Hello Anand,
Very Impressive, beautiful build,
Great write up.
Hope she sounds glorious.
Scott
Very Impressive, beautiful build,
Great write up.
Hope she sounds glorious.
Scott
Hello Anand,
Amazing build and fantastic compilation of build!.
Congratulations. all the best.
regards
prasi
Amazing build and fantastic compilation of build!.
Congratulations. all the best.
regards
prasi
For those of you who are interested, here is a video link showing how slow and soft, the softstart is. Mind you, there is a 2 second timer on the softstart board and then an additional 10 seconds because of the Hifisonix MRE (capacitance multiplier). It reaches +/-50V in about 25 seconds, but it’s a good 90 seconds (as the MOSFETS turn on) before the amp reaches about +/- 52 volts!
Amp takes about 15 minutes to reach thermal equilibrium on the heatsinks which sit at about 33 deg C. Bias is 250mA/ch, so Class A power is as follows: 8 watts/32 ohms, 4 watts/16 ohms, 2 watts/8 ohms and 1 watt/4 ohms.
Remember loudspeakers have impedance swings and if you know the impedance curve (by DATS measurement or equivalent), you’ll see that for a majority of the time, you are probably listening in Class A with this amount of bias. My main speakers are 96dB sensitive.
On stress bench testing I could only get it up to 45 deg C max and that was only after letting it cook for about 5 minutes at 56 watts/ch/4 ohms (15V RMS). In the real world, with the dynamics of music and crest factor included, I don’t see this heatsink (0.31 degC/watt) having any thermal impediments with this design.
Best,
Anand.
Amp takes about 15 minutes to reach thermal equilibrium on the heatsinks which sit at about 33 deg C. Bias is 250mA/ch, so Class A power is as follows: 8 watts/32 ohms, 4 watts/16 ohms, 2 watts/8 ohms and 1 watt/4 ohms.
Remember loudspeakers have impedance swings and if you know the impedance curve (by DATS measurement or equivalent), you’ll see that for a majority of the time, you are probably listening in Class A with this amount of bias. My main speakers are 96dB sensitive.
On stress bench testing I could only get it up to 45 deg C max and that was only after letting it cook for about 5 minutes at 56 watts/ch/4 ohms (15V RMS). In the real world, with the dynamics of music and crest factor included, I don’t see this heatsink (0.31 degC/watt) having any thermal impediments with this design.
Best,
Anand.
Hi Anand,
I didn’t know you were using a cap multiplier in your PSU. Generally, I only use them on SE Class A amps where there is very poor PSRR but since the FH9HVX is a balanced LTP input and push-pull bipolar amp, it will tolerate supply ripple very well and not need a cap multiplier. Having one of course, makes for an ultra quiet amp. One thing to make sure of is that the pass transistor on the cap Mx doesn’t limit the max peak current that can be released by the PSU on heavy bass peaks. Looks like you might have a massive cap bank after the cap Mx, in which case, it’s not a problem. I suppose an SLB on the FH9HVX followed by a cap bank would achieve a similar thing.
If you can annotate one of your photos to show what each component does. I think a see a small low noise TPS7A4XXX 12v PSU for the BTSB power in. I also see a couple SSR for the speakers. You have a soft start and cap Mx mounted on the front panel it seems. A lot of good stuff in this box!
Looking forward to your listening impressions.
Thanks for an awesome build.
I didn’t know you were using a cap multiplier in your PSU. Generally, I only use them on SE Class A amps where there is very poor PSRR but since the FH9HVX is a balanced LTP input and push-pull bipolar amp, it will tolerate supply ripple very well and not need a cap multiplier. Having one of course, makes for an ultra quiet amp. One thing to make sure of is that the pass transistor on the cap Mx doesn’t limit the max peak current that can be released by the PSU on heavy bass peaks. Looks like you might have a massive cap bank after the cap Mx, in which case, it’s not a problem. I suppose an SLB on the FH9HVX followed by a cap bank would achieve a similar thing.
If you can annotate one of your photos to show what each component does. I think a see a small low noise TPS7A4XXX 12v PSU for the BTSB power in. I also see a couple SSR for the speakers. You have a soft start and cap Mx mounted on the front panel it seems. A lot of good stuff in this box!
