Hi Sten
Perfectly OK chassis for FO. Mount the module in between two ribs or flatten them before and install FO modules to mid-lower horizontal position. 0,43C/W is more than enough for normal bias arrangement.
L.C.
How are things with heatsinking L modules?
That's great news. Thank you fluid and LC for chiming in.
I plan on removing both ribs and mounting the modules in the mid-lower portion. The flat area between the ribs is about 85mm wide which should hopefully leave enough room to mount the insulating pads.
I also just noticed that the heatsinks are painted black and not anodized which is slightly less optimal. Guessing it'd be best to carefully remove the paint from the mating surface for the best heat transfer.
I plan on removing both ribs and mounting the modules in the mid-lower portion. The flat area between the ribs is about 85mm wide which should hopefully leave enough room to mount the insulating pads.
I also just noticed that the heatsinks are painted black and not anodized which is slightly less optimal. Guessing it'd be best to carefully remove the paint from the mating surface for the best heat transfer.
The power devices are about 78mm from edge to edge so there will be enough room when the ribs are removed.
You may not need to remove the paint, it is a lot of work to make heatsinks perfectly flat. As long as the paint is still in good condition a light sanding with some 400 grit wet and dry paper might be enough.
It may be best to just make a test first before removing the paint. When the module is on if the heatsink gets quite hot then you know the thermal transfer is working.
You may not need to remove the paint, it is a lot of work to make heatsinks perfectly flat. As long as the paint is still in good condition a light sanding with some 400 grit wet and dry paper might be enough.
It may be best to just make a test first before removing the paint. When the module is on if the heatsink gets quite hot then you know the thermal transfer is working.
Me too.
At this very moment finishing touches to First One L PCB performed, since 8 SMD parts added to already fully populated PCB a little magic will help.
This will be the most tested module I've ever released.
L.C.
Thanks for all the details and guidance fluid. You've been extremely helpful.
Me too.
At this very moment finishing touches to First One L PCB performed, since 8 SMD parts added to already fully populated PCB a little magic will help.
This will be the most tested module I've ever released.
L.C.
Is there a chance for FO 1.4L to be heard in Belgrade this autumn ?!? 
On Multimedia HiFi Show Ljubljana October 2016 for sure, in Belgrade maybe.
Hi all,
I received my FO M few days ago and it is the most professional unit I have purchase from Internet.
I happily hook it up to the hypex psu and it was playing for few hours using a Pi/Hifiberry and then I hear some small buzz noise on one of the side. So hand itchy I try to move the RCA cable without powering down the amp and accidentally the cable came out from the FO M. Without thinking I just plug back the RCA and smell puff of smoke from that channel. But the channel still play and sounds normal even before the smoke dispersed. It has been playing for few mins now like nothing has ever happen.
Anyone experienced this and know if there is any damaged to the board? Or how can I check whether the board is fine?
Thanks in advance.
Ck
I received my FO M few days ago and it is the most professional unit I have purchase from Internet.
I happily hook it up to the hypex psu and it was playing for few hours using a Pi/Hifiberry and then I hear some small buzz noise on one of the side. So hand itchy I try to move the RCA cable without powering down the amp and accidentally the cable came out from the FO M. Without thinking I just plug back the RCA and smell puff of smoke from that channel. But the channel still play and sounds normal even before the smoke dispersed. It has been playing for few mins now like nothing has ever happen.
Anyone experienced this and know if there is any damaged to the board? Or how can I check whether the board is fine?
Thanks in advance.
Ck
I did the same thing when testing and posted the information in post #1749 http://www.diyaudio.com/forums/vendors-bazaar/248996-first-one-mosfet-amplifier-module-175.html#post4196134 the next few pages have information about the issue
It is quite likely that you have the same problem in that you have burned the zobel resistors. The advice I was given was to replace them, but it turned out to be quite difficult to remove them, and I ruined one board in the attempt.
Be very careful with cables as losing the ground connection is what caused it.
It is quite likely that you have the same problem in that you have burned the zobel resistors. The advice I was given was to replace them, but it turned out to be quite difficult to remove them, and I ruined one board in the attempt.
Be very careful with cables as losing the ground connection is what caused it.
Thank Fluid for your advice. I did inspect the board and saw the 4 39R0 resistor around the coil is blacken. I tried to measure then across and compare to the other board. The resistor are all not open and it has a 40.2 ohm plus minus value which is almost the same as the other channel.
It is still working now guess I am just lucky. The 2 resistor under the coil must be quite hard to replace unless u remove the coil first. Let me run it in for few days and see if there is any ill effect. If the resistor is really damaged does the amp just no sound or any other symptoms?
Ck
It is still working now guess I am just lucky. The 2 resistor under the coil must be quite hard to replace unless u remove the coil first. Let me run it in for few days and see if there is any ill effect. If the resistor is really damaged does the amp just no sound or any other symptoms?
Ck
Same problem in Copenhagen Hifi Club. People registrated some white smoke. I was afraid but they still work.
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Thanks for all your help. Past few hrs the amp continue to play wonderfully driving my Rogers LS3/5A. Hopefully it will least till the FO L is available )
But now I encountered another problem...L channel shutting down. I went back to read Fluid's post 1749 and LC mentioned heatsink and all metal parts to be earthed, I've committed the same mistake hanging the heatsink and PSU mid air cause my chassis has not arrive yet. So I took 2 wire and earthed both heatsink. Then suddenly when i power the amp, L channel LED comes on, a pop sound and then the LED power off. Seems like the DC error kicks in. R CH is ok. I swap the rca cable and waited few min and power on again, and the same problems follows on the right amp module. L CH ok. So it must be my Audionote 4.1 DAC problem. But it was singing before the zobel resistor problem (btw the zobel resistor one is R ch. I tried to remove the earth wire and still the L ch shutdown.
