Help: Annoying background noise from new Phil Jones Combo

[lonestar]

[quote name='wateroftyne' post='708484' date='Jan 11 2010, 08:12 AM']Wow and wow...



I stand to be correctet, but I'm pretty sure that was back in the days of Bassworld. Assuming it was Mr. Jones, it was pretty entertaining approach to making friends and influencing people...[/quote]

I think that you're quiet right WOT. It was a vitriolic response to someone that suggested PJB amps weren't as good as the hype.
I tried one in the Bass Centre and came away with a Markbass.
Mike

[martinbass7750]

[quote name='Beedster' post='708518' date='Jan 11 2010, 08:47 AM']Cheers Michael

Yes, it's odd, but some amp noise deson't bother me at all (e.g., fans and hiss), but the noise from this PJB bugs the hell out of me. The closest I can get is that it's like having a mosquito in the room when you're trying to sleep; it's not loud, but it's constant and, well kinda insistent.

In terms of identifying the cause, when I turn off the power, the pitch of the noise rises fro about a second until the power dies. Anyone got any ideas?

C[/quote]


I doubt it's the switching power supply, although it could be.

The class D amp and the poswer supply are both switching types. It might be a beat between the two frequencies that you can hear. Or it could be that the filtering on the class D low pass filter is not quite right.

When you switch off, as the voltage drops the switching frequency of the ampm and psu will shift, so the audible effect will change.

Switching power supplies generally operate way above normal audible frequency, as do class D amps, so the most likely culprit is a beat between the two.

For example, if the PSU is running at 42KHz, and the class D amp is running at 40 KHz, there will potentially be a beat of 2 KHz.

Edited January 11, 2010 by martinbass7750

[MIJ-VI]

[quote name='martinbass7750' post='708607' date='Jan 11 2010, 05:24 AM']I doubt it's the switching power supply, although it could be.

The class D amp and the poswer supply are both switching types. It might be a beat between the two frequencies that you can hear. Or it could be that the filtering on the class D low pass filter is not quite right.

When you switch off, as the voltage drops the switching frequency of the ampm and psu will shift, so the audible effect will change.

Switching power supplies generally operate way above normal audible frequency, as do class D amps, so the most likely culprit is a beat between the two.

For example, if the PSU is running at 42KHz, and the class D amp is running at 40 KHz, there will potentially be a beat of 2 KHz.[/quote]

Most informative martinbass7750.

[Beedster]

[quote name='MIJ-VI' post='708697' date='Jan 11 2010, 12:04 PM']Most informative martinbass7750. [/quote]

+1, thanks Martin. I'll mention that when, or if, PJB's technical department get back to me

C

[MIJ-VI]

[quote name='Beedster' post='708726' date='Jan 11 2010, 07:32 AM']+1, thanks Martin. I'll mention that when, or if, PJB's technical department get back to me

C[/quote]

If the issue is as martinbass7750 has described that it might be, then it is worth noting that the Super Flightcase BG-300 employs an SMPS + a Class A/B power amp.

[Beedster]

[quote name='MIJ-VI' post='708736' date='Jan 11 2010, 12:44 PM']If the issue is as martinbass7750 has described that it might be, then it is worth noting that the Super Flightcase BG-300 employs an SMPS + a Class A/B power amp.[/quote]

Thanks MIJ, could you put that in words a non-tech dude will understand In short, is that a better thing or a worse thing?

Cheers

Chris

[chris_b]

[quote name='Beedster' post='708501' date='Jan 11 2010, 08:31 AM'].... go back to Markbass (for my small gig amp anyway)....[/quote]
That sounds like a plan. Would sound good with a quality neo 110 or 112.

[MIJ-VI]

[quote name='Beedster' post='708741' date='Jan 11 2010, 07:50 AM']Thanks MIJ, could you put that in words a non-tech dude will understand In short, is that a better thing or a worse thing?

Cheers

Chris[/quote]

Hi Chris.

It's a better thing.

