Crown IC150A mods

[tony9409]

I'm upgrading my quad405 with newer op amps and got to looking at my Crown IC150A noticing it uses an LM301A in the phono section and a LF356 on the main board. Are there mods for the Crown to improve it ? Could I just swap those op amps for OPA134 chips or do I need to do other mods.

thanks
Tony

[dshoaf]

This pre amp came out when tantalum caps were considered all the rage. Crown ended up replacing quite a few of them when they became leaky - specifically I remember the output side of the phono preamp board seemed to prone to this symptom.

Something to think about. I've been through one wife and well onto another since I've had one of those in my system (1977).

Can't speak to any other mods, though.

Cheers,

David

[tony9409]

Thanks, When the caps are leaky what does it do ? does it stop the signal or make the sound scratchy.

regards,

[BlackBLOOD]

Hi All.
I`m thinking of bridging a Quad405 amp by inverting the second amp.

Is there someone who already made something like that?
Can someone give mi scemathik or something?

10x
Sorry for posting hire.I`m not allowed to make new theard...

[dmfraser]

If you don't have it already, the schematic for the IC150A is posted ae www.schematicsforfree.mattsoft.net in the Files/Audio/Products/Pre-amps section.

[Blue]

All you dablers thinking of upgrading a 405 should check out...

http://www.dc-daylight.ltd.uk/Valve-...-405-Mods.html

but Blackblood? you could apply the input mod to one side only as it is non inverting, the standard amp being inverting.

could make an interesting variation.

Regards Blue

More like blown since the hurrican..........

[SY]

The only really worthwhile mod of the IC150 is to gut it and build a new preamp in the case- you could retain the raw supply, jacks, and the switching. An IC-based preamp using modern ICs, caps, regulators, and the like could easily fit in there. A 797-based phono amp and a unity-gain buffer line stage would be ideal. If you're ambitious, you could incorporate a tone-tilt control.

[Brian Beck]

Boy, I couldn't agree more with the "gut and start over" posting. My first "high end" preamp was an IC150 many, many moons ago. It wasn't until I heard a dead-stock Dynaco PAS 3X that I realized what damage the Crown was doing to music. I never looked back and have used tubes ever since for my main rigs. But back to your question: If I found an IC 150 (A or not) for cheap today, I'd buy it for the pretty chassis, knobs, etc. You might be able to salvage the power supply transformer, but if I recall correctly this part was pretty dinky. Then you can employ some nice opamps, of which there are many to choose from today, along with better passive components and power supply. it really would be a redesign and probably require a new PC card design. It would be a lot of work, but maybe worthwhile. Or, you could consider tubes....