Suhr

[Alistair]

Having received my PT 100 Signature Edition last July, I finally got a Reactive Load on Monday. I connected everything up as per the instructions and tried to do some recording but nothing came through the XLR output and I could hear what sounded like tube squeal coming from the RL, so I switched everything off. I then tried to get the amp to play normally to check it was OK and, despite powering on, no noise came from the speakers. The lights were all on and the tubes glowing but not a sound.

I checked the HT fuse and, sure enough, it had blown, so I've replaced that with a similar 2amp/250V fast blow fuse and everything seems to be fine. I do think the gain channels sound a bit "flat" though. Hard to describe and could just be me being paranoid, but I've ordered a new set of power tubes from Ed at customer services, but it got me thinking. Does the PT100 have any protection against the load failing? I'm assuming that, during recording, a faulty power tube just went and took the fuse with it, but I've also had a Rivera Rockcrusher attached to the PT100 that produced weird noises when no input was going through it which may also have been that bad tube, but if either of these devices was faulty and not letting the amp see a load, could there be any other damage, such as the output transformer? Or could any damage have previously occurred to it before I bought it? I'm always paranoid about having a speaker attached but I know most stores really aren't, at times, and I've read stories of amps being switched over in shops to do an A to B demo without switching them off.

Which is all a long winded way of asking whether the PT100 has any inbuilt protection against harmful voltage reflections? I know Fender have output jack protection for when no cable is attached, Koch use a dummy load and Peavey were using flyback diodes in their amps. Do we have anything similar?

Hopefully everything will be fine once the tubes are replaced and I can carry on as per normal. But won't be connecting the Reactive Load until I'm happy it was just a tube, just in case there's a fault.

[cs@suhr.com]

Hi Alistair, we are sorry to hear about the recent trouble. Based on your description of the issue, it doesn't sound like you damaged the amplifier. It may be coincidence that the fuse blew when connected with the Reactive Load. Sometimes power tubes can short, or the fuse can fatigue and fail. The HT fuse is there to prevent excessive current from damaging the amplifier.

The PT100 output transformer is quite resilient and if it is damaged, it will be obvious because the amp won't sound anywhere close to normal. Based on your description, it doesn't sound like the output transformer is damaged.

It is normal to hear some sound coming from the Reactive Load itself or the amp's output transformer during play. That does not indicate a failure of the amp or Reactive Load. All amps do this even when connected to a cabinet, but the speakers overpower the transformer noise.

I know we have some new tubes on the way to you and our recommendation in the interim is to try the Reactive Load again. You can try a different amp, or run the PT100 at a low volume, but let's make sure you are getting signal through the Reactive Load.

What are you plugging the Reactive Load into?

Do you see the blue light on the Reactive Load light up when you are playing through it?
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Customer Service
JS Technologies / Suhr

[Alistair]

Thanks for the reply and John has also put my mind much more at rest on one of the Facebook groups as well.

I'm running it through a Focusrite Scarlet 2i2 then into a Macbook Pro running Logic X. Managed to get some sounds coming through tonight and it's sounding much better. I do seem to be getting a clicking coming through the speaker on channel 1, though , so those valves are a definite necessity, just to be safe!

I'm beginning to think there's a faulty one in there and pushing the amp a bit more through the load made it take out the fuse. Seems to be intermittent though. I'll keep the volume down until the new tubes arrive. And then it's into the horrible world of which IR to use and what to mix with what!

[Suhr]