Amplifier hum [Archive] - The Art of Sound Forum

Pigmy Pony

24-09-2018, 12:03

Hi technical bods,

I am getting a fairly low level hum from my speakers, since I connected up a recently bought Bow Wazoo amplifier. The hum stays fairly quiet up tp about 3/4 on the volume knob, where it then is quite loud. When amp is on 'standby', the hum is still there, but does not increase with volume.

I've checked connections between it and deck and CD player, and I've also had it on with EVERYTHING, TV, a/v amp, sky box etc., everything unplugged. but the hum remains. Any suggestions? I've seen mention of 'filter capacitors' but don't know if this would be appropriate, nor what costs would be involved.

I can live with it for now, as long as nothing is coming to any harm, but it will bug the shit out of me long term.

It is a straight swap from my Audion Silver Night, which had no such problems.

anthonyTD

24-09-2018, 12:35

Hi Steve,
Sounds like it could just be hum induced into the chassis from the mains transformer, being picked up on the inputs, or speaker output wiring, but as you say, it could also be cap failiar, either way; the only sure way of knowing is to get it looked at!
A...
Hi technical bods,

I am getting a fairly low level hum from my speakers, since I connected up a recently bought Bow Wazoo amplifier. The hum stays fairly quiet up tp about 3/4 on the volume knob, where it then is quite loud. When amp is on 'standby', the hum is still there, but does not increase with volume.

I've checked connections between it and deck and CD player, and I've also had it on with EVERYTHING, TV, a/v amp, sky box etc., everything unplugged. but the hum remains. Any suggestions? I've seen mention of 'filter capacitors' but don't know if this would be appropriate, nor what costs would be involved.

I can live with it for now, as long as nothing is coming to any harm, but it will bug the shit out of me long term.

It is a straight swap from my Audion Silver Night, which had no such problems.

AD Audio

24-09-2018, 15:47

If the hum is still present on standby, then there is a fault with the amplifier and you should get it looked at
David

Sent from my ONEPLUS A5000 using Tapatalk

Light Dependant Resistor

24-09-2018, 16:32

Test with another amplifier if the noises still occur, if its the Wazoo, have the unit looked at and tested by the manufacturers
to repair. Also test your RCA cables for discontinuity of their earthing - you can inspect each RCA individually , or if you have
a multimeter test each signal cable, set to ohms for continuity of the inner and separately the outer shield.

Amplifiers that run warm/hot need adequate cooling particularly on warm days. Also check for recently placed extension leads
, ideally have a a 1- 2 metre mains lead connecting that is in good condition.

Pigmy Pony

24-09-2018, 17:02

Thanks for all your suggestions guys, unfortunately I have no technical abilities whatsoever. I have never used a multi-meter, and even had to google shorting plugs! I suppose the real question is: does anyone know of someone/somewhere that could carry out the necessary repair? I had a look at Bow Technologies' website, which is "under construction".

The Wazoo is a straight swap for my Audion Silver Night, which had no such problems.

In case any repair is going to be expensive, my other question would be: am I harming anything by using it? Having weighed up the pro's and cons of Wazoo vs Audion I was undecided whether to keep the Audion and sell the Wazoo on. But with this problem I couldn't in all conscience do that. So it looks like I may be selling a perfectly good amp and keeping a faulty one.

Serves me right really for scratching an itch that didn't need scratching!

Macca

24-09-2018, 18:08

Is it a valve amp Steve?

For repair you've got Jez Arkless to the north east of you, I know someone round my way who could fix it for you, and there's Alan Firebottle who might sort it out for you too, he's down in Brum.

Pigmy Pony

24-09-2018, 18:38

Thanks Martin. It an ss integrated.

Given the choice I would ask Alan Firebottle (a very nice man) if he can sort it, but not sure if it's his sort of thing.

But what I was wondering was whether I was harming anything by using it like this for a while - after driving 400 miles and shelling out £1000 on it, the thought of informing Mrs. P just one week later that I need another couple of 200mile round trips plus the cost of repairing it fills me with dread. Need a few weeks to build up to that one.

