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neyman
Intermediate Member
Username: neyman

Post Number: 110
Registered: 7-2002
Posted on Friday, July 13, 2012 - 8:07 am:   Edit Post

So here's the problem,

My Series II sounds great running with the DS-5R into a Trace Elliot AH600SMX amp, for about 3 sets. In the middle of the 3rd set, the bass starts buzzing and humming like nobody's business. I still can hear the bass, but the buzz/hiss is pretty loud. If I unplug the DS-5R, remove the 5 pin cable from the bass, and run straight into the amp with a 1/4" cord (running on batteries) the buzzing stops and I go back to that great bass sound.

This has happened on 2 gigs so far, and when I get home and plug things in everything works fine.

Any suggestions?
neyman
Intermediate Member
Username: neyman

Post Number: 111
Registered: 7-2002
Posted on Friday, July 13, 2012 - 9:21 am:   Edit Post

I should also mention that the first time this happened I was using my home-made DS-5, the second time was with my Alembic DS-5R. Both times was with the same cable.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3021
Registered: 6-2002
Posted on Sunday, July 15, 2012 - 12:47 pm:   Edit Post

I had a similar problem with the DS-5 when using my Series guitar and bass. I took the DS-5 to a Musical equipment electronics engineer and he said there was a problem with the earthing in the DS-5 and also he added more smoothing capacitors and now its silent.

jazzyvee
cozmik_cowboy
Senior Member
Username: cozmik_cowboy

Post Number: 1241
Registered: 10-2006
Posted on Sunday, July 15, 2012 - 7:07 pm:   Edit Post

If the problem goes away when you remove the 5-pin cable & power supply from the chain, that points to one of those as the culprit. Happens with 2 power supplies? Time for a new cable.

Peter
neyman
Intermediate Member
Username: neyman

Post Number: 112
Registered: 7-2002
Posted on Monday, July 16, 2012 - 8:04 am:   Edit Post

Plugged everything in and let the amp run all day on Saturday, couldn't reproduce the noise.

Will try a second cable on the next gig.

Jazzyvee, do you have any pics of the mod? Or maybe the specs on the smoothing caps?
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3025
Registered: 6-2002
Posted on Monday, July 16, 2012 - 11:05 am:   Edit Post

I haven't even looked order the hood to be honest so there may be nothing new under there. I will open it up and take a pic for you when I get a moment.

Jazzyvee
sonicus
Senior Member
Username: sonicus

Post Number: 2561
Registered: 5-2009
Posted on Monday, July 16, 2012 - 4:32 pm:   Edit Post

Smoothing caps ? Do you mean filter caps ?
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3026
Registered: 6-2002
Posted on Monday, July 16, 2012 - 7:34 pm:   Edit Post

Smoothing capacitors for the rectifier circuit not in the signal path.
For the remaining DS-5 that is just waiting for a new transformer, The engineer has suggested installing voltage regulation as well as the smoothing capacitors. I need to contact Mica to see if there is a view from Alembic about voltage regulation before he carries out that modification.

If you are reading this Mica I would welcome your input.
Jazzyvee

(Message edited by jazzyvee on July 16, 2012)
jzstephan
Intermediate Member
Username: jzstephan

Post Number: 103
Registered: 1-2012
Posted on Monday, July 16, 2012 - 7:40 pm:   Edit Post

Smoothing is performed by a large value electrolytic capacitor connected across the DC supply to act as a reservoir, supplying current to the output when the varying DC voltage from the rectifier is falling. The diagram shows the unsmoothed varying DC (dotted line) and the smoothed DC (solid line). The capacitor charges quickly near the peak of the varying DC, and then discharges as it supplies current to the output.

smoothng.gif
sonicus
Senior Member
Username: sonicus

Post Number: 2562
Registered: 5-2009
Posted on Monday, July 16, 2012 - 8:14 pm:   Edit Post

LOL_____ take a look at the real diagramDS5

This diagram has been floating around here on this site for a few years and I believe has been posted a few times. I have repaired my own unit with it a while ago and works like new and vary quiet. I also rebuilt my IN-2 serial #24 with a regulated power module, that is quite close to stock. Jazzy , you plugged your Series bass into my rebuilt IN-2 at the Northern California Alembic Gathering V with my 5 pin cord and played it. My IN-2 is regulated .
neyman
Intermediate Member
Username: neyman

Post Number: 113
Registered: 7-2002
Posted on Monday, July 16, 2012 - 8:43 pm:   Edit Post

That's the schematic I used to build my DS5 copy. Its interesting that I've only had this problem when running through the TE amp.

