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?

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.

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

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

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?

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

Smoothing  caps ? Do you mean filter caps ?

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)

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.  
 
 

LOL_____ take a look at the real diagram
 
  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 .

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?

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.

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

I meant impedance compatability, not voltage!
 
Be interested in hearing what your tech says.

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.