AD Audio

24-09-2018, 19:36

Good luck with that[emoji3]
David

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simon g

24-09-2018, 20:04

Bow went out of business many years ago. At one time the original designer did have a small business repairing/upgrading product. He may still do that? In Denmark though.

This amp could be 20 years old; always a risk buying old kit from long gone manufacturers. Having said that, these were good amps. I'm sure it could be fixed and would most likely be worth it.

Mixc

24-09-2018, 20:07

Hi Steve, cant you go back to the person you bought it from and say you think its faulty?
Its a lot of money for something that's not working as you would expect.

A suggestion, With only the CD player and speakers connected,
Play a CD, then push pause.
Now adjust the volume.
Does the noise(Hum) change with adjustment of the volume?

Mick

Firebottle

24-09-2018, 20:21

Given the choice I would ask Alan Firebottle (a very nice man) if he can sort it, but not sure if it's his sort of thing.

Glad to look at it for you Steve, I do all sorts.
You could post ir down to me.

Pigmy Pony

25-09-2018, 08:02

Good morning,

I have had a bit more of a tinker with this amp.

First I tried Mick's suggestion with CD player only connected - makes no difference.

I then connected amp to second system (just Amazon Echo and on to Celestion 5's. Humming is still there. I found that when amp is on standby thr hum remains at a low level. When powered on with selector set on an empty input (does that make sense?) - low level hum which increases slightly at max volume. When selecting a connected input, the volume of the hum increases quite a lot when the wick is turned up.

I could contact the seller, but I'm not sure if I'm being unreasonable here. I can only really hear it when I get to within a metre or so of the speakers, and with the TV on (sound off) the Plasma's fans cover it. Also it looks like the hum is more noticeable through my Zu speakers than with the Celestions (98dB vs. 88dB if that makes any difference).

I'm doing this secretly while Mrs. Pony is out of the house (if she gets wind of this, my name will be mud) and as far as telling her about it, I'll have to pick my moment. Which is why I was asking if the amp is safe to use in the short term.

Stratmangler

25-09-2018, 10:29

Halifax is fairly near to Chorley.
You could have a chat with Nick Gorham http://www.longdogaudio.com/

Macca

25-09-2018, 11:10

.

I could contact the seller, but I'm not sure if I'm being unreasonable here. I can only really hear it when I get to within a metre or so of the speakers, and with the TV on (sound off)

If it was like this when you got it then you are not being unreasonable. Any hum at all is completely unacceptable. Obviously in a private sale caveat emptor applies so you've got no real legal comeback but might be worth contacting him, perhaps he is a reasonable man.

Pigmy Pony

25-09-2018, 11:15

Hi Andrew,

I've just had the amp on with no sources connected, and the hum is the same as it was when an "empty" input was selected before, ie low level and with a slight increase when volume knob is turned fully. The hum increases a lot more at full volume when a source is connected and selected.

As I said before, the hum is less noticeable through the Celestions except when volume knob is turned to full. And that's not going to happen in normal use. So maybe it's normal - perhaps all amps will hum to some degree at full volume. The sensitivity of the Zu's perhaps are just exaggerating this, in which case I'll probably sell the Audion (with a heavy heart) and have the Wazoo checked over in the next few weeks.

Bigman80

25-09-2018, 11:22

AD Audio

25-09-2018, 12:10

This is what I would suspect Also. Try tightening the transformer bolts or if you feet confident try adding a bit of isolation underneath it. Neoprene is useful.

Sent from my VKY-L09 using TapatalkOP has said several times the hum comes out if the speakers ie it's not mechanical hum........

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Bigman80

25-09-2018, 12:11

Ah, that'll teach me to read the thread!

As you were. .
OP has said several times the hum comes out if the speakers ie it's not mechanical hum........

Sent from my ONEPLUS A5000 using Tapatalk

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Macca

25-09-2018, 12:16

. So maybe it's normal - perhaps all amps will hum to some degree at full volume. .

