I had previously tried moving the transformer with a scope in place to measure frequency/voltage, but wasn't seeing any changes as it moved around (including placing it vertically). Now that I have minimized the loop, I will try that again.
Does anyone think replacing the input/output wiring with a shielded, single conductor wire would be any improvement over the twisted pairs I have in place? I have a bunch of Mogami W2333 lying around.
Does anyone think replacing the input/output wiring with a shielded, single conductor wire would be any improvement over the twisted pairs I have in place? I have a bunch of Mogami W2333 lying around.
Yes, I would try on input. Also, transformer shield (purple) should go directly to chassis ground. Not before the thermistor. Won't likely make a difference in hum though.
Thanks — the reading across the two grounds was quiet. I think I’ve gotten the amp as quiet as it’s going to get it in its current form after rerouting the one ground wire to minimize the loop. I understand why the PSUs in the commercial amps are laid out the way are now. I may rebuild the PSU down the road to mirror that layout.
I appreciate everyone’s help. I’ve learned a lot about how ground loops physically look in a completed build, which was really helpful since I’ve had trouble understanding the various papers on the topic (absolutely zero technical background here).
One last question since I haven’t been able to get a definitive answer — how much transformer hum is normal? As I mentioned in my first post on this topic (#15927) the transformer itself hums — audible when lid is off and ear about 6 inches or so. Just wanted to confirm this is normal given the issues I had early on with the soft start board not functioning properly.
I believe that would be pretty common. Pass Labs check all their transformers for hum, but Nelson has indicated the reject rate is pretty high.
FWIW, my Rogue Audio amplifier's transformer hums when within 6 inches. While Rogue isn't an ultra-premium brand, I'd still say they make quality gear.
Thanks! I’ll call it a day then and enjoy some music. Sounds like we have similar taste, since my main amp is a Rogue Cronus Magnum II.
The mechanical hum from transformers should not get into your signal path as hum - depending on what amp you are talking about, there might be something you can do to get rid of the noise. I have built a lot of first watt clones and the push pull ones have been very quiet compared to the aleph style. If you have significant hum in a F5 build, it would be worth investigating.
Probably your Mains supply have some DC component, you can try some DC stopper.
It's real quiet. I doubt I could measure it above background noise. My refrigerator running in the kitchen will drwn it out.
Our Kitch-en-Aid refrigerator sounded like a truck idling. Drove me nuts. Wasn't that old. Replaced it with an LG with a linear compressor, Consumer Reports chart showed it as the quietest
. The bottom under the pull out freezer drawer built up an inch thick ice block because the drain hole froze over and the defrost cycle water built up. Youtube has a vid on how to modify the heating coil to keep the drain hole ice free. Has been good ever since.
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Hello Daddy Pass,
hello dear Diy community
F5, B1 and Pearl Two I finished, I'm still excited about the sound and I want to imitate a turbo v3 but only half.
Without Q9, Q10, Q11, Q12 with 24V power supply. So I want to compensate for missing gain in B1 but equal to achieve good playback as F5 original. And for proven stability of the schemes this should also be involved.
Am I right about thinking here?
Has the topic been discussed?
then I need a link for that
Thanks together!
Dezibaby.
hello dear Diy community
F5, B1 and Pearl Two I finished, I'm still excited about the sound and I want to imitate a turbo v3 but only half.
Without Q9, Q10, Q11, Q12 with 24V power supply. So I want to compensate for missing gain in B1 but equal to achieve good playback as F5 original. And for proven stability of the schemes this should also be involved.
Am I right about thinking here?
Has the topic been discussed?
then I need a link for that
Thanks together!
Dezibaby.
F5Tv1 or v2.
I suggest v2
Read the F5Turbo article by Nelson;
http://www.firstwatt.com/pdf/art_f5_turbo.pdf
F5Turbo Illustrated Build Guide
I suggest v2
Read the F5Turbo article by Nelson;
http://www.firstwatt.com/pdf/art_f5_turbo.pdf
F5Turbo Illustrated Build Guide
hello 6L6,
on F5Tv3, I assumed that Q7 and Q8 could compensate for lack of gain in B1. My thoughts are that control voltage is too low for the power transistors, which can do more in all the same conditions.
And v3 with eight power transistors is the power consumption too expensive for me, also my transformer is "only" 1kW.
Because of consumption I stay at 24V supply.
That's why this "abbreviated" version of v3.
Sorry for English, I use Google.
Thank you very much.
Dezibaby.
on F5Tv3, I assumed that Q7 and Q8 could compensate for lack of gain in B1. My thoughts are that control voltage is too low for the power transistors, which can do more in all the same conditions.
And v3 with eight power transistors is the power consumption too expensive for me, also my transformer is "only" 1kW.
Because of consumption I stay at 24V supply.
That's why this "abbreviated" version of v3.
Sorry for English, I use Google.
Thank you very much.
Dezibaby.