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Old 9th September 2008, 07:19 AM   #1
diyAudio Member
 
Join Date: Oct 2004
Location: Adelaide South Oz
Default A DIY Interruptus Moment

Hi guys,
A couple of weeks ago one of my local contacts dropped in with a Shanling CD player on which he had attempted a major upgrade. Unfortunately, while his Audio skills are fantatsic (lecturer at the local conservatorum of music) his DIY skills are a bit sus and the thing had ceased to work. He had pulled half of the plate throughs of the plate through holes in the PCB right out, put some HEXFRED replacement power supply diodes in backward resulting in blown filter caps and several blown voltage regulator chips (one of them blown clean in half) etc..

I repaired all his problems and noted the Blackgate caps, high grade resistors, Analog Devices Op Amp replacements etc etc.

That got me thinking - had I even ever had the case off my Dennon DCD-1550AR CD Player? Well NO.

Since I have an "Audio Jewellery" bag of Blackgate Caps and similar I decided to rectify the omission right there and then.

What a lovely surprise was in store. The Audio section of the Dennon was seriously impressive. Top of the line Analog Devices Op Amps, all Elna Silmic II Caps, Separate Voltage regs for each channel etc. There was ONLY one thing I did'nt like the look of - The ouput coupling was via a pair of back to back 100uF/50V Silmic. A squizz in the Audio Jewellery bag turned up a pair of 100uF/50V Blackgate N (non-polarised) - so out with the back to back Silmics and in with a Blackgate N for each channel (Yes I know I effectively doubled the coupling cap value).

Sounded better immediately and so I got back to fine tuning the latest Baby Huey Power Amps. An hour later I was scratching my head, the amps just got worse and worse, nothing I did could get them sounding as good as they had the week before.

Finally after shreading copious quantities of the little remaining hair it finally clicked. Those new caps I'd put in the CD player were doing the the "Blackgate Thing" - turned total schizoid, bass disappeared, tops disappered, the mids went really metalic, harsh and nasty - I had forgotten that these things need a serious run in time. They sound pretty good straight away, then turn nasty and it takes 40 odd hours for them to come good.

Now 2 weeks later the "bloody" Blackgates have finally settled in and I can get back to fine tuning the Baby Huey Power Amps.
Was it worth the aggravation? Well yes. The Blackgate Ns are seriously lovely - once they settle in that is.

A lesson in "change ONE thing at a time".

Cheers,
Ian
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