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My Shuttlemax 9.2 is hissing like sid on the tube channel, but oddly,  ( or not ? )  kicking in the compressor on my Zoom B3 increases this a lot. In fact i tried 4 different compressors on the Zoom  to see if it was one in particular , but they all did it.

There's a lot less hissing sid on the FET channel.  The hissing on the tube channel is loud enough to be annoying, and as said above, the compressor kicking it makes it even more so.

There's a guy on TB  ( think its AgedDonkey or something ) who does Genz  support and have read that he thinks this could be a dodgy valve.  First trick to try was re-seating but that did nothing.  Next is to replace it, which i think is next on the list.  It has the stock Ruby 12AX7 Select in it right now.

I shall give Watford Valves a bell and see what he recommends - any body swapped there's out , perchance ?

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Damn - shoulda stuck this in technical

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What's your recommended preamp valve, either 12 AX7 / ECC83 ?

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1 hour ago, Ricky 4000 said:

Hello, technical dept - How may I help you today? 😃

Hello Kitty :D

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Posted (edited)
3 hours ago, fleabag said:

What's your recommended preamp valve, either 12 AX7 / ECC83 ?

Well, that's a little bit tricky... it's my first day working on the technical help desk, and we don't have many valves here at the international call center in Abyssinia... you could try switching it off and back on again? ... and your call is very important to us. 😀

1 hour ago, Teebs said:

Hello Kitty :D

Teebs...

hqdefault.jpg

😃

Edited by Ricky 4000
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Imagine winding up the treble on your amp, the tweeter on your cab, the tone wound up on your bass, all to the max.  The chances are you will probably get some hissing sound.

Thats what hissing is, in a nutshell.

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3 hours ago, Newfoundfreedom said:

I don't even understand the original post, but "Hissing Sid" is a great name for a band. 

Hissing Sid is the villain of the poem “Captain Beaky and His Band” which came to my attention back in the late seventies/early eighties when it featured heavily on the Noel Edmonds Sunday morning radio show.

 

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6 hours ago, fleabag said:

Imagine winding up the treble on your amp, the tweeter on your cab, the tone wound up on your bass, all to the max.  The chances are you will probably get some hissing sound.

Thats what hissing is, in a nutshell.

Yeah I know what hissing is. 😂

It's the "Sid" reference I didn't get until it was explained by Skinnyman above. 😉

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13 hours ago, Newfoundfreedom said:

I don't even understand the original post, but "Hissing Sid" is a great name for a band. 

Ah,  all i heard was you didnt understand the post.  You never mentioned about not knowing about Sid,  but Skinny to the rescue   :)

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20 hours ago, fleabag said:

My Shuttlemax 9.2 is hissing like sid on the tube channel, but oddly,  ( or not ? )  kicking in the compressor on my Zoom B3 increases this a lot. In fact i tried 4 different compressors on the Zoom  to see if it was one in particular , but they all did it.

There's a lot less hissing sid on the FET channel.  The hissing on the tube channel is loud enough to be annoying, and as said above, the compressor kicking it makes it even more so.

There's a guy on TB  ( think its AgedDonkey or something ) who does Genz  support and have read that he thinks this could be a dodgy valve.  First trick to try was re-seating but that did nothing.  Next is to replace it, which i think is next on the list.  It has the stock Ruby 12AX7 Select in it right now.

I shall give Watford Valves a bell and see what he recommends - any body swapped there's out , perchance ?

He's on here too Fleabag: @agedhorse 👍

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Yup thats him Ricky, horse, not donkey. Apologies if you're reading this AH :)

Spoke to Derek at Watford Valves and a Sovtek 12 AX7WC is on it's way.

 

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Silly question,  but do you get hissing when there is no pedal in the circuit at all? 

I know this is sacrilege, but try it with just the bass and amp.

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7 hours ago, fleabag said:

Spoke to Derek at Watford Valves and a Sovtek 12 AX7WC is on it's way.

 

Nice, that what I was going to recommend.

Like I always say - You can't go far wrong with a 12 AX7WC.

(whatever that is!?)

👍

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Something to do with a toilet  ..?

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Hissing, especially when it's present on both channels, is unlikely to be the tube (valve). The recommended valve for this amp is a 12AX7A (the AC5 is a selected/graded version, selected for lower noise and lower microphonics). In this circuit, its life expectancy is over 20 years (I designed this amp, so I have a pretty good point of reference here) and I have diagnosed only one defective tube in the last 5 years of the factory service/support program. These amps have a low noise floor, and have been a very reliable with no known issues over the past 10+ years.

