EBS TD650 Issues

[Josh]

 

Good Evening All,

 

So, I managed to snag a whole EBS TD650 and Proline 4X10 rig recently and it's been fantastic thus far. However, I started to notice recently that when recording at night that when I would turn off stand-by and with the master volume at 0, that my bass could be heard coming through the cab but distorted. I've included a video which hopefully helps to show the issue. 

 

Any help would be appreciated,

 

Thanks Guys!

 

Josh.

UPDATE:

 

I have taken the whole rig to Tony at Hurstbatch Services and we quickly found that the cab is perfectly fine and that it is just the TD650 that has a problem. The tube is working perfectly fine, so that eliminated the easiest solution. So, hopefully he will be able to find out what’s causing the issues! 

 

Edited May 22, 2023 by Josh
Cab is not the issue.

[thodrik]

It seems that even with the volume set at zero there is a signal coming through the speakers. If you are just plugging the amp into the interface then just disconnect the cab.  The EBS heads do not need to be connected to a cab to be used as a preamp. 

 

Those cabinets are designed for loud stages and high volume applications. I don't think that making sure that the cabs are dead silent when the master volume is at zero and the stand by is turned off was a design consideration. 

So long as there is no audible distortion when the cab is connected and the volume is turned up then I would consider it to be an issue. 

Great set up!

[Josh]

1 hour ago, thodrik said:

So long as there is no audible distortion when the cab is connected and the volume is turned up then I would consider it to be an issue. 

 

Thanks for that mate!

 

I generally have the cab connected for when I do covers so I have some room volume instead of relying solely on my monitors.

 

I should've stated that unfortunately the distortion is still there when the master is turned up, albeit quiet but it's definitely there. 

Edited May 8, 2023 by Josh

[thodrik]

Hmm, I had something similar with my old Mesa combo. I think it ended up being a faulty driver. I eventually replaced the driver. 

If you could identify which speaker that the distortion is coming from then that would be a start. 

[Josh]

On 08/05/2023 at 23:13, thodrik said:

Hmm, I had something similar with my old Mesa combo. I think it ended up being a faulty driver. I eventually replaced the driver. 

If you could identify which speaker that the distortion is coming from then that would be a start. 

 

On closer aural inspection I believe the distortion is coming from one of the top 10" speakers. I'm also starting to think the TD650 itself could do with a once-over due to its age and the previous owner left it unplayed for over 6 months roughly. I guess I'm going to need to find a amp tech somewhere in Somerset. 

Edited May 11, 2023 by Josh

[DGBass]

The peak light flashes when I hear distortion on the video clip. Could it just be you are blasting the input level and its then being picked up as a distorted high level signal? The charachter button is also on which gives amongst other things a +6db boost at 75hz. Thats going to boost the input level significantly.  Even with the master down, there could be a small amount of distorted signal from too high an input getting through. If you back off the input gain until the clip led stops flashing does it still distort? There's also a mention on the TDS blurb about checking a toggle swtich on the rear panel for phantom power. Should be set to off if you are not using an active bass that will work with phantom power. Might be worth a quick look🙂

Edited May 14, 2023 by DGBass

[Josh]

On 14/05/2023 at 23:50, DGBass said:

The peak light flashes when I hear distortion on the video clip. Could it just be you are blasting the input level and its then being picked up as a distorted high level signal? The charachter button is also on which gives amongst other things a +6db boost at 75hz. Thats going to boost the input level significantly.  Even with the master down, there could be a small amount of distorted signal from too high an input getting through. If you back off the input gain until the clip led stops flashing does it still distort? There's also a mention on the TDS blurb about checking a toggle swtich on the rear panel for phantom power. Should be set to off if you are not using an active bass that will work with phantom power. Might be worth a quick look🙂

As per the instructions/product demos, EBS recommends to set the gain level by getting it to peak and to then immediately bring the level down to get the sweet spot before it peaks, as annoyingly there is no pad switch. And for the purpose of the video I did hammer it a bit to prove that it did it even on the lowest amount of gain. I did also check the phantom power switch before as well and it’s been off the whole time👍🏻

 

I have now taken the whole rig to Tony at Hurstbatch Services to have a complete once over and we very quickly found out the cab is absolutely fine and that is just the head that’s causing the problem. We checked the tube and that was perfectly fine as well, so Tony is going to investigate and hopefully find out what the fault is. 

