Yorkville XS800H (hiss) need advice

[cwmont]

Hi

I have a Yorkville / Traynor XS800H that has a hissing sound in the background that is audible while the amp is at idle. It sounds like white noise. It stops when the mute switch is on but otherwise is present even if the gain and tone controls are all the way off.

Power and tonewise the amp is performing as it always has. I've checked all the connections and tried a different 12AX7 to make sure it's not the tube. I also tried all the tone, volume, other controls and switches to see if any of them were causing the hiss. The chassis is clean inside and all connections are tight. Other than the hiss, there are no snaps, crackles, or pops in the amp.

I also tried all the usual stuff. Different basses, cords, effects all with the same result. Still has the hiss.

I'm thinking it's something in the power section causing this but don't exactly know. Has anyone else had had a problem like this with this model amp? Or does anyone have an idea what might be causing the hiss?


TIA

[Enzo]

I don't know the amp, but by your mention of "the tube" can I assume it is largely solid state with one tube in the preamp for tone?

My first thought is a noisy op amp in the signal path.

[Garydean]

A long shot but, have your tried jumping the effects send and receive to see if it goes away? Those jacks may be dirty. Once I replaced that single 12AX7 with a good old school Sylvania brand tube and that worked.

Enzo's suggestion!!
I've also had a few Valve-state Marshalls with noisy Op Amps, swapped them out and that worked.

[cwmont]

I don't know the amp, but by your mention of "the tube" can I assume it is largely solid state with one tube in the preamp for tone?

My first thought is a noisy op amp in the signal path.

Yes. You are correct. The Traynor has a single 12ax7 with SS output.

Carl

[cwmont]

A long shot but, have your tried jumping the effects send and receive to see if it goes away? Those jacks may be dirty. Once I replaced that single 12AX7 with a good old school Sylvania brand tube and that worked.

Enzo's suggestion!!
I've also had a few Valve-state Marshalls with noisy Op Amps, swapped them out and that worked.

I'll try the suggestion tonight and post up the results.

Carl

[cwmont]

Yorkville Hiss

OK here we go.

I tried patching the effects send/return with no effect (pardon the pun) still hisses. Preamp out from another amp to "amp in" on the traynor and I get hiss. Using the effect send of the Traynor to the power amp in of another amp, no hiss on the other amp but hiss from the traynor.

With the speakers unplugged from the Traynor, the signal going from the Traynor effect send to the other amp is nice and quiet with no hiss.

I'm still thinking it's in the power amp section somewhere.

Any ideas where to start looking? I downloaded the schematic from Traynor and I have to admit that I'm not the best at reading one. I'm decent with a meter and soldering iron and usually can get something fixed if pointed in the right direction. If it is an op-amp as Enzo suggested and they are socketed, I can probably get it going. I've replaced soldered IC's and components on PCB's before so no problem there either.

I hate to have to box this thing up and send it in if it's possibly something as simple as replacing an op-amp.


Any ideas or suggestions are appreciated.

Carl

[Enzo]

OK, so if you plug something into the AMP IN jack, it still hisses, so the trouble is after the AMP IN jack. That is mostly the power amp, but there are a bunch of ICs in between here and there.

The AMP IN jack is on page 13, lower right. From there the signal path flows through: U7c, the master volume, ... wait. Does the master turn th hiss down? if not, it is after the master. COntinuing: Then U6b, and off the page as AMP-IN.

From there we travel to page 9, where AMP-IN continues from the left at pin 7 of that connector. From there through U4B, the U1A:A, and U1A:B, and finally U3A and off the page to the right as AMP-SIGNAL.

Finally we hit the power amp on page 8, where AMP-SIGNAL enters at left and flows through U3D and then on into the transistors of the power amp.

In my experience, transistors don't usually get hissy. They can sure get noisy, but I wouldn't call it hiss as a rule. But noisy op amps often make noise you'd call hiss.

SO between the AMP ON jack and the power amp are all those op amps I mentioned: U7, U4, U1, U3. I wouldn't have any trouble locating which stage it might be at, but describing those techniques to a novice might be difficult. They involve using a scope, selective signal path grounding - with or without a cap involved.

[cwmont]

OK, so if you plug something into the AMP IN jack, it still hisses, so the trouble is after the AMP IN jack. That is mostly the power amp, but there are a bunch of ICs in between here and there.

The AMP IN jack is on page 13, lower right. From there the signal path flows through: U7c, the master volume, ... wait. Does the master turn th hiss down? if not, it is after the master. COntinuing: Then U6b, and off the page as AMP-IN.

From there we travel to page 9, where AMP-IN continues from the left at pin 7 of that connector. From there through U4B, the U1A:A, and U1A:B, and finally U3A and off the page to the right as AMP-SIGNAL.