Before getting too deep into this whole tube thing, the very first thing I would recommend is systematic troubleshooting. Specific things to eliminate as possible causes external to the amp are: 

1. Is the amp quiet without using any pedals? The most common cause of noise is from pedals, especially compressor pedals. All of the noise generated internally by pedals gets amplified by the amplifier, so a pedal that generates noise ultimately defines the noise floor because this noise is amplified by the total gain of the amplifier. Compressor pedals are especially suspect because the gain reduction circuit (called the gain cell) in the pedal works by starting out with a higher gain under low signal conditions and then reducing the gain as the signal level increases. For every dB of gain cell reduction, this adds a minimum of 1dB of noise to t he noise floor. It's intrusive because the worst noise floor is when there is no signal. This is why high quality pro audio compressors invest so much cost into lower noise circuitry and VCA's, the results are clearly audible.

2. If you are using a lot of treble boost, or if you have the tweeter attenuator all the way up on a cabinet that has an inefficient woofer section, this can make the noise of all preceding electronics appear noisier than they really are. If you are after a bright, in your face tone than this might be something you have to live with, or invest in a line level noise gate inserted into the effects loop. When using a gate, choosing the least amount of gate attenuation as possible to achieve the necessary noise floor improvement will help it sound and feel more natural. A 6dB gate attenuation will cut the noise power by 75%, so generally there is no need to use very deep cuts.

3. If you are using an active bass, be sure that your battery is good. Some active electronics packages can get very noise as the battery voltage falls.

4. If your active bass has eq built in, excessive treble boost can exaggerate noise within the on-board electronics which is then amplified by the amplifier.

5. Is the amp quieter with the tone shaping switches disengaged? Each filter can add a little bit of noise, especially the attack filter when a high amount of attack used.

6.With nothing plugged into your amp except the speaker, is the amp quiet with the channel gain, channel volume, master volume and eq all set to the 12:00 position? When switching between the tube channel and the FET channel, it's normal for there to be a just couple dB more noise in the tube channel.

Where do you typically operate the controls?

 

Hope this helps.

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22 hours ago, Grangur said:

Silly question,  but do you get hissing when there is no pedal in the circuit at all? 

I know this is sacrilege, but try it with just the bass and amp.

Missed this for some reason Gran, apologies, but going into the amp direct does not make a difference

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Posted (edited)

@agedhorse

1. Is the amp quiet without using any pedals?

Yes, the hiss is loud without any pedals.  With the compressor on, its much worse as you mention,  but direct into amp, the tube channel has loud annoying hiss.

2. If you are using a lot of treble boost, or if you have the tweeter attenuator all the way up 

Both treble knobs are off completely.  My PJB cabs dont have tweeter attenuators, although they may have tweeters ? Not sure on that - they're PJB C4 - 4x5"  - 2 cabs

3. If you are using an active bass, be sure that your battery is good. Some active electronics packages can get very noise as the battery voltage falls.

Bass is passive

5. Is the amp quieter with the tone shaping switches disengaged?

No

6.With nothing plugged into your amp except the speaker, is the amp quiet with the channel gain, channel volume, master volume and eq all set to the 12:00 position? When switching between the tube channel and the FET channel, it's normal for there to be a just couple dB more noise in the tube channel.

The only way to stop the hissing is to wind the channel volume off or master volume off. Doesnt matter where the other knobs are. But that was yesterday

Tonight, hissing has almost completely gone.  Maybe it needs warming up ?  How annoying - wonder whats going now now ?

Where do you typically operate the controls? 

I'll be back with a photo - much easier  :)

 

 

Edited by fleabag

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These are my settings and the amp has been warming for 10 - 15 mins now and  cannot hear any hissing unless i stick my ear to the cab. test done with the knobs set in this photo. no bass connected

 

amp.jpg

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Posted (edited)

PS as can be seen , none of the Global switching presets are in use, though i do use the mid-scoop when switching to the FET channel.  That doesnt make any difference, because the loud hiss was coming from the tube channel. When i said the FET channel was quieter, its  a lot quieter. Have to have ears to the cab to hear any hiss from the FET channel.

But having said all that, i wonder whats happened since yesterday - the hiss is now barely audible - i'm about  8ft from the amp right now, tube channel on, and i can only just hear the faintest of hiss.  Yesterday it was so loud, i turned the amp off.

Edited by fleabag

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Posted (edited)

Slightly better photo. Have click on it couple of times for the full size .jpg

 

amp2.jpg

Edited by fleabag

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On 17/04/2019 at 19:14, agedhorse said:

[...] unlikely to be the tube (valve) [...]

I told him it was unlikely to be a valve, but does he ever listen to me? Oh noooo... no he don't...

 

😃

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Posted (edited)

It's dead obvious what the problem is!

Spoiler

There's a snake in the amp & you've woken it up!

smiley

 

 

Edited by Teebs
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Posted (edited)
5 minutes ago, Teebs said:

It's dead obvious what the problem is!

  Hide contents

There's a snake in the amp & you've woken it up!

smiley

 

 

I once had a mouse living in a 2x15 Fender (135) Bassman cab'.

He used to come to gigs and rehearsals with me.

I suppose he was probably deaf.

Hope that helps. 👍

Edited by Ricky 4000
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