Maybe a voltage compatability problem?
sonicus
Senior Member
Username: sonicus

Post Number: 2563
Registered: 5-2009
Posted on Monday, July 16, 2012 - 9:11 pm:   Edit Post

Jazzy & John, Smoothing caps/ power supply filter caps ,I think were talking semantics here.(same thing)

http://en.wikipedia.org/wiki/Rectifier


Dan , I would not want to make a guess without a schematic or a bench test and specific documentation regarding your Trace Elliot.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3035
Registered: 6-2002
Posted on Wednesday, July 18, 2012 - 1:23 pm:   Edit Post

Maybe I spoke too soon. I turned my DS-5 on today for a practice session and it started buzzing again. It was fine yesterday after my practice session in the afternoon.

So left a message for the electronics engineer to revisit his solution.



Jazzyvee
neyman
Intermediate Member
Username: neyman

Post Number: 114
Registered: 7-2002
Posted on Wednesday, July 18, 2012 - 2:12 pm:   Edit Post

I meant impedance compatability, not voltage!

Be interested in hearing what your tech says.
mica
Moderator
Username: mica

Post Number: 7812
Registered: 6-2000
Posted on Wednesday, July 18, 2012 - 3:23 pm:   Edit Post

I'm reading buzzing/humming and buzz/hiss but these are not the same sounds to me.

Can you clarify that there is no actual "humming" coming from the bass (60Hz or 50Hz depending on where you live (since there are 2 folks talking about this here))?

You can perform a simple test to isolate the power supply section of the DS-5/R from the signal path to see if it is the culprit.

Use a connector in the 1/4" jack. You can use a free connector of just do not plug the other end into the amplifier. We just want to turn the batteries on, so make sure you have nice new ones for the test.

Then, use the 5-pin cable and the DS5/R. You will now hear the signal coming through the 5-pin cable and DS5/R, but the power will be coming from the batteries. Tell me what you hear now.

Also, please try and be as descriptive as possible with the buzzing/hissing sound. The type of noise you hear matters, and right now, all I know is there is some noise.
neyman
Intermediate Member
Username: neyman

Post Number: 115
Registered: 7-2002
Posted on Wednesday, July 18, 2012 - 3:35 pm:   Edit Post

Good point! The noise I'm hearing sounds like someone touching the end of a 1/4" jack that is plugged into a live amp, or a short in an instrument cable.

It isn't a directional single coil hum I'm hearing. The bass is very quiet in that respect.

I'll try your test and post the results.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3036
Registered: 6-2002
Posted on Wednesday, July 18, 2012 - 4:28 pm:   Edit Post

I'm hearing the same sound as you neyman. If I use the jack to the amp from the bass just using the batteries all is quiet.

I will try your test tomorrow Mica and post here what the result is.

Jazzyvee
neyman
Intermediate Member
Username: neyman

Post Number: 116
Registered: 7-2002
Posted on Wednesday, July 18, 2012 - 6:38 pm:   Edit Post

Followed Mica's directions. No noise, just good bass sounds. Tried both power supplies and both cables.
mica
Moderator
Username: mica

Post Number: 7813
Registered: 6-2000
Posted on Wednesday, July 18, 2012 - 6:47 pm:   Edit Post

Did you play as long as three sets yet?
neyman
Intermediate Member
Username: neyman

Post Number: 117
Registered: 7-2002
Posted on Wednesday, July 18, 2012 - 7:27 pm:   Edit Post

Hah! There' s the rub. I'll have to wait til the weekend to try that.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3038
Registered: 6-2002
Posted on Thursday, July 19, 2012 - 7:59 am:   Edit Post

Hi Mica, I've tried your test and have the following results.

What I hear from the DS-5 output sounds like when you put your finger on the end of a jack lead that is plugged into an amp input. When the jack is put into the bass in the manner you described above, nothing changes, the hum is still there.
Even with the PSU turned off and no mains supply to the unit the hum is still present in the output signal if the DS-5 cable is connected to the bass.

Using battery only and jack lead only, the sound is bright and clean.

Something else I noticed by accident but not sure if there is any relevance to the current problem is this.

Ignore the noise for a moment. When the output from the DS-5 is using the Bass output to my amp and my bass has just the bass pickup turned on, the volume of bass signal is twice as loud when the DS-5 is switched to stereo than when it is switched to Mono. When this is repeated the other way round with the treble pickup switched on, on the bass and the DS-5 output taken from the treble socket, the volume is the same whichever position the Stereo/Mono switch is active.



Jazzyvee

:-(
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3043
Registered: 6-2002
Posted on Friday, July 20, 2012 - 10:16 am:   Edit Post

More confusion. I was doing some practice today. At the start of my session the buzzing was as normal.
About 2 hours later everything was silent.


