rmorris

4 hours ago, dmccombe7 said:

I've been using a stuff called Dylek Electronic cleaner i got from work many many years ago. It freezes and then evaporates very quickly but it clears dirty pots really well.

Its classed as an electronics cleaner but i wasn't aware of the grease element on the pots so that's news for me. I've had the can since the late 90's and its only just gone empty.

I used to use it to clean cassette heads back in the old days. Spray onto a cotton bud and clean the heads. Worked a treat.

I'm going to order some Deoxit D5 from Amazon as it seems to get most praise out of them all.

Dave

 Ha! I guess cassette heads are a very niche interest now - some retro interest notwithstanding. It's never going to be like Vinyl. Young people have never experienced seeing long lengths of cassette tape in gutters after a jammed cassette was thrown out of a Ford Capri in frustration 🤣

But I guess there are still some Big Reel tape decks where the same cleaning is applicable. For that it's hard to beat IPA tbh (Isopropyl not Pale Ale 🙄) although I recall that it was important not to use the pure stuff on the rubber capstan wheel as it would dry it out and cause it to crack.

+1 for DeOxit 5 btw. Think whether the flushable or non-flushable version is best for your application.

4 hours ago, agedhorse said:

There are still products (including g interfaces and mixers) that can’t accept true nominal +4dBu line level balanced signals. This alone makes a mic signal more universal as a line level signal won’t work in that situation. 
 

 

yes it can be useful to have the option to work at 'non-professional' nominal level eg -10dBv (lower level and different dB reference - standards are great - that's why we have so many 🙄) and I have been in the situation where I've chosen to configure a DIY attenuating pad to archive some stuff from DAT (remember when that was a thing ???) using my now old multichannel TDIF interface that has unbalanced inputs at a low nominal level. But I still prefer to work at +4dBu until I have to attenuate.

In reality all audio going into an ADC is going to be squeezed down to a 5V range or less. But attenuating directly before the ADC gives best SNR.

Also worth noting that signals that are impedance balanced or 'Ground Cancelling' are likely to be at -2dBu nominal level. Since the -ve leg of the signal isn't driven.

As for mixers that don't handle +4dBu - tbh I'd just say use a different mixer. 

Yes. I guess I'm more biased toward recording rather than live work. 

Agree wrt your keys player - unless his keyboard is mains earthed itself and so the DI would give him the opportunity to avoid a hum loop in the system.

On 11/11/2021 at 09:35, Jus Lukin said:

A DI is to take line or instrument level and bring it down to mic level, lowering the impedance and balancing the signal to match, usually, a mic preamp on a sound board.

 

Good points re terminology wrt Pre-Amp / DI etc. Much of the time people are discussing what is really a preamp or effects unit that incorporates a DI output.

A "Pure DI" function isn't intended to colour the sound. It just provides a low impedance balanced signal suitable for a mixing desk channel or similar.

I have to dispute that it should necessarily produce a low 'mic' level signal though. This has certainly been the 'traditional' practice and it's basically inherent in a passive (transformer only) based DI that is taking a signal directly from a passive Hi-Z pickup*.

But now that mixing desks / interfaces etc often have proper Line Level inputs there's often no advantage and some disadvantage in deliberately attenuating a signal when you don't need to.

Much depends on what goes on 'under the hood' of the receiving channel in terms of gain/attenuation - but in general it's not a good idea to attenuate then amplify. It's all about 'Gain Staging' really.

As it happens this has recently been the topic of a discussion on a pro audio orientated forum where I dabble. One member was most adamant that only mic level was   'legitimate' but couldn't really articulate why.

There are, of course, good reasons why mic level might be preferred eg the user simply likes the sound of a particular mic pre working at some gain.

And more pragmatically a live mixing setup may have a default configuration of expecting only mic levels from the stage lines. And mix in whether active DIs are being powered from Phantom 48V and whether line level is accepted on the XLR Inputs or only on TRS Jacks (Where there won't be Phantom 48V).

* Technically this never seems a good idea since using a typical 5:1 stepdown transformer into a typical mic channel input  with 2K2 input impedance presents  c. 55K impedance to the pickup. When an amplifier etc input typically presents a minimum of 470K and often 1M0. Additionally driving a transformer from a high impedance will tend to increase distortion. But I'm aware of at least one DI box that has/had options to use a buffered output or go straight into the transformer - and have it on the designer's authority that for bass guitar most people preferred the direct to transformer option.

EDIT: Reading this back it occurs to me that I should mention that the designer in question is Cyril Jones of Raindirk fame. The obvious question is what was the specific transformer. Unfortunately when I asked him more recently he couldn't actually recall the detail.

6 hours ago, agedhorse said:

You can still impedance balance the signal, it just requires a custom cable with matching resistance in the ring line. 
 

