Topping PA5 Review (Amplifier)

[wjp007]

As I've been looking at ways of feeding the PA5, I'd love any suggestions on best ways to drive for my particular setup. I have KEF LS50s but I'm using a subwoofer as the LS50s just don't go deep enough. Right now I feeding the PA5 single ended using an RCA to TRS adapter. I have a Y splitter to feed the subwoofer. The problem with this is the LS50 is getting all frequencies routed to it. I would prefer to have a crossover in front of the PA5 that matches the setting on the subwoofer. I'm thinking the best route is to get an AVR with a preamp out with an internal crossover. Thoughts?

 

[AudioArchitech]

Could try some inexpensive Passive Line Level Crossovers such as this FMOD High Pass filter $30 a pair. Parts Express, Amazon... has them too.

I would be interested to find other ones or build some myself using better caps... maybe ask Danny at GR Research...? I'm even throwing around the idea of just modifying the PA5 inside.

 

[anotherhobby]

As I've been looking at ways of feeding the PA5, I'd love any suggestions on best ways to drive for my particular setup. I have KEF LS50s but I'm using a subwoofer as the LS50s just don't go deep enough. Right now I feeding the PA5 single ended using an RCA to TRS adapter. I have a Y splitter to feed the subwoofer. The problem with this is the LS50 is getting all frequencies routed to it. I would prefer to have a crossover in front of the PA5 that matches the setting on the subwoofer. I'm thinking the best route is to get an AVR with a preamp out with an internal crossover. Thoughts?

I am currently running very similar to this, except I'm using Harrison Labs FMOD 70 Hz High Pass filters in front of the PA5 to match the 70 Hz crossover I have set on the sub. Then I am applying EQ from my Mac, which is the source. This actually works very well, but I don't love the setup and I want much more control for EQ than just the whole signal. I have a miniDSP Flex with balanced connections on order.

EDIT: Ha! AudioArchitech beat me to the punch.

The aqua line is my current room response just using these, a 70 Hz low pass dialed in on the sub, and EQ on the Mac compared to the purple line which is just my speakers alone (Revel M105s) with no filters and with zero EQ. The point with this is that you see zero issues at the crossover point and those filters work just fine. The 50 Hz null is from the room and can only be dialed out with a 3rd sub.

 

[AudioArchitech]

I wanted to get the Flex as well. But I am concerned about connecting the Pecan Pi Streamer/Dac then going through the Flex DAC afterwards. I think I will just High Pass the PA5 then potentially just run a 2x4HD for the Sub only. Or maybe I'm missing something with Flex?

 

[AudioArchitech]

Do you have the 2 subs connected as a left and right?

 

[wjp007]

Could try some inexpensive Passive Line Level Crossovers such as this FMOD High Pass filter $30 a pair. Parts Express, Amazon... has them too.

I would be interested to find other ones or build some myself using better caps... maybe ask Danny at GR Research...? I'm even throwing around the idea of just modifying the PA5 inside.

Thanks, that's definitely a possibility. Thanks. And anyone know where to get Y cable that takes both the right and left channels for a sub with some kind of isolation? I couldn't find anything (I actually had one a long time ago that came with my Yamaha AVC-50 integrated AMP). I ended building something with series resistors that seems to work well.

 

[anotherhobby]

Do you have the 2 subs connected as a left and right?

Currently yes I am running a R and L sub, and it works just fine, even though it's not optimal. That will change when I get the flex.

I wanted to get the Flex as well. But I am concerned about connecting the Pecan Pi Streamer/Dac then going through the Flex DAC afterwards. I think I will just High Pass the PA5 then potentially just run a 2x4HD for the Sub only. Or maybe I'm missing something with Flex?

I'm replacing my current DAC with the Flex since it fits my use case perfectly. I can see where if you wanted to keep your DAC, it may not be as ideal. The diagram below will be my setup once the Flex gets here. Now I just have a normal DAC where the Flex is shown, along with the filters going into the PA5 and a crossover set on the Crown amp, as well as no balanced connections, and stereo subs:

 

[Paco De Lucia]

If the RCA out from the DX3 Pro+ doesn't give you enough volume, you can also drive the PA5 using its 3.5 mm headphone output (with the appropriate adapter, see below for examples). The DX3 Pro+ headphone out goes to 8 V.