Jazzyvee
dfung60
Senior Member
Username: dfung60

Post Number: 559
Registered: 5-2002
Posted on Friday, July 20, 2012 - 1:09 pm:   Edit Post

I think neyman and jazzyvee are actually seeing two different problems here.

Neyman, if this noise problem occurs somewhat repeatedly after the bass has been in use for some time, that might actually be a problem with one of the preamps overheating. They don't draw much power and shouldn't get hot to where it affects the sound, but it's not impossible. The interesting thing for you to check is to look at the quality of output from your DS-5. If you can read DC volts between pins 4 and 5 (V+ and V-) you should see between 30-40 volts. If it's more than that, that may be the problem. I think this is unlikely to be the problem if your equipment has no mods, but with a homemade unit, or a unit operating with a different line voltage than it was made for, this may be a problem. The easiest way to test this is to open the DS-5 and trace back the wires that connect to pins 4 and 5. While you're there, you can also test to see if you have any AC voltage - it should be 0, even on the most sensitive range of your voltmeter.

If the voltage is too high on V+/V-, then you would want to take a look at the transformer to make sure it's the right part.

If the supply voltage to the bass it too high or noisy, then the preamps may overheat or show other problems. Unlike an overheating power amp, they will probably return to normal seconds after you unplug the power supply, which is why a quick change to the 1/4 plug (an 18V power) seems to be an immediate fix.

You might also check to make sure that that 20K resistors that sum the individual outputs to mono are both present. If you connect the outputs directly, this shorts out the internal preamps which would be another condition that could cause high power draw (in this case, it's more likely that you'll get no output at all).

The classic way to test this problem is to wait until the problem is occuring (it may not happen when you're not actually playing the bass, although that's an interesting test too). Do this with the backplate that has the EQ board off the bass. When the humming is happening, you want to shoot the three preamp chips with a can of cold spray or even just one of those canned air bottles. If the hum goes away when you spray the chip (do each one separately), then this is the chip that's causing the hum. But the problem is more likely to be the power supply than the preamps, I think.

Jazzyvee, I think you're more likely to be suffering from a bad cable or bad connector. You've only got noise when the audio is travelling through the 5-pin cable, so I think this is much more suspect. I would also check those 20K summing resistors to make sure they're properly in place. A problem there might explain what you're seeing with the Stereo/Mono switch.

The Alembic stuff is quite different than what most techs would have seen in the wild, and rare enough that they have nothing to compare it to. If you work with active EMGs (which also have individual preamps in the pickups), you don't need the summing resistors, so they might have changed the values or left them out when servicing the box.

Hope this helps,

David Fung
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3050
Registered: 6-2002
Posted on Wednesday, July 25, 2012 - 3:25 am:   Edit Post

Now I don't even know what to think.
I got the DS-5 back on Monday and took it home. Plugged into Mesa boogie Walkabout amp... and got loads of hum still.

Rigged up my Alembic Rig with F1-x and QSC and no noise. Set up the rig in stereo and still no noise. However the bass pickup is still louder when the DS-5 is switched to stereo compared to when both pickups are selected in mono mode. I will wait till my other DS-5 comes back from having the transformer changed and see if it behaves in the same way.


Jazzyvee
ps: you may remember a while back I had problems with a regular clicking noise from my Roland JC120 when using my Dragon Series guitar.
I've found that the problem is due to one of these lovely things.
http://www.pcworld.co.uk/gbuk/devolo-1383-dlan-highspeed-ii-85mbps-powerline-starter-kit-00939029-pdt.html?intcmpid=display~RR~Computing~00939029

When it's on the signals are getting into the amp vial the power socket.
Turned off... silence.
Time to get a filter cable or mains conditioning unit for my gear.

Jazzyvee
lmiwa
Advanced Member
Username: lmiwa

Post Number: 328
Registered: 2-2008
Posted on Wednesday, July 25, 2012 - 9:36 am:   Edit Post

One other thing to check for neyman - my Trace Elliot preamp had both a ground lift switch and a polarity reverse switch. If yours has those, you may want to try various combinations of them.

You may have some variation of a ground loop / open ground causing the hum.
neyman
Intermediate Member
Username: neyman

Post Number: 118
Registered: 7-2002
Posted on Wednesday, July 25, 2012 - 10:09 am:   Edit Post

Is it synchronicity or coincidence?

I flipped the ground switch the other day, and I'm waiting for the next show to see if it worked. Still can't replicate the noise at home.

Thanks Imiwa!
mica
Moderator
Username: mica

Post Number: 7832
Registered: 6-2000
Posted on Monday, August 06, 2012 - 2:01 pm:   Edit Post

Is your bass plugged in when you get the hum or buzz?
neyman
Intermediate Member
Username: neyman

Post Number: 119
Registered: 7-2002
Posted on Monday, August 06, 2012 - 3:26 pm:   Edit Post

Not sure I understand. Yes, the bass is plugged in when the noise starts. The amp was not buzzing before the bass was plugged in, and the buzzing stops when the DS-5R is unplugged (power cord disconnected).

