Is a SVT Pro 7 supposed to hiss this much?

[Marcus Cornall]

I changed the tube,but the hiss was still the same.There was a small metal Bush loose inside.couldnt find anywhere it had detached from.

I found there are no SVT 7 pros available new for 2 month

I thought of a Minimega instead.Also seemingly not available for same period.

Do all amp manufacturers go on a works holiday or  something? 

So now choices a keep a hiss amp,

What 2 months and spend double just to possibly end up with the same hiss, 

Wait 2 months for a minimega

Or abscond to Markbass or someone else, just because their amps are actually available.!

Thanks everyone for your input anyway.

[BassmanPaul]

The Pandemic has caused a huge rift in the electronic parts supply chain.  This is affecting products being made and released across the world from cars and trucks to yes, bass amplifiers

[Elfrasho]

I'm sure this has already been covered but if the tweeter is adjustable I'd do that. Or even try it with a different cab just to see if it's the cab that's emphasising the hiss.

 

Also... have you tried it out in the wild yet? A hiss at house volumes will seem far worse than once you actually crank the amp at a rehearsal or gig?

[MrDinsdale]

Might help if you could record a clip of the hiss along with some playing to compare. Maybe people will be in a better position to help assess if it's to be expected. 

[Marcus Cornall]

Thanks guys.

On 07/04/2023 at 18:35, BassmanPaul said:

The Pandemic has caused a huge rift in the electronic parts supply chain.  This is affecting products being made and released across the world from cars and trucks to yes, bass amplifiers

Of course I am mindful of how things have been affected.I just found it strange considering giant brands presumably hold huge stocks and manufacture large amounts of units,that it affected several amps at once.Perhaps they share chips?

 

On 08/04/2023 at 08:09, Elfrasho said:

I'm sure this has already been covered but if the tweeter is adjustable I'd do that. Or even try it with a different cab just to see if it's the cab that's emphasising the hiss.

 

Also... have you tried it out in the wild yet? A hiss at house volumes will seem far worse than once you actually crank the amp at a rehearsal or gig?

Yes,it has ,but thanks.If I turn the tweeter down it goes away.Fine for my current gig,but I do some gigs where I need a lot of treble (Geddy type tone) and think it  might be an issue then.

And no I haven't tried it in the wild yet,and that's a very good point.

 

21 hours ago, MrDinsdale said:

Might help if you could record a clip of the hiss along with some playing to compare. Maybe people will be in a better position to help assess if it's to be expected. 

It's difficult for me to record here at suitable quality.but the other thing is,the hiss goes with the master, so I could put that up half and the gain at,say half,and get one relative level of hiss, and then turn the volmdown and the gain up and get the same volume but with less hiss, so I don't know if it would help.

But thanks for being willing to listen to it in order to help.

 

[Reggaebass]

Hi Marcus, I never use the tweeter on my bb2 it’s permanently off as I find it quite a clean sound anyway, have you tried it with it off and the treble up on your amp for the highs you want , do you still get the hiss 

Edited April 9, 2023 by Reggaebass

[Marcus Cornall]

4 hours ago, Reggaebass said:

Hi Marcus, I never use the tweeter on my bb2 it’s permanently off as I find it quite a clean sound anyway, have you tried it with it off and the treble up on your amp for the highs you want , do you still get the hiss 

Hello ! Good to hear from you. Youve been really supportive man NUFF RESPECT!

Well, if I turn the tweeter down much of it goes away.there's a little bit left coming from the woofer although it's 'grey noise/ upper mid hiss .'

 

It goes away slightly more if I leave the tweeter up but put the treble down.

 

I hadnt actually tried your suggestion of turning the tweeter off but the treble up! 

I tried it just now.i get more of the grey hiss in the woofer.

For what we're doing I wouldn't turn the tweeter on,and would have the treble off as well.

I do take the points that I haven't used it at a gig and yes you hear far more at home. 

And that if you're going to amplify a signal to 600w the innate gain of that is a lot bigger than  your hifi,so you'll hear more noise floor.

And that all amps hiss,especially through a good tweeter.

 

On the other hand, I might be getting more noise than I should be. 

I don't know how I can know without a lot of hassle.

 

So at the moment I am inclined towards keeping it,using it for my current gig, as that was the purpose of buying it. And if I ever did a Prog gig with it, I'd just make sure they DI'd it,as it would sound nasty mic'ed with the treble and tweeter up!

And maybe i'll get something else quiet for at home and recording. 

