Db Technologies Opera Sub 15 - Banging, popping and humming

[soundsalarming]

Hello everyone.

http://i66.tinypic.com/2zf3a6b.jpg

I own a pair of Db Tech Opera Sub 15 which I really like but they both seem to have developed a fault. When powered on there is an audible hum even with no inputs plugged in - one sounds a little bit worse than the other.

Another thing is when I go to adjust the output knob on the back the sub protests loudly with bangs and pops and hisses! It's like the knob is sensitive to the touch.

The back panel (black area within red box in pic) is also very sensitive - tapping it results in the tapping noise being amplified and output by the speaker.

Is there something I can do or are they broken? I ask because both subs are doing it all of a sudden after PAT testing was done though one is more sensitive than the other. Is it an expensive repair?

Thanks



Thanks

[Nakatomi]

Sounds to me like it could be quite a cheap & simple fix. The level controls have gone scratchy & need to be replaced. Should only cost a couple of quid each plus Labour.

[Excalibur]

Re the hum, usually an earth loop issue. If there's an earth lift switch, try it in both positions. One of my Proels was set wrong, and gave a very noticeable hum till we flicked the switch. For safety's sake, it's advisable to do this when it's powered off.


Sounds to me like it could be quite a cheap & simple fix. The level controls have gone scratchy & need to be replaced. Should only cost a couple of quid each plus Labour.
I would tend to agree with you, were it not for


I ask because both subs are doing it all of a sudden after PAT testing was done though one is more sensitive than the other. Is it an expensive repair?



I know it's possible to damage kit if you're a bit gung ho with the PAT tester. The admirable Davesounds would be able to shed more light. I'll give him a nudge.

Repair cost? If Justin's right, perhaps twenty or thirty pounds.
If old Cassandra's on the money, probably considerably more.

[soundsalarming]

Thanks for the responses guys.


Sounds to me like it could be quite a cheap & simple fix. The level controls have gone scratchy & need to be replaced. Should only cost a couple of quid each plus Labour.

Is it something I can try myself? The local dj shop just quoted me £35 to assess each speaker so £70 just to tell me what is wrong!


Re the hum, usually an earth loop issue. If there's an earth lift switch, try it in both positions. One of my Proels was set wrong, and gave a very noticeable hum till we flicked the switch. For safety's sake, it's advisable to do this when it's powered off.

I know it's possible to damage kit if you're a bit gung ho with the PAT tester. The admirable Davesounds would be able to shed more light. I'll give him a nudge.

Repair cost? If Justin's right, perhaps twenty or thirty pounds.
If old Cassandra's on the money, probably considerably more.

Thanks Guys

I have had a look at the back panel and there is no earth switch. There is an earth screw point and that's it. Cost wise....been quoted £70 and 2 weeks to have a look...must have been Cassandra's mother on the phone....

[Excalibur]

...been quoted £70 and 2 weeks to have a look...must have been Cassandra's mother on the phone....

That really doesn't sound good service to me. Replacing a couple of pot(entiometer)s isn't rocket science, but it's more than a five minute job, and involves a soldering iron, so not a novice job.
I wouldn't do anything rash, see if you know or can find someone with enough knowledge to have a look and listen. That shouldn't cost £70, more like a couple of pints. :beer1:

I don't wish to be all doom and gloom, but if the PAT testing has caused this, I'd say that:
1) It's likely to be costly.
2) as long as he's a reputable tester, he ought to have PLI to cover damaging your kit.
Keep us posted, we'll do our best to help.

[DAVESOUNDS SERVICES]

Hiya.
Theres a possibility of damage but its remote and would only be if your PAT tester used a Bigger / Industrial PAT Tester and DIDNT set the Earth Test current to a "Low" figure or IT setting.
What sort of tester did he use ??? have you got the results sheet to show us?.
Scratchy volume controls are not a PAT Testing problem though.
Kind Regards
DAVESOUNDS

[Excalibur]

Hiya.
Theres a possibility of damage but its remote and would only be if your PAT tester used a Bigger / Industrial PAT Tester and DIDNT set the Earth Test current to a "Low" figure or IT setting.
What sort of tester did he use ??? have you got the results sheet to show us?.
Scratchy volume controls are not a PAT Testing problem though.
Kind Regards
DAVESOUNDS

Thank you for that Dave, much appreciated. As a fully paid up sceptic I'm inclined to regard the close proximity of test with the sudden appearance of seemingly identical faults in two items as suspicious. I hope the lad finds someone to look at them soon at a sensible figure.