Finally we hit the power amp on page 8, where AMP-SIGNAL enters at left and flows through U3D and then on into the transistors of the power amp.

In my experience, transistors don't usually get hissy. They can sure get noisy, but I wouldn't call it hiss as a rule. But noisy op amps often make noise you'd call hiss.

SO between the AMP ON jack and the power amp are all those op amps I mentioned: U7, U4, U1, U3. I wouldn't have any trouble locating which stage it might be at, but describing those techniques to a novice might be difficult. They involve using a scope, selective signal path grounding - with or without a cap involved.

Enzo

The hiss is present even with the master vol down all the way but DOES increase in volume as the master is turned up. It's never loud enough to be heard while playing but can always be heard whenever the amp is just sitting with no input. If you think it might be an op-amp, I'm up for swapping them out. I've done similar on a Music Man amp I owned before. Did a replacement set of driver transistors, op-amps and filter caps on that one. Actually turned out quite nice. I can't remember if the op-amp's are socketed in this amp or not. If so maybe I can swap em out.

As always your help is appreciated.

Carl

[Enzo]

All those ICs are not identical, so if replacing any, please note what types each might be.

[cwmont]

All those ICs are not identical, so if replacing any, please note what types each might be.

Enzo

Thanks. I already took a look at the schematic noting the signal path you mentioned. I also took a look at the the layout drawings so I know what I'm looking at and made a note of which IC's are where and their types. I'll take a look inside tonight.

My dealer contacted Traynor as the amp is under warranty. It seems that even though I live in an area where the greater population is in the millions, Traynor has no warranty centers here. My choices are shipping the amp back in for repair either to the dealer (out of town) or back to Traynor. Both of which are to be honest a hassle.

I don't know which is sadder. That an amp less than 1 1/2 years old with less than 30 hours of play time and has always been racked and never dropped is crapping out, or that Traynor doesn't have a service dealer here.

I think a new amp is in my future.

Carl

[Enzo]

And we have no idea what level of noise is normal for the amp.

Do you have a trusted amp repair shop for other brands? You might contact one of them and ask if they would consider signing up as a Traynor/Yorkville repair center. It won't cost them anything, and if they are any kind of shop at all, they are already authorized to fix something. so they know the routine. I have personally been recruited to become an authorized repair center for a couple brands, but for the most part, shops ask the manufacturers to become a service center, the factories don't usually look in the yellow pages for shops to recruit. SO if no one in your area asked to become one, there won't be one.

A lot of service centers are dealer repair shops. If no one sells Traynor in your area, there is less likelihood there will be a shop for that reason. A shop that has authorizations from a few major brands would have no trouble getting approved immediately. And then you'd have a local repair center.

A long time ago, I got a letter from Kustom asking if we would like to become one of their service centers. I immediately said yes, why not? After 5 years, the listing expired, and I did not bother to renew it. WHy? Because in all the 5 years, I never saw a single Kustom product for service. At least not one under 30 years old. If someone local started selling Kustom, I'd sign back up. SO without local sales, most shops won't bother to get listed unless they see a lot of itinerant bands or they want to pad their resume.

But ask anyway.

[cwmont]

And we have no idea what level of noise is normal for the amp.

Do you have a trusted amp repair shop for other brands? You might contact one of them and ask if they would consider signing up as a Traynor/Yorkville repair center. It won't cost them anything, and if they are any kind of shop at all, they are already authorized to fix something. so they know the routine. I have personally been recruited to become an authorized repair center for a couple brands, but for the most part, shops ask the manufacturers to become a service center, the factories don't usually look in the yellow pages for shops to recruit. SO if no one in your area asked to become one, there won't be one.

A lot of service centers are dealer repair shops. If no one sells Traynor in your area, there is less likelihood there will be a shop for that reason. A shop that has authorizations from a few major brands would have no trouble getting approved immediately. And then you'd have a local repair center.

A long time ago, I got a letter from Kustom asking if we would like to become one of their service centers. I immediately said yes, why not? After 5 years, the listing expired, and I did not bother to renew it. WHy? Because in all the 5 years, I never saw a single Kustom product for service. At least not one under 30 years old. If someone local started selling Kustom, I'd sign back up. SO without local sales, most shops won't bother to get listed unless they see a lot of itinerant bands or they want to pad their resume.

But ask anyway.

Enzo

True regarding the noise level. I read some reviews and comments where a few users reported that the power section noise level on these amps was higher than they liked.

No dealers stock any of the Traynor stuff here, so that IS probably the reason for the lack of authorized service center. The major retailers here are Sam Ash and GC so the local shops work with them for service.

I'm just going to send the Traynor in for service. I'm looking for a new head that I can get serviced locally if I ever need to.

I find myself looking at the Genz Benz GBE 750 more and more lately.

Carl