rmorris

A properly engineered balanced output shouldn't have a problem with 48V Phantom Power as it is likely to be capacitively coupled and also the 48V appears in Common Mode. But I'd suggest to contact the manufacturer to confirm 😳 But yeah - it's a good while since I played live - but the SEs often have their way of doing things and don't like to deviate from that even when there's a technical alternative. Eg reduce everything to mic level and all inputs go to desk inputs configured to mic inputs.

But some electronic devices eg OpAmps don't operate to the same spec' at lower voltages. A 9V supply means that an OpAmp is running at only +/-4.5V. Let's say it needs a 1V headroom so a 3.5V peak. This approximates to a 2.5Vrms signal. A transient from a medium to high output passive pickup can exceed this. Plus spec in terms of THD+N etc is likely worse than at higher voltage supply. Then if it's on a battery then that battery voltage will fall a bit over time and make the situation worse. (How it decreases depends on the battery chemistry type). Increasing the voltage to 18V likely more than doubled the signal headroom (because the 1V gap needed to the voltage rail doesn't double) and the audio spec is probably better. Of course, if you are running some high gain "Ultra Shred" pedal it probably doesn't matter and you may prefer the result with lower supply voltage. Hence the thing about "vintage" batteries that 'sag' analogous to voltage sag in some amp designs

Does the Helix DI have a 'Ground Lift' option ? It shouldn't be necessary but sometimes it is due to the way some equipment is configured in a sub optimal manner.

Just to confirm what Nile days here. Passive DIs use transformers in a step down configuration. Basically trading level for a lower impedance output that is also balanced.

Sounds like a paint / varnish stripper type product may be a better option to sanding ?

Impressive !

As it happens I have a similar thing on a Marshall guitar combo' that I recently got free with no loudspeaker (it has one now). Not stopping the amp working but it doesn't short the input as intended with nothing plugged in so it stays a bit noisy. Yes - I can see that while it handles the jack plug okay, it doesn't have enough 'spring' to short when no plug there. It's actually a 'stereo' socket configured to also short some internal points - presumably to stop the OD channel boosting internal noise when there's no input. Obvs not much use when the socket has lost its zing ! Pain to replace because of all the pcb pots etc that mount to the front panel and another socket - 'Aux Input' or similar has the same problem. So I'm thinking to do a bit of metalwork and put in panel mount sockets in parallel.

What degree of volume change are you hearing ? Is the amp very hot (as far as you can tell) when the volume change starts to kick in kicks in. It seems to be time dependent ? So that sort of points toward a thermal issue.

Understood. But the 'driving a 'Fuzz-Face' type circuit with a lowish source impedance is the big thing that arises. Beyond that - yeah - it's all in the circuit details. Amongst other issues a 'box' may be designed with an input impedance more suited to 'line level' sources that is generally regarded as too low for passive Hi-Z pickups - although, of course, sometimes that will be a sound that people like and want as it will, for example, go towards less sustain. At the other extreme a very high input impedance can result in resonances that over emphasise particular frequencies. Would be interesting to hear what differences you found with Ho/Lo Z on specific pedals/boxes. Cheers.

Just a note to say that 600 Ohm is on the high side for a 'Low Impedance' Output although still an order of magnitude below that of a standard Hi-Z pickup. A 'real' low impedance output has an impedance below, say, 100 Ohm. Typically 68 Ohm. In the simplest case simply set by a resistor in series with the OpAmp output. It primarily serves to keep the output stable with a capacitive load - basically cables. It also limits the current if the output is shorted. So in some battery powered pedals etc it can be 1 kOhm or so to protect the battery. But higher resistor value does increase noise. The '600' Ohm standard is something of a legacy thing from old electronic gear where power transfer and hence impedance matching was important. With modern solid state kit it's voltage transfer that is the issue.

If I'm understanding what you propose correctly I'd say: Won't affect the tone since (afaik!) poly' resin has no magnetic characteristics I wouldn't do it since it would appear to prohibit any future height adjustment of pickups (or replacement) ?

