Ampapa D1 Stereo Amplifier Review

[Bipolarbear]

Thanks. I got the Meanwell for half the price of the Nobsound, and the socket adaptation was a soldering pleasure rather than a trouble (that's just me). I'll try to get accurate temp measurements 48 vs 36v.
EDIT : the Meanwell is 1.5x the volume of the amp or of he 48v GAN supply, ridiculously big and heavy

Power is power, not really possible for it to be 1.5x the volume with less power.

 

[Ykar]

Power is power, not really possible for it to be 1.5x the volume with less power.

True. And the thing is shielded with heavy metal plates all around the components. I should have taken a picture while it was open.

 

[Bipolarbear]

True. And the thing is shielded with heavy metal plates all around the components. I should have taken a picture while it was open.

I took 'volume' as sound in db. Not as in 'weight'. The reason the Meanwell has the extra weight and shielding is because it's a medical supply which is way overkill an unnecessary for such an affordable amp.

 

[john61ct]

yep old school has its downsides

 

[john61ct]

I interpreted "volume" as in physical dimensions, cm³

 

[Ykar]

FYI, I think my D1 just died on me. Usual soft start, everything looked fine, but no sound coming out from speaker output, and nothing detected from RCA in (It goes to standby after 2min or so). I've tried different DACs but no luck. Since the return window was ending tomorrow I didn't investigate further and just sent it back (mentioning the defective unit).

 

[Oeilvert]

I picked one up the other day... Was quite surprised by the heat this thing generates, my IR temp sensor says the output inductors reach 74c and there's two of them 10mm from the 2200uf PVDD capacitor which is rated for 2000 hours@105c. By my reckoning, any D1's which get a lot of use with the supplied 48v power supply will be mostly dead within 5 years. Sure no big deal it's a budget amp but lets be honest, it's far from intelligent design... Or as the kids say, cringe.

I dismantled it earlier to investigate potential avenues of improving thermal dissipation, I've considered installing an 18x18x4mm 5v fan on the left side panel beside the inductors, forced cooling would definitely help things. In my amplifier there was also a hot spot on the PCB directly above where the TPA3255 is mounted... Upon disassembly I discovered a comically child like over generous application of thermal compound between the TPA3255 and aluminium heat spreader and no compound at all between heat spreader and chassis (!) I removed most of the compound from the TPA/heat spreader side and added Dow 340 to the heat spreader/chassis side, doing so provided a large decrease in ambient temp inside the amp.

So far with my testing nothing has been as beneficial combatting heat as decreasing the supply to 36v. That seems to be the sweet spot and the maximum this amplifier was designed to use (with any reliability.) The PCB layout and thermal dissipation capabilities cannot cope with 48v long term in my opinion.

This is how it came out the chassis... The heat spreader is screwed directly to the chassis with no compound whatsoever, and yes the board was that filthy.

 

[xlinknz]

@Oeilvert thank you for flagging the above heat findings.

1. Is the heat spreader the the black rectangle attached to the blue ribbon cable?
2. When you say you reduced the power to 36V do you mean using a different external power supply?
3. I'm still considering a Aiyama A80 (although I am tempted by the D1 2 year warranty) but I suspect it may suffer the same heat issues since its the same unit less HPF but with DAC

 

[Oeilvert]

@Oeilvert thank you for flagging the above heat findings.

1. Is the heat spreader the the black rectangle attached to the blue ribbon cable?
2. When you say you reduced the power to 36V do you mean using a different external power supply?
3. I'm still considering a Aiyama A80 (although I am tempted by the D1 2 year warranty) but I suspect it may suffer the same heat issues since its the same unit less HPF but with DAC

Correct, it's a block of anodised aluminium, TPA3255 one side and chassis the other. It's the exact solution Naim use on their amplifiers, only they use thermal compound both sides of the spreader and their chassis is 3mm thick so it works very well... This budget implementation is suboptimal but does now work after correctly applying compound. FYI It's not actually attached to the ribbon cable, just how the photo angle makes it appear. The ribbon cable is attached to the PCB and runs from there to the front panel, both ends of the ribbon cable were hot glued in place which made removal slightly more fiddly.

Yes, I started using a 36v 5A supply in place of the original 48v 5A. Quality doesn't seem very important, mine is a generic cheapie from Amazon but the sound quality is unaffected and there is no detectable added noise or hum etc.