As I understand it, Class A/B is an analogue technology: a tried & true old fashion design which doesn't use a clock frequency like digital power amps do.

Therefore the "beat" which martinbass7750 described as being a possible cause of the noise which you are hearing from your PJB Flightcase would not occur in the BG-300.

Disclaimer: I am not a tech. (However I can read & parrot product manuals.)

Gary.

[Musicman20]

Maybe a refund on the PJ and then go for a second hand MB combo or the super small amp they do? If I remember correctly, you had a MB combo a while back? Would you go back to something like that?

Hope you get it sorted....its annoying when things turn up with problems, or unexpected quirks.

[largo]

Why not call another PJB supplier, i.e. guitarguitar and ask ?
They tend to keep amps in stock and if you explain the scenario to them I think they'd offer some advice.
I played a PJB Flightcase in the Edinburgh Shop and it sounded silent, but then I wasn't listening that intently. Call Andy aka Duck at the Edinburgh shop, and ask is my opinion.

[Musicman20]

[quote name='largo' post='708774' date='Jan 11 2010, 01:16 PM']Why not call another PJB supplier, i.e. guitarguitar and ask ?
They tend to keep amps in stock and if you explain the scenario to them I think they'd offer some advice.
I played a PJB Flightcase in the Edinburgh Shop and it sounded silent, but then I wasn't listening that intently. Call Andy aka Duck at the Edinburgh shop, and ask is my opinion.[/quote]

I went to guitarguitar in Newcastle the other day for a mooch about and they had plenty of PJ stock. This sounds like a good idea.

[martinbass7750]

[quote name='Beedster' post='708741' date='Jan 11 2010, 12:50 PM']Thanks MIJ, could you put that in words a non-tech dude will understand In short, is that a better thing or a worse thing?

Cheers

Chris[/quote]

Hi Chris,

Class D (for digital) is small, lighweight and power efficient. The output transistors (FET's) are being switched at a high frequency, way above audible. The signal from your bass is modulated onto the high frequency signal, then a low pass filter is used to remove the high frequency and leave you with just the bass sound.

The advantage is size/weight.

Class A/B is older analogue technology, which is neither better or worse than class D (IMO). It will be heavier, larger and less power efficient, but it will still work well. It's easier to design a class A/B amp that sounds good.

Class D is a maturing technology, and maybe PJ haven't quite got it right yet - I'm sure they will.

I use a mark bass F1 with either 1 or 2 Berg 1x12 cabs (the neo type which many don't like, but I love them). The F1 will fit in my guitar gig bag. It's a great rig, and goes pretty loud with both berg cabs.

The only noise I get is the normal hiss you would expect when I turn the gain and volume up high.

In my opinion, if you're not happy with the PJ solution you should insist on a replacement that works to your satisfaction, either PJ or something else.

Cheers

Martin

Edited January 11, 2010 by martinbass7750

[Bill Fitzmaurice]

[quote name='Beedster' post='708480' date='Jan 11 2010, 03:07 AM']I received a brief reply...confirming that the noise is usual on this model.[/quote]Odd that it doesn't say so in their ad copy.

[Beedster]

Guys

Many many thanks for all the advice above. I've taken it, the responses from the dealer and from PJB on board, and have arranged to return the Flightcase in exchange for a Super Flightcase (with a bit of cash from me as well). There's a number of reasons for this, one of which is the consistency between a lot of the explanations as to the problems I was experiencing - perhaps best put by Martin and MIJ above - that is, Class D is an emerging technology, and even PJB have acknowledged problems with noise from the Flightcase which are not present in the Super Flightcase. I spent a lot of time reading amp comparisons and reviews on here, Talkbass, Harmony Central and the like in deciding to buy Phil Jones in the first place, and I've also had to deal with some pragmatics re size - my Mesa, despite it's awesome tone at high volumes, is simply too big and powerful for most gigs I play, and that reduces it's useful tonal range somewhat.

