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I am considering buying JBL 305p MKII with Topping D50s. Anyone with the same setup or solid advice?

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#1
Hello there.

I am (strongly) considering pairing a Topping D50s with a pair of JBL 305p MKII.

The D50s will be used as a preamp.

Through the DAC I will use the USB for Roon through a Mac Mini, the Toslink for TV and the bluetooth for quick, on the fly phone streaming.

The small form factor is very appealing, as is having a minimal amount of equipment.

I have concerns about using RCA to XLR and noise.

My understanding is that the following wiring scheme ( https://www.monoprice.com/product?p_id=35811 )is the correct one:

1599059609918.png


Anyone using this pairing?

Any cogent advice?

Genuine thanks in advance.
 

3125b

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#2
As RCA is an unbalanced connection, you will run into ground loop issues if you have multiple grounded devices connected electrically.
With the setup you are planning on using, that should not be the case, the Mac Mini is an IEC class II device (no grounding), TOSLINK is a galvanically isolated connection and bluetooth a wireless one of course.
 

daftcombo

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#3
If you plug the speakers on a different outlet than the rest, there shouldn't be a ground loop.
 
OP
H
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Thread Starter #4
If you plug the speakers on a different outlet than the rest, there shouldn't be a ground loop.
If the speakers are the only devices with a ground on the plug, will I still need to use separate outlets? I'm asking because 3125b's reply sounds as though I will be ok without using separate outlets. I am ignorant in this domaine, and by no means doubting your advice.

Thanks.
 
OP
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Thread Starter #5
As RCA is an unbalanced connection, you will run into ground loop issues if you have multiple grounded devices connected electrically.
With the setup you are planning on using, that should not be the case, the Mac Mini is an IEC class II device (no grounding), TOSLINK is a galvanically isolated connection and bluetooth a wireless one of course.
So if the speakers are the only components with a ground tab on the plug, I should be fine using one outlet?

That's good news.

Thanks again.
 

AnalogSteph

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#6
the Mac Mini is an IEC class II device (no grounding)
Yeah, but still with power supply filter leakage currents that will want to find their way somewhere.

The Monoprice cable configuration should work well in this scenario. It'll divert said leakage currents around the audio connection and into mains earth via chassis ground on the JBLs.

And no, you won't have to use different outlets.

I'm not sure why the "different outlet" tactic seems to help in some cases at all, you'd think keeping the ground potentials closer together and loop area smaller would be better. Maybe the increase in ground resistance between the devices involved when using separately outlets is more beneficial though.
 
Last edited:
OP
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Thread Starter #7
Yeah, but still with power supply filter leakage currents that will want to find their way somewhere.

The Monoprice cable configuration should work well in this scenario. It'll divert said leakage currents around the audio connection and into mains earth via chassis ground on the JBLs.

And no, you won't have to use different outlets.

I'm not sure why the "different outlet" tactic seems to help in some cases at all, you'd think keeping the ground potentials closer together and loop area smaller would be better. Maybe the increase in ground resistance between the devices involved when using separately outlets is more beneficial though.

Thanks for taking the time to share this. It's appreciated.
 

Aldoszx

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#9
I have this setup. I am using RPi4 to feed D50s and RCA - 1/4" cables.
No ground loop or other issues. Everything is working just fine !
 

Neddy

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#10
I have a similar setup, but w/PC rather than Mac as a source (and Mk1 versions of both), and RCA->XLR cables (nothing fancy).
My 305s came with foam tilt/riser blocks, which actually help a bit for aiming right at my ears.
Hard to beat this setup for quality/cost/small footprint/SQ - though I will be adding an el cheapo sub I have laying around at some point.
I did have some line noise from the PC USB power supply, but found a nice quiet USB power strip which solved that. I can't hear any hiss or noise, even at 2ft distance from ears.
PS. I use an analog control knob (NLA, from Emotiva) for volume - very handy for desktop setup.
Should be a fine little system!
 
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#11
I bought the 305s recently.
I would strongly recommend to spend a little bit more and go for 306s or 308s.

The 305s sound very very nice, but they feel quite strained if you pump the volume up a little. You will most likely have buyer's remorse if you buy 305s :)

There is one thing to watch out. You need to switch on the 305/6/.. first and wait for a few seconds and then turn on the upstream device. The manual says so too. In your case this should not be a problem. This is an issue if there are other devices upstream that are connected to a common source.
For example, I have: RPI --> Khadas --> 305. Same RPI also feeds Topping D10 --> Hypex DLCP --> another system. Switching on the 305s caused the upstream DLCP to go silent. I don't know what's happening, and this is very much repeatable. This is only a problem if you have 2 systems connected to a common source upstream.

Regarding cable connection, I would suggest you to please read this, https://benchmarkmedia.com/products/benchmark-rca-to-xlrm-adapter-cable, and buy a cable accordingly.
 
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