[soundsalarming]

Hiya.
Theres a possibility of damage but its remote and would only be if your PAT tester used a Bigger / Industrial PAT Tester and DIDNT set the Earth Test current to a "Low" figure or IT setting.
What sort of tester did he use ??? have you got the results sheet to show us?.
Scratchy volume controls are not a PAT Testing problem though.
Kind Regards
DAVESOUNDS

I had a look at the report sheet and it says Seaward Europa. It was a yellow portable device about the size of a ream of A4 paper.


Thank you for that Dave, much appreciated. As a fully paid up sceptic I'm inclined to regard the close proximity of test with the sudden appearance of seemingly identical faults in two items as suspicious. I hope the lad finds someone to look at them soon at a sensible figure.

Thanks guys. At least I have an idea what might be wrong so if I hear something rediculous I will question it. Will also shop around for a cheaper price. Will update once I know in case it helps someone else.

Out of interest, how do you rate these subs? I bought them because I found the rcf 705s I had too heavy.
I run them with a pair of rcf 722s.

I also occassionally use a pair of the original Mackies SRM 450 which are the first speakers I ever bought but find them heavy. I don't really need or use them but maybe it's sentimental attachment?:daft: Usually I use 1 sub but use 2 in bigger venues or for weddings.

My target market is weddings and parties for over 30s - I'm part time and play maybe twice a month at most.

Is there a setup you recommend out there that would justify me selling everything above and topping up a bit to end up with a better bang for buck system? Weight and size reduction would be nice but sound quality is more important to me.

[Nakatomi]

Oh yikes. I missed the bit about them being PAT tested. Read it on my phone originally. D'oh! It might just be a sad coincidence (hopefully) or it could end up being very costly indeed. Still think you need the level controls replaced whatever happens though (which'll happen when the amplifier modules are replaced, if it comes to that).

The hum could still be all down to the dodgy level controls though.

Whoever you asked for a quote to repair them really needs a rocket up em IMHO. £70 just to have a look, plus a 2 week waiting time?! That's ridiculous!

[CRAZY K]

As a fully paid up sceptic I'm inclined to regard the close proximity of test with the sudden appearance of seemingly identical faults in two items as suspicious.

Have to go with that---wonder what odds you would get from the bookies on that happening---very generous odds ill bet:rolleyes:

[Excalibur]

Is there a setup you recommend out there that would justify me selling everything above and topping up a bit to end up with a better bang for buck system? Weight and size reduction would be nice but sound quality is more important to me.

Here's the left of centre suggestion ( mainly cos I haven't heard it together yet. Young Wayne is a bit far away frm me, even when I'm as far south as I go )

The lad's running a pair of Yamaha DXS 12 subs, and the eight inch active Yamaha tops. Ticks a lot of boxes.
Your current rig isn't at all shabby, a lot of folks would kill for it. If you're wanting to go all RCF, I believe the 905 subs are much lighter.
Again, I wouldn't swap anything you presently have without good reason. The golden rule is as always " listen before you buy "

[ckpr2]

If tapping it cause noises then I would suspect something mechanical like loose wire, connector or dodgy volume control.

[soundsalarming]

Here's the left of centre suggestion ( mainly cos I haven't heard it together yet. Young Wayne is a bit far away frm me, even when I'm as far south as I go )

The lad's running a pair of Yamaha DXS 12 subs, and the eight inch active Yamaha tops. Ticks a lot of boxes.
Your current rig isn't at all shabby, a lot of folks would kill for it. If you're wanting to go all RCF, I believe the 905 subs are much lighter.
Again, I wouldn't swap anything you presently have without good reason. The golden rule is as always " listen before you buy "

I've had a look at that setup on a youtube video...looks nice and compact - excellent. Wonder how good/low a 12 inch sub is - my tops are 12 inch and sound rather bright on their own but then they are not set up as subs. I think my local PMT shop has them setup in their store so will pop down for a listen.

I once saw the 905 subs and they looked good - thanks for the weight tip - will look into it. I'm not a badge snob so not particularly bothered about matching brands. Actually, aren't DB Technologies really RCF with a lower price tag?:rolleyes: lol. You said it very well regarding swapping for no reason - I hope to only switch/upgrade if something is clearly better or makes my life easier - fighting to keep the gear slut in me in check!

[soundsalarming]

If tapping it cause noises then I would suspect something mechanical like loose wire, connector or dodgy volume control.

Thanks for the response. I unscrewed the input module (red box in picture) and had a look. It seemed fine and connector to amp secure. I hope you and juski are right and it's a simple volume control fix. Will hopefully find somewhere to take them on Monday.

