I'd just bung it across on the track side.Thermionic Idler wrote: ↑Mon Nov 11, 2019 12:39 pm Thanks Mike - might be worth a try. This bit is on the PCB so adding it could be a touch fiddly.
Dieselpunk Preamp of Doom and the Beast with Two Backs
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#286 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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#287 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
What frequency is the oscillation at?
If we're over a few 100 kHz, then just using a suitable ferrite bead close to the first grid may well be enough. Won't effect AF at all but will kill most RF.
I use these: https://uk.farnell.com/wurth-elektronik ... dp/1635667
Never notice any audible difference from the insertion, but they kill RF. I've given some to other group members who have used them with success.
If we're over a few 100 kHz, then just using a suitable ferrite bead close to the first grid may well be enough. Won't effect AF at all but will kill most RF.
I use these: https://uk.farnell.com/wurth-elektronik ... dp/1635667
Never notice any audible difference from the insertion, but they kill RF. I've given some to other group members who have used them with success.
Vivitur ingenio, caetera mortis erunt
#288 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
Already asked that question.What frequency is the oscillation at?
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#289 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
116.2khz calculated, says it in a post on the last page
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#290 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
Forgot about ferrite beads. Good thought.
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#291 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
Sadly it's a double sided PCB with insulated tracks...Mike H wrote: ↑Mon Nov 11, 2019 2:03 pmI'd just bung it across on the track side.Thermionic Idler wrote: ↑Mon Nov 11, 2019 12:39 pm Thanks Mike - might be worth a try. This bit is on the PCB so adding it could be a touch fiddly.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
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Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
#292 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
I think Mike means the side without components. You can scrape the resist of the tracks if there isn't a convenient soldered point.Thermionic Idler wrote: ↑Tue Nov 12, 2019 2:32 pmSadly it's a double sided PCB with insulated tracks...Mike H wrote: ↑Mon Nov 11, 2019 2:03 pmI'd just bung it across on the track side.Thermionic Idler wrote: ↑Mon Nov 11, 2019 12:39 pm Thanks Mike - might be worth a try. This bit is on the PCB so adding it could be a touch fiddly.
is there any frequency compensation in the feedback loop?
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#293 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
Good point Nick.Nick wrote: ↑Tue Nov 12, 2019 2:39 pmI think Mike means the side without components. You can scrape the resist of the tracks if there isn't a convenient soldered point.Thermionic Idler wrote: ↑Tue Nov 12, 2019 2:32 pmSadly it's a double sided PCB with insulated tracks...
is there any frequency compensation in the feedback loop?
I believe there is but I'm not sure I understand the circuit well enough to be sure. I'm sending you a PM.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
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#294 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
LOL ..
Obviously it seems er, obvious, only to me
What I meant was:
Presumably there is a solder pad for V1A anode. Also presumably, there is a solder pad for C10 positive end wire. Solder the small cap between those two. If too far apart, add on a bit of wire. Seemples.
Obviously it seems er, obvious, only to me
What I meant was:
Presumably there is a solder pad for V1A anode. Also presumably, there is a solder pad for C10 positive end wire. Solder the small cap between those two. If too far apart, add on a bit of wire. Seemples.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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#295 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
Thanks - missed that - bit late to this party...
Quite possible that there's something far higher going on and that 'scope can't see it. I'd definitely try the ferrite beads.
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#296 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
What is the bandwidth of the oscilloscope?
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#297 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
My point entirely...
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#298 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
It's a second-hand Tektronix 466 which apparently goes up to 100 MHz, or at least it did when it was new. I might need to get better probe connectors for it though, the one it came with disintegrated a few years ago and I bought rather cheap replacements...
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
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#299 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
OK fairy nuff!
Any higher RF stuff should be noticeable then.
Any higher RF stuff should be noticeable then.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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#300 Re: Dieselpunk Preamp of Doom and the Beast with Two Backs
Maybe. Maybe not!
I would try the beads for sure.
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