Hi Renron
Yeah i bought a 465 (I think, 200mhz) off ebay for a few hundred (ex Saudi airforce according to plate on it). Has a few buttons damaged but works fine.
However when I've used this to measure noise on the Aikido it's been unable to lock given the broadband nature of the signal - all you can measure is the overall level.
A PC based probe/spectrum analyser would give more useful information potentially regarding cause/frequencies, particularly related to PSU induced noise.
Been looking but most are $500 up that I've seen.
Yeah i bought a 465 (I think, 200mhz) off ebay for a few hundred (ex Saudi airforce according to plate on it). Has a few buttons damaged but works fine.
However when I've used this to measure noise on the Aikido it's been unable to lock given the broadband nature of the signal - all you can measure is the overall level.
A PC based probe/spectrum analyser would give more useful information potentially regarding cause/frequencies, particularly related to PSU induced noise.
Been looking but most are $500 up that I've seen.
tun sol 6sn7
Hi,
I'm also using tun sol 6sn7 tubes, new and matched.
I'm using J.B.'s pcb and simple CR-LC power supply
suggested by J.B. himself. DC heaters with floating ground
via cap.
I'm getting very low frequency hum, motorboating(?)
it's sound like star trek engines. does not seem to increase
in volume with volume turn up. I've tried shorting the inputs.
would this be related to the tubes or wiring issue. I've wired several times, I thought it went away but with my final wiring I hear it again. Tried swap tubes around, only have one set.
using a passive step attenuator for volume control.
thanks for any suggestions.
Hi,
I'm also using tun sol 6sn7 tubes, new and matched.
I'm using J.B.'s pcb and simple CR-LC power supply
suggested by J.B. himself. DC heaters with floating ground
via cap.
I'm getting very low frequency hum, motorboating(?)
it's sound like star trek engines. does not seem to increase
in volume with volume turn up. I've tried shorting the inputs.
would this be related to the tubes or wiring issue. I've wired several times, I thought it went away but with my final wiring I hear it again. Tried swap tubes around, only have one set.
using a passive step attenuator for volume control.
thanks for any suggestions.
Hi Ron,
yes, IEC Jack Earth GND grounded directly to chassis.
then aikido pcb is ground to chassis via 10R resistor and 0.1uF cap by the mounting post.
if I touch the chassis, hum is not affected. increase volume or shorted input, hum does not change. when volume is off position, it's basically shorted since it's a step attenuator.
I disconnect outputs from aikido to my mini-A amp, without aikido connected, there is no hum so it's definately from the aikido.
sounds really good but like you said, silence is golden, I listen at low volumes and this annoying. would be great to get rid of it.
btw, when I tried different psu combo's, I tried 1000uF caps too, hum is still there but at as loud. so it's not so much cap value to low.
thanks.
yes, IEC Jack Earth GND grounded directly to chassis.
then aikido pcb is ground to chassis via 10R resistor and 0.1uF cap by the mounting post.
if I touch the chassis, hum is not affected. increase volume or shorted input, hum does not change. when volume is off position, it's basically shorted since it's a step attenuator.
I disconnect outputs from aikido to my mini-A amp, without aikido connected, there is no hum so it's definately from the aikido.
sounds really good but like you said, silence is golden, I listen at low volumes and this annoying. would be great to get rid of it.
btw, when I tried different psu combo's, I tried 1000uF caps too, hum is still there but at as loud. so it's not so much cap value to low.
thanks.
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here is photo. the little diode board that is not connected is to drop the voltage into the volt. reg since I have 9vac transformer.
234V transformer is going into F.W.B. then to 100uF-604R-600mH choke-100uF(1R snubber) || 1.2uF(1R snubber).
little relay board on top of F.W.B. is +B delay. it's not hum that is picked up from touching anything, it's a low oscillating hum, like the star trek engines, best way I can describe it.
234V transformer is going into F.W.B. then to 100uF-604R-600mH choke-100uF(1R snubber) || 1.2uF(1R snubber).
little relay board on top of F.W.B. is +B delay. it's not hum that is picked up from touching anything, it's a low oscillating hum, like the star trek engines, best way I can describe it.
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Bengali,
It looks like you have a ground wire from the negative side of the B+ connected to the Aikido board, yes? It also looks like you have a ground lift capacitor on the board to ground, yes? If so, remove the negative wire to ground from the Aikido board and run it to your chassis earth with a 20R 2W. You don't need 2 grounds to the board.
