Does anyone care to ask an amplifier designer a technical question? My door is open.
Here's a schematic of the ST-120 version (sans values for resistors and capacitors), which is apparently the same schematic as the ST-70 except for resistor sets. Nice circuit, simple. The 16 ohm tap is a bit silly and taking the feedback off it can have both good and bad effects. Otherwise, classic Marantz, Heath, Eico, etc. |
@cardiff Here is one nobody seems to have asked yet... I put the proper cord on my RM-9 but now people want me to put an IEC on there so they can use theirs. I did opimize but thats not good enough for the PC and fuse people. May I also offer that a captive cord has one less pair of connections. When you pull current on a IEC it gets hot, is that good? Before audiophiles got into power cords most manufacturers went to IEC connectors for no other reason that it makes the amp easier to handle and pack up, not so people could go fooling around with wire. |
@atmasphere A choke is helpful as it can be used to help filter out the 60Hz sawtooth waveform that is part of the rectification process. Ralph, Im sure you meant to say 120 Hz ripple, not 60 Hz unless you are using half wave power supplies. Chokes are indeed great things and not found in many amplifiers these days because its just too much trouble for some designers to have them made. I put two in the RM-9 MK II as Ultralinear amps benefit from them greatly. The G2 on an ultralinear has the same ripple as the plate. Where a pentode amp can have additional filtering for the G2. |
@teo Some Ignorance is so manifold that it is used to commit to attacks so libelous and underhanded... that the person initiating is practically kicked off a given forum. So obvious to all, that there aren’t even words for it.And then that illiteracy and ignorance is paraded about as somehow being informed. That we can all be that dense. Jebus. What a horrific world that would be. So far gone that it can’t even be explained to a given person how far off base and wrongheaded a given comment might be. I think im being called out but so poetically I can hardly be certain. I think Teo has a better future as Poet and Philosopher. His verse is almost Shakespearian https://en.wikipedia.org/wiki/Sonnet_94 Bruce De Plama (Brians brother) often quoted the last of this. For sweetest things turn sourest by their deeds; Lilies that fester smell far worse than weeds. |
@mrdecibel Roger, this is a GREAT thread, thank you. I agree that all of the nasty comments and bickering should be kept out of this thread ( as well as all threads ). This thread is about learning, as I see it, and I am learning a great deal ( maybe understanding 1 % of it ) And yes, this thread has me thinking about trying tubes again in a power amp. : Going back to damping. In my early years, I owned several ss power amps, a few high powered. Two in particular, were an original Ampzilla, and a factory built Dynaco 400. Having many speakers at the time ( DQ10, AR 3, Klipsch Lascala, just to name a few ), the Dynaco had a bloated, slow, ill defined bass in comparison to the Ampzilla. Both were rated at 200 wpc into 8 ohms ( as I mentioned, these characteristic were also in all of the tube amps I had at the time ). Can you explain if these characteristics between the Amnpzilla and Dyna had anything to do with damping ? Thank you in advance. Enjoy ! MrD. Thanks, the nasty comments and bickering are charateristics of the people who make the comments. I ignore most of them. When I look at the threads they get on I can hardly imagine what sort of person they are. I am happy to have little of them here. I guess every forum has its trolls. At to your sonic observations. Ampzilla was and is a great amp. I think Jim B designed the Dynaco also, but I am unsure. If you find a schematic I can likely tell. People should know that some designers art is easy to spot, just as an artist’s paintings or sculptures. Bongo Jim, as we called him, was a really great amp designer, great pianist and all round fun guy. I have a picture of him Bacsom King, Mike and Laura Elliott at a BBQ at my home in Santa Barbara many years ago. Ill try to find and post it. Sounds like you have had some bass issues. Both SS amps should have good damping, I know Zilla did. Tube amps with poor damping = bloated bass and other problems. Would love for you to hear the listening test we have going on right now with two identical amps except that one has been modified to have 4x damping and 1/4 x distortion. The bass difference, clairty and air on the QUAD 57 are quite apparent. We are doing some serious listening with a very tight setup. |