 

Yes. Good point. Though not exactly convenient 🙂. and you may also want a "ground lift" circuit in the Screen connection. It's a lot to fit in a standard Jack plug body - although you can get those larger bodies jacks from Neutrik...

3 minutes ago, agedhorse said:

If you wish to have a DI output, any passive DI will work, and just about all have a parallel in/out on the unbalanced side.
 

1K output impedance is very common, and is intended to drive any input of typically 10K or greater. Passive DI’s are all greater than 10K.

 

This pedal was not intended to be a DI. It’s a filter-EQ pedal.

Yes. 1K0 is a common output impedance for fx pedals etc. I meant that it high for a DI output.

I understand that it is not intended to be a DI. A post indicated that the poster thought that it was a DI so I was correcting that.

Yes - you can of course use a separate DI (active or passive) - but I still say that in general it's a shame to miss the opportunity to provide an impedance balanced DI signal on most audio units.

I do understand why it's not done.

7 hours ago, Stingraychris said:

It’s a CIJ 60s reissue jazz bass from around 2000-2002 I googled the spec with no luck. Any idea how I can find out the radius? this was mentioned last time I had the bass setup. We filed down the frets at the weekend which helped slightly and made sure they are even. Thanks for the comments !

Your luthier should be able to tell you ?

Following on from Matte_black comment - what is the radius of the neck and is it a compound radius ?

Although I thought 12" was quite a flat radius cf a 'vintage' radius. Happy to be corrected as I'm too tired to look it up myself atm !

34 minutes ago, Dan Dare said:

If you do make up your own, use real Speakons. Most imitations are rubbish (some won't even fit actual Speakon terminals without persuasion). It really isn't worth saving £1 per connector for the aggravation.

 tbh I didn't know there were 'imitation' Speakons. I'd have thought the potential market share would be too small to be worthwhile. OTOH I've seen more surprising things on counterfeit semiconductor products do what do I know 🤔

On 06/11/2021 at 18:24, Dan Dare said:

Save your money and make them up yourself. Buy good quality cable - Van Damme or similar with 2.5 mm conductors - and the Speakons. If you can cut and strip cable and turn a screwdriver (no soldering required with Speakons), it's a piece of p1ss.

+1. For this application it's all about mechanical strength and integrity. As the OP seems to have discovered with the 'Stagg' failures - would be interesting to know where they are breaking physically.

Essentially you just need a decent gauge of conductor protected by a robust jacket and properly attached to good quality connectors.

I'll say that you don't particularly need audio branded cable though it does no harm. I favour two core stranded mains appliance cable. And preferably the 'Orange' jacket type intended for external appliance use (eg lawnmowers etc)

because a) the jacket should be robust enough to survive being trod on etc, b) You can see it easily in  the 'cable bag' and less likely to leave it behind 🙂

OP already has the Speakons so just requiring to properly strip to the correct lengths that should be available via Neutrik info'.

Personally I tend to 'tin' the exposed copper ends to give the screws something 'solid' to bite into - but I know opinion varies on that.

For the jack cable or adaptor piece then I suggest one of those large bodies Neutrik jacks to allow for a good cable diameter and give plenty of room to solder / insulate the connections.

Is this for amp head to speaker cab ? Or a PA ? What sort of length ?

22 minutes ago, Supernaut said:

All I'm after is a good quality DI that I can use live and send a strong signal to the FOH. Possibly for recording also. 

I think you probably already have what you need with the MXR ?

5 minutes ago, Cuzzie said:

I get your point - but unless I am massively wrong it will still be able to go straight to desk or amp so long as you have the correct cables?

that was more the point I was trying to say

You'll be able to plug it in and get a signal into the desk of course.

But that doesn't require any particular level.

For a 'DI' output best suited for the task the signal should be balanced (several variants possible) and low impedance - typically <100R for an active signal.

Some would also say it should be at a low 'mic' level but that's a slightly different question.

Without some form of balanced output you lose the benefit of noise(interference) rejection and breaking any 'Ground Loop' issue.

Basically your signal may well be noisier.

I also noticed there's one output only. A DI would normally have some form of parallel output so, typically, one output can go to an amp and the other straight into a desk.

12 hours ago, Cuzzie said:

Nah mate - there is a DI out - don’t be fooled by it not having a 3 pin plug - the ‘out’ can be line or instrument level

It's not a DI output though from the block diagram.

It's simply an unbalanced output. Output level is not what defines a DI (in fact they'll often have a low 'mic' level output designed to be the input to a mic channel on a mixer).

Primarily a DI out needs to be balanced or 'Ground Cancelling'. And 1K0 output Impedance is rather high.