Nice explanations there. If people ask me I usually go along the lines of: If an 'Active Bass' has Hi-Z Pickups then it has a powered buffer or a more featured preamp with active tone controls and whatever. It's basically putting some or all of the functionality of your preamp section into your bass. Advantages: Your pickups are not directly loaded by the capacitance of the cable to the amplifier. The output signal has a lower impedance. This good because lower impedance signals are less susceptible to interference. Additionally low-Z signals are not as troubled by cable 'handling noise' as Hi-Z signals. You may not need 'Low Noise' instrument cable that has the semiconducting layer in it to reduce this noise. * See note on impedance below If you prefer to have EQ etc controls on your bass then there you go. Disadvantages: The circuitry is generally battery powered - one or two PP3 batteries. So if your batteries run out of steam then you have a problem (although there's sometimes an option to switch to passive operation to get out of trouble). And in most cases accidentally leaving the bass plugged in will run down the battery. Players love to have a long battery life for obvious reasons. But this doesn't always go hand in hand with the highest audio performance so there can be a trade off compared to your mains powered preamp. Also if you then plug your active bass into your preamp then you are sort of duplicating functionality and increasing noise by going through more amplifier stages. *Impedance - worth noting that 'Active' basses might have a lower output impedance than passive basses. But often it is not really 'Low Impedance' in pro-audio terms as it's just the unbuffered output directly from a potentiometer wiper. The output impedance will vary with the wiper position. (This is similar to the case with many fx pedals). Don't be fooled by the use of an XLR socket - they are often (though not always) used for security of connection but the signal is not necessarily a proper 'DI' signal in terms of level / balance / impedance. re: A hi-Z output drives a fuzz/OD/dist effect in a different way than its lo-Z counterpart. I'll just note that applies to "Fuzz Face" type circuits which basically depend on the signal source having a highish impedance for their operation. Other OD/Dist/Clipping fx work fine with lo-Z signals - they often have a buffer so that the pickup doesn't see the bits that produce the effect directly.

What is your technique for doing that ? Do you fill the existing holes before drilling ? or clamp to a supporting piece and use that to align/centre the drill ? Or...

What songofthewind said. If anyone is going to have the tools/technique to do this then it should be Status. Otherwise I can see it all going wrong !

Yes.

So True !

If you are referring to a constant highish frequencies hiss (ssss...white/pink noise) then that isn't interference It's inherent noise bring amplified. The noise comes from the pickup itself, the preamp/amp and interaction between the two. Normal passive pickups are High Impedance and regarded as a noisy source in electronic terms. Actual noise level will depend a bit on the preamp/amp it is plugged into. Try low pass filtering / treble cut to reduce audible noise. How much you can do much depends on your desired tone. But bear in mind that there's little signal from a bass above a few kHz.

Potting doesn't affect interference noise. Wax has no RFI shielding properties. It can help to minimise microphonic effects where the pickup magnets/coils move in relation to each other.

That's a bit different - to stop you making skin contact with exposed pole pieces and causing noise. Depends on playing technique whether it's an issue. Any colour will do the job ! Although real solution is to have pickups with non-exposed pole pieces / rails. I was meaning that the pickups themselves are usually not themselves shielded by design.

Nice. It would have been easier to check the bridge continuity with a multimeter rather than remove/refit. Bear in mind that you can't totally eliminate noise pickup as some will 'get in' via the pickups themselves.

Also be aware that the D5 comes in flushable / non-flush versions. As it happens I recently picked up a Marshall Guitar Combo. All pots were crackly or unusable. A first round of D5 sprayed into the 'hole' on the pot casing and a good exercise of the pots made a huge improvement with only two pots showing some crackling these were the 'Driver' channel treble and contour potrs so maybe greater audible sensitivity. A bit more twisting of the pots next day and crackling almost, but not quite gone. second round of D5 and all good since.

Still seems to me that they were ungenerous with their offer to take it back but at your packing/postage cost.

Mmmm..looks like metallic Alu screening on the control plate with conductive paint to interface to that - but not clear if that has continuity to 'Ground'. And lots of cavity looks to be unscreened. I see you might be in / near Brighton ? As am I. Will PM but tomorrow as getting late here now.

Having Tone Control Open or boosting treble (in the bass guitar sense) usually emphasises buzz. It's not unusual to get a transient when you go from not being in contact with the grounded metalwork to being in contact. The machine heads may have a surface finish that doesn't give a great connection when touched and the partial intermittency can give a problem. I have a similar thing on a bass where I have some coated strings and the contact is variable and results in transients / crackles. The problem does imply that there may be a screening issue where you are acting as an antennae for noise and the bass isn't adequately screened. What screening is there in the control / pickup cavities ?

Yes - mojo indeed. It shouldn't affect the intonation setting on the bridge assuming the strings run properly from bridge saddles to nut.