That's a very subjective question, but...
Ultralinear is a way of connecting a pentode in a 'triode-ish' way. It is also a form of local feedback. It will sound different.
You will have less power, as it is less efficient. It does, however, have more power than triode-strapping the screen.
Try it, and tell us your impressions. You could also try it triode-strapped, it too is quite simple. I would like to read about your results!
Ultralinear is a way of connecting a pentode in a 'triode-ish' way. It is also a form of local feedback. It will sound different.
You will have less power, as it is less efficient. It does, however, have more power than triode-strapping the screen.
Try it, and tell us your impressions. You could also try it triode-strapped, it too is quite simple. I would like to read about your results!
A totally unrelated question. I've included a bleeder resistor for the testing stages. The resistor is tied from the B+ on the large cap to ground. Can I leave the resistor in place or do people normally remove them? (Not sure if it affects performance?)
If keeping the resistor - what is a good value?
Thanks for all the help.
If keeping the resistor - what is a good value?
Thanks for all the help.
Bleeders are a good safety measure. I leave them in (but I also always check with a meter before touching anything). The ideal size depends on the size of the cap you are bleeding down.
I hope you are enjoying the amp. I sure like mine!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I hope you are enjoying the amp. I sure like mine!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Done!
Well, the amp is done!
I ended up using a 5H Hammond choke (158Q), Antek power transformer (275-0-275v for 292v on B+) and Edcor GXSE 15w transformers. Fostex 206en speakers are almost dead-quiet in spite of their high efficiency. I am using 47uf on the first cap and 100+100uf on the second cap. (Similar to RH84 schematic.)
Overall this is a noticeable improvement over my old Miniwatt N3. More bass response and the music is more 'energetic'. Better detail as well. Response is from a tad below 30hz up to about 19khz.
BTW - I am using a 100k resistor for the bleeder resistor.
Well, the amp is done!
I ended up using a 5H Hammond choke (158Q), Antek power transformer (275-0-275v for 292v on B+) and Edcor GXSE 15w transformers. Fostex 206en speakers are almost dead-quiet in spite of their high efficiency. I am using 47uf on the first cap and 100+100uf on the second cap. (Similar to RH84 schematic.)
Overall this is a noticeable improvement over my old Miniwatt N3. More bass response and the music is more 'energetic'. Better detail as well. Response is from a tad below 30hz up to about 19khz.
BTW - I am using a 100k resistor for the bleeder resistor.
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Wow, that is snug! Tube amps can be darn quiet. My RH84 versions are quieter than any chip amp or class-t I've tried, and noise is obnoxious on high-efficiency speakers!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Nice build! I love small chassis (chassi?) asthetically.
Very happy to hear that it's up and working well.
A suggestion, but emphatic -- don't make any changes (Transformer hookups, specifically) until the unit is all good and broken-in. Then fiddle as much as you want, but only make one change at a time. That way you can understand what the changes actually sound like.
Very happy to hear that it's up and working well.
A suggestion, but emphatic -- don't make any changes (Transformer hookups, specifically) until the unit is all good and broken-in. Then fiddle as much as you want, but only make one change at a time. That way you can understand what the changes actually sound like.
That should be about right. You might also consider removing the 100K Rfb as well.
The closer you get to a direct connection between screen and plate, the more it will be like 'true' triode connection. As I understand it, the low-value resistor (100 ohms?) is to forestall potential oscillation problems.
For comparison, a Champ 6V6 (pentode-connected) has the screen connected via a 25k resistor (RC filter) to the B+.
Will try this amp for a first not-kit build also - it has a seductively simple schematic and looks like I might be able to do it without blowing myself up. Question: I've built PCB amps in the past but would like to try hard-wiring. How does one go about it, just try to replicate the schematic with wires and components, or should I use a tag board? (I'm sure this question has been asked before the but the search on this forum baffles me.) Finally, can this amp be used without a preamp - and if I do put a pot or stepped attenuator what value would be optimal? Thanks in advance for helping a beginner.
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