Absolutely not. It's either faulty or it was junk to begin with.

Light Dependant Resistor

25-09-2018, 12:47

A well designed amplifier, (applying to separate pre and power amps as well ) will have total silence at all volume levels.
Its not hard to do , where opto coupling, or transformer coupling is used between stages.

A totally silent audio system adds immensely to your enjoyment of music. vs music + noise

Pigmy Pony

25-09-2018, 13:10

That's good - it means we can rule out an earth loop as the problem.

Lots of amps do have some residual hum which is low enough to get away with. Maybe Wazoos just hum a bit more than Audions.
Still, if the amp has a lot more hum when a source is connected than when one isn't it suggests to me that the amp is simply amplifying hum that is being fed into it along with the signal. Maybe the problem was there all along but the Audions have less gain, therefore the problem wasn't as noticeable. Do you have the volume control on the Wazoo at a lower setting to get the same kind of listening level compared to the Audion? If so, that would suggest the Wazoo has more gain, hence the hum at its inputs is getting amplified more.
How long are your interconnects and are they well shielded? That's where the problem could be.

I tried the amp in both my systems, one of them being just an Amazon Echo and some Celestion speakers and in a different room. The Wazoo is 75wpc channel, whereas the Audion is only 7wpc. But as I said before, the hum is only really noticeable through the super-sensitive Zu's. The interconnects are Atlas Equator and have had no problems with them thus far.

I need to sell one of these amps soonish as not being able to work with a broken hand is taking its toll financially. And it'll probably have to be the Audion, as I can't sell the Wazoo amid this uncertainty. Then I will get the Wazoo sorted (if it is indeed faulty). First off though, I should contact the guy who sold it to me, and see what happens there.

anthonyTD

25-09-2018, 13:33

:)
All amplifiers have a signal-to-noise ratio. There has never been an amplifier with a signal/noise ratio of infinity.

Mixc

25-09-2018, 15:05

First off though, I should contact the guy who sold it to me, and see what happens there.

Hi That would be my recommendation.

RE: hum and noise, I have a large valve amp 1985 vintage all original (125w pc) into 90 ish db speakers just turned my volume to max with no noise / buzz / hum evident unless i put my ear to the speaker, and then its only just audible.
I supect its faulty, prob a cap failed or a dry joint,
Get it to Alan (Firebottle) would be my recommendation. Unless there is someone closer to you that you trust!

Pigmy Pony

25-09-2018, 17:25

Hi Mick,

No doubt there will be people closer who can carry out diagnostics/repairs, and Alan's is a bit of a trek (don't want to courier it), but I've met Alan, like him, and have faith in him.

I've just sent the seller a message, basically suggesting that I take it to be checked over and if a repair is needed, would he halve me on it? And I will cover any travelling/courier costs myself. Do you think that's reasonable?

I'll just wait now and see what reply I get.

Thanks again everyone for your advice and suggestions.

Mixc

25-09-2018, 18:43

I've just sent the seller a message, basically suggesting that I take it to be checked over and if a repair is needed, would he halve me on it? And I will cover any travelling/courier costs myself. Do you think that's reasonable?.

Hi Steve, I think that's more than reasonable.
If the seller is a gent he will offer to pay for the full costs or offer a refund, but you said you traveled some distance to collect..

Good luck i hope you get it sorted one way or the other.

Pigmy Pony

25-09-2018, 19:13

Thank you, I will of course keep you posted...

Light Dependant Resistor

25-09-2018, 19:36

All amplifiers have a signal-to-noise ratio. There has never been an amplifier with a signal/noise ratio of infinity.
Agreed, but reaching for something which suggests as difficult is what is needed, not resigning to accepting noise as being somehow acceptable.

Exceedingly low noise in an audio system, is easy to do by using optocoupling between stages.
and coaxial cables for interconnects, and speaker cables. Try it you will be surprised with just how effective it is.
Music then just sounds as it should, without noise.