Are your signal RCAs isolated from the chassis?
Ron
It looks like you have a ground wire from the negative side of the B+ connected to the Aikido board, yes? It also looks like you have a ground lift capacitor on the board to ground, yes? If so, remove the negative wire to ground from the Aikido board and run it to your chassis earth with a 20R 2W. You don't need 2 grounds to the board.
Are your signal RCAs isolated from the chassis?
Ron
Hi Ron,
correct, +B and GND wire from PSU twisted going
to +B and GND on aikido board.
at the psu, it's star grounded, central point is between
the two big 120uF solen caps, all the grounds are tied
together there.
I'll give that a try, taking GND wire from PSU through a
20R resistor to Chassis GND. 10R 3W should work as well?
yes, RCA's are isolated from chassis, but I found that after
you wire the signal wires to aikido pcb, it no longer stays
isolated. it's chassis grounded now, since the grounds
tie together on the pcb itself, right?
may I ask, what output caps have you tried? I did the cap selector and can switch between the Jantzen Superior
and Auricap. Very, very subtle differences.
my step attenuator goes from first 2 clicks(low volume)
to 3rd click, very loud! I'm thinking of going back to a pot
for better volume control.
thanks! I'll keep you posted.
correct, +B and GND wire from PSU twisted going
to +B and GND on aikido board.
at the psu, it's star grounded, central point is between
the two big 120uF solen caps, all the grounds are tied
together there.
I'll give that a try, taking GND wire from PSU through a
20R resistor to Chassis GND. 10R 3W should work as well?
yes, RCA's are isolated from chassis, but I found that after
you wire the signal wires to aikido pcb, it no longer stays
isolated. it's chassis grounded now, since the grounds
tie together on the pcb itself, right?
may I ask, what output caps have you tried? I did the cap selector and can switch between the Jantzen Superior
and Auricap. Very, very subtle differences.
my step attenuator goes from first 2 clicks(low volume)
to 3rd click, very loud! I'm thinking of going back to a pot
for better volume control.
thanks! I'll keep you posted.
On the 9-pin mono PCBs, there is a jumper that ties the PCB ground to chassis ground through one of the standoffs. I thought leaving the jumper out (or capacitor if you fancy) would not ground the PCB to chassis. I'll have to check to see if my sig -ve's are grounded to chassis through the PCB. My hum is presently minimal, but I'd like to get it quieter if possible.
Bengali said:
Bengali,
Since the negative side of the B+ goes to the board, and the B+ is D/C, the D/C is mixing with the signal A/C. This is what caused my problem. The Aikido is grounded to the chassis through the .01 cap, called "lifted". Remove the (-)B+ from the board. If you want, run a seperate ground wire from the (-) to the chassis star point. (but, this will negate the .01 cap (lifted ground) The ground lift is to help eliminate the hum issues.
Output caps I have tried. (all were burn in for >250 hours prior to installation. All of this is IMO, of course, YMMV
Obbligato 2.0 Film & Oil --------Sounds similar to the stock caps provided with the Aikido board, but somewhat better bass and cleaner highs. I like them alot.
Westcaps. .33 PIO, smaller cap size yeilds a leaner bass but faster mids and highs. Good if speakers are close to rear wall.
AuriCap 2.2 I think they are film and oil but I'm not sure. They sound very close to the Obbligato F&Os. I doubt I could tell the difference in a blind test. Clean sound, good bass, kinda slower mids and highs compared to the Westcaps. (could be the size
)I have Russian Telfons I want to install, but I haven't done so yet. I'm anxious to hear what the fuss about Teflon caps is about.
Do your (-) signals go to star earth then to chassis earth? are they lifted with a R/C with 2 diodes? worth a try, it's cheap.
If your chassis ground earth is between your 2 caps and the IEC earth connector is on the other side of the chassis, have you measured the potential difference in Ohms? Between the Aikido lifted ground and IEC ground earth?
boywonder said:
BW,
Correct, board is "lifted" from ground with the cap. (jumper) I have no (-) B+ wire from my Aikido to ground. It's dead quiet. Ground wire from PSU board goes to 20R ---->Chassis earth.
Ron
Hi Ron,
(-) signal wires are coming directly from rca connector
to the step att. then to the input (-) of the aikido pcb.
it's not tied to earth/chassis ground at all.
I'll rewire the (-) +B to chassis ground, removing the one
from the aikido tonight. hopefully it will go away.