[soundsalarming]

Here's the left of centre suggestion ( mainly cos I haven't heard it together yet. Young Wayne is a bit far away frm me, even when I'm as far south as I go )

The lad's running a pair of Yamaha DXS 12 subs, and the eight inch active Yamaha tops. Ticks a lot of boxes.
Your current rig isn't at all shabby, a lot of folks would kill for it. If you're wanting to go all RCF, I believe the 905 subs are much lighter.
Again, I wouldn't swap anything you presently have without good reason. The golden rule is as always " listen before you buy "

Popped down to my local PMT store and had a look at the Yamaha gear. Guy in there recommended the 10 inch top with the 12 inch sub and set it up as in the pics below. The other speaker is an RCF 705 which I used for comparison - size difference is easy to see.

http://i66.tinypic.com/k1yvwp.jpg

http://i65.tinypic.com/3307bir.jpg

http://i63.tinypic.com/2ym92k3.jpg

The setup sounds good but I found the 12 inch sub a little lacking. I expected a tighter bass than the 15 inch RCF but it sounded not too bad - good so far. As it played, I had a look round the back and the 10 inch top (DXR10) and he had the gain at about a 1/4 way up. I looked down at the DXS12 sub...and it was maxxed out!:eek:...all in at low volume and just about keeping up! Cranked up I think it would struggle.
When the RCF came on - the bass sounded great...but now I noticed the boom...hmmm.

I think you were right in saying it is better matched with an 8 inch top as the 10 inch is just too much for it - might go back for another play. Size wise, the 8 inch top and 12 inch sub looks nice and compact. However, with such small tops you will always have to take a sub with you however small the event.

The shop guy recommended Yamaha over the RCF Evox 12 or Bose L1 system they also had in store for prerecorded music. 7 year warranty - very nice.

So I'm mixed at the moment but like what I saw and will look into it some more.

Just thought I'd share my experiences.

[Excalibur]

The setup sounds good but I found the 12 inch sub a little lacking.

I think you were right in saying it is better matched with an 8 inch top as the 10 inch is just too much for it - might go back for another play. Size wise, the 8 inch top and 12 inch sub looks nice and compact. However, with such small tops you will always have to take a sub with you however small the event.

The shop guy recommended Yamaha over the RCF Evox 12 or Bose L1 system they also had in store for prerecorded music. 7 year warranty - very nice.

So I'm mixed at the moment but like what I saw and will look into it some more.

Just thought I'd share my experiences.

Thank you for that. That's interesting. I don't think Wayne feels his subs are lacking, but he's not running against 10s as you did. We'll have to see what he thinks.

[soundsalarming]

Hello everyone.

Just thought I'd let you know the final outcome regarding my speaker fault (in case it helps someone).
I found a local place and all sorted within 2 days. Below is copied from invoice:

Item Make/Model: DB Technologies Opera 15 Sub
Reported Fault: Rumbling, Sounds like noisy pot.

Details Net Cost VAT Rate VAT
Stripped module and airlined. Cleaned sockets, switches and pots.
Reass, soaked and audio test ok.

£ 45.00 20% £ 9.00
Net Cost £ 45.00
Freight £ 0.00
Total VAT £ 9.00
Repair Total £ 54.00

So, seems it needed a clean...nothing needed replacing. I'm relieved and appreciate the honesty of the repairer but cannot help but be a little "dissapointed" that all it needed was a simple clean...well, a £54 clean!:rolleyes:

You know that happy-irritated feeling you get when the gas engineer finally turns up and turns a knob which fixes your boiler in under 2 minutes? That feeling made worse by the fact you've been freezing your nuts off for the last 3 days waiting for him to turn up and are sure you turned that very same knob yourself about 20 times and nothing happened? Then get charged that standard call out fee...:Censored:
You know it's your fault for being so thick and not knowing how to do anything yourself....


Ahh well, could have been worse....live and learn. Hope it helps someone:D

[Nakatomi]

Nah cleaning is only a temporary fix. The pots really need to be replaced. Have that done in a couple of months when they go scratchy again.

[CRAZY K]

Nah cleaning is only a temporary fix. The pots really need to be replaced. Have that done in a couple of months when they go scratchy again.

Absolutely, its unlikely to last a long time. Its wear on the track.

Although volume controls are a moving feast--I have one I use dozens of times a night for increasing and reducing volume for my Barn Dance Calling.

Usually last about 25 bookings. My current pot though must be into 50 plus bookings--always buy them from Maplins--no idea on that:daft:

In my opinion you should have been offered a replacement volume pot quote, even if you turned it down. ( Ooops unfortunate pun there :D )

This happens a lot with my car--they say this is the cheap short term fix quote---this is the long term fix quote.