I've been pulling my hair out over the Flightcase for one reason and one reason only; the tone is EXCEPTIONAL, at both low and high volumes. My Precision sounds quite stunning through it, the tone is sweet and soulful without too much coluring, which is what I need at present. Having said that, the tonal options are still impressive, if needs be I can produce some lovely effects. To my mind the tone is someway beyond comparable Markbass equipment (remember tone is a subjective phenomenon so I'm not passing judgement here), or I would have gone back to the Italians. OK, perhaps with a small Markbass combo and a decent para, I might get exactly the same, but I'm really trying to keep to a simple gigging protocol now, bass in one hand, amp in the other, and I've never liked anything sitting between bass and amp anyway. On top of all this is the upward facing speakers, which really do make a hell of a lot of difference when like me you have to stand very close to your amp on a small stage (in fact, it's interesting that it was the almost 'surround sound' effect of these speakers that made the whistling so irritating in the first place, I'm sure had the speakers been conventionally arranged in space and I had stood next to the amp, I wouldn't have been so bothered by it). The UK suppliers are apparently going to give the FSC the once over before it's sent out, just to be sure!

I have to say I've learned a lot during this process, and can't thank all of you enough for your time and input (both above and on the previous 'Wanted' and 'Amps/Cabs' threads). The SFC should be with me for a full volume rehearsal on Wednesday evening and a gig this Friday so I'll keep you all posted

C

Edited January 11, 2010 by Beedster

[MIJ-VI]

[quote name='Beedster' post='708819' date='Jan 11 2010, 08:52 AM']Guys

Many many thanks for all the advice above. I've taken it, the responses from the dealer and from PJB on board, and have arranged to return the Flightcase in exchange for a Super Flightcase (with a bit of cash from me as well). There's a number of reasons for this, one of which is the consistency between a lot of the explanations as to the problems I was experiencing - perhaps best put by Martin and MIJ above - that is, Class D is an emerging technology, and even PJB have acknowledged problems with noise from the Flightcase which are not present in the Super Flightcase. I spent a lot of time reading amp comparisons and reviews on here, Talkbass, Harmony Central and the like in deciding to buy Phil Jones in the first place, and I've also had to deal with some pragmatics re size - my Mesa, despite it's awesome tone at high volumes, is simply too big and powerful for most gigs I play, and that reduces it's useful tonal range somewhat.

I've been pulling my hair out over the Flightcase for one reason and one reason only; the tone is EXCEPTIONAL, at both low and high volumes. My Precision sounds quite stunning through it, the tone is sweet and soulful without too much coluring, which is what I need at present. Having said that, the tonal options are still impressive, if needs be I can produce some lovely effects. To my mind the tone is someway beyond comparable Markbass equipment (remember tone is a subjective phenomenon so I'm not passing judgement here), or I would have gone back to the Italians. OK, perhaps with a small Markbass combo and a decent para, I might get exactly the same, but I'm really trying to keep to a simple gigging protocol now, bass in one hand, amp in the other, and I've never liked anything sitting betweem bass and amp anyway. On top of all this is the upward facing speakers, which really do make a hell of a lot of difference when like me you have to stand very close to your amp on a small stage (in fact, it's interesting that it was the almost 'surround sound' effect of these speakers that made the whistling so irritating in the first place, I'm sure had the speakers been conventionally arranged in space and I had stood next to the amp, I wouldn't have been so bothered by it). The UK suppliers are apparently going to give the FSC the once over before it's sent out, just to be sure!

I have to say I've learned a lot during this process, and can't thank all of you enough for your time andd input (both above and on the previous 'Wanted' and 'Amps/Cabs' threads). The SFC should be with me for a full volume rehearsal on Wednesday evening and a gig this Friday so I'll keep you all posted

C[/quote]

Please do!

I'm eying a BG-300 as well for the same sonic reasons.

[Beedster]

[quote name='MIJ-VI' post='708845' date='Jan 11 2010, 02:09 PM']Please do!

