Connecting EP2500 - humming problem

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M

mvc

Enthusiast
Update: Orginally, when I simply inserted the RCA end of the Neutrik into the sub-out cable while the XLR end was not plugged anywhere, I heard the hum. Now I can't repeat it exactly that way. The hum is still there, but only when I insert the the XLR end of the Neturik into the amp. Can't figure out what was different earlier.

TLS Guy:

Thanks for some of the suggestion. Though I am trained in Science, I am terrible in electronics and this was a reason I tried not to do anything that involve soldiering, as I do not own any soldiering kit. But I am planning to learn some electronic assembling in near fututre as my next DIY project call for that skill (want to build a pair of Linkwitz Pluto speakers myself). As a first step I just got a multimeter and I have yet to figure out how to use this.

Anyway, I tried to use a simple Radioshack RCA to 1/4inch phono plug, but I still see that hum. At this point I am just going to wait until I receive my ART DTI box. I just placed the order.
 
M

mvc

Enthusiast
WmAx:

Please see my post above regarding the update on the hum.
I have just placed the order for the ART DTI. I have a Denon 3805. I hope that it has enough gain to drive the ART DTI. Is there a way to measure this - don't know how to do that - I just got a multimeter. I am hoping to receive the ART DTI within a week and get back to the forum by next weekend.


Right now I am only trying to use one channel of the EP2500. But in the future I am planning to add one more sub to even out as you have suggested in many of your posts. My ultimate desire is to build a pair of Linkwitz Pluto speakers and combine it with a pair of either JL 12W7 or the Kappa drivers. The Yamaha amp would be nice, but currently I am trying to keep my costs down. Once I fix the current hum issue, I will look into replacing that fan - yes I find it noisy.

Thanks everyone.
 
TLS Guy

TLS Guy

Audioholic Jedi
mvc said:
Update: Orginally, when I simply inserted the RCA end of the Neutrik into the sub-out cable while the XLR end was not plugged anywhere, I heard the hum. Now I can't repeat it exactly that way. The hum is still there, but only when I insert the the XLR end of the Neturik into the amp. Can't figure out what was different earlier.

TLS Guy:

Thanks for some of the suggestion. Though I am trained in Science, I am terrible in electronics and this was a reason I tried not to do anything that involve soldiering, as I do not own any soldiering kit. But I am planning to learn some electronic assembling in near fututre as my next DIY project call for that skill (want to build a pair of Linkwitz Pluto speakers myself). As a first step I just got a multimeter and I have yet to figure out how to use this.

Anyway, I tried to use a simple Radioshack RCA to 1/4inch phono plug, but I still see that hum. At this point I am just going to wait until I receive my ART DTI box. I just placed the order.
Click to expand...
The simple RCA to 1/4 inch phono would not work, it needs to be the one I sent you, that is a transformer. Basically it is the same as the ARTDTI box.

However from you now say, there maybe a ground loop. If you connect two to the hot of the RCA and connect one and three to the ground of the RCA, when you plug everything in there should be no hum.

For a test lift the ground of the amp and see if there is still hum. If it goes away with the ground lifted, then you have proved you have a ground loop.

By the way when cables are no connected at both ends, it is the rule to get variable degrees of hum. Both ends of the connection have to be correctly terminated.

The fact you now have hum with the cables plugged in, as long as they are correctly configured there should be no hum. If there is hum, the transformer per se will not correct this.
 
M

mvc

Enthusiast
TLS Guy said:
The simple RCA to 1/4 inch phono would not work, it needs to be the one I sent you, that is a transformer. Basically it is the same as the ARTDTI box.

However from you now say, there maybe a ground loop. If you connect two to the hot of the RCA and connect one and three to the ground of the RCA, when you plug everything in there should be no hum.

For a test lift the ground of the amp and see if there is still hum. If it goes away with the ground lifted, then you have proved you have a ground loop.

By the way when cables are no connected at both ends, it is the rule to get variable degrees of hum. Both ends of the connection have to be correctly terminated.

The fact you now have hum with the cables plugged in, as long as they are correctly configured there should be no hum. If there is hum, the transformer per se will not correct this.
Click to expand...