I've not been inside an A80 but just looked on Google images and I agree with you, same problem but that means same solution, just use a 36v supply. The A80 also appears to use many electrolytic coupling caps, whether they affect the sound is endlessly debatable however it has been accepted good practice in higher quality consumer grade gear not to use them in the signal path since the early 80s making the A80 very unappealing to me.

I do intend to push on increasing the D1's long term reliability @48v. This will involve replacing the capacitor near the largest heat source (inductors) with something better, for example the UBY1J182MHL is rated up to 135c, has double the ripple rating and half the ESR of the factory installed Rubycon, it's essentially heaven sent for a Class D PVDD. I would also like to install a fan such as this:

Installation would be simple as there is sufficient room, a local 5v rail and there is already ventilation with the Ampapa cutout, my only concern is noise... If I can hear the fan running at low volumes that would be a problem. Will have to experiment with resistor values to reach an equilibrium between sufficient heat extraction and noise level.

 

[RandomEar]

@Oeilvert That fan runs at 13000 RPM using 5 V and still only pushes 0.24 m³/h when unobstructed. I do not think it is worth the trouble and it will probably sound like an endlessly screeching cockroach. If you are concerned about temperatures, I would look into replacing the acrylic top plate with a custom lasercut one with ventilation holes. That's 100% silent and will help quite a bit. If you are still concerned afterwards, I have seen people put a 140 mm PC fan below their Fosi V3 Monos using 4 small feet on each side of the fan. With an additional 12 V supply and a fan controller, this can be configured to run at inaudible speeds (~800 RPM) while still offering decent forced convection on the case.

That being said, you can easily calculate the expected life of the cap based on its specs: Assuming 48 V peak, 63 V rated and 75 °C temperature (which is extremely pessimistic, seeing that the 75 °C components are not literally glued to the cap), I arrived at an estimated 21000 hrs of projected life. That does not sound concerning at all. You need to keep in mind that each reduction in temperature of 10 K roughly doubles the projected service life of a cap. In this case, I would expect one of the MLCCs above the TPA3255 to die from thermal cycling before the electrolytic caps sign off, but that's just a hunch.

 

[Oeilvert]

@Oeilvert That fan runs at 13000 RPM using 5 V and still only pushes 0.24 m³/h when unobstructed. I do not think it is worth the trouble and it will probably sound like an endlessly screeching cockroach. If you are concerned about temperatures, I would look into replacing the acrylic top plate with a custom lasercut one with ventilation holes. That's 100% silent and will help quite a bit. If you are still concerned afterwards, I have seen people put a 140 mm PC fan below their Fosi V3 Monos using 4 small feet on each side of the fan. With an additional 12 V supply and a fan controller, this can be configured to run at inaudible speeds (~800 RPM) while still offering decent forced convection on the case.

That being said, you can easily calculate the expected life of the cap based on its specs: Assuming 48 V peak, 63 V rated and 75 °C temperature (which is extremely pessimistic, seeing that the 75 °C components are not literally glued to the cap), I arrived at an estimated 21000 hrs of projected life. That does not sound concerning at all. You need to keep in mind that each reduction in temperature of 10 K roughly doubles the projected service life of a cap. In this case, I would expect one of the MLCCs above the TPA3255 to die from thermal cycling before the electrolytic caps sign off, but that's just a hunch.

Duly noted on the fan, it was only an idea but I like yours better... Honestly I would prefer it if there were no window at all so black acrylic would definitely be the way to go for me.

The ambient temp inside the amp is now relatively cool compared to previously, the only real source of heat is those pesky inductors. The factory Rubycon cap could work out fine but for the sake of a £4 component I'm not going to leave it to chance. I have enough experience replacing caps beside monolithic regs that have been cooked to death in a short time regardless of what their datasheet claimed to follow my instinct on this one.

Aside from all this I am impressed with it, side by side with a Meridian class A/B amplifier I could discern no audible difference.

 

[CptKaos]

@Oeilvert thank you for flagging the above heat findings.

