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Ever had a passive DI load a pedal/signal?

Discussion in 'Effects [BG]' started by Red Planet, Apr 19, 2019.


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  1. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    Was moving some stuff around on my pedal board and ran across an odd problem.

    I had a passive DI I decided to stick at the end in case I have a need for straight in situation but the passive DI does not play well with the signal on my Diamond BCP-1 compressor even if I put another pedal between them. Its like it sucks the gain down and some of the hi end off from when the compressor pedal is on, when its off the signal is fine.

    Now on my board I go Shure GLXD16 wireless, to Keeley Bassist, DOD Meat Box, Diamond BCP-1, OCD V3, to DI, Thru to amp and I'm talking about the sound going to my amp. My bass is passive but that should not matter since I'm going through a wireless.
     
  2. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    So I took a Boss TU-3 and put it between my OCD and DI and and the issue went away. So I'm thinking a standalone buffer will cure this problem. I really like my old passive DI I built with the OEP transformer, volume control, and passive tone control but it does not play well with my Diamond.
     
  3. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    The passive vol and tone controls will also load the signal significantly, so those plus the transformer, not surprised you would need extra buffering to overcome that load.
     
  4. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    10-4 never had a problem before but that was due to whatever chain I had going at the time.

    I had another active DI in that spot recently but I'm moving it I wanted to put this one back on my board but then ran into this problem.

    I ordered an Emerson Concord Buffer today hopefully get it next week. I'm limited on space and lay out so that's why I went with it.
     
  5. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    Also I knew this thing would load but I didn't think it would load without a passive bass connected.
     
  6. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Yeah it's a moving target, balancing between the output impedance of each device, the input impedance of the next device in line, and the capacitance of the cable between them. Having an active bass with high output can push a strong enough signal to mitigate noticeable loading in many cases, but the box you described would be a pretty steep hill to climb.
     
  7. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    Which I might add I originally built this box to go with a stingray classic five and it worked great with it and it works great in this situation except it loads that pedal when the pedal is on there is no loading when the pedal is off it works fine as intended only when it's on
     
  8. micguy

    micguy

    May 17, 2011
    The wireless he's using has an output impedance of 50 ohms - that's really low (lower than most active basses), and as that's what's driving the pedalboard (not his bass) having an active bass instead wouldn't change the situation impedance wise on the pedalboard. The issue has to be a pedal later in the chain.
     
  9. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.

    Yes indeed.

    And as I stated before I have no issues until I turn the Diamond BCP-1 on at that point the DI loads the Diamond from two pedals away. Take out the DI problem goes away, put a TU 3 between them problem goes away. Odd little ditty, I think the Concord I ordered should be a permanent solution.
     
  10. micguy

    micguy

    May 17, 2011
    Unless your DI has a really low input impedance, that's sloppy work on Diamond's part.
     
  11. sunbeast

    sunbeast Supporting Member

    Jul 19, 2006
    Los Angeles, CA
    As mentioned, I think it’s mostly the result of the volume/tone controls- the relatively minimal loading from a good DI transformer shouldn’t make that much difference on its own.

    I noticed similar issues when I was younger when trying to passively control signals from loud effects using a basic passive resistance mixer- certain pedals hated that solution!
     
  12. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.

    I dont think its an issue with the Diamond more my DI design.
     
  13. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    Actually other than this particular loading issue with this pedal the DI functions quite well. At the time when I built it I was using it with a couple different active basses and needed a passive tone to assist in a specific area of frequency that the treble controls of both basses really couldn't get. As these basses were active and fairly hot the passive nature of the DI was not an issue and it actually adds a little character.

    This DI is an OEP transformer wired up the way they recommend with the addition of a volume pot (which is probably not loading the Diamond) on the XLR output side of the transformer so the level control is on the output side not input. Then there is a passive tone circuit I built in front of the transformer which yields a roll off of highs on both the XLR output and the Thru 1/4" to Amp and then there is also a hard ground lift at pin 1. Its a very simple and yet warm sounding DI with not a lot of bells and whistles but some cool features too.

    Anyway I originally intended this DI for use with active basses as a DI only option for a specific performance in mind and now it has transcended that use and landed on my pedal board. As I mentioned with a buffer between my OCD and DI the problem goes away so I will continue to use this very warm sounding DI.