 

 

[basstone]

On 08/05/2023 at 18:41, Josh said:

 

 

Good Evening All,

 

So, I managed to snag a whole EBS TD650 and Proline 4X10 rig recently and it's been fantastic thus far. However, I started to notice recently that when recording at night that when I would turn off stand-by and with the master volume at 0, that my bass could be heard coming through the cab but distorted. I've included a video which hopefully helps to show the issue. 

 

Any help would be appreciated,

 

Thanks Guys!

 

Josh.

UPDATE:

 

I have taken the whole rig to Tony at Hurstbatch Services and we quickly found that the cab is perfectly fine and that it is just the TD650 that has a problem. The tube is working perfectly fine, so that eliminated the easiest solution. So, hopefully he will be able to find out what’s causing the issues! 

 

The EBS TD650 rig was making horrible noises when Josh brought it to me, actually sounding like the noise of a failed speaker driver. However substitution of the EBS with my GK MB500 immediately proved that the cab was fine. I must praise Mats Kristoffersson at EBS for providing me with the amp technical information (after signing a NDA with them - which is perfectly understandable).  It's great to find a manufacturer who is willing to support small independent repairers and so help keep our treasured gear going.

 

As Josh said, the ECC 83 preamp tube tested out fine and I subsequently learned that it is not in the signal path anyway unless the tube mode is enabled! The standby switch is a nice detail to keep the preamp tube heated and immediately available if needed.

 

Apparently the amp had been unused for several months and I now think that there was a poor connection within the amp causing the distortion and low audio level bleed with the master turned down. A good clean and lube of the internal and external jack connectors seems to have restored normal operation. I also noticed that there was quite a big (~1V) DC offset at the output, but there is a trim setting for that and it's now ~20mV. I also checked the power amp bias setting and the compressor bias, all to factory specification. I have left the amp on soak test with a 4 ohm dummy load for a while and all seems fine. I will check it again periodically over the next few days then  pop the lid back on for collection.

[basstone]

On 23/05/2023 at 13:44, basstone said:

The EBS TD650 rig was making horrible noises when Josh brought it to me, actually sounding like the noise of a failed speaker driver. However substitution of the EBS with my GK MB500 immediately proved that the cab was fine. I must praise Mats Kristoffersson at EBS for providing me with the amp technical information (after signing a NDA with them - which is perfectly understandable).  It's great to find a manufacturer who is willing to support small independent repairers and so help keep our treasured gear going.

 

As Josh said, the ECC 83 preamp tube tested out fine and I subsequently learned that it is not in the signal path anyway unless the tube mode is enabled! The standby switch is a nice detail to keep the preamp tube heated and immediately available if needed.

 

Apparently the amp had been unused for several months and I now think that there was a poor connection within the amp causing the distortion and low audio level bleed with the master turned down. A good clean and lube of the internal and external jack connectors seems to have restored normal operation. I also noticed that there was quite a big (~1V) DC offset at the output, but there is a trim setting for that and it's now ~20mV. I also checked the power amp bias setting and the compressor bias, all to factory specification. I have left the amp on soak test with a 4 ohm dummy load for a while and all seems fine. I will check it again periodically over the next few days then  pop the lid back on for collection.

I'm now happy to report that the amp is back to full health with the addition of a replacement foam air filter behind the front panel, the original was disintegrating. Final test was with @Josh own bass and cab and the amp sounded great with loads of dynamic headroom even at high volume.