Cyrus 3 gainclone project

[barry.childs]

I thought I would mention my latest project. I recently aquired a Cyrus 3 Integrated Amp. On comparing it with my gainclone I was disappointed with the sound. So next I used the pre-amp stage with the gainclone and was pleasantly surprised. It sounded good and gave me all the posh bits available with a commercial amp. eg. lots of inputs, balance, mute, phono stage, ease of operation etc. Now what if I fitted the gainclone into the Cyrus case. Surely, I would create a Super Cyrus. Now the faint hearted have to look away! I removed all the major amp components from the Cyrus to make room for my two small cards. I used the internal heatsink chassis to fit the boards. Wired the inputs to the pre-amp socket and outputs to the speaker sockets by drilling holes in the Cyrus Main board. I re-wired the PSX socket to the gainclones, so now the internal power supply drove the pre-amp only and my external power supply drove the gainclone. Voaila!! A Super Cyrus better than anything else iv'e heard. Now I have one question. Should I put resistors between the inputs and earth or is this done for me in the cyrus pre-amp? Seems to work fine, but is this OK? If anyone out there can help, I would be gratefull. Barry

[Nuuk]

Now I have one question. Should I put resistors between the inputs and earth or is this done for me in the cyrus pre-amp? Seems to work fine, but is this OK? If anyone out there can help, I would be gratefull.

A circuit diagram of what you have actually built would be very helpful!

[anatech]

Hi Barry,
Sorry, I missed your post entirely.

Too bad you removed the Cyrus amplifier. It has a known problem and should really blow your gainclone away. Oh well. You just missed a chance of having something really nice. The design of these amplifiers is now been superseded by the "X" series designs, but that design is beyond the norm for audio equipment. Also, now you need to resurface the original mounting surfaces (I hope you did anyway!).

As for the resistance to ground question, I've never had to consider that. I don't know that it matters since the outputs will be mV from ground anyway. If you include high value resistors, you will not load anything down and still achieve your goal of referencing that signal to ground.

As for what you have done, I don't see any problems with it. With the obvious problem that you've eliminated an expensive amp in favour of a chip amp solution. I would have repaired the Cyrus. If it is at all possible to rebuild the original amp, do it. There are several smt's that need replacement. If you have damaged traces on the board, this is no longer an option.

-Chris