I'm not clear on your (-) signal wires going to earth chassis
via R||C||2 diodes. are you saying to try and remove the
input (-) signal from the aikido pcb and connected those
to earth chassis via the R,C,Diodes? I could try that next.
do you get any turn off pops/thump? with aikido preamp,
I get small thump with my mini-A. with aikido connected and
power on, when I turn off mini-A, I get big thump! I have
a velleman k4700 spkr protector in the mini-A, but relay
is not disengaging quick enough to prevent turn off thump.
thanks!
Bengali said:
Bengali,
I have my input RCA jacks isolated (outputs too) from the chassis, I also have a wire with the R/C/2D from the input (-) to the chassis earth ground. I can't remember where I read about doin' it that way, but it works well for me. You NEED the negative signal input to the attenuator and then the Aikido board.
I do not have any turn on or off Thump. I get a small amount of tube rush sound when I turn it on. I have tube rectification 6x5.
SS rectification is instantanious. There are ways around this. I can't remember off the top of my head but I think it's called a thermsistor...could be wrong. Brain Fart. excuse me.
Remember, I'm a complete newb too. So be careful and try different things. Like I was told, "It's more of an Art than Science".
Ron
Hi Ron,
well, you did an excellent job for just starting! congrats and you got it be quiet too!
I rewired as you suggested. interesting, it no longer produces an osciallating low freq. hum but a steady low hum. next week when I have a chance, I'll try adding a larger cap to see if it can supress the hum some more.
I don't think I've wired anything else incorrectly. It does not seem related to the signal wires since those have been shorted and hum is still present. only other thing is the heaters.
I tried the 100K/300K float above +75 method, that was horrible. hum was so loud.
my next version will be using JB's Janus kit. I'll go nuts if the hum is there with that kit.
thx
well, you did an excellent job for just starting! congrats and you got it be quiet too!
I rewired as you suggested. interesting, it no longer produces an osciallating low freq. hum but a steady low hum. next week when I have a chance, I'll try adding a larger cap to see if it can supress the hum some more.
I don't think I've wired anything else incorrectly. It does not seem related to the signal wires since those have been shorted and hum is still present. only other thing is the heaters.
I tried the 100K/300K float above +75 method, that was horrible. hum was so loud.
my next version will be using JB's Janus kit. I'll go nuts if the hum is there with that kit.
thx
Attachments
I was sent an Email by a concerned Diyer stating that I should not have disconnected the retun wire for the B+. (negative side)
As now my B+ returns through the chassis. Makes sense to me.
I'll replace the wire and hope I don't get the hum back. I'll report on this and how the Russian Telfons differ from the Obbligato oil in the coupling cap position.
Ron
As now my B+ returns through the chassis. Makes sense to me.
I'll replace the wire and hope I don't get the hum back. I'll report on this and how the Russian Telfons differ from the Obbligato oil in the coupling cap position.
Ron
I have replaced the wire that connects the (Ground) from the Aikido board to the (Ground) on the PSU board. Only a little (very) added hum. It is a 60Hz low pitch sound.
I removed the Auricaps and replaced them with F3 Russian teflon caps that had been burnt in for ~120 hours. How long do these caps take to burn in??? The siblance is noticable on some songs with a blaat on the high pitch notes. I know I'm skating on thin ice with my equipment but I like the clarity of the Teflon caps.
I think I need better room treatments. I don't have any and I have hardwood floors.
Man the Aikido sounds superb!
Bengali,
You do have your heaters biased right?
Ron
I removed the Auricaps and replaced them with F3 Russian teflon caps that had been burnt in for ~120 hours. How long do these caps take to burn in??? The siblance is noticable on some songs with a blaat on the high pitch notes. I know I'm skating on thin ice with my equipment but I like the clarity of the Teflon caps.
I think I need better room treatments. I don't have any and I have hardwood floors.
Man the Aikido sounds superb!
Bengali,
You do have your heaters biased right?
Ron
Hi,
I'm reading this thread, looking for a solution to my own Aikido hum problem and I think I have the same issue you had. To get things clear, is this the way you connected everything? I left out any volume or selector pots to keep it simple.
Tnx a bunch
Cj
I'm reading this thread, looking for a solution to my own Aikido hum problem and I think I have the same issue you had. To get things clear, is this the way you connected everything? I left out any volume or selector pots to keep it simple.
Tnx a bunch
Cj
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