Axiom Home Page Forums General Discussion Stereo Dynaco Stero 70 tube amp

BTW, aboug...m, a modified Dynaco Stereo 70 will produce spectacular music. I nice pair of M3Tis and an EP500 or a high end Velodyne will be quite a combination.

If you can get your hands on a pair of Reference 3a de capo mm i's to audition, you will hear audio bliss.

I don't believe that a previous charge lingering on the capacitors is the issue. If it doesn't work after first inspection and repair, he most probably will have to make some voltage measurements with the unit turned on. That's where, IMO, the saftey issues really begin.

Guys:

I gotta say that safety goes first, and I do appreciate all your concerns regarding safety.

I had worked with HV before. I am a power systems engineer, and I used to play with motors, generators, transformers, variacs, etc.. in excess of 400V (way in excess when we did high tension experiments in the lab back in college, close to 13.8Kv). Since then, I havent work too much on it. I've been growing a "safe workplace" kind of style, as I work on the oilfield, where safety is the number one matter to think in any work area.

So, thanks for your concerns.

Now, back to the Stereo 70: I did check wiring, soldering points, loose components, cleaned the board and transformers, and did some basic continuity checks. Everything worked fine, but the owner (my boss) did not know kaput of tube amps (me neither, but I am researching), and he did plugged the amp without a load... I screamed without really knowing what was going to happen). So I unplugged it, and connected a 8ohm resistors to both left and right 8ohm taps.

Plugged it again and check the bias.. 1.7 and 1.6... put it back to 1.56 as the manual states.

Took it to my place, connected the M22's side by side with the m80's using the secondary zone in the processor (to be able to switch M80's and M22's), and the magic started...

I must say that my apartment / setup is not the perfect one, neither I am an audiophile by no means or intentions. But thre is somehting about this Stereo 70 and the M22's that I havent heard before from them. I will do more positioning test, but so far, I just heard magic... soundstage and imaging were superb (this was at 03:00am, so I did not heard it for too long, but I will tonight again, and post better results of this amp.

I am very glad that the amp is working for you!!!!

Glad to hear your up and running. I lot better than this all thumbs guy could have done.

aboug...m

Please let us know how that Dynaco is coming along and how it's sounding.

What kind of tubes are you running?

2x6spds:

I have been working long hours this last 3 days. I have only heard the amp for few minutes, but so far I am very impressed with its sonic performance, and the clear loudness it makes with just 35W.

I know that its not on its prime, and some components must be changed ir order to have it prime, but I just can wait. Its running the original EL34 tubes for output stage (am I right? I am not sure, if those are output and the 7199 are drivers and the GZ34 is the rectifier)

I found an extremely detailed soundstage and imaging coming from the M22 with the ST70. I never heard that spatial accuracy with a stereo pair of speakers, and I thought I needed sorround speakers. I am absolutely impressed with this setup... M22 bright? no way... my Outlaw 770 is known to be a little bright, so M22's + 770 has not been that impressive combo to listen to, but that is something that does not happen with the ST70

Now, before blowing more bells and whistles, I need to re-arrange the M80's and the M22's and actually set them up favorably, in order to created that seamless soundstage and be able to discern if the amp is making a change or was just the effect of the positioning. I am sure that the M80 are just not positioned good enough for me to appreciate the perferct soundstage, and I knew that from the purchase time. They are overkill for my apartment, but I got them with the intentions of moving them to a bigger place (soon to happen!!)

Tthere is less noise (humm and hiss) that with my ICBM and 770 amp. I like that. I found that a little weak on bass, but punchy enough to satisfy me so far... again I am impressed of what the M22 can do now.

I will be on days off soon, and I will connect everything properly and do a fair comparison, plugging the M80's to the ST70. I do not want to blame my SS amp and throw it away that easily, but I do take my hat off in front of the Dynaco ST70.

I will post about the results of the M80's with the ST70, and I already invited some friends home that were eager to listen to tube gear. That will let me have more opinions on the ST70 and I will be happily posting them.

I've got a Dynaco amp running a pair of 1960 Acoustic Research AR3's. Very, very good sound.

Pete
Oooh! I bet that sounds sweet. I have been looking to find a pair of AR3's. Are they also a recent aquisition? I know you just recently got the Dynaco.
Not too long ago I got an old Stromberg/Carlson and set it up to my computer hooked up to some M3's. I am very very pleased with the results. I am now saving my lunch money for a TAD 30 with the Tad 150 Pre Amp to go with it. Of course my mind will probably change many times before I do it, but that is what I could realistically envision as possible. Of course if I hit the lotto I would probably go for some VTL mono blocks.
Enjoy your new toys. How much did it run to overhaul your Dynaco if you don't mind my asking?
oz

Well:

I havent have more time to spend with the ST70, as my boss took it home after he listened to it. He will run it with Polk's RTi10 and check if he likes it. He also states to have a pair of Acoustic Research speakers in the same basement where the ST70 was, but he thinks that they need repair. So, if he does not have the AR speakers in a repairable state, then he will sell me the ST70... sweet.

Now, I learn how important placement was. The M22 in the front where much amazing for sounstage, and I was wondering what happened with the M80?? well, a little bit of tweaking position here and there, and some considerable toe-in, and voila!! they sound more open and spatially correct, so it was not just the ST70 amp, but the fact that the M22 for their size and my listening room are a much better fit than the M80's.

Anyhow, I did enjoyed the ST70, and looking forward to buy it. There is a little bit of repair to do, mainly wiring, and who knows, maybe installing one of the mod kits available in the internet (thanks for the links guys).

Cheers