It's a shame that lots of pedals miss a DI out. Passive impedance balancing costs next to nothing.

On 15/09/2019 at 16:14, ped said:

Full disclosure: This bass was sent to me by Glarry Music. We were in discussion about advertising and I wanted to try the product beforehand. They sent me a bass to try in return for a review on Basschat.

The Glarry GP bass retails for an incredible £72.99 with free shipping. 

Yes that's right - this bass costs about the same as an effects pedal or a couple of packs of strings. It can't be any good, surely? Maybe OK for a beginner? I had to try one for myself to see just how bad a bass in this price range would be.

 

 

Interesting stuff.

A couple of related queries. You mention notes choking at the first couple of frets. Doesn't this make the instrument as is basically unplayable or was it only when bending etc ?

Related to that - unless I missed it - there's no mention of the neck relief or any truss rod adjustment you made.

Would be good if you could clarify these points.

Thanks again for the review.

On 30/10/2021 at 14:27, Jus Lukin said:

As for an overdrive it will push the clipping points further round the dial, making for less saturation, but greater range at the bottom of the dial.

It depends on how the circuit operates. If the effect is due to a signal getting 'near' a voltage rail (or something a bit more complex related to the voltage eg affecting the operating point of a transistor) then yes.

But if the process is basically independent of the voltage level as long as it doesn't go too low - eg clipping levels defined by diodes - then the controls won't really alter. Although the circuit will probably have a different audio spec performance due to differing voltage rails. Of course, some pedals etc will have internal voltage regulation in which case - to a first level - everything will be the same until the voltage is too low and it starts to go wrong !

17 hours ago, bassman7755 said:

 

But nevertheless high end hifi gear can exceed 100 db snr at much lower signal levels than this. 

Audio specifications can be, let's say, a somewhat confusing area. I know. Been there Done that etc. But basically, depending on the definitions you are using, you don't really get better than 100dB SNR.

Yes - a good mic amp may give an Ein of, say -127dBu. But that is typically at a gain of 60db. So actual noise level at the output is -67 dBu. So if you are setting the gain at 60dB to give an output level of +4dBu then your nominal SNR is 71 dBu.

As gain decreases the Ein increases a bit. So while the signal may increase by, say, 20dB, thus requiring a gain of 40dB to give the same output level, the noise added at 40dB is a bit  more than that added at 60db so the actual SNR wrt the input signal is better than the figure at 60dB gain but not by the full 20dB decrease in gain and noise may have already been added by any preamplification.

12 hours ago, Jack said:

I believe it's intermittent during use. I've never actually had the problem, the soundmen we work with don't match the descriptions given on BC. 😉

Yeah - it's difficult when you don't control the whole signal chain. A live setup isn't the ideal environment to optimise stuff. Cheers.

8 hours ago, Stub Mandrel said:

18V can compensate for poor design, allowing you to be careless about gain levels during processing.

 

In theory, you don't need that headroom even if processing signals for line level inputs.

But what are you taking as "Line Level" ? 

+4dBu / -10dBu or ???

8 hours ago, bassman7755 said:

 

So why does hifi and studio equipment get by just fine with high SNRs when using  line level signals everywhere, the highest level being +4db / 3.5v peak to peak ?. 

 

 

Hi. I see your whole post. But quickly on this - cos I'm on mobile and a tediously slow train from London to Brighton 🙄 - the pro line level is nominally +4dBu that does indeed equate to approx 3.5V pk-pk. But any system is expected to handle peak levels in the range of typically 21 to 24 dBu requiring Voltage rails in excess of +/- 9V or 12V.

Typical pro audio gear runs OpAmps at minimum +/-15V and typically +/-17V.

1 hour ago, Jack said:

We're perhaps a little off topic now but the common wisdom for helices is that whilst phantom won't harm, it does make weird noises. 

Okay. Is that just when it's being switched or constantly ? 

6 hours ago, Jack said:

No unfortunately, nor any way of blocking phantom power. I should have elaborated some more in my first post really, no DI needed as long as you trust and have a competent soundman! I do take a DI box to those situations and sometimes use it. You forget these things when you run your own pa, sorry. 

 

 

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.

9 hours ago, bassman7755 said:

 

I call cow poop on 18v, the vast majority of audio processing in the world is done at half a volt or less so not sure why bass preamps or effects would get some magic benefit from a massively higher voltage. I cant hear any fundamental difference between my 18v status and a 9v active (or even passive) instrument. 

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 

11 hours ago, Jack said:

If it helps at all the HX Stomp's outputs are balanced, no DI box needed.

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.

23 hours ago, nilebodgers said:

Yes. A passive DI reduces the signal level down to something that works well with a microphone input. The loss is usually -20dB (one 10th) with 1:10 transformers.

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.