In the case of the amplifier in question - images of its internal construction show very poor aptitude to applying such knowledge, as the volume potentiometer is
adjacent to the mains entry cables, dramatically increasing propensity for noise such as hum. I could add audio signal switching and mechanical volume adjustment
that is quite possible to also remove, once you have your ears and mind, set on expanding away from accepting noise.

Stratmangler

13-02-2019, 20:54

Thank you, I will of course keep you posted...

You didn't .....

Pigmy Pony

14-02-2019, 07:21

You didn't .....

Bloody hell Chris, you're right, I didn't!

Well I contacted the seller, who offered to pay for any repairs (if needed), or even take it back. I took it down to Alan's (Firebottle) and left it for him to check it out, and it he gave it a clean bill of health. That, as well as the seller having had no such problems led me to the conclusion that it was something to do with the rest of my set up. The Audion also hums similarly, but to a much lesser degree.

Anyway, I had Alan check out the Audion while he was at it, and he found the sound rather underwhelming. So he had a bit of a tinker (I was warned he has a tendency to do this :):)) and the resulting improvement in my system decided it for me - the Audion was a keeper. Anita preferred the look of the Audion anyway, so the Wazoo has been sulking in a corner ever since.

I now have it for sale now as I'm working towards making my second system "vintage" (as in a bit like my first ever stereo), and I cannot justify having a thousand pound notes sitting on the shelf, not when there are bills to pay. :(

goraman

16-02-2019, 03:49

I had the first Audion Silver Night phono stage (chrome body ) it was fantastic but I sold all my LP's and TT phono stage ect...
I have heard the Golden Dreams and would be very happy with the Silver Night 300B integraded.
What where you thinking to give up that amp. David makes amps that just sound amazing.

Pigmy Pony

16-02-2019, 09:10

Thing is, Jeff, with the set up I have, there is a certain thing about the sound, perhaps best described as a 'glare' in the upper midrange, which can be quite irritating for me as I love female vocals. Only really a thing at higher volumes, and at low to moderate levels it is fine. I started a thread about this some time ago, indeed it was my first ever post.

I initially thought the problem may have been with the Audion, and quite a few others on here thought so too, suggesting that I may be overdriving the amp.However after trying alternative amps, namely an Amptastic Mini-T (kindly loaned by a fellow member) and more recently the Bow Wazoo integrated, have led me to conclude that the issue is actually with the speakers. Shame really, as they do so many things right for me.

Anyway, Anita likes the unique quirky looks of the Audion, and as it now sounds better than ever to me, my mind was made up. It is a keeper :)

walpurgis

16-02-2019, 09:22

If you like female vocals, I'd say get a pair of vintage Tannoys. But then, I would say that wouldn't I? :)

struth

16-02-2019, 09:27

good call. Tannoys do a lot right. Depending on your needs good full range speakers can achieve much of the Tannoy sound, especially in the mids, but at a fraction of the cost.

Pigmy Pony

16-02-2019, 10:08

Are the speakers I have not sort of full range? Each cab has two identical ten inch drivers plus a sort of super tweeter. There are no crossovers.

walpurgis

16-02-2019, 10:14

Are the speakers I have not sort of full range? Each cab has two identical ten inch drivers plus a sort of super tweeter. There are no crossovers.

I believe that's correct.

struth

16-02-2019, 10:14

Are the speakers I have not sort of full range? Each cab has two identical ten inch drivers plus a sort of super tweeter. There are no crossovers.

in that case they are, sorry. They are not all made equal tho, and the tweeter may be coming in too early for your ears. It will no doubt have a cap in line, and that could be adjusted i suppose. Just a thought. Mine have 2 10" drivers too, but no tweeter. female voices are very nice imo

Macca

16-02-2019, 12:39

Pigmy Pony

16-02-2019, 13:27

These work well with a 300B http://reiver-acoustic.com/products.html no glare or harshness. Not that far from you too.