1. Is the heat spreader the the black rectangle attached to the blue ribbon cable?
2. When you say you reduced the power to 36V do you mean using a different external power supply?
3. I'm still considering a Aiyama A80 (although I am tempted by the D1 2 year warranty) but I suspect it may suffer the same heat issues since its the same unit less HPF but with DAC

excess heat has not been an issue with my D1
in fact it feels no warmer than the A80 that it and the Q1 DAC replaced

 

[Oeilvert]

excess heat has not been an issue with my D1

It's entirely possible the improper thermal compound application in my unit is an exception and not the norm. Would be just my luck to receive one made on the Friday afternoon shift. Will require someone else to check theirs for comparison.

As for the 70c+ inductors when using a 48v supply, it's not an immediate or even short term issue but could potentially become one in a few years. See previous couple of posts, RandomEar disagrees it's an issue and I see his point, it may be fine for the limited lifespan most people will use these for and there are actually others more likely to fail before it... Time will tell but one thing is certain: D1's on 36v supplies will outlive those on 48v supplies, almost without exception so if you don't need that extra output power it would be utterly foolhardy to run it at 48v.

 

[CptKaos]

It's entirely possible the improper thermal compound application in my unit is an exception and not the norm. Would be just my luck to receive one made on the Friday afternoon shift. Will require someone else to check theirs for comparison.

As for the 70c+ inductors when using a 48v supply, it's not an immediate or even short term issue but could potentially become one in a few years. See previous couple of posts, RandomEar disagrees it's an issue and I see his point, it may be fine for the limited lifespan most people will use these for and there are actually others more likely to fail before it... Time will tell but one thing is certain: D1's on 36v supplies will outlive those on 48v supplies, almost without exception so if you don't need that extra output power it would be utterly foolhardy to run it at 48v.

70c is not hot
the interior of my truck gets that hot in the summer

 

[bozodidthedub]

As I was testing the unit, by accident I shorted out the positive terminal of the left channel to the chassis. I saw a spark and that channel shut down. Worried that I had damaged the unit, I power cycled the amp using front panel and it came back to life. So pretty robust protection circuit.

By the end of the testing, the amp was warm but nothing concerning. There is plexiglass on top that allows you to swap op-amps (don't!).

Why do you recommend not swapping the op-amps?

 

[RandomEar]

Why do you recommend not swapping the op-amps?

It's a waste of money and typically has no audible effect. In general, you'll end up with a device which measures the same or a bit worse but sounds identical. On rare occasions, you'll end up with very high distortion or oscillations of the amp.

Does Op-amp Rolling Work?

When I post my last video on review of Douk A5 amplifier, I mentioned that rolling (changing) op-amp ICs in there is fruitless. I got have a dozen comments under that video in youtube asking why so I thought I experiment again with the A5. Note that I have done the same testing with both DACs...

www.audiosciencereview.com

Objective Guide to Op-Amp Rolling - Part 1

As per moderator, here is full article from the site: Objective Guide to Op-Amp Rolling - Part 1 July 30, 2021 Op-Amp Test Board This blog article/post is a deep dive into currently available 8-pin DIP dual op-amps, for those that like to swap op-amps in their designs and/or DIY projects. The...

www.audiosciencereview.com

Fosi Audio V3 op-amp rolling, has anyone tried it? Snake oil? Or are there actual differences?

A plastic cup holds water. A glass looks better, has better specs in certain areas... but still it just needs to hold water, which it does fine be it crystal, Ikea glass or plastic. And sometimes the "worse" component, a plastic cup, is just what was specified for the job and lasts longer and...

www.audiosciencereview.com

3e Audio TPA3251 TPA3255 Finished Amplifier with PFFB is coming!

No additional features, no sub out, no nothing. No power supply options to save 10$ - just offer the biggest one that really supports the specifications - and these should be honest. Overall, a simple product that focuses on quality and power for an affordable price, and just works Fully agree...

www.audiosciencereview.com

Sparkos SS3602 Opamp Rolling In Fosi P4

1% is four orders of magnitude, even less audible. You also need to take the Klippel distortion test to inform yourself how much distortion is actually audible. You can't pass 80dB even with a pure tone. If you can, please post your results. Someone pointed this out to you earlier when you...

www.audiosciencereview.com

 

[bozodidthedub]

It's a waste of money and typically has no audible effect. In general, you'll end up with a device which measures the same or a bit worse but sounds identical. On rare occasions, you'll end up with very high distortion or oscillations of the amp.