Cheap adapter cable:

https://www.amazon.com/Hosa-CMP-153-Stereo-Breakout-Cable/dp/B000068O3C?th=1

Expensive adapter cable:

https://www.sweetwater.com/store/detail/Gold3.52TS06--mogami-gold-3.5-2-ts-06-accessory-cable-3.5mm-trs-male-to-dual-1-4-inch-ts-male-left-right-6-foot

I was thinking of doing this with my DX3 pro+ and PA5 combo, but so far i haven't needed the extra volume. I can't remember how the headphone amp measures according to Amir. I'm assuming there will be a small tradeoff ?

 

[AudioArchitech]

@anotherhobby Wow, impressive diagram with photos! Have you tried setting up your subs just inside (and between) your speakers facing forward. Then also setup Left corner, pointing towards the Right sub. Right corner, pointing towards the Left sub. to compare the differences? If not, give it a try.

 

[anotherhobby]

@anotherhobby Wow, impressive diagram with photos! Have you tried setting up your subs just inside (and between) your speakers facing forward. Then also setup Left corner, pointing towards the Right sub. Right corner, pointing towards the Left sub. to compare the differences? If not, give it a try.

I did play around with moving them, but aside from the 50 Hz null, the spots they are in are actually pretty good. That null is caused by the left and right walls. I can eliminate it with a third sub, but that seems like a lot for just one bad null. Once I get the miniDSP I'll be able to play around with positioning a little more, but until then I'm keeping them by the channel they share a signal with. My office space is pictured below. On a scale of 1-10, I am a full 10/10 happy with my PA5 with this setup.

Below is a better pic of the little 8" subs I built. I actually just finished them 2 days ago.

 

[AudioArchitech]

nice finish. Is that Lino flooring or maybe arborite?

 

[anotherhobby]

nice finish. Is that Lino flooring or maybe arborite?

It's Wilsonite Madagascar laminate.

 

[AudioArchitech]

Good job, they look cool

 

[Paco De Lucia]

I did play around with moving them, but aside from the 50 Hz null, the spots they are in are actually pretty good. That null is caused by the left and right walls. I can eliminate it with a third sub, but that seems like a lot for just one bad null. Once I get the miniDSP I'll be able to play around with positioning a little more, but until then I'm keeping them by the channel they share a signal with. My office space is pictured below. On a scale of 1-10, I am a full 10/10 happy with my PA5 with this setup.

View attachment 178931

Below is a better pic of the little 8" subs I built. I actually just finished them 2 days ago.

View attachment 178934

Good looking enclosures, nice work

 

[DanielT]

I did play around with moving them, but aside from the 50 Hz null, the spots they are in are actually pretty good. That null is caused by the left and right walls. I can eliminate it with a third sub, but that seems like a lot for just one bad null. Once I get the miniDSP I'll be able to play around with positioning a little more, but until then I'm keeping them by the channel they share a signal with. My office space is pictured below. On a scale of 1-10, I am a full 10/10 happy with my PA5 with this setup.

View attachment 178931

Below is a better pic of the little 8" subs I built. I actually just finished them 2 days ago.

View attachment 178934

 

[NTK]

I was thinking of doing this with my DX3 pro+ and PA5 combo, but so far i haven't needed the extra volume. I can't remember how the headphone amp measures according to Amir. I'm assuming there will be a small tradeoff ?

It is true that is a measurable degradation, but it is at a level that is of academic interest only. Below is the THD+N graph of the headphone output. When the graph is a straight line that slopes down by 10 dB every 10x increase in output, it is an indication that the THD+N is totally dominated by a constant level idle noise. And this is the case for the DX3 Pro+ in pretty much its entire operating range.

To calculate the voltage of this idle noise, I took the point on the (high gain) curve at 10 μW which gave a THD+N of -77 dB. The load is 300 Ω and the output voltage at 10 μW is sqrt(1e-5*300) = 0.0548 Vrms. The idle noise level is therefore 0.0548*(10^(-77/20)) = 7.7 μV.

Relative to the standard voltage of 2.83 V speaker sensitivities are reported, with the 19.1 dB gain of the PA5, 7.7 μV is 20*log10(7.7e-6/2.82) + 19.1 = -92 dB. Therefore, if your speaker has a sensitivity of 90 dB SPL at 2.83 V, the noise contributed by the DX3 Pro+ headphone out will be -2 dB SPL at 1 m, which is completely insignificant.

Amir's test of the RCA output reported a dynamic range of 118 dB. Whilst it is mathematically better than the headphone output of 111 dB (= -92 - 19, when not counting the PA5 gain of 19 dB), it isn't anything close to a practical benefit.

 

[tvrgeek]

Could try some inexpensive Passive Line Level Crossovers such as this FMOD High Pass filter $30 a pair. Parts Express, Amazon... has them too.

