I think I killed my Splawn...

SFW

SFW

Well-known member
So I arrived late to band practice tonight. In a hurry to get my gear up and running, I missed the connection from the speaker out to my attenuater. I started the why do I not have sound search on my pedalboard- as that is normally why signal isn’t coming though. A loose cable or something. When I still didn’t have sound I plugged straight into the amp. Nothing. Looked at the back of the amp and saw the cable dangling from the attenuater. HD a holy fuck moment and them plugged the speaker out in to the cab.

So I get full volume sound for about two minutes and then the volume drops in half. Then slowly comes back after about 30 seconds. This repeats about every two minutes. After the fourth time, I shut the amp down. So did I just fry my OT?!!?
 
I assume you have an older Splawn without loop volume? Attenuator can be hard on tranny. I would try powering it on again and if it happens again, bring it to tech.
 
Let the tubes cool down and wait a while, they were trying to match to an infinite impedance which of course isn’t possible. Splawn uses high quality parts so IMO your next step should simply be to let things cool down and try again later, I think you’ll be fine.

If in case it does it again, you’d want to check OT and power tubes both.
 
My 2005 Splawn Competition volume cut in and out like that. I changed the power tubes and it fixed the issue. Not sure if yours might be same issue? Can not having a load connected affect power tubes?
 
Briman24 said:
My 2005 Splawn Competition volume cut in and out like that. I changed the power tubes and it fixed the issue. Not sure if yours might be same issue? Can not having a load connected affect power tubes?
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It can and will, power tubes expect to see a particular output impedance matched to the plate impedance of all conductive tubes in parallel at a time. OT matches the combined plate impedance to the speaker impedance - that’s all it does. So yes, power tubes are put under a lot of internal stress when all of the power generated is then reflected right back at the plate with nowhere to go. It can cause tubes to overheat and depending on the tube, coatings to delaminate.
 
Thanks for the recommendations. I have been running Ruby EL34BHT tubes. Which I cannot seem to locate now...lol! I am highly embarrassed that I made such a foolish mistake.
 
I did something similar years ago, albeit not on a splawn, my tech wound up having to replace power tubes and screen grid resistor that blew but no major damage and I was running it far longer than it sounds like you did...
 
I would say to open the chassis and inspect the SGR, if it's good swap tubes and bias up. I say that in order. Because you need to open up the chassis to bias anyway and if the SGR is the culprit it would take the tube.

Honestly if that doesn't do it, call Scott. Super cool guy and ALWAYS willing to help with a problem. He knows his amps better than anyone.
 
About 10 yrs ago, at a gig I had no sound at sound check. But, I could barely make out the sound as I stood next to the amp. Turns out the speaker cable was out just like the OPs. I had tuned up prior and had sound when I muted with my tuner...sound guy was messing with things and pulled out my cable by mistake. But, it was weird how I could ‘hear’ the amp not attached to any speaker. Very quiet but it was there. After shutting it down, waiting 10 I fired it up and had no issues
 
GOHOINC said:
I did something similar years ago, albeit not on a splawn, my tech wound up having to replace power tubes and screen grid resistor that blew but no major damage and I was running it far longer than it sounds like you did...
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Pretty much what GOHOINC says. Replace the power tubes, check to make sure the each screen grid resistor on the power tube sockets are not open(blown) even if they look good they could be partially open, check these with a multimeter, they are usually 1K ohms 5 watt white ceramic resistors. If all of these are good then start with the new power tubes.

If you still don't have sound or it intermittently fades or fuzzes out then the Output transformer is suspect as well.

I'm sorry this happened to you Splawn as I know it is your favorite amp but I think we all have a story where we forgot to plug in the speaker jack then felt like an idiot. I did it a few times on my 79 2203 over the years, it survived for a long time before it started having issues.
 
Oh man. The FIRST thing I do if I get no sound is to put the amp on standby and check the speaker cable first. :oops:
 
ZEEGLER said:
Oh man. The FIRST thing I do if I get no sound is to put the amp on standby and check the speaker cable first. :oops:
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I haven't made this mistake in 15 years. Lately, if I don't have sound its because something has come loose on my board. So that's why I started there.
 
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Usually when an OT goes it happens fast. I would change power tube, measure screen resistors to make sure one is not cooked and try again.
Just because change your mains fuse and HT fuse. I could tell you a story about an intermittent fuse making connection and then not
 
Good luck SFW.
Saw your thread over on the Pro Boards but can't really help.
Most of my happiness is with the JJs, Mullards and SED =C=
Looks like you are on the right track. A blown screen grid resistor will cause new tubes to fail, so take the advice on checking those.
But the transformers Scott uses are huge. I bet yours has Heyboers too? Your OT should be fine.
One time I had a buddy over and we were swapping heads around and he accidently plugged the speaker cable into the effects send :LOL:
No issue though

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Others mentioned it but I forgot to say to check your High Tension HT fuse as it more than likely blew when the tubes became overstressed because they didn't see the proper load. Even is the HT fuse looks good it can still be bad so replace it anyway when you replace the power tubes.

As glip22 says is probably wouldn't hurt to check and or replace the mains fuse as well.

I would not power up the amp with the old power tubes because they more than likely are damaged to some extent so install some known good tubes even if they are not new for the first power up with the new HT fuse, then go form there.

Usually the HT fuse will blow to protect the Output transformer when the tubes draw too much current and fail. I would be surprised if the Output transformer is damaged Heyboer makes a pretty robust unit.

I have read the Ruby BHT's are no longer being made so you might have a hard time finding them you may have to go with a Russian variant, seems Davie Friedman has been using mostly EH tubes in all of his amp line and feels they are pretty reliable.

Let us know how things work out....:thumbsup:
 
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