Looking forward to your listening impressions.
Thanks for an awesome build.
X,
Yeah, this was an experimental build to see if I can cobble up together a basic power supply using 4pole caps and see how good Andrew's cap multiplier works. In essence, we are supposed to have at least 40dB ripple (100X) reduction up to 1khz and at least 50dB (316X) up to 10khz. There is a minimum load current, and that is 50mA. Since mine is 250mA/ch, it works fine - I consulted Andrew regarding this specifically.
Another experiment I did was drive this amplifier hard on a 4 ohm load. Hard clipping was achieved at about 170+ watts RMS, but I also observed the voltage rails at the same time. Because of the cap multiplier, the sag was greater, down to about 43V from the usual 52V. Mind you, the cap multiplier chews up about 1-2V. This is one of the negatives of a cap multiplier, amongst others. The pass transistor I used were Sankens (2SC3519A and 2SA1386A), which are limited to 180V and 15A. The other negative with cap multipliers is their response during 'brown outs.' AC ripple reduction is lost and hum results. Thankfully, my area doesn't suffer from brown outs.
On hindsight, what I should have done was stuck to my original premise of using 40V secondaries instead of 38V secondaries. I downgraded to 38V secondaries because my AC mains line voltage typically hovers at 123V AC and not 120V AC. I didn't want the rectified secondaries to be >55V. So I backed down to 38V, realizing that my peak power output would be compromised (note that my non clipped 8 ohm power is 95 watts RMS, and 153 watts RMS for 4 ohms).
All in all, I think this supply is fine even with smaller class A amplifiers (I would upgrade my main PSU caps to 15-22mF instead of 10mF) and I'll probably reuse this recipe for some future builds. So in essence, the FH9HVX was the guinea pig. The other addition I would try is to eliminate the HexFred rectifier and dive right into an active rectifier solution such as the new Saligny Universal which is backwards compatible with center tapped rectification psu topologies. This would result in even less voltage sag at peak transients. For non center tapped solutions, the LT4320 option from your SLB will do just fine.
I'll see about updating one of photos with some annotation.
Best,
Anand.
Yeah, this was an experimental build to see if I can cobble up together a basic power supply using 4pole caps and see how good Andrew's cap multiplier works. In essence, we are supposed to have at least 40dB ripple (100X) reduction up to 1khz and at least 50dB (316X) up to 10khz. There is a minimum load current, and that is 50mA. Since mine is 250mA/ch, it works fine - I consulted Andrew regarding this specifically.
Another experiment I did was drive this amplifier hard on a 4 ohm load. Hard clipping was achieved at about 170+ watts RMS, but I also observed the voltage rails at the same time. Because of the cap multiplier, the sag was greater, down to about 43V from the usual 52V. Mind you, the cap multiplier chews up about 1-2V. This is one of the negatives of a cap multiplier, amongst others. The pass transistor I used were Sankens (2SC3519A and 2SA1386A), which are limited to 180V and 15A. The other negative with cap multipliers is their response during 'brown outs.' AC ripple reduction is lost and hum results. Thankfully, my area doesn't suffer from brown outs.
On hindsight, what I should have done was stuck to my original premise of using 40V secondaries instead of 38V secondaries. I downgraded to 38V secondaries because my AC mains line voltage typically hovers at 123V AC and not 120V AC. I didn't want the rectified secondaries to be >55V. So I backed down to 38V, realizing that my peak power output would be compromised (note that my non clipped 8 ohm power is 95 watts RMS, and 153 watts RMS for 4 ohms).
All in all, I think this supply is fine even with smaller class A amplifiers (I would upgrade my main PSU caps to 15-22mF instead of 10mF) and I'll probably reuse this recipe for some future builds. So in essence, the FH9HVX was the guinea pig. The other addition I would try is to eliminate the HexFred rectifier and dive right into an active rectifier solution such as the new Saligny Universal which is backwards compatible with center tapped rectification psu topologies. This would result in even less voltage sag at peak transients. For non center tapped solutions, the LT4320 option from your SLB will do just fine.
I'll see about updating one of photos with some annotation.