Ok, i took the Audionote Dac out and use a squeezebox touch analog output into the FO M... everything is fine and playing for the past few hrs with the earth wire on the heatsink.
This AN dac was playing nice with my main system and only slight buzz on 1 CH. Seems like there is some oscillation or ground loop when using with my AN dac (it has C-core output transformer). Anyone here has experience in using these output trans with FO M module? i have check on both side (Dac and FO M) RCA is not connected to earth. Anyone can help suggest where I should start looking?
regards,
ck
)But now I encountered another problem...L channel shutting down. I went back to read Fluid's post 1749 and LC mentioned heatsink and all metal parts to be earthed, I've committed the same mistake hanging the heatsink and PSU mid air cause my chassis has not arrive yet. So I took 2 wire and earthed both heatsink. Then suddenly when i power the amp, L channel LED comes on, a pop sound and then the LED power off. Seems like the DC error kicks in. R CH is ok. I swap the rca cable and waited few min and power on again, and the same problems follows on the right amp module. L CH ok. So it must be my Audionote 4.1 DAC problem. But it was singing before the zobel resistor problem (btw the zobel resistor one is R ch. I tried to remove the earth wire and still the L ch shutdown.
Ok, i took the Audionote Dac out and use a squeezebox touch analog output into the FO M... everything is fine and playing for the past few hrs with the earth wire on the heatsink.
This AN dac was playing nice with my main system and only slight buzz on 1 CH. Seems like there is some oscillation or ground loop when using with my AN dac (it has C-core output transformer). Anyone here has experience in using these output trans with FO M module? i have check on both side (Dac and FO M) RCA is not connected to earth. Anyone can help suggest where I should start looking?
regards,
ck
Thanks Mark... so guess the output transformer is not always a good thing after all... maybe I will just use my Pi/hifiberry Dac+ pro for the time being and try maybe build a preamp between the AN Dac and FO M.
BTW, when power down the FO M (switch off the AC), my speaker will buzz down like the PSU is discharging for few sec. Is this normal and will it cause any harm to speaker? anyway to prevent this?
thanks in advance.
ck
BTW, when power down the FO M (switch off the AC), my speaker will buzz down like the PSU is discharging for few sec. Is this normal and will it cause any harm to speaker? anyway to prevent this?
thanks in advance.
ck
Fitting FO 1.4 M in my (not so) old Gainclone LM3886 case
Hi,
I've been reeding this thread for a while, thinking of
upgrading my present amplifier (LM3886 dual mono) with FO 1.4 S modules.
LC just told me that they're not available these days, and that 1.4M would also fit.
My chassis is a dual mono system, with 2 toroidal 300VA xfos, filtered and regulated, giving 2 x +/- 32 volts, with a large enough amount of power for my system.
I don't need a huge power for my speakers, I'm just wondering if this +/- 30 volts DC won't make any problem.
Somebody having an experience with that type of voltage supply ?
Thanks for your comments and sharing experience.
JM
Hi,
I've been reeding this thread for a while, thinking of
upgrading my present amplifier (LM3886 dual mono) with FO 1.4 S modules.
LC just told me that they're not available these days, and that 1.4M would also fit.
My chassis is a dual mono system, with 2 toroidal 300VA xfos, filtered and regulated, giving 2 x +/- 32 volts, with a large enough amount of power for my system.
I don't need a huge power for my speakers, I'm just wondering if this +/- 30 volts DC won't make any problem.
Somebody having an experience with that type of voltage supply ?
Thanks for your comments and sharing experience.
JM
Hi JMK,
when you say your PSU is regulated, does it mean you have some transistor or regulator in series between the capacitor bank and the lm3886 ? this make sense for 3886, but for the FO, the Power suply rejection ratio is so good that you dont need any regulation. Also this regulation might geopardize the amp behaviour as it would bring a specific impedance response which migh impact the sound.
The only drawback of a PSU with low voltage is that you will limit the FO power capabilities, due to mosfet output stage you should consider a margin of say 10V per rail compared to your max peak output. As you question potential "problem" the way to secure this would be to put the FO with this PSU on a bench , with a 6ohm load and measure the max output before clipping. Then if you stay within this limits you would not have "problems"
when you say your PSU is regulated, does it mean you have some transistor or regulator in series between the capacitor bank and the lm3886 ? this make sense for 3886, but for the FO, the Power suply rejection ratio is so good that you dont need any regulation. Also this regulation might geopardize the amp behaviour as it would bring a specific impedance response which migh impact the sound.
The only drawback of a PSU with low voltage is that you will limit the FO power capabilities, due to mosfet output stage you should consider a margin of say 10V per rail compared to your max peak output. As you question potential "problem" the way to secure this would be to put the FO with this PSU on a bench , with a 6ohm load and measure the max output before clipping. Then if you stay within this limits you would not have "problems"
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I choose to have a regulator between the capacitors bank and the LM3886 because the AC power was very unstable in the place where I lived before (Paris) - it would vary from 230V to 260V in an instant - believe it or not, this is a very common situation in France. Refrigerators washing machines etc don't mind, but it's not very good for audio equipment, and most people are not aware of this. I even used an old magnetic power regulator to tame the AC for my system. It would reduce the variation by a factor of ten, which was acceptable. AC is more stable where I now live, and the magnetic regulator is now sleeping on a shelf.
I did some measurements, and the maximum input voltage I have from my DAC preamp is under 1 Volt peak to peak, usually much less.
According to my input voltage, the +/-30V I'll have on my rail, and the FO gain, I guess I'll be way under the clipping area ............... ?
Would it still be a problem to keep my regulation in this area ?
Thanks a lot for your answer
JM