Regarding the audible transformer buzz, either you have a really bad transformer or you have dc on the lines.
I would start with fixing this first, since even if you fixed the hum at the speaker output, you're still going to be losing sleep over the transformer buzz.
I would start with fixing this first, since even if you fixed the hum at the speaker output, you're still going to be losing sleep over the transformer buzz.
I need to try it on the mains circuit it will actually be used on.
The stereo gear is on a dedicated 21stC line whereas I was testing it on a 1950s line with all the computers on it....
The stereo gear is on a dedicated 21stC line whereas I was testing it on a 1950s line with all the computers on it....
Fixed the internal wiring. Still on the old mains circuit so the transformer is still buzzing and motorboating a bit, but the speakers are now dead-silent. 😎
My case won't *quite* support the bias I had in mind. The plan was 3A, but my heatsinks are currently running at 54º with 2.8A.
Lou Reed and Nico sound all right in mono, but I probably need to build another one....
Lou Reed and Nico sound all right in mono, but I probably need to build another one....
Jam would probably recommend to do some stability checks. Look for any little problems. That kind of thing.
Try and test it out on a different circuit or try turning off every single electrical appliance in your home. Bloody everything then give it another go.
... but it is much quieter on the circuit it will be used on. My ear needs to be less than 18" away from it to hear it, where as previously it was 3 to 4'. And no motor-boating; just a constant hum. (It's now pretty similar to the EI mains transformer on my Rogue Audio Cronus Magnum.)
Interestingly, when I use a mechanic's stethoscope on it, the loudest parts are the transformer centre-bolt and the Ametherm thermistor. I'm starting to think suspending the Jammy Bridge board on the diode legs might not have been the best idea. I might try a bit of Dynamat on the back of the board....
Interestingly, when I use a mechanic's stethoscope on it, the loudest parts are the transformer centre-bolt and the Ametherm thermistor. I'm starting to think suspending the Jammy Bridge board on the diode legs might not have been the best idea. I might try a bit of Dynamat on the back of the board....
I played around a bit with the centre bolt and the diode board -- neither the diode board nor the case bottom appears to be acting as a sounding board. (Ie: dampening either made no difference.)
I think I'll leave it for now and perhaps build a DC Trap later.
I think I'll leave it for now and perhaps build a DC Trap later.
Read page 5 of this article. James Bongiorno (designer of "Ampzilla", founder of GAS, etc.) has a few things to say, which you may enjoy reading.
After reading that,
Build an EXTERNAL box like the PS Audio Humbuster. Dirty AC in, clean AC out. Your audio amplifier's AC mains cord plugs into the clean-AC-out socket on this external box.
Then you can install a whopping enormous collection of high-ripple-current electrolytic capacitors (remember: 10V rating is all you need!) and a 50 ampere GBPC bridge rectifier. Or else you could buy the pre-made PCB by diyAudio member Per-Anders Sjostrom: DCT-03 discussion ... followed by PCB web shop
search terms... James Bongiorno : humbuster: PS Audio : AC mains : DC
After reading that,
Build an EXTERNAL box like the PS Audio Humbuster. Dirty AC in, clean AC out. Your audio amplifier's AC mains cord plugs into the clean-AC-out socket on this external box.
Then you can install a whopping enormous collection of high-ripple-current electrolytic capacitors (remember: 10V rating is all you need!) and a 50 ampere GBPC bridge rectifier. Or else you could buy the pre-made PCB by diyAudio member Per-Anders Sjostrom: DCT-03 discussion ... followed by PCB web shop
search terms... James Bongiorno : humbuster: PS Audio : AC mains : DC
Might want to check if is the bolt that is making noise. If so, another type of bolt material might be worth trying. If steel, maybe try stainless or brass.
Also, if the thermistor is making noise, might want to shunt it with a relay after allowing time for any transformer turn-on surge to settle.
Also, if the thermistor is making noise, might want to shunt it with a relay after allowing time for any transformer turn-on surge to settle.
Buy four of these 68,000uF, 16V, 8.5A ripple current, B41231A4689M000 capacitors for USD 4.42 per piece.
Add one of these 600V, 50A bridge, GBPC5006W-G for USD 3.50.
Now you're good for 8.5*2 = 17A of mains AC current, which in a 230V country means you can drive any mains transformer up to 3900VA (17 * 230). The first implementation of JamJar will probably install a smaller transformer than 3900VA, so you have plenty of safety margin.
Add a 16 amp IEC inlet including EMI filter, P/N 5130.1100 for USD 15.23. This brings AC mains into your external humbuster box.
Add one or more high-end AC mains sockets suitable for your country (I have no idea whether these sockets are terrible, average, or excellent). This brings AC mains out of your external humbuster box.
Add a chassis. Done!
_
Add one of these 600V, 50A bridge, GBPC5006W-G for USD 3.50.
Now you're good for 8.5*2 = 17A of mains AC current, which in a 230V country means you can drive any mains transformer up to 3900VA (17 * 230). The first implementation of JamJar will probably install a smaller transformer than 3900VA, so you have plenty of safety margin.
Add a 16 amp IEC inlet including EMI filter, P/N 5130.1100 for USD 15.23. This brings AC mains into your external humbuster box.
Add one or more high-end AC mains sockets suitable for your country (I have no idea whether these sockets are terrible, average, or excellent). This brings AC mains out of your external humbuster box.
Add a chassis. Done!
_
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@JeffYoung, the house is beautiful but let's see what the miniature train set looks like now.
Great looking lawn btw!
Great looking lawn btw!
I don't believe your level of OCD is at the correct level. Where is your dedication to this hobby.
Hahahahaha
Nice home though.
Great piece about one of the great audio designers, also a nice and
generous guy.
I had the pleasure of a few conversations with him.
A little story:
Some long time ago our own member Armin Paya was given a quantity of
Sony VFETs by JB, and when he realized that he wasn't ever going to get
around to building with them he sent them to me (don't feel bad, I later
sent him one of the larger Sony Vfet amps).
These particular VFETs fit nicely in a variation of the upcoming Sony Vfet
amps from diyAudio, and they will complete their journey in the hands of
DIYers, a gift well given three times.
It's a box made of aluminum, which contains circuit boards made of epoxy fiberglass. Soldered to these circuit boards are passive devices (resistors etc) and active devices (field effect transistors etc) made of silicon. Connecting these boards together are wires made of copper. On the periphery of the box, a few electrical connectors are disposed. These communicate signal-in, loudspeaker-out, power-in, as they transition between the external world and the interior of the box. Pretty straightforward really. You've seen similar examples before.
First we need to get the first release of 180 channels of the P channel version
for the 2SJ28 and then the 180 channels of the N channel 2SK82.
Real soon now....
And following are versions for 2SJ18 and 2SK60 which are mostly pieces salvaged
from old stashes and old Sony amplifiers.
Finally, these same circuits can be used for other SITs (VFETS) and Mosfets, and power Jfets.
for the 2SJ28 and then the 180 channels of the N channel 2SK82.
Real soon now....
And following are versions for 2SJ18 and 2SK60 which are mostly pieces salvaged
from old stashes and old Sony amplifiers.
Finally, these same circuits can be used for other SITs (VFETS) and Mosfets, and power Jfets.