TRANSIENT SUPRESSION DIODES

[RCGPNY1]

Whats up with these? I noticed some folks use them....some don't. I understand that they are supposed to protect transformers against no/or
bad load(short-open) situations. I notice Ken Fisher& RJ dont use them-Ceriatone, amongst others do. Is there anything negaive sonically to using them...if not why doesnt everybody use them? Just something else to fail?

[John_P_WI]

Why not ask Bruno?

[morcey2]

I tried using transient suppression diodes, but they still kept showing up. They'd just walk over them because they were so small. I ended up getting a transient suppression german shepherd and a transient suppression taser. No more transients.

[RCGPNY1]

Why not ask Bruno?

I'm just asking...I'm good freinds with Bruno and Andy Fuchs...two guys that are comming from very different places as far as the amps they build( for the most part)and they both have their opinions....why the sarcasm?

[M Fowler]

Andy builds Train 45 and 45 II both TW Express amps with Andy's improvements and features.

I don't install the protection diodes mainly because I haven't had any problems taking out power tubes. They are just a safety measure.

Mark

[John_P_WI]

From my past experience and discussions with Kevin O'Connor and Dante Carrer of Island Amps, there are better methods than the suppression diodes which can be problematic.

[Mark]

Thanks John, these better methods are?

I've heard people complain the diodes can effect the tone of the amp. I have not experienced any tonal changes myself though.

[John_P_WI]

Use a "tethering" resistor, basically a 330k flame proof power resistor strapped from the anode (plate of the power tube) to ground. Supposedly it does a much better job of suppressing the voltage spikes. Quantity two used for push-pull amps, one "each side".

[RCGPNY1]

The first amp I remember seeing them in was Music Man.I used to do about 80% of Fuch's mod wiring for him when he was still working in his house, and we modded quite a few MM's. I was just asking Andy(Fuchs) and he said .."well you have been around good tube gear long enough to not do anything stupid, so you don't need them!" I would imagine as a company has to meet all kinds of codes and make things a little more idiot proof". WE dont want some kid(or ignorant adult) blaming the builder because they forgot to plug in a speaker. As most of us are building for ourselves(or others that we know alot about) I'll pass on the diodes.

[Mark]

Thanks for the reply John. The diode only works once the voltage on the plate drops below ground potential otherwise it's biased off. I'd imagine the 330K resistor is having some effect upon the circuit all the time, why would it suppress voltage spikes?

[John_P_WI]

Mark, there was a very good thread over at the now defunct powerscaling.com, I recall KOC saying something like that the resistor acted similarly to a "tether on balloon" and kept transient voltage spikes in check.

I have a hot rodded liverpool designed with them but did not get it built yet.

Additionally, Dante Carrer of Island Amps used to build wicked bullet proof and chimey amps, believe me, there was no affect on tone with the resistors.