TLS Guy: You are right! I added a 3pin to 2pin connector to the EP2500's power plug and the hum is gone.

Right now my plan is to make use of the ART DTI as a short term solution. Once I get a soldiering iron, I will try to soldier the XLR grounds to the RCA grounds according to your suggestions. I would prefer this over the transformer since, WmAx mentioned that there may be small attenuation at the low end.

For the amount of money I wasted buying multiple cables and connectors, I wish I had bought a soldiering iron and tried that route first :eek:

Now, I have to see how the ART DTI would work.
 
WmAx

WmAx

Audioholic Samurai
mvc said:
TLS Guy: You are right! I added a 3pin to 2pin connector to the EP2500's power plug and the hum is gone.

Right now my plan is to make use of the ART DTI as a short term solution. Once I get a soldiering iron, I will try to soldier the XLR grounds to the RCA grounds according to your suggestions. I would prefer this over the transformer since, WmAx mentioned that there may be small attenuation at the low end.

For the amount of money I wasted buying multiple cables and connectors, I wish I had bought a soldiering iron and tried that route first :eek:

Now, I have to see how the ART DTI would work.
Click to expand...
If you plan to make connectors and what not for now on, you should get a decent iron. Weller has a low cost adjustable temperature base station iron for about $45-$55 that I highly recommend. This one is great: http://www.amazon.com/Weller-WLC100-Soldering-Station-Hobbyist/dp/B000AS28UC

Be sure to get a variety of extra tip types - like a small point tip, small blade tip - and the one blade tip included is too large IMO.

-Chris
 
M

mvc

Enthusiast
Finally the sub is working. As suggested by Chris, I added the ART DTI box and all the hum is gone. I set the volume control on the EP2500 midway then let the Denon 3805 automatically calibrate using the set-up mic. I noticed that the sub gain was set at +6db. The system seems to work fine. Only thing that annoys me is that the amp's fan is too loud to me. I wish I bought that Yamha amp - I will consider doing that in the future when I add one more sub and expand the system. In the meantime I will look into replacing the fan as suggested by Chris.

Thanks a lot for the forum members for all the help. I truly appreciate your suggestions to solve the problem.
 
M

mvc

Enthusiast
WmAx said:
If you plan to make connectors and what not for now on, you should get a decent iron. Weller has a low cost adjustable temperature base station iron for about $45-$55 that I highly recommend. This one is great: http://www.amazon.com/Weller-WLC100-Soldering-Station-Hobbyist/dp/B000AS28UC

Be sure to get a variety of extra tip types - like a small point tip, small blade tip - and the one blade tip included is too large IMO.

-Chris
Click to expand...

Chris, Thanks for the suggestion. I will add this item to my shopping list - I think I will certainly make use of this.
 
Haoleb

Haoleb

Audioholic Field Marshall
Have you performed the fan mod on the amp yet? The quieter fan is significantly quieter than the stock one.
 
M

mvc

Enthusiast
Haoleb said:
Have you performed the fan mod on the amp yet? The quieter fan is significantly quieter than the stock one.
Click to expand...
I haven't done that yet - but planning to do it soon. Can you suggest a specific model of fan that works best for this amp. Thanks.
 
Matt34

Matt34

Moderator
I just did the fan mod now I have the hum.:rolleyes: Guess I'll give the ART DTI box a try.

If it's not one thing it's another.
 
ParadigmDawg

ParadigmDawg

Audioholic Overlord
The fan mod works perfectly. Mine is so quite you can only hear it when you put your ear right to the amp.

I have a hum too.....
 
ParadigmDawg

ParadigmDawg

Audioholic Overlord
I hate the ps3 fan!

What do you run your sub level from the AVR at? Didn't know if the pro amps like a higher level or if it doesn't matter.
Matt34 said:
Yeah, it makes my PS3 seem like a jet turbine now.;)
Click to expand...
 
Matt34

Matt34

Moderator
ParadigmDawg said:
I hate the ps3 fan!

What do you run your sub level from the AVR at? Didn't know if the pro amps like a higher level or if it doesn't matter.
Click to expand...
Right now it's at zero. I had to bring it up originally to get a strong enough signal to the EP2500.
 
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