While its all taken apart might as well fix it properly.

If you are selling the unit go for short term--if not go long term.

[soundsalarming]

Nah cleaning is only a temporary fix. The pots really need to be replaced. Have that done in a couple of months when they go scratchy again.


Absolutely, its unlikely to last a long time. Its wear on the track.

Although volume controls are a moving feast--I have one I use dozens of times a night for increasing and reducing volume for my Barn Dance Calling.

Usually last about 25 bookings. My current pot though must be into 50 plus bookings--always buy them from Maplins--no idea on that:daft:

In my opinion you should have been offered a replacement volume pot quote, even if you turned it down. ( Ooops unfortunate pun there :D )

This happens a lot with my car--they say this is the cheap short term fix quote---this is the long term fix quote.

While its all taken apart might as well fix it properly.

If you are selling the unit go for short term--if not go long term.

Oh dear....You guys are making a lot of sense. I'm glad I posted before going to collect.

I'm about to go and pick it up. Will ask about guarantee, what if it happens again etc. Not a good feeling...


Is replacing a volume pot difficult?

[CRAZY K]

Is replacing a volume pot difficult?

Not when you are an engineer :rolleyes:

Depends on time taken though. Labour cost etc.

I think Juski will know more than me, BUT if its been stripped I would guess thats what you do when you replace a volume pot?

Unscrew locking nut from plate and solder a few terminals usually UNLESS this is a particularly difficult piece of equipment to work on.

I obviously dont know.

I do know one of my mini mixers lost a couple of pots with crackling noises and because of labour charge to access the equipment it was almost cheaper for me to buy another mini mixer about £130 which I did.

As it happened im glad I did as there was a lot of noise on the old mixer I hadnt noticed building up over the years.:rolleyes:

Depending on your location Labour rates for this work can be higher than garages ( not Mercedes or BMW though :daft:)

Guarantee? Hmmm not sure you will get that?

[soundsalarming]

Not when you are an engineer :rolleyes:

Depends on time taken though. Labour cost etc.

I think Juski will know more than me, BUT if its been stripped I would guess thats what you do when you replace a volume pot?

Unscrew locking nut from plate and solder a few terminals usually UNLESS this is a particularly difficult piece of equipment to work on.

I obviously dont know.

I do know one of my mini mixers lost a couple of pots with crackling noises and because of labour charge to access the equipment it was almost cheaper for me to buy another mini mixer about £130 which I did.

As it happened im glad I did as there was a lot of noise on the old mixer I hadnt noticed building up over the years.:rolleyes:

Depending on your location Labour rates for this work can be higher than garages ( not Mercedes or BMW though :daft:)

Guarantee? Hmmm not sure you will get that?

Just got back from collecting the sub.

Yup...you are right - no guarantee as such because nothing was replaced.

However he did say that all was cleaned and soldered and that he saw no reason to change the pot as it was in good condition and was good quality. Problem actually might be that I hardly move the knobs so stuff gets dirty and dusty.

Will see how long it lasts.

[CRAZY K]

Just got back from collecting the sub.

Yup...you are right - no guarantee as such because nothing was replaced.

However he did say that all was cleaned and soldered and that he saw no reason to change the pot as it was in good condition and was good quality. Problem actually might be that I hardly move the knobs so stuff gets dirty and dusty.

Will see how long it lasts.

I will wait for Juski to comment.

Good quality---yes--Im not sure how you can say its in good condition--unless you split it apart and look at the inside.

If it started playing up im not sure about that statement.

I dont understand why soldering is involved, I thought the pot was just squirted with a spray---unless it has to be removed by desoldering?

I dont think not using a pot would make it a problem--more likely excessive use as in my case :rolleyes:

See what others think and lets hope its all ok.

[Nakatomi]

Moisture, dirt & cack can get inside a pot making it crackly & unreliable (good quality pots are generally more resilient to this). More often than not though, contacts become loose with age & wear too. In the case of a level pot, it's possible it just needed a bit of a spray to relubricate it. In my experience once a pot goes crackly you get a couple of goes re-lubing (so-called cleaning) it & then you need to replace it.

Generally it's a relative doddle to replace a pot once you've managed to get at it. The body of the control is usually fixed to the case by a hexagonal nut under the knob. Remove the knob to find the nut.. sometimes it might be under another panel. Once you've got the thing down to the bare board there'll either be 3 or 6 terminals to desolder (3 in the case of a single gang pot & 6 for a dual gang pot).