The package has arrived today! Many thanks to Nelson Pass and Qwertyl for making this happen.
Built into a test bed chassis 'just to see' rather listen...very very nice indeed but I do have an issue with ringing errrr. I have tried double sided foam beneath as per Jim's build notes but Ive had to resort to blue tac under and a slab on top of the nutube though this has cured 90% of the issue at higher vol levels it creeps in..I know the answer is to listen at lower vols levels but.... Any ideas guys.
Attachments
In addition to the foam, I am going to try use rubber grommets as stand offs rather than metal ones. That may add a little dampening. For my turntables in past years when the floor and rack were too sensitive, I have built an open bottom wooden platform and placed inside it a partially inflated inner tube. Works wonderfully. Of course this unit is so small, but maybe float it on some kind of air filled or gel pad or bubble wrap. It really comes down to devising a vibration absorbing suspension system. Some type of springs under the board may help.
I also got my package today and also thank you to Nelson Pass and Qwerty for this nice Christmas present!!
I have some 2200uF/50V in stock I want to use as the large capacitors on Korg PCB. But my caps has 7.5 mm leg spacing and on PCB it is 5 mm. Is there a trick or a tool which can decrease the leg spacing so it still looks nice?
As E-caps has short shelf live it would be good to use those I have "on the shelf".
I have some 2200uF/50V in stock I want to use as the large capacitors on Korg PCB. But my caps has 7.5 mm leg spacing and on PCB it is 5 mm. Is there a trick or a tool which can decrease the leg spacing so it still looks nice?
As E-caps has short shelf live it would be good to use those I have "on the shelf".
Some might have an interest in a relay circuit for slow-on fast-off to
suppress output thumps, posted here:
LX-mini Crossover Article
suppress output thumps, posted here:
LX-mini Crossover Article
Pass DIY Addict
Joined 2000
Paid Member
... Or just a few dabs on corners of Sikaflex or similar compound
Attachments
Thanks Nelson, I’ll give it go.
And many thanks for making this available to us. Just the first day in and for the DIYer vinyl spinning enthusiast, it is a must have or should be on their list as a must have along with a pearl II (and a LXmini in an active system) for a sublime listening experience.
I await the next instalment ( if any) of your ongoing project releases, in what ever form.
😃👏🏾👏🏾👏🏾
Oh Yeah the glue!
Show on the photo at: 6moons: audioreviews FirstWatt B1 with Nutube
This preamplifier is working the best if kept away from direct physical contact with vibrating:
CD-players, loudspeakers, big power transformers etc.
Like most of the vacuum tubes 😀 Chassis closed of course
Show on the photo at: 6moons: audioreviews FirstWatt B1 with Nutube
This preamplifier is working the best if kept away from direct physical contact with vibrating:
CD-players, loudspeakers, big power transformers etc.
Like most of the vacuum tubes 😀 Chassis closed of course
Attachments
Tec7 mounting glue is very nice. It can glue everything and never gets 100% hard so can take up vibrations:
TEC 7 Sealant Sort 50 ml
TEC 7 Sealant Sort 50 ml
I had zero ringing when I kept the the PCB standoffs relatively loose. Once I tightened them up, the Nutube started ringing when the case jostled — specifically when I pressed the power button or changed the input. Anything that gives the PCB some give should help.
I installed the linear power supply to the chassis and attached it to the fuse/ on-off switch assembly. It measures a perfect 24V DC at the output. AC by a voltmeter drops below the spec'd 5 mV spec, though I think I will attempt to look at it with my little handheld oscilloscope to see how to use that.
I put surgical silicon gel under the transformer and gave it some degree of motion. It wobbles a bit on the gel, so it has some vibration protection. I'll put the same gel under the circuit board when in hand.
I put surgical silicon gel under the transformer and gave it some degree of motion. It wobbles a bit on the gel, so it has some vibration protection. I'll put the same gel under the circuit board when in hand.
That's great info, thanks for sharing!
Now looking for rubber mounts from an old CD transport for isolation, they're bound to be 'round here somewhere...
If the PCB board is not properly attached and eventually comes loose the soldering points could touch the case and short out the preamp. This could happen with the Noctua NA-SAV2 silicone standoffs I suggested before or if any screws are loose. You could isolate the inside of the case with some plastic material to not have bare metal that the PCB board can come into contact with.