BTW, I haven't had a chance to run it 3+ hours at a gig yet.
sonicus
Senior Member
Username: sonicus

Post Number: 2588
Registered: 5-2009
Posted on Monday, August 06, 2012 - 4:47 pm:   Edit Post

I would move the DS-5 away from the amp while plugged in and see what happens. Use longer 1/4 patch cords if needed and do not put the DS-5 near (on top) the amp or preamp. What happens now ?

I had an old Trace Elliot GP7 SM preamp once that picked up power supply EMI noise. Moving the DS-5 further away fixed the problem.
neyman
Intermediate Member
Username: neyman

Post Number: 120
Registered: 7-2002
Posted on Tuesday, August 07, 2012 - 8:13 am:   Edit Post

I tried moving the power supply (DS-5R) to the floor when the noise started. No change.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3092
Registered: 6-2002
Posted on Thursday, August 09, 2012 - 10:55 pm:   Edit Post

I have got my second DS-5 back from the repair today and it has a new transformer ( torroidal one) inside. Not had a chance to try it out yet but will do that over the weekend and see what the noise problem is like.

But just to be clear. Should it be as silent ( noise wise) via the DS-5 as it is using a standard jack cable?

Jazzyvee
jon_jackson
Intermediate Member
Username: jon_jackson

Post Number: 148
Registered: 12-2008
Posted on Friday, August 10, 2012 - 4:23 am:   Edit Post

yes it should be quiet with the DS-5.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3093
Registered: 6-2002
Posted on Friday, August 10, 2012 - 12:40 pm:   Edit Post

Silence is golden :-)


jazzyvee
mica
Moderator
Username: mica

Post Number: 7838
Registered: 6-2000
Posted on Friday, August 10, 2012 - 1:24 pm:   Edit Post

Yes, it should be quiet with the 5-pin connected to the instrument.
neyman
Intermediate Member
Username: neyman

Post Number: 124
Registered: 7-2002
Posted on Saturday, September 01, 2012 - 8:55 pm:   Edit Post

Update:

Played the SII on Friday. 4 sets and no problems. The only changes were a switch in ground polarity on the amp, and the temp was a comfortable 74 degrees as opposed to the 90's when the noise occurred.
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3185
Registered: 6-2002
Posted on Sunday, October 14, 2012 - 11:01 pm:   Edit Post

:-(((
Hey, I got my new "DS-5 Mini" on Saturday and only managed to try it out yesterday. I was hoping silence indeed would be golden but no. I still get a buzz from my system using this one.

So I tried the following. Turned off all the electrical appliances in my home, wifi computers, tv radio's and anything i thought could put some interference on the line. Still buzzing

Took the output from DS-5 to F1-x, output to QSC = noisy.
Took the output from DS-5 to SF-2 output to QSC = noisy.
Took the output from DS-5 to F1-x with SF-2 in the send and return then output to QSC = noisy.
Took the output from DS-5 to F1-x then full range out to SF-2 then output to QSC = noisy.
(I've notice on previous practice sessions that sometimes the above starts noisy then goes quiet or vice versa).

Took output from DS-5 to QSC input = no noise. ( in fact that sounded great with a balanced response across the frequency range)


Took output from jack socket on bass to F1-x then to QSC = no noise.
Took output from jack socket on bass to SF-2 then to QSC = no noise

Any suggestions.

Jazzyvee
jacko
Senior Member
Username: jacko

Post Number: 3273
Registered: 10-2002
Posted on Monday, October 15, 2012 - 8:03 am:   Edit Post

Do you have your amps on the same powerbar? Could there be an earth loop in there somewhere?

Graeme
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3186
Registered: 6-2002
Posted on Monday, October 15, 2012 - 8:45 am:   Edit Post

They are all powered from an extension lead from one wall socket.

Jazzyvee
terryc
Senior Member
Username: terryc

Post Number: 2008
Registered: 11-2004
Posted on Tuesday, October 16, 2012 - 6:10 am:   Edit Post

jazzy..maybe one of those power conditioners would solve the problem, do you know anyone who has got one so you can try it out before purchasing one.
Mind you, maybe get an electrician to do a electrical system check on your house wiring and PAT test your gear.
On a cheaper note I would check all your 13amp plugs to make sure the wires are secure in the pins, it's a common fault that we overlook especially if they are gigged and wrapped up and thrown into the 'power lead bin'. I once thought I had an amp failure until I did the obvious and found the live(brown) wire had come adrift in the plug!

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