I'm eying a BG-300 as well for the same sonic reasons.[/quote]

Cool, it's going to be interesting to see how it compares with the Flightcase.

Thanks for your help

Chris

[martinbass7750]

[quote name='Bill Fitzmaurice' post='708809' date='Jan 11 2010, 01:45 PM']Odd that it doesn't say so in their ad copy. [/quote]

[Beedster]

[quote name='martinbass7750' post='709088' date='Jan 11 2010, 05:35 PM'] [/quote]

I missed that first time, nice one Bill!

[BB2000]

[quote name='martinbass7750' post='708607' date='Jan 11 2010, 10:24 AM']I doubt it's the switching power supply, although it could be.

The class D amp and the poswer supply are both switching types. It might be a beat between the two frequencies that you can hear. Or it could be that the filtering on the class D low pass filter is not quite right.

When you switch off, as the voltage drops the switching frequency of the ampm and psu will shift, so the audible effect will change.

Switching power supplies generally operate way above normal audible frequency, as do class D amps, so the most likely culprit is a beat between the two.

For example, if the PSU is running at 42KHz, and the class D amp is running at 40 KHz, there will potentially be a beat of 2 KHz.[/quote]

That assumes they operate at a fixed switching frequency, most modern class-D amps are self oscillating (although I've no idea if the flightcase is).

[martinbass7750]

[quote name='BB2000' post='709688' date='Jan 12 2010, 07:47 AM']That assumes they operate at a fixed switching frequency, most modern class-D amps are self oscillating (although I've no idea if the flightcase is).[/quote]


Ok that's interesting, I didn't know they were self oscillating. That mean the frequency changes in use. What would cause it to change, changes in psu voltage?

I guess there must be somthing in the design that would make the amp osciallate within a known range of frequencies during normal use.

[BottomEndian]

[quote name='martinbass7750' post='708607' date='Jan 11 2010, 10:24 AM']The class D amp and the poswer supply are both switching types. It might be a beat between the two frequencies that you can hear. Or it could be that the filtering on the class D low pass filter is not quite right.

When you switch off, as the voltage drops the switching frequency of the ampm and psu will shift, so the audible effect will change.[/quote]
So is this what causes my Little Mark II to do a sort of falling "ptschooooo" noise when I switch off, regardless of where the master volume's set? I always wondered about that.

I kind of like it -- it's kinda cute.

[Beedster]

Update on this. PJB suspect the noise might be a function of the 240v UK power supply and the switching power supply on the Flightcase. The noise they have acknowledged in previous communications is apparently not audible in normal use, whereas the noise from my amp most certainly is. Anyway, they, or at least the UK distributor, will be getting mine back to try with a few different power supplies

Chris

[lemmywinks]

[quote name='BottomEndian' post='709981' date='Jan 12 2010, 01:45 PM']So is this what causes my Little Mark II to do a sort of falling "ptschooooo" noise when I switch off, regardless of where the master volume's set? I always wondered about that.

I kind of like it -- it's kinda cute. [/quote]


LMII is class A/B i think?

[BottomEndian]

[quote name='lemmywinks' post='710126' date='Jan 12 2010, 03:57 PM']LMII is class A/B i think?[/quote]
Oh yeah. Of course. I'm even more confused about the noise now then. :wacko:

EDIT: No, wait. It's still got a switching power supply, so is it possible that the power supply kind of "runs down" its clock speed as it powers down, thus creating a falling-frequency noise?

Edited January 12, 2010 by BottomEndian

[Bill Fitzmaurice]

[quote name='BottomEndian' post='710130' date='Jan 12 2010, 11:00 AM']Oh yeah. Of course. I'm even more confused about the noise now then. :wacko:

EDIT: No, wait. It's still got a switching power supply, so is it possible that the power supply kind of "runs down" its clock speed as it powers down, thus creating a falling-frequency noise?[/quote]I've heard that with many amps, it's just an artifact of the supply caps discharging.