Snubber for single ended OT

[ampbldr2]

I have a High Octane single ended 5 watter that has a ringing OT. The decay of the bass notes result is a fizz type sound riding the note. I am not sure but if I try adding a snubber circuit to the OT primaries will cut down this ringing?

There is some topics on the net for this snubber circuit for push pull output trannies were mine is single ended so not sure what values etc to use.

http://www.tubesandmore.com/sites/defau ... k-snub.pdf

anyone have any experience with this type of issue?

[xtian]

Yes, I built an ax84 SEL (single ended lead) with KT88 output tube. I used a conjunctive filter on the output. From my thread:

https://tubeamparchive.com/viewtopic.ph ... 28d36dd90f

I tried a number of remedies for the fizz, but the clear winner was adding a conjunctive filter (0.03uF and 4.6K 5W in series) across the OT primaries, with an SPST switch.

[Stevem]

If this happens at low volume with clean tones than it's likely a bad preamp tube and or poor connections from tube to socket due to tarnished or dirty pins.

[xtian]

Agreed. The conjunctive filter was useful for high gain and loud.

[ampbldr2]

xtian, in your post you mentioned "adding a conjunctive filter (0.03uF and 4.6K 5W in series) across the OT primaries, with an SPST switch."

What were the other things you tried before settling on the conjunctive filter?
Why do you need a switch on the filter?
How did you solve the values for the filter?

[xtian]

1. sorry, don't remember

2. it was like a bright switch, (darker when engaged) so it was nice to take it out when playing quietly

3. trial and error, starting with values suggested on the intertubez

[cbass]

xtian, in your post you mentioned "adding a conjunctive filter (0.03uF and 4.6K 5W in series) across the OT primaries, with an SPST switch."

How did you solve the values for the filter?

I maybe be uncorrect here but I think the constant change of impedance of your speaker would pretty much make it unpossible to calculate

edited for spelling

[xtian]

[img:500:500]http://makeameme.org/media/created/thats-unpossible.jpg[/img]

[Meat&Beer]

+1 for trial and error. The maths/research/suggestion/ballpark guess told me a cap value, my ears told me they liked a different value better.

Hmmmm... On a switch, ay? Depends on if you're putting it on the primary or secondary, but switching something with HT on it while the amp is on always scares me. Thought I'd just mention that.

[shane]

Well you could of course put the filter on the secondary side...

[Meat&Beer]

Well you could of course put the filter on the secondary side...

Right. I just wanted to mention it is all. Secondary, all good. Primary, I wouldn't put a switch on that...

Sometimes builders put all the output taps on separate jacks. So then, you'd have to use a 3PDT and 2x the parts if you wanted to be able to still utilize all the jacks if need be with the Zobel.

Some use the inpedance selector, in which case, simple. I don't know which style the OP is using on the OT.

[labb]

JMO--The filter would be treating the symptom not the problem. I have built three of the High Octane amps and never had this problem.

[tubeswell]

Have you got a decent-sized, gapped-core SE OT?

[ampbldr2]

I had tried this last night with the only parts i could find (.047/600 and 6.8k/5w). It brought down the fizz alot to were I can barely notice it. I will have to try some other values to see what my ears can hear. I will also try on the secondary to see if that makes a difference. It did cut the high end down a bit but I can add it back with more treble on the dial. I actually like the sound better.

This amp always had this fizz from day one. When I built it I had a bad episode on start up and the pt was omitting some smoke. Later to find one of my IN4007 diodes was internally shorted (ouch). The PT still works and later moved to UF4007 diodes. The OT was from Musical Power Supplies and they may have used cheep wire, parts etc.