Cary rocket 88 vs dynaco st70

I had a problem similar to yours. Turned out to be weak output capacitors.

Output capacitors? What are those? I've owned both amps. Had no noise from either, at all. Over the years I had upgraded the coupling caps, multi-section cap(which could be your issue), and added some capacitance to the B+ supply(plus a few other mods). The Rocket 88 was still an improvement, especially in triode mode. If you move to the Cary; you won't regret it. BTW- Try flipping the Dynaco's plug over in your wall outlet. If it's still stock; the prongs should be the same size.

Rodman: Dunno what they are. You'll have to call Cary and ask. This was a while back, too, so I'm probably a bit loose in the jargon. Anyway, it was a capacitor that made the same hum that Dav65mus is experiencing. When fixed, things were dead quiet.

A bad power supply filter cap(in any electronic component) can cause a variety of noises. Could that be what you're thinking of?

Might be a problem with the upgrade/rebuild job? A friend with the big 104db Klipschorns swaps amps for variety,and no hum on his stock Stereo 70.

The dynaco amp is a completely rebuilt unit from a reputable audiogoner that has several st 70's currently offered now.

Every part is new and upgraded in the st 70.... a brand new stock driver board.... all new caps, resistors, tube sockets, etc. The only thing original are the 2 cloth lead output transformers and power transformer.It has upgraded rca inputs and 5 way binding posts for the speakers, along with an upgraded power cord that I can isolate ground from.

I have a comcast cable ground loop hum that causes about 50% of the hum in the system.... when I am not watching movies or t.v., I disconnect the cable and it is much quieter.

But there is still a low hum from the dynaco that is not there when I have the bryston amp installed.

When there is music source playing the amp sounds incredible..... way better than the bryston.... but during silent passages you can hear a slight low hum even on the 86db quad 11L speakers.

My preamp has balanced xlr outputs that I can use on the cary rocket 88 which are obviously not able to be used with the st70. Maybe this would help in overall sound in the system also.

So anyone who may have heard both amps, would the cary be a decent improvement over the warm musical sound of my st70 (slight hum and all).

I would like to have an amp that can be switched between ul and triode to see if I might want to work my way up to a 300b set with matching speakers someday.

Thanks Dave

I have one in the closet and the only time it had a hum was when I had to replace the 7199's.It showed a short on the tube tester.I'm not familiar with the Cary Rocket.Maybe somebody will still see the post.A Cary owner most likely went through a Dynaco too.Maybe somebody on Audio Asylum might know.

I own a Rocket 88R coupled to a passive preamp and speakers with 87db sensitivity. Dead quiet. I almost bumped my head into the tweeter trying to hear something. No noise. I've read elsewhere that the Rocket is known to be pretty noise-free with even higher sensitivity speakers.

No experience with the Dynaco's, see a lot of rebuilt ones here. But at what used Rockets are going for, it's almost a shame to get such a well made amp for so little coin.

Rodman: Read though my old receipts last night trying to figure out what it was that Cary replaced. Here it is: 2-1200wf 450v VCC and 1-270K 2 WATT Mouser. If that's any help.

Calbrs03- The two first ones are power supply filter caps. The other is a resistor.

Dave- Like I said: I've owned both amps, and the last ST-70, from stock to rod-rodded(16 years). You won't miss your ST-70, once you've tried the Rocket 88 in triode mode(especially with some NOS inverter/driver tubes).

I’m enjoying my Rocket 88. It is controlled in Triode currently, by my Bluesound Node and it’s nifty remote (extra$), (or your cell phone/ iPad app). Paired up with my Klipsch (Gen 1) Forte, absolute bliss @96db sensitivity. I’m selling my Dynaco SCA-35, currently, on EBay… cannot top the Rocket for hiss free bliss. 

Get VAC a big upgrade.