100% sure is a sure way to miss a problem. Leave it for a day or two then cone inspect again. It's a grounding problem. I'm 99% sure
Get a few long wires and put alligator clips on them. Attach to earth and poke around other grounds while listening. Works for me.
Don't signal and speaker ground connect to the pcb's with a single wire then going to power supply ground.Thats how I did mine with cvillers boards and its as quiet as a mouse.
http://www.diyaudio.com/forums/blog...e-pcb-version-2-f5_v2_front_stock_f5_rev2.jpg
http://www.diyaudio.com/forums/blog...e-pcb-version-2-f5_v2_front_stock_f5_rev2.jpg
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Actually my F5's internals look even better
no offence,but leads are much shorter, star ground is at PSU PCB, ground runs only to diode bridges, and to audio PCB's from there...Plus one lead to chassis, via thermistor 4.7ohm. I have a suspition , that trafo secondaries are catching noice from primary windings...
Sounds easy and promissing, will post about results100% sure is a sure way to miss a problem. Leave it for a day or two then cone inspect again. It's a grounding problem. I'm 99% sure
Get a few long wires and put alligator clips on them. Attach to earth and poke around other grounds while listening. Works for me.
Thanks
No offence but its not how it looks on the inside it is how it sounds. Sometimes in trying to keep things neat and tidy the best grounding practices are not followed. I did initially wire the PCB's amp and PS according to layout and I did have hum / buzz. Its only when you start pulling things apart that you find the solution.Actually my F5's internals look even better
Actually my F5's internals look even better
I have a suspition , that trafo secondaries are catching noice from primary windings...
do not make a starground on the PSU pcb. thats a dirty ground.
can it be a groundloop you have? if its 2 ch amp with common PSU.
if thats the case. try a short fat cable between the 2 amp's GND.
I would like to comment that a typical toroid will pass likely the whole audio band albeit not flat, thru it's primary - core and secondary windings if that's what the line has to offer. What I just read makes it sound like a 50-60Hz bandpass filter which it is far from
The forever argument? There are high current transients thru the diodes, first caps and back to the xfrmr. One recomended spot for the GND is at the -connection of the second cap(likely still on the Pwr Supply board). The reason is simple, you dont' want all that current going thru the extra wire to the amp circuit board GND having a resistnce that makes your low esr caps have the DSR/ESR of that wire added to the Vcc or Vee... But, the circuit board GND is also a good place IMHO
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I would like to comment that a typical toroid will pass likely the whole audio band albeit not flat, thru it's primary - core and secondary windings if that's what the line has to offer. What I just read makes it sound like a 50-60Hz bandpass filter which it is far from
Of course, but what he describes is a hum which is often 50 or 60hz depending where we live. Thats what I was responding to. Then turn all the frequencies to DC and filter.
Hi, it seems i have had an internal ground loop, but it is gone forever now, thanks to :
The Leach Amp - Part 2
If you are sure that the hum is due to an internal ground loop, the procedure for breaking this loop is as follows:
Thanks to everyone
The Leach Amp - Part 2
If you are sure that the hum is due to an internal ground loop, the procedure for breaking this loop is as follows:
- Turn the amplifier off and wait for the power supply to discharge. Do not perform this procedure with the amplifier on.
- Cut the wire to the central ground on the input side of one circuit board.
- Solder a short circuit jumper wire between the ground lugs on the two input jacks.
- The circuit board with the cut ground wire is now grounded back through its input ground lead to the ground of the other circuit board. Use an ohmmeter to verify the new ground connection before turning the amp back on.
Thanks to everyone
Tried to search this giant thread but must lack the talent to do it right. A probably dumb pair of question here.
Background, I have been using an F2, Papa built, on my full range augmented system for a few years and have loved it. I just bagged a "factory" F5, which I have wanted for a long time. I put it on the Full range speakers just to test it for function but fell for the sound BIG TIME. But the bass enhancement the F2 brings is gone re: the F5's damping factor of 80.
Questions - will loading the F5 output with resistors (in the style of the F1) do horrible things to the sound or the equipment? If not, is the said resistor placed across the output terminals of the amp? Or similarly across the speaker terminals? I'm thinking non-inductive wirewounds of perhaps 15 ohms 10 watt. These speakers are around 100dB/w/m so there will not be much current.
