my AV system...Confused!

[tonewheelkev]

Hi Folks
...here's one for you!

For some time now, I've been using an old Arcam Alpha 8 Power amp to drive main L/R Channels in my Yamaha based AV system.
Signal taken from Pre-Outs of the Yamaha to inputs of Arcam...with some success!

If I replace Arcam with my even older Crimson Power (Kit built in the80's, and just updated by the designer of that amp, and I know this is working perfectly in it's own right!).....sound is noisy/distorted...even distant.

I had assumed that any power amp could be driven by any pre-amp....but not so!!

Any thought on how I might correct this.....the Crimson is a MUCH better amp!?

Confused....let's face it....doesn't take much!!

 

[JonSnell Electronic]

Model number and schematic of the Crimson would help.

 

[Douglas Blake]

I had assumed that any power amp could be driven by any pre-amp....

That's true. Modern equipment (since the early 1960s) use Impedance Bridging rather than impedance matching. In this scheme the output of one stage has a relatively low impedance (typically 75 ohms) and input to the next stage has a relatively high impedance (typically 10k ohms) which allows the willy nilly interconnection of devices without serious problems.

The signal levels have also been standardized into Consumer and Pro line levels (CLL and PLL for short).

One possibility is that the amp requires PLL signals but your Yamaha system is outputing at CLL which would make the amp sound weak or too quiet. In the reverse a PLL signal will overload a CLL amp very easily.

Then... not all amps can drive all speakers. Some lack the simple horespower for the job, others don't like low or higher loads, still others with output transformers can be damaged by the wrong speaker load.

To be sure what's going on you would need to dig into both the amplifier's and the speaker's specifications and determine if your speakers are within the acceptable load ranges for the amp and it is being driven at compatible levels.

 

[tonewheelkev]

Model number and schematic of the Crimson would help.

...of course...It's the CK1100


...Hhhhmmmnn...schematic.......I've attached schematic for Mk VII
Brian Powell has just updated the boards from Mk VI to Mk VII, so I think this is the one! (BP is on holiday for a fortnight .......starting today as it happens )

 

[tonewheelkev]

That's true. Modern equipment (since the early 1960s) use Impedance Bridging rather than impedance matching. In this scheme the output of one stage has a relatively low impedance (typically 75 ohms) and input to the next stage has a relatively high impedance (typically 10k ohms) which allows the willy nilly interconnection of devices without serious problems.

The signal levels have also been standardized into Consumer and Pro line levels (CLL and PLL for short).

One possibility is that the amp requires PLL signals but your Yamaha system is outputing at CLL which would make the amp sound weak or too quiet. In the reverse a PLL signal will overload a CLL amp very easily.

Then... not all amps can drive all speakers. Some lack the simple horespower for the job, others don't like low or higher loads, still others with output transformers can be damaged by the wrong speaker load.

To be sure what's going on you would need to dig into both the amplifier's and the speaker's specifications and determine if your speakers are within the acceptable load ranges for the amp and it is being driven at compatible levels.

Thanks Douglas.....but just to re-state...the amp is perfect, and capable of driving speakers....it's just that it won't sit 'behind' the Yamaha AV Pre amp outs!
(It runs beautifully as a stand alone system...same speakers!!)

 

[tonewheelkev]

.........a PLL signal will overload a CLL amp very easily..........

A bit of digging around, and it looks like Yamaha's output PLL


If this is the case, is there a way of 'attenuating' the signal so that it is acceptable to CLL???


Am I being too simplistic here!!??

 

[Douglas Blake]

A bit of digging around, and it looks like Yamaha's output PLL


If this is the case, is there a way of 'attenuating' the signal so that it is acceptable to CLL???


Am I being too simplistic here!!??

Not at all. Mismatches like this are very common.

First check the Yamaha, see if you can turn down those outputs in the setup...

Does the amp have input gain or level controls... if so just turn them down until the distortion clears up. If not you can look into a passive attenuater to hook up between the Yamaha and the Amp... Like This ... or if you're handy with solder and a drill, it's basically just a volume control in a box.

 

[bepowell]

Hello

Get in touch with me. I designed the Crimsons, if you have not resolved this issue.

Brian Powell