Best,
Anand.
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Let’s see if this annotated pic helps:
Shot in the dark:
Best,
Anand.
Shot in the dark:
Best,
Anand.
Hi Anand,
Thanks for the diagram. Lots of goodies in there.
Is there a cap bank after the cap Mx or is that before?
Thanks for the diagram. Lots of goodies in there.
Is there a cap bank after the cap Mx or is that before?
There is a large one before and a small one after. I’ll ask Andrew of the relevance of having a larger cap bank after in a Class AB design with respect to his cap multiplier design, especially for small 100 watt amplifiers.
I do have space to add one if need be though…
Best,
Anand.
I do have space to add one if need be though…
Best,
Anand.
Another amazing build from poseidonsvoice!
Question for you my friend, do you ever sleep? So many beautiful builds!!
What's next on the bench?
All the best!
Do
Question for you my friend, do you ever sleep? So many beautiful builds!!
What's next on the bench?
All the best!
Do
@pinnocchio
Thank you for the compliments. Honestly, your builds and sledwards‘ are legendary.
I’m going to house my Modulus 686 in a 4U/400 chassis next, and then there is a nice laundry list of builds in the queue. Probably 2 more builds including the 686 for 2023 (fingers crossed).
I sleep about 7 hours/night.
Best,
Anand.
Thank you for the compliments. Honestly, your builds and sledwards‘ are legendary.
I’m going to house my Modulus 686 in a 4U/400 chassis next, and then there is a nice laundry list of builds in the queue. Probably 2 more builds including the 686 for 2023 (fingers crossed).
I sleep about 7 hours/night.
Best,
Anand.
Anand, another amazing build. You are a DIYAudio god among men. Just beautiful. Looking forward to your listening impressions, and also listening comparisons to other A/B designs popular around here (AB100, Honey Badger, Wolverine if you've built any of those)
Also, where'd you get those Ground Lift and Composite Ground Lug boards?
Also, where'd you get those Ground Lift and Composite Ground Lug boards?
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@pinkfloyd4ever
Thank you, you are too kind.
Ground Lift PCB info is here.
T-Ground/Composite Ground PCB info is here.
The AB100 and Wolverine are in my build queue. But rehousing the Modulus 686 is next.
Best,
Anand.
Thank you, you are too kind.
Ground Lift PCB info is here.
T-Ground/Composite Ground PCB info is here.
The AB100 and Wolverine are in my build queue. But rehousing the Modulus 686 is next.
Best,
Anand.
Nice, thanks! Definitely going to get a few of those 2 ground boards. So much cleaner looking than doing that free flopping, or than using perf board.
Looking forward to seeing your upcoming builds. You should do a tutorial about how you make them all so neat and clean (in your spare time, haha)
Looking forward to seeing your upcoming builds. You should do a tutorial about how you make them all so neat and clean (in your spare time, haha)
Well, that was fun whilst it lasted...
I have been running this amp now for several months, its been fantastic.
I used it yesterday afternoon, no problems.
This morning, I go to turn it on and POP goes the main fuse.
I've disconnected the amp boards an then the PSU powers on ok.
Connect right amp and its OK,
But left causes the fuse to pop immediately.
Thought on where to start checking things on the AMP board?
Thanks.
Nik
I have been running this amp now for several months, its been fantastic.
I used it yesterday afternoon, no problems.
This morning, I go to turn it on and POP goes the main fuse.
I've disconnected the amp boards an then the PSU powers on ok.
Connect right amp and its OK,
But left causes the fuse to pop immediately.
Thought on where to start checking things on the AMP board?
Thanks.
Nik
OK, I've just tested the FETs and looks like they are the issue, all leads are <1ohm between,
On the good board its Open...
Ideas on why it would suddenly die?
On the good board its Open...
Ideas on why it would suddenly die?
I’ve had similar thing happen but mine was due to fake mosfets. Did you purchase from a reputable supplier?
For a MOSFET to suddenly go might be caused by a turn-on spike or a non-optimal thermal contact with the heatsink. This can lead to thermal runaway and that can fry a MOSFET in a few seconds. Check to see if the thermal paste or insulator pad are well mounted.