 

[Reggaebass]

It’s a tricky one isn’t it, not knowing whether it’s how they are or if it’s something else, i think @beastie had one a few years back, perhaps he could advise 

[Beedster]

Bottom line is that there is no objective measure of noise here, I’ve owned units by PJB, Markbass, Fender, and many others whose hiss and/or fan noise was too much, while I’m sure to others the levels were tolerable. None were faulty per se but each was moved on.

[BassmanPaul]

As your years of playing live music passes, less and less will hiss be a factor or even heard!

[Downunderwonder]

On 01/04/2023 at 14:59, Downunderwonder said:

Danger Will Robinson!!!

I just noticed the date on this exchange. Seriously?!?

 

What is up with everyone ignoring the rattle of presumably conductive parts inside this amp?

 

Or am I the April Fool?

[Marcus Cornall]

23 hours ago, Reggaebass said:

Thanks again guys.

15 hours ago, Reggaebass said:

It’s a tricky one isn’t it, not knowing whether it’s how they are or if it’s something else, i think @beastie had one a few years back, perhaps he could advise 

yes,that's the position.and thankfully ,he did...

 

12 hours ago, Beedster said:

Bottom line is that there is no objective measure of noise here, I’ve owned units by PJB, Markbass, Fender, and many others whose hiss and/or fan noise was too much, while I’m sure to others the levels were tolerable. None were faulty per se but each was moved on.

Thanks that's a really good way to look at things. 

 

11 hours ago, BassmanPaul said:

As your years of playing live music passes, less and less will hiss be a factor or even heard!

Ahaha! Sorry,what was that? I have still got treble up to about 18k.i've been  careful, and lucky.but yeah eventually it will al go ,and then at least this won't be an issue.

 

9 hours ago, Downunderwonder said:

I just noticed the date on this exchange. Seriously?!?

 

What is up with everyone ignoring the rattle of presumably conductive parts inside this amp?

 

Or am I the April Fool?

No, you are not the April fool,and no I didn't forget that.I'm sorry I thought I had posted about it.

It turned out to be a little metal sleeve encased in some mangled plastic.i'm attaching a couple of pictures. It doesn't look like a component. I can't find anywhere where there's a part like it or a gap where it should be.

When you say conductive,then yes since it's metal.

It was in the bottom of the tray below the boards when I turned it on,so it wouldn't have shorted anything. Or do you mean it's conductivity implies it'll be missed if it did break off? And please forgive my lack of knowledge of circuitry.

I suppose I sort of discounted it as being responsible,and now feel a bit dumb.

[Downunderwonder]

Hopefully it's random junk but it is kinda looking like an electronic part with code so worth another go.

 

The camera is picking up and focusing on texture and writing on your background rather than the item itself. Can you trick it into the right plane of focus?

[Downunderwonder]

My eyesight improved and I can make out VAC so it's definitely something electronic...

[Marcus Cornall]

DOWNUNDERWONDER you certainly deserve your name! 

You've solved it.I am eternally grateful .

There's NOTHING wrong with your eyes.

I hadnt even made out writing ,and I wear reading glasses.

I worked out how to zoom on my tablet camera, and here are the results,and oh dear.lots of writing and yes it is a component.

So back it goes.

Here are the pics.i could only make it out when I zoomed.

 

[paul_5]

That was an electrolytic capacitor, it certainly shouldn’t look like that!

[Chienmortbb]

Where did it come from? What I mean is the component reference i.e. C1-C302 etc.

[Marcus Cornall]

6 minutes ago, paul_5 said:

That was an electrolytic capacitor, it certainly shouldn’t look like that!

Thanks.i read 'uF' on there and thought I remembered that as a capacitor.

Have messaged the guy and told him it's going back. He has already said he would give me a refund.

[Marcus Cornall]

38 minutes ago, Chienmortbb said:

Where did it come from? What I mean is the component reference i.e. C1-C302 etc.

It was rattling about inside the amp.

[DGBass]

It's definitely the remnant of an electrolytic capacitor. Difficult to tell the rating but I can make out a 47uf or maybe 0.47uf rating and maybe 25V or 250V voltage rating. There isn't anything anywhere near those ratings on the pre-amp schematic. On the power amp schematic there are a few possibilities

 

C141   0.47 250V

C173  0.47 250V

C25     47uf 25V

 

I'm not familiar enough with these amps ( class D design possibly as it uses a pair of IRS209555 driver chips ). Whatever happened to the suspect cap, it must have let go in a spectactular fashion as the pressure cap is completely gone as are the leads that connected it to the board. Odds on if it came from your amp, there will be a couple of stubby wires protruding from the board somewhere. C25 looks the most likely candidate as the other caps C141 and C173 are integral to the driver chip circuits and i'm guessing the amp might not work at all if those failed. Class D amps by design require noise filtering because of the high frequencys involved in their workings. I know its probably not helpful but if I was to venture into non full blown tube SVT territory, I'd plump for the tube pre-amp class A/B power amp SVT3 Pro and give the class D SVT7 Pro a wide berth. I'm sure the SVT7 Pro is a capable enough amp, and a good replacement might be just what you are after. If its going back to where it came from at least you'll have an option to think about a replacement amp whether thats Ampeg or something else.

