Dynaco ST-70 and Magneplanar 1.6QR

By the way, when you get your new amp I'll take the Dynaco off your hands!

Seriously, the Dynaco is a nice piece, but just doesn't have the muscle needed for the Maggies. However, before you dispose of it, you might try biamping the MG 1.6. The Dynaco would suffice to power the tweeters, and you would retain that "tube sound" (warm-sounding harmonic distortion).

Eldartford, thanks for suggestion, but I have a question, do you mean that ,if merely running the tweeters, the dyna could deliver more volume?

also , it does indeed seem like I have to sell the dynaco, so if you are interested, here is a link to the closed ebay auction where I bought it.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3045847351&category=39783

I will try the tweeter setup tonight. Thanks;

Andersd...Volume means voltage gain (not really power) so it's possible that your preamp is just not driving the power amp with enough signal. One thing that you could try would be to connect your 4 ohm speakers to the 8 ohm outputs of the power amp. This will get you more voltage to the speakers although the power amp wattage capability (which may not be the limiting factor) will be less.

It's a long time since I played around with tubes, but I suspect that there is a 12AX7 input stage in the power amp. I hope you don't have a 12AU7 pluged in by mistake: that would lower gain. The driver for the output stage is probably a 12AU7: they might be swapped around.

You really ought to be able to play those speakers loud with your amp, and the symptom of insufficient power would be distortion, particularly clipping, rather than low volume.

All this being said, I still suggest you try a much more powerful amp, and find out how good your speakers really are.

Eldartford, which adcom amp are you using?

A

Andersd...My amp is the GFA-5503, which is the three-channel version of the GFA-5502 that you probably want. These amps are rated at 200 watts into 8 ohms, and 350 watts into 4 ohms (which is what the MG 1.6 are). I paid only $875 for my amp which was "B stock" (demo or mfg repaired) and it came from an authorized dealer with full warrantee, and I have no problems. (Someone "broke it in" for me, if you believe in that).

Magneplanar speakers are a very "easy" (resistive) load for the power amp, so I doubt that some of the very expensive amps would do much better than the Adcom when used with Magneplanars. If you were driving the MG 1.6 with the Adcom you would have a valid basis of comparison if you ever were to consider one of the very high end amps.

Go look at the Adcom website www.adcom.com for full details.