KRK Rokit 8 G2 Very Low Sound! Please Help me!

[Soundfreak87]

Hi everyone!

I'm wondering if any of you knowledgeable people can help me.

I produce music now and then and I have a pair of KRK Rokit 8 Gen 2's.

One of them is extremely quiet, to the point where I have to put my ear up to the speaker to hear anything at all (this is on full blast volume) however the volume control works even though the sound is so low.

I have taken out the amplifier to look for bad caps and I have replaced all the electrolytic caps on the preamp board with audio grade Nichicon caps and tested all the rest of the caps on the board with an LCR meter and they check out within spec. (all caps were removed from circuit whilst testing).

I think I have narrowed the problem down to the pre amp board because when I was checking for voltages, I touched one of the legs on a JRP4580D operational amplifier (this is the 2nd op amp in circuit) and I had loud sound like I have touched the end of an RCA cable whilst plugged into the speaker jack. I then took an 3.5mm to twin RCA cable splitter and plugged it into my iPod. I grounded one side and touched the same pin on the JRP4850D (which I believe is the 'out' leg) with the other RCA and I had good, clean, loud, normal sound but with no volume control as I believe the problem lies between the RCA connector, volume pot and the op amps.

I have also checked all zener diodes on the board. I haven't paid much attention to the resistors though as none of them are burnt up.... should I be paying attention to them?

There's 6 of these JRP4580D op amps on the pre amp.

Does anyone have any idea what could be causing or has had the same issue and has repaired it?

Could it be the 4580D's? I can get these for around 27p each from an electronic component distributor, however I'd rather know what exactly is causing this issue and replace that rather than replacing everything.....

I really want to start making music again but can't do this with one speaker lol

Any guidance will be appreciated!

Thanks in advance.

 

[TBTL]

Did you try swapping the speakers to rule out cabling and the source?

 

[Soundfreak87]

Did you try swapping the speakers to rule out cabling and the source?

Hey thanks for your reply TBTL. I just tried the amp in my other Rokit 8 cab and this presented the same issue. However in both cabinets if I take an RCA splitter lead grounded on one side and touch pin 1 of the 1st op amp on the faulty pre amp board the sound returns loud and clear..... this kind of rules out the power board, tweeter and woofer.

I've attached a picture of the pin layout of the operational amp.

The source of sound works perfectly with the other monitor.

I'm thinking about just placing an order for the op amps and just replace them anyway.... They are hardly going to break the bank at 27p a go.

If you think of anything in the meantime I will surely give it a shot.

Thanks 🙂

 

[adason]

Install socket...lot more handy if that opamp is going to blow again.

 

[Soundfreak87]

Install socket...lot more handy if that opamp is going to blow again.

Thanks adason. Do you think the op amps are the problem?

I've just found 8 pin DIP sockets on the component shop site for 18p... I think I will be ordering some of these too! 😎

 

[Soundfreak87]

Sooooooo changing all the 5 op amps and also the 4580L op amp which is the long 8 legged version didn't make any difference at all....

Any suggestions people?

Starting to feel this monitor and it's amp getting closer and closer to my second storey window......................

 

[Mayuri]

Maybe a faulty solder joint somewhere on the signal path before the op amp? They can be very hard to detect, maybe use multimeter and trace signal path from input.