JBL 305 MkII paired with a NAIM Nait 5i

[mmm]

Just received new JBL 305 MK II I 2 weeks ago. I have had my 2008 NAIM amp repaired and was working great. Plugged my new JBL's sounded great, now it sounds as if they are blown. Scratchy, can't turn them up. Sound fine at low volume. Tweaked everything I can. I think I blew them out in 2 weeks. No way right? I I had beautiful old BW's for 20 years. No way to blow the JBL's out? How do I trouble shoot? Bad amp?

 

[amirm]

Do you have another speaker to make sure it is not the amp that is blown?

What happens if you gently push in the woofer? Does it feel like they are stuck, scratchy or hard to push in?

 

[mmm]

Both speakers are new. 2 weeks old. perfect woofers. no physical damage or anything I can see. The amp is old and has been repaired. Naim Nait 5i. Suggestion on trouble shooting amirm?

 

[mmm]

They worked and sounded beautiful for 2 weeks. thinking it's the amp?

 

[Jason]

Isn't the Naim an integrated amp? How were the speakers connected?

 

[mmm]

Personally, I don't think you can blow brand new JBL 305P MkII in 2 weeks. Gotta be the amp. What do you think amirm. I have tweaked the volume levels on both speakers, coordinating with the amp. Even at low levels voice audio sounds scratchy and gross. On a great vinyl, sound ok.

 

[Blumlein 88]

How did you use an integrated amp with the LSR speakers? They only need line level inputs. I don't recall the Nait having those line level outputs to feed the LSR inputs.

Amir is asking you to push on the woofers to find out something. Burned woofers will get off center, maybe melt some of the windings, get scratchy, sticky and not move smoothly. Visually they might still look pristine.

 

[mmm]

Half inch plugs to the speakers and butterflies to the amp

 

[mmm]

Nope woofers are fine.

 

[mmm]

Like brand new.

 

[Blumlein 88]

Half inch plugs to the speakers and butterflies to the amp

Explain further. Sure sounds like you may have overloaded the input to the speakers effectively burning it up or damaging it. Best way to find out is try the amp with another speaker and the LSR speakers with another source. Even something low level like a phone jack output from a smart phone.

Were you using speakler level output from the amp to feed input to the LSR?

Also you might try changing the input sensitivity switch on the speakers to see if it is scratchy on both settings.

 

[mmm]

Sorry bannana plugs

 

[Jason]

Were the speakers connected to the speaker out terminals on the amp?

 

[mmm]

1/2 inch plug in's to the speaker to the amp with banana plugs

 

[mmm]

worked fine for 2 weeks sounded amazing. then scratchy vocals and no beauty when turning up the volume. sound ok at very low volume. not great.

 

[Blumlein 88]

Something like this or something that let you feed the amp speaker jack output into the TRS jack on the LSR305?

 

[Jason]

The speakers are active which means they include their own amplification. You have probably killed something in the electronics of the speakers or maybe the amp. Try what Blumlein 88 suggests above.

 

[mmm]

Yes with the banana's going into the amp. Like a guitar plug in to the speaker

 

[Blumlein 88]

Yes with the banana's going into the amp. Like a guitar plug in to the speaker

There are PA speakers where amplifier power feeds over TS plugs to power the speaker. It is one of those gotchas. You weren't supposed to feed power amp levels into the TRS jack on the 305s.

It is possible the amplifier without a low impedance load at some point oscillated and is damaged. It is possible the input voltage which could be over 20 volts was too much for the input to the 305s and damaged the input to them.

I hope it was a TRS plug and not a TS plug from a guitar plug. If you used a TS plug you may have shorting some of the power amp output to ground.

TRS:

TS:

 

[mmm]

Plugged into a 1/2 inch