Those Edingdales look the business, and as I've said before, if I could go back in time to before buying my speakers, They would be at the top of my list. But I wouldn't commit any cash until first hearing some big JBL's though, I just have a feeling that they could be right up my street.

Unfortunately I have to consider Mrs. P in these decisions, and I know I would meet some resistance there, same with Tannoys. I only got away with these big Zu's after spending an extra £1800(!) on piano black finish.

Had a poke around Zu Audio's website, and they offer a tweeter upgrade kit for my speakers, comprising new tweeters complete with something called high pass networks and Clarity Cap MR capacitors, whatever that all means. For $300, less $100 trade in for the old tweeters. Might be worth considering.

goraman

16-02-2019, 21:23

I would strongly recomend the Tekton Lore with the new crossover, Nothing is more tube friendly and they do vocals right.
The fist gen crossover could be sibilant and had a hump at 5 to 8 khz. Everything about the new 2.0 crossovers are better.
They are also not extremely expensive but shipping may be a little money.
All you need to drive them is 2 watts and you can fill a room.
Diana Krall and Gilian Welch sounds as they are in the room with you.
If your ever in Nor Cal do stop by for a listen.I am in old town Roseville , funny because in England everything is old town ! You all have so much History there. Here a 50 year old neighborhood is ancient.
Your amp will be happier driving an 8 ohm load, I belive the Zu is 16 and they swing a pretty wide impedance if memory serves me well.

https://www.tektondesign.com/lore.html

https://positive-feedback.com/Issue60/tekton.htm

Macca

16-02-2019, 22:21

Those Edingdales look the business, and as I've said before, if I could go back in time to before buying my speakers, They would be at the top of my list. But I wouldn't commit any cash until first hearing some big JBL's though, I just have a feeling that they could be right up my street.

Unfortunately I have to consider Mrs. P in these decisions, and I know I would meet some resistance there, same with Tannoys. I only got away with these big Zu's after spending an extra £1800(!) on piano black finish.

Had a poke around Zu Audio's website, and they offer a tweeter upgrade kit for my speakers, comprising new tweeters complete with something called high pass networks and Clarity Cap MR capacitors, whatever that all means. For $300, less $100 trade in for the old tweeters. Might be worth considering.

Hard for me to offer any advice as your system is a totally different approach to what I prefer. I know the Edingdales do the biz with a 300B, the price is sensible and they are not far away which is why I mentioned them. I think they'd do you piano black if that's a requirement. As for matching JBLs with a 300B type - I have never heard that combo or even read about anyone trying it. By the laws of hi-fi someone must have though.

Pigmy Pony

17-02-2019, 10:42

Hard for me to offer any advice as your system is a totally different approach to what I prefer. I know the Edingdales do the biz with a 300B, the price is sensible and they are not far away which is why I mentioned them. I think they'd do you piano black if that's a requirement. As for matching JBLs with a 300B type - I have never heard that combo or even read about anyone trying it. By the laws of hi-fi someone must have though.

No, if I ever did go JBL, The 300b would be swapped for something a bit chunkier, like Krell (good chance that combo has been done before). But anyway I'm dreaming.

If I had my time (and money) over again, I would certainly approach things differently. For one thing I would have joined AoS first, and no doubt the collective knowledge and experience here would have saved me fortunes.

I have considered the Edingdales before, but the thought of selling the £6k Zu's for perhaps a quarter of that, and then have to find more cash to add to it makes me squirm a bit. And money's rather tight at the moment. I know what Anita would say - the new speakers aren't gonna sound that great when the leccies been cut off :(

I wonder sometimes if a second, more experienced pair of ears might help me to avoid more fruitless and expensive choices, unfortunately I have no "Hi Fi buddies". So an open invitation to anyone travelling north (or south), very welcome to pop round for a brew on the way. Might even have biscuits.

Macca

17-02-2019, 11:22

I know what Anita would say - the new speakers aren't gonna sound that great when the leccies been cut off :(

.

Women with their inconvenient common sense approach. What can you do?