Does Op-amp Rolling Work?

When I post my last video on review of Douk A5 amplifier, I mentioned that rolling (changing) op-amp ICs in there is fruitless. I got have a dozen comments under that video in youtube asking why so I thought I experiment again with the A5. Note that I have done the same testing with both DACs...

www.audiosciencereview.com

Objective Guide to Op-Amp Rolling - Part 1

As per moderator, here is full article from the site: Objective Guide to Op-Amp Rolling - Part 1 July 30, 2021 Op-Amp Test Board This blog article/post is a deep dive into currently available 8-pin DIP dual op-amps, for those that like to swap op-amps in their designs and/or DIY projects. The...

www.audiosciencereview.com

Fosi Audio V3 op-amp rolling, has anyone tried it? Snake oil? Or are there actual differences?

A plastic cup holds water. A glass looks better, has better specs in certain areas... but still it just needs to hold water, which it does fine be it crystal, Ikea glass or plastic. And sometimes the "worse" component, a plastic cup, is just what was specified for the job and lasts longer and...

www.audiosciencereview.com

3e Audio TPA3251 TPA3255 Finished Amplifier with PFFB is coming!

No additional features, no sub out, no nothing. No power supply options to save 10$ - just offer the biggest one that really supports the specifications - and these should be honest. Overall, a simple product that focuses on quality and power for an affordable price, and just works Fully agree...

www.audiosciencereview.com

Sparkos SS3602 Opamp Rolling In Fosi P4

1% is four orders of magnitude, even less audible. You also need to take the Klippel distortion test to inform yourself how much distortion is actually audible. You can't pass 80dB even with a pure tone. If you can, please post your results. Someone pointed this out to you earlier when you...

www.audiosciencereview.com

I appreciate the reply!

 

[CptKaos]

Why do you recommend not swapping the op-amps?

I swapped op amps in my 3e Audio A7 mono amps and feel that it sounds better, no empirical data just my ears and brain
plan to swap Sparkos SS3602's into my D1 just to see if I will hear a difference

 

[RandomEar]

I swapped op amps in my 3e Audio A7 mono amps and feel that it sounds better, no empirical data just my ears and brain
plan to swap Sparkos SS3602's into my D1 just to see if I will hear a difference

Unless you test in a controlled way (level-matched, blind, quick switching), results of such tests are sadly meaningless. Your brain will tell you all sorts of things. Hearing is an interpretation based on multiple senses and past experiences, it's not a reliable or deterministic process.

AES Paper Digest: Sensitivity and Reliability of ABX Blind Testing

This is abbreviated synopsis of the paper, Ten Years of ABX Testing, by David Clark: http://www.aes.org/e-lib/browse.cfm?elib=5549 ABX testing as you may know is a double blind testing methodology aimed at determining if someone can reliably identify A from B. Both A and B are presented to the...

www.audiosciencereview.com

Audio Blind Testing - You Are Doing It Wrong! (Video)

Just uploaded a video on the basics of performing controlled tests in audio. It was motivated by saving myself text in having to write all of this down when telling someone who to do these tests right. And as a counter to a few online personalities to keep saying they do "blind" tests yet when...

www.audiosciencereview.com

 

[CptKaos]

Unless you test in a controlled way (level-matched, blind, quick switching), results of such tests are sadly meaningless. Your brain will tell you all sorts of things. Hearing is an interpretation based on multiple senses and past experiences, it's not a reliable or deterministic process.

AES Paper Digest: Sensitivity and Reliability of ABX Blind Testing

This is abbreviated synopsis of the paper, Ten Years of ABX Testing, by David Clark: http://www.aes.org/e-lib/browse.cfm?elib=5549 ABX testing as you may know is a double blind testing methodology aimed at determining if someone can reliably identify A from B. Both A and B are presented to the...

www.audiosciencereview.com

Audio Blind Testing - You Are Doing It Wrong! (Video)

Just uploaded a video on the basics of performing controlled tests in audio. It was motivated by saving myself text in having to write all of this down when telling someone who to do these tests right. And as a counter to a few online personalities to keep saying they do "blind" tests yet when...

www.audiosciencereview.com

do as you wish with your system
as for me and my ears in my room with my gear the swap was worth the effort whether the difference is totally psycho-acoustic or actually measurable doesnt matter as I liked it