    I was actually thinking of buying an Active DI but instead opted to get the buffer and continue to use this one.
     
    sunbeast likes this.
  14. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    This is basically what I built except no 2nd thruput, and the Volume control on the XLR out and Tone control on the Input:

    "
    BAE PDI Passive DI Box

    PDI
    The BAE PDI Passive DI Box is a new design that combines premium quality components with a rugged construction to create a reliable DI with full, rich tones. For this we use an OEP/Carnhill transformer made in the UK.


    The high quality audio transformer along with through hole component technology provide a more reliable secure connection and audio signal. All circuit traces are gold-plated for maximum conductivity.


    The frequency response of the circuit is ±2 dB from 10 Hz to 40 kHz, with extremely low distortion and self-noise figures.


    A high-impedance unbalanced input signal is converted into a low impedance balanced signal plus two thru puts. The frequency response of the circuit is ± 2dB from 10 Hz to 40 kHz, with extremely low distortion and self-noise figures.


    House in a steel chassis, with recessed switches and connectors, this rugged construction is virtually indestructible, able to easily withstand the wear and tear of gigging and anything asked of it in the studio. with recessed switches and connectors.

    Features:

    • Solid steel chassis
    • Carnhill Transformer/OEP
    • The same hand-wired construction that BAE is known for"


    So signal goes into unit via 1/4" jack paralleled to another 1/4" jack for Thru, then passive tone on signal that affects both Thru Output and Input to Transformer/XLR Output, and passive volume control on XLR output wired as recommended for this application. The thing works wonders but does have its issues in certain situations as per the thread. And as stated instead of Pad circuit I opted for a volume at the transformer side, works quite well. I haven't seen anyone else build one like this.

    Also I didn't really copy the BAE instead I worked with OEP to build my little DI box for a specific purpose. I got two transformers from them and intended to build two but never got around to the second one.
     
  15. foal30

    foal30

    Dec 3, 2007
    New Zealand
    I couldn't get my Sadowsky Pre/DI to run with my Diamond Compressor. I might try the tuner I between thing

    Cheers.
     
    Red Planet likes this.
  16. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.

    Please do and let us know the results. I ordered a buffer but it will be end of the week before its here I think. I wasn't paying attention and ordered one from California and I'm in Georgia. :roflmao:
     
  17. tech21nyc

    tech21nyc Commercial User

    Aug 17, 2010
    Manufacturer: Tech 21
    On a pedal like the Diamond there is no output buffer after the volume control. This means the output impedance will vary. Transformer quality aside you need to know the input impedance and it's most likely much lower than 1MegOhm which is what the Diamond was designed for. It's meant to be plugged into an amp. Using the Boss Tuner corrects the input impedance the Diamond sees and the Boss has a low Z output as well. The OCD has a similar issue that the Diamond does. The volume control is after the circuit and has no buffer after it. This is why Fulltone added an output buffer to the OCD V2 (not to be confused with V1-V7 circuit changes of the original).

    There's a reason why Bob Bradshaw uses buffers in his switching systems. With TB effects your impedance is constantly shifting as well as your tone. In some cases like with the Diamond it becomes quite apparent.
     
    foal30 and Rich Fiscus like this.
  18. Red Planet

    Red Planet Banned

    May 29, 2005
    Atlanta
    I'm cranky in my old age.
    Update I purchased a stand alone buffer and that did the trick.

    Problem solved.

    Next delima I purchased the Buffer off Ebay on Saturday and it shipped out of California USPS and it delivered on Tuesday. It was showing to deliver on Friday . Time warp?
     
    foal30 likes this.
  19. Under promise and over deliver!
     
    Red Planet likes this.
  20. foal30

    foal30

    Dec 3, 2007
    New Zealand
    Managed to get this happening

    Passive Fender - EB Bass Wah - Diamond Comp - Korg PB Tuner- Sadowsky preAmp/DI - into the front of an old Ashdown Klystron 400ABM

    It works

    Now to try effects loop
    Then add in the other pedals

    Cheers for the advice team.
     
    Red Planet likes this.

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