I agree your midrange glare issue is a speaker problem. I wonder if it can be solved without changing the speakers? I take it you have experimented with raising and/or lowering the speakers relative to your head height when listening? Have you tried any acoustic treatments in the room?

Pigmy Pony

17-02-2019, 12:08

Women with their inconvenient common sense approach. What can you do?

I agree your midrange glare issue is a speaker problem. I wonder if it can be solved without changing the speakers? I take it you have experimented with raising and/or lowering the speakers relative to your head height when listening? Have you tried any acoustic treatments in the room?

It would be nice if something could be done with my existing speakers, and Zu Audio's tweeter upgrade kit looks like an affordable(ish) option. No soldering required, the only tool needed is a tiny torx bit. Shit, even I can't balls that up!

I have experimented with lean-back, toe in, and positioning, but in this size of room there's only so much you can do. I'm probably making it sound worse than it is, and a second pair of ears may think it sounds fine. Or they may run from the room, clutching their bleeding ears.

Macca

17-02-2019, 12:20

Pigmy Pony

17-02-2019, 12:35

Can't find any measurements of the Omen Definition anywhere but looking at the reviews and the other Zu speakers that are measured I'd say the issue was the main drivers going into break up at the top of their range. Even so it shouldn't be a major issue unless you are very fussy about such things. I am and so I am guessing are you. So not sure the tweeter upgrade would resolve this. But could be worth a try.

If you were closer I'd come and have a listen. Not sure I could offer an experienced pair of ears but could at least give you a second opinion. I guess Alan had a listen when he was up there, what did he think?

No, Alan has never been here, I went to his place.

I too am wondering whether the tweeter upgrade would hit the spot - the sound 'artefact' I'm describing is somewhere around the upper midrange I'd say. Unless an interaction between the fr drivers and the tweeter are creating a harmonic? Is this possible, or am I just making shit up now?

Lawrence001

17-02-2019, 12:39

If I were you for that price relative to the original price of the speakers I'd give the tweeter upgrade a shot. However, in case you prefer the sound of the original, you're probably better off keeping them than trading in, could be a major false economy. Never a bad thing to have spares either. The new tweeters would benefit from a good run in before coming to a judgement however.

Sent from my BLN-L21 using Tapatalk

struth

17-02-2019, 12:41

might find the tweeter comes in earlier than you think too. might not, but a lot do.

Macca

17-02-2019, 12:47

No, Alan has never been here, I went to his place.

I too am wondering whether the tweeter upgrade would hit the spot - the sound 'artefact' I'm describing is somewhere around the upper midrange I'd say. Unless an interaction between the fr drivers and the tweeter are creating a harmonic? Is this possible, or am I just making shit up now?

Sometimes if you change one ingredient you change the taste of the whole stew. So maybe it would help. As usual in this hobby there's really only one way to be sure.

walpurgis

17-02-2019, 12:59

If you can identify where the peaky area seems to be in the response, you might be able to use an LCR filter to drop output across that point. There are circuits on the net.

walpurgis

17-02-2019, 13:05

I'd say the issue was the main drivers going into break up at the top of their range

I suspect that will be correct.

walpurgis

17-02-2019, 13:08

I too am wondering whether the tweeter upgrade would hit the spot

Disconnect the tweeter if you can and then listen to them. If the problem is still there, a tweeter 'upgrade' won't help.

Pigmy Pony

17-02-2019, 15:11

Disconnect the tweeter if you can and then listen to them. If the problem is still there, a tweeter 'upgrade' won't help.

After my last post, that very thought occurred to me too. And there also have been times when I've thought how good it would be if I could just attenuate the offending frequency, but never thought it possible (except with some kind of equaliser, and that seemed a bit of a sledgehammer approach). I just need to get my hands on a little torx screwdriver to disconnect the tweeters. I will then put my findings on here.

If I do end up buying the tweeter upgrade, I will certainly follow Lawrence's sound advice, makes good sense. Thanks for all your help guys :)