I would be interested to find other ones or build some myself using better caps... maybe ask Danny at GR Research...? I'm even throwing around the idea of just modifying the PA5 inside.

Useless as you do not know the input impedance of the amp and what blocking cap is in these.
Amps run from 10 to 50K typically.

You can get a simple crossover from folks like Rolls. Not as bad as it looks. You can DIY a really good crossover like the X-Kitx. I agree with your want. A really good 2nd order HP filter for the mains. I suggested that to a couple companies. In the mean time, I am just doing my own.
If more people asked, maybe someone would produce one. People like JDS, SMSL, Topping and Schiit have proven you can make a very very good preamp very cheap, so a $100 box seems reasonable.

 

[Paco De Lucia]

It is true that is a measurable degradation, but it is at a level that is of academic interest only. Below is the THD+N graph of the headphone output. When the graph is a straight line that slopes down by 10 dB every 10x increase in output, it is an indication that the THD+N is totally dominated by a constant level idle noise. And this is the case for the DX3 Pro+ in pretty much its entire operating range.

To calculate the voltage of this idle noise, I took the point on the (high gain) curve at 10 μW which gave a THD+N of -77 dB. The load is 300 Ω and the output voltage at 10 μW is sqrt(1e-5*300) = 0.0548 Vrms. The idle noise level is therefore 0.0548*(10^(-77/20)) = 7.7 μV.

Relative to the standard voltage of 2.83 V speaker sensitivities are reported, with the 19.1 dB gain of the PA5, 7.7 μV is 20*log10(7.7e-6/2.82) + 19.1 = -92 dB. Therefore, if your speaker has a sensitivity of 90 dB SPL at 2.83 V, the noise contributed by the DX3 Pro+ headphone out will be -2 dB SPL at 1 m, which is completely insignificant.

Amir's test of the RCA output reported a dynamic range of 118 dB. Whilst it is mathematically better than the headphone output of 111 dB (= -92 - 19, when not counting the PA5 gain of 19 dB), it isn't anything close to a practical benefit.

great, thanks for doing the legwork.

 

[anotherhobby]

You can get a simple crossover from folks like Rolls. Not as bad as it looks.

I was using the Rolls SX45 in my desktop system between my mains and subs for a few weeks. The audio chain is Topping E30 > Topping L30 > Rolls > Topping PA5 (high pass) and a Crown XLS1500 (low pass). One observation about the Rolls is that if the input signal is too high, a clipping light comes on, and it doesn't seem to take very much input voltage before that happens, relative to how much output voltage it's providing.

Since I'm currently feeding both balanced amps unbalanced signals, I need all the voltage I can get. In that respect, I've come to the conclusion this Rolls is a bad choice for my setup. I would not recommend the Rolls for use with the Topping PA5. The passive Harrison Labs FMOD works much better from a volume/output perspective.

I sent the Rolls SX45 into Amir, so it'll get tested here once he gets his whole flooding situation under control.

I've ordered a miniDSP Flex to solve this for good.

 

[BoredErica]

So now I have ls50 meta to test the pa5 with. Sounds just fine to me. Goes as loud as I'd ever want it, and I dare not increase the volume even more for my own sanity (though I prefer quieter listening compared to average listener). As a normal end user, I still can't detect any build quality issues. Low gain is a benefit to me but might be annoying to some. To me pa5 in the right application is a great, cheap amp.

Saving money is good.

I have o2+odac and I'm feeding the pa5 with that. I think there's a bit of ground loop/noise that gets through. I have to wait a while for it to get quieter in here (loud day) to test for noise yet again, but at 2PM (noiser outside) the loop/hum/noise is inaudible at 15in away and farther. This satisfies my minimum requirement of no noise at 18in but there is a huge room for improvement.

In future when I get Motu UL5 and go balanced, I hope noise will appreciably decrease from here. (None of this is blamed on pa5 btw, if anything pa5 is doing a great job making my noise phobic life more convenient.)

I want to not hear any noise with ear at 3in from the tweeter and I may or may not get that with UL5. It'll get close enough to satisfy me, I think.


When it comes to noise when being turned off: For me, it's not silent when turning off the amp but it's quite quiet. Certainly a lot quieter than turning my o2/odac on and off. Haven't tried turning pa5 on and off via cutting the power to the power strip.


edit:
I listen 19.5in away these days, so I listen close. Obviously check Amir's data and run the SPL calcs yourself before buying. What I'm saying is there are no nasty surprises here.