Troubleshooting Active /Passive input

[xxcody2gunsxx]

Forgive me if this thread is in the wrong category .
I recently bought a TMB105 and when I plugged it into my Bugera BXD12 amp . With the -15db engaged it seemed to dampen the sound more then I liked so I disengaged the active (-15db) to see how it would sound in passive mode but doing so actually cut the volume big time . Tried a different bass the active and passive modes and it worked correctly . So I'm thinking it has something to do with the bass itself.
Checked the wiring to see if there were any loose connections or crossing wires but could not find anything .
Do you guys have any idea what this could be ?

 

[BassmanPaul]

What is a TMB105?

 

[xxcody2gunsxx]

Its a Ibanez Talman Series Bass .

 

[BassmanPaul]

Here’s something to read through i came across: Bugera bxd12 - hi power combo - ghost product?

Take your bass to a store and plug it into something better. That will at least let you know what the bass should sound like.

 

[beans-on-toast]

It could be the setup of your bass. The pickups might need adjusting so that they ate closer to the strings. Or the neck or bridge might need adjusting. Any new bass needs a setup.

With a passive bass, best not to use the -15dB input.

 

[agedhorse]

By chance were you using a TRS type cable rather than TS?

 

[xxcody2gunsxx]

It could be the setup of your bass. The pickups might need adjusting so that they ate closer to the strings. Or the neck or bridge might need adjusting. Any new bass needs a setup.

With a passive bass, best not to use the -15dB input.

Thanks for chiming in . I too thought maybe pickup height could be a factor but unfortunately it didn't help when I raised them . I checked the wiring and everything is correct . In my 13 years of playing I have never ran into this kind of problem or even heard of this kind of problem .
The active and Passive mode works as it should with my other basses but for this bass the passive mode cuts volume at least half and doesn't sound right at all . any other idea's ?

By chance were you using a TRS type cable rather than TS?

At Agedhorse . I am running the TS type cable and thanks for bringing that up .I didn't not think to try another cable . Unfortunately trying another cable did not change anything .

 

[beans-on-toast]

The active and Passive mode works as it should with my other basses but for this bass the passive mode cuts volume at least half and doesn't sound right at all. Any other idea's ?

The evidence indicates a problem with your bass. There are two pickups and they both seem afflicted with low output.

It is a nice looking bass. Looking at the specs, the pickups are passive but the EQ is active. There is a battery in the bass, the box is on the back. Swap in a known good battery. It is important to remove the cable when the bass is not in use, otherwise the battery runs down.

If that doesn’t resolve it, the electronics should be checked out. It could be a simple solution.

 

[Spacecase]

Can you tell if the on-board electronics were replaced or modified? If not powered during bypass, the preamp could be loading down the pickups.

 

[xxcody2gunsxx]

The evidence indicates a problem with your bass. There are two pickups and they both seem afflicted with low output.

It is a nice looking bass. Looking at the specs, the pickups are passive but the EQ is active. There is a battery in the bass, the box is on the back. Swap in a known good battery. It is important to remove the cable when the bass is not in use, otherwise the battery runs down.

If that doesn’t resolve it, the electronics should be checked out. It could be a simple solution.

Thanks and you are correct .Passive Pickups with active preamp . The first thing I did was swap out the Battery though the tongue test of the original one indicated it was fresh .
I checked out the electronics and everything seems to be correct .all contact points are secure .

Can you tell if the on-board electronics were replaced or modified? If not powered during bypass, the preamp could be loading down the pickups.

It has all original electronics . How would I know if the preamp is loading down the pickups ?

 

[Spacecase]

It has all original electronics . How would I know if the preamp is loading down the pickups ?

If you can trace the pickup signals to the input of the preamp, you can disconnect its input wire and test it in passive mode to see if it sounds like it should. Of course, that assumes you have the wherewithal to do so.

 

[beans-on-toast]

Thanks and you are correct .Passive Pickups with active preamp . The first thing I did was swap out the Battery though the tongue test of the original one indicated it was fresh. I checked out the electronics and everything seems to be correct .all contact points are secure .

Some preamps have an internal output level pot.

Setting aside the level issue, do the treble and bass boost/cut, the balance, and the volume knobs work?

 

[xxcody2gunsxx]

If you can trace the pickup signals to the input of the preamp, you can disconnect its input wire and test it in passive mode to see if it sounds like it should. Of course, that assumes you have the wherewithal to do so.

The inputs are some what quick connects "solder less to the preamp " How should I go about this ?

Some preamps have an internal output level pot.

Setting aside the level issue, do the treble and bass boost/cut, the balance, and the volume knobs work?

View attachment 3076572

Yes . The treble and bass boost /cut pots works as well as the volume and balance knobs

 

[beans-on-toast]

Yes . The treble and bass boost /cut pots works as well as the volume and balance knobs

So the EQ circuit is functioning, it's just the level. If there isn't an internal pot that you can try, it would need to be checked out with test equipment.

A long shot, if you have deoxit, scrub all the ¼" jack contacts. If you don't have deoxit, you can use rubbing alcohol (isopropyl alcohol), or a little vodka. Oxidation or dirt on the jack or a bad connection to it can act like a resistor in the circuit, lowering the level. Make sure that the jack nut is tight, don't use pliers, just your fingers.

 

[Spacecase]

The inputs are some what quick connects "solder less to the preamp " How should I go about this ?

Yes . The treble and bass boost /cut pots works as well as the volume and balance knobs

Take a picture of the control cavity and post it.