 

[Marcus Cornall]

25 minutes ago, DGBass said:

It's definitely the remnant of an electrolytic capacitor. Difficult to tell the rating but I can make out a 47uf or maybe 0.47uf rating and maybe 25V or 250V voltage rating. There isn't anything anywhere near those ratings on the pre-amp schematic. On the power amp schematic there are a few possibilities

 

C141   0.47 250V

C173  0.47 250V

C25     47uf 25V

 

I'm not familiar enough with these amps ( class D design possibly as it uses a pair of IRS209555 driver chips ). Whatever happened to the suspect cap, it must have let go in a spectactular fashion as the pressure cap is completely gone as are the leads that connected it to the board. Odds on if it came from your amp, there will be a couple of stubby wires protruding from the board somewhere. C25 looks the most likely candidate as the other caps C141 and C173 are integral to the driver chip circuits and i'm guessing the amp might not work at all if those failed. Class D amps by design require noise filtering because of the high frequencys involved in their workings. I know its probably not helpful but if I was to venture into non full blown tube SVT territory, I'd plump for the tube pre-amp class A/B power amp SVT3 Pro and give the class D SVT7 Pro a wide berth. I'm sure the SVT7 Pro is a capable enough amp, and a good replacement might be just what you are after. If its going back to where it came from at least you'll have an option to think about a replacement amp whether thats Ampeg or something else.

 

That's so UNBELIEVABLY kind ,helpful and insightful and I  ant thank you enough.

Your knowledge of these things is obviously consumate.

I am going to relook at the 3 pro.

I was trying to keep weight down, and then there's the cab- I have a Barefaced Big Baby Ii ,And it's able take 800w. The designer recommends 600w to get the maximum out of it. I am unsure if a lower wattage amp will give me enough ,given jt's only putting out some but not all it's potential.

I dont play stupidly loud onstage,but it's Reggae and I have learned that the bigger wattage is to deliver the bigger lows (I hope I have that right.it's all been a steep learning curve as I am replacing a 30yr old rig of low quality and dont have experience of other amps and cabs.

I will say that the BB II is AMAZING. Such deep clear lows and seeminlgy instant transient response.a total revelation.

I chose the 7 Pro as it gave 600w at 8 ohms,and I wanted the kind of colour you get from ampegs.(I rehearse with someone else's pf350) 

It's a whole other can of worms I know.

I am beginning to feel like I ought to avoid class D .

Thanks again SO MUCH for your input here.

[Marcus Cornall]

The help inhave had here has been just outstanding! Thankyou so much. And your time was not wasted.i have learned a great deal from the experience.

Especially not to be such an idiot, and to magnify any loose bits immediately:) 

[DGBass]

Just for info, I had a look at the SVT7 Pro SMPS power board schematic and there are a few possibilities on it for similar spec caps as well. It's the age old issue of trying to figure out whats wrong from a forum post and the SVT7 Pro is also fairly complex bit of kit anyway. A Tech and some bench time are probably the best option when it comes down to it if you have an amp problem. I wouldn't write off class D, I've used Markbass kit as an example regularly and it was very impressive and reliable in my experience. 

[Marcus Cornall]

4 hours ago, DGBass said:

Just for info, I had a look at the SVT7 Pro SMPS power board schematic and there are a few possibilities on it for similar spec caps as well. It's the age old issue of trying to figure out whats wrong from a forum post and the SVT7 Pro is also fairly complex bit of kit anyway. A Tech and some bench time are probably the best option when it comes down to it if you have an amp problem. I wouldn't write off class D, I've used Markbass kit as an example regularly and it was very impressive and reliable in my experience. 

Thanks again .I' d say you'd managed the diagnosis pretty well! The seller intends to have it repaired ,and was grateful that I had told him what you had said about it.

[Downunderwonder]

I wouldn't expect output from a power stage that's had a capacitor go MIA. Maybe have another look through the preamp schematic?