Sorry to invade a knowledgeable DIY forum with such ignorance, but I know your advice will be solid. Unrelated, RIP SemiSouth. Sniffle.
Background, I have been using an F2, Papa built, on my full range augmented system for a few years and have loved it. I just bagged a "factory" F5, which I have wanted for a long time. I put it on the Full range speakers just to test it for function but fell for the sound BIG TIME. But the bass enhancement the F2 brings is gone re: the F5's damping factor of 80.
Questions - will loading the F5 output with resistors (in the style of the F1) do horrible things to the sound or the equipment? If not, is the said resistor placed across the output terminals of the amp? Or similarly across the speaker terminals? I'm thinking non-inductive wirewounds of perhaps 15 ohms 10 watt. These speakers are around 100dB/w/m so there will not be much current.
Sorry to invade a knowledgeable DIY forum with such ignorance, but I know your advice will be solid. Unrelated, RIP SemiSouth. Sniffle.
Thank you! Most grateful. My wirewound parts bin is long empty so off to Mouser I go.
Nope, it's not you, the forum software search function is basically worthless.
Way too much resistance. That will make all the damping of the F5 go away, and kill it even more. Let's look at what AndrewT says -
AndrewT said:
(By the way, 1r0 is 1.0 ohm, and 0r1 is .1 ohm . With 100db speakers, 3 or 5 watt resistors will be fine. )
He is saying to start with 1 ohm, and make it less resistive (adding a parallel 1 ohm will make .5ohm) or starting with .1 ohm and adding, in series, more .1 ohm until you get the bass tuning you prefer.
No apology necessary! We salute you with your quest for factual information, instead of audiophile hearsay...
My wild guesses were based on my previous setup. My attempt here was to create a Thevenin equivalent of the F2's current source configuration, which Nelson had written was the angel gifting the F2 (and my speakers) with its enhanced bass response. The F2J (mine) as well as the F2 is published as using three parallel three watt 47 ohm resistors; my geriatric brain figured a 15 ohm 10w piece.
My full range speaker is a Hammer Dynamics Super 12, a twelve inch unit with wizzer, and can usefully employ to good effect more damping than a smaller Fostex or Lowther, which is to say still hardly any, having been designed for .7 watt 45 amps. It sounds great on the F2J but I like the sound quality from the F5 much better. I am one of those "if it is on the recording I want to hear it" guys, so the F5 is heaven sent and heaven inducing for my listening. I wanted my cake and still wanted to eat it - the bass - too.
In any case, that is the ignorant process that hatched my ignorant estimates. BTW, if I need another F5 I will certainly build it. Between the boards and the enclosure you guys have essentially produced a kit amp. The stock F5 has more power than I could ever use, so I wouldn't need the enhanced versions. To paraphrase Mr Pass, did I mention I love the sound?
My full range speaker is a Hammer Dynamics Super 12, a twelve inch unit with wizzer, and can usefully employ to good effect more damping than a smaller Fostex or Lowther, which is to say still hardly any, having been designed for .7 watt 45 amps. It sounds great on the F2J but I like the sound quality from the F5 much better. I am one of those "if it is on the recording I want to hear it" guys, so the F5 is heaven sent and heaven inducing for my listening. I wanted my cake and still wanted to eat it - the bass - too.
In any case, that is the ignorant process that hatched my ignorant estimates. BTW, if I need another F5 I will certainly build it. Between the boards and the enclosure you guys have essentially produced a kit amp. The stock F5 has more power than I could ever use, so I wouldn't need the enhanced versions. To paraphrase Mr Pass, did I mention I love the sound?
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I encountered enough people with the F1 (including reviewers) who seemed
dazed and confused by the notion of output loading, which is ok, unless they
are unwilling to try it to get the right output impedance for their speaker.
From experience, I figured that the maximum output impedance anyone will
want is probably 16 ohms or so, and so I put that in as a default value.
dazed and confused by the notion of output loading, which is ok, unless they
are unwilling to try it to get the right output impedance for their speaker.
From experience, I figured that the maximum output impedance anyone will
want is probably 16 ohms or so, and so I put that in as a default value.