bumping this query.
Anyone able to take an educated guess about how it's done?
Search found 54 matches
- Thu Jul 17, 2014 10:43 am
- Forum: Technical Discussion
- Topic: hybrid master-plus
- Replies: 5
- Views: 1699
- Sun Nov 17, 2013 6:33 pm
- Forum: Technical Discussion
- Topic: Corrective filter in 4xEL84 amp
- Replies: 34
- Views: 6216
zener 'Ruby fix' with vvr
just remembered there was also a thread about the feasibility of a variable zener approach similar to Paul Ruby's fix for inclusion in a scaled/vvr'd 18 watt. I believe the outcome was that the modder ended up with testing a succession of zeners and settling on a low value zener which suited the who...
- Sun Nov 17, 2013 6:10 pm
- Forum: Technical Discussion
- Topic: Corrective filter in 4xEL84 amp
- Replies: 34
- Views: 6216
fizzy with low vvr setting
unsurprisingly, there is a lot of info on the 18 watt site about taming the fizz associated with heavily overdriven el84s. I can sympathise with the poster's comments about the swirly fizz at low voltages. I tried all the suggested fixes for dealing with fizz in the 18 watt circuit, including the co...
- Sat Jun 22, 2013 10:15 pm
- Forum: Trainwreck Discussion
- Topic: trainreck on european voltages
- Replies: 3
- Views: 873
Re: trainreck on european voltages
presumably a smaller fuse in the mains supply too
- Sat Mar 16, 2013 10:00 pm
- Forum: Trainwreck Discussion
- Topic: Building a Rocket in the UK
- Replies: 12
- Views: 3124
Re: Building a Rocket in the UK
Steve at valvepower appears to have expanded his transformer line. Follow the link to ebay from the valvepower web page.
- Thu Feb 28, 2013 11:01 am
- Forum: Technical Discussion
- Topic: el85 tubes
- Replies: 3
- Views: 1447
Re: el85 tubes
so, am I correct in assuming I can put the speaker on the next lower tap for these and be reasonably in the ballpark? i.e a typical transformer for an el84 18w amp.
- Tue Feb 26, 2013 8:55 pm
- Forum: Technical Discussion
- Topic: el85 tubes
- Replies: 3
- Views: 1447
el85 tubes
has anyone tried / seen these in a push pull cathode-biased output stage?
I'm trying to get some advice about bias resistor and transformer requirements.
Thanks
I'm trying to get some advice about bias resistor and transformer requirements.
Thanks
- Thu Jul 26, 2012 9:34 am
- Forum: Technical Discussion
- Topic: hotter bias with low plate voltages
- Replies: 3
- Views: 1135
Re: hotter bias with low plate voltages
I was wondering whether it might be another option to consider by those trying to eliminate fizz from their vvr'd el84 power amps
- Wed Jul 25, 2012 3:01 pm
- Forum: Technical Discussion
- Topic: hotter bias with low plate voltages
- Replies: 3
- Views: 1135
hotter bias with low plate voltages
I would be interested to know whether anyone has experimented with hotter than typical bias settings in cathode biased vvr/scaled amps. I'm making the assumption that if you always run your amp at home/practice levels, then the plate voltage will be nowhere near high enough to cause the tube to reac...
- Tue Jul 24, 2012 8:28 pm
- Forum: Technical Discussion
- Topic: Marshall 9100
- Replies: 8
- Views: 3012
Re: Marshall 9100
I'm sure there was a design fault documented for these. Something like the bias supply being the wrong side of a fuse ?? i.e potential for the power tubes to lose bias in an unrelated fault condition. Might be worth checking into and budgeting for a modification.
- Mon Jul 23, 2012 9:52 am
- Forum: Trainwreck Discussion
- Topic: 2x el84 Rocket Trannies
- Replies: 7
- Views: 2312
Re: 2x el84 Rocket Trannies
if you're preferring UK based, Steve at Valvepower has some decent transformers for 18 watt el84 builds
- Tue May 29, 2012 8:09 am
- Forum: Technical Discussion
- Topic: question about power scaling
- Replies: 41
- Views: 12236
Re: question about power scaling
Lindz, thanks for the additional description. Somehow, I need to school myself on these mechanisms a little more. The ultimate 18 watt scaling solution may be within our grasp!
Any chance of some clips?
Any chance of some clips?
- Mon May 28, 2012 8:59 am
- Forum: Technical Discussion
- Topic: question about power scaling
- Replies: 41
- Views: 12236
Re: question about power scaling
So, if I'm following correctly, you've applied a zener that is not within 2 volts of the bias on a fixed bias AND a cathode biased amp, both of which have a Hall vvr fitted. The amps sound normal throughout the vvr range? How low are you going on the vvr? I second the point about hoping we can get a...
- Tue May 22, 2012 11:46 am
- Forum: Technical Discussion
- Topic: question about power scaling
- Replies: 41
- Views: 12236
Re: question about power scaling
After trying different grid resistor values, zobel filter, and higher value el84 cathode resistor bypass cap, the only way I removed the 'vvr dialled down fizzies' was to disconnect the el84 cathode resistor bypass cap altogether. The caveat here is that my amp is permanently run at low vvr settings...
- Tue May 15, 2012 5:01 pm
- Forum: Technical Discussion
- Topic: Amnesia - Which brand has PP with 1 x el84 + 1 x 6v6 ??
- Replies: 7
- Views: 1404
Re: Amnesia - Which brand has PP with 1 x el84 + 1 x 6v6 ??
the rebel has 2x el84 and 2x 6v6 , not one of each sharing the push- pull