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What is on your workbench right now?

restorer-john

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A little ol' Dynaco ST-35 power amp with 6BQ5 peanut pentodes. I'm trying the Dave Gillespie EFB mod on it.
Pics or it didn't happen. ;)
 

sabristol

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Just finishing a Luxman L-190
4.jpeg

Cleaned, repaired, re-biased, plus full Nichicon recap:
1 (1).jpeg

2 (1).jpeg


And then carried out some testing:

Luxman L-190 Frequency Response.png

Frequency response is in OEM spec (Aux in) :)

Whereas the phono stage......seems a little on the warm side.
Luxman L-190 Frequency Response MM Phono.png


Luxman L-190 Power vs THD.png

Rated power and THD are within factory spec :)
Screenshot 2021-04-05 at 20.49.10.png


More testing to do before advertising on eBay.
 

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Rick Sykora

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Squeezing a Neurochrome Guardian-686 into my Hypex MC502MP to improve power up/down...
3EEE80A3-C001-4EFF-A1C7-E409EFEE5BB9.jpeg


Not crazy about some of the routing of the wiring, but not much choice as there was only one spot that the power board would fit.
 
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MakeMineVinyl

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Squeezing a Neurochrome Power-686 into my Hypex MC502MP to improve power up/down...
View attachment 125275

Not crazy about some of the routing of the wiring, but not much choice as there was only one spot that the power board would fit.
What does that added board do?
 

Rick Sykora

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Oops, wrong Neurochrome board name (I fixed). I added to handle the nasty pop I would often get when I powered down my Hypex amp. The amp module was bought about a year ago and Hypex has since revised and improved.

I could have gotten a warranty replacement, but shipping the amp back was pricey. Hypex had suggested a relay, but know Tom does good work and wanted to be sure the fix was worthy. :)
 

MakeMineVinyl

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Oops, wrong Neurochrome board name (I fixed). I added to handle the nasty pop I would often get when I powered down my Hypex amp. The amp module was bought about a year ago and Hypex has since revised and improved.

I could have gotten a warranty replacement, but shipping the amp back was pricey. Hypex had suggested a relay, but know Tom does good work and wanted to be sure the fix was worthy. :)
Thanks, that makes sense. I'd still be curious what the cause of the original problem was that Hypex fixed, and how they fixed it.
 

Rick Sykora

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Thanks, that makes sense. I'd still be curious what the cause of the original problem was that Hypex fixed, and how they fixed it.
yes, would like that too, but Hypex was not that forthcoming. :(
 

Rick Sykora

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Squeezing a Neurochrome Guardian-686 into my Hypex MC502MP to improve power up/down...
View attachment 125275

Not crazy about some of the routing of the wiring, but not much choice as there was only one spot that the power board would fit.
And that wiring is not going to work at all! 1% distortion before hitting 10 watts :eek:...

Was hoping I might avoid having to redo all of the speaker output wiring from the amp, but apparently have no choice.
 
OP
pma

pma

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Thread Starter #276
And that wiring is not going to work at all! 1% distortion before hitting 10 watts :eek:...

Was hoping I might avoid having to redo all of the speaker output wiring from the amp, but apparently have no choice.
Do you have some plots, measurements?
 

Rick Sykora

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Do you have some plots, measurements?
I did, but no use to post. I elevated the board away from the coils and all is good again...

Am planning to reroute that wiring. Do you have other suggestion?
 

Rick Sykora

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You are right, the distance is the best cure. So maybe to re-arrange the boards placement? Low level signals should be far from output binding posts and power supply components.
Understood, but no room in existing case. If next round does not work, may have to mount externally. :oops:
 
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