[Brinkman]

There's 4 220nF capacitors in the Bugle (C1, C3, C4, C6). How far can I stray from this rating in capacitance before the functionality of the circuit is compromised? I ask because I have some auricaps and Solen caps lying around...

Best,
Benjamin

[avahifi]

It would be nice to know the voltage, type, tolerance, circuit application, heat requirements, and a whole lot more.  Your question is kind of like asking, I have four 36 pound max tire pressure tires on my car, what is the max I can stray before the wheels come off?

Very seriously you need to know and supply a lot more info before useful help can be supplied from someone who actually knows about capacitor engineering and use.

Regards,

Frank Van Alstine

[Brinkman]

Your question is kind of like asking, I have four 36 pound max tire pressure tires on my car, what is the max I can stray before the wheels come off?

No it's not. It's posting a query about a product on a webforum were that product is discussed and online product support is provided, oftentimes by the gentleman who designed it.

Here's a partial schematic, though I'm pretty sure Jim Hagerman is familiar with it:
www.hagtech.com/images/bugleschem.gif

Best,
Brinkman

[hagtech]

The first pair are in the EQ, so keep a tight tolerance.  Second pair is just ac coupling to remove the dc offset that was multiplied by the first two stages.  You can vary quite a bit.  With the ~56k, it has an RC rolloff of about 13Hz (unit is specified at 15Hz).  If you want the IEC rolloff you can shift to maybe 150nF or so. 

Personally I like to push the bandwidth lower so that there is virtually no effect on low bass phase and amplitude (let the speakers screw it up).  But keep in mind, you have tonearm resonances around 8Hz and turntable rumble and footfalls.  Often it is better to not pass this on down the line.  The price point of the BUGLE means it is usually used with a comparable table (i.e. not a megabuck machine).  With a Galibier table and Shroeder arm you are able to push bandwidth down to single digits no problem.  I guess I am trying to say that it helps to look at this as a system-wide issue.  If you run a budget $250 table, then don't be swapping in 1uF auricaps, they might actually cause more harm than good.  Stick with something between 100nF and 330nF.

jh

[Brinkman]

Thanks Jim.
I was thinking if the specs were "loose" I could get by with larger capacitances (i.e. expensive unused caps I already have). Seeing as this isn't the case, I may just get 4 .22uF Sonicaps. It'll help pad out another Sonicraft order.
As for the turntable, well, I do rely on the budget-conscious ProJect Debut, but have a couple Lenco L75s waiting to be replinthed in a fairly intense dampening procedure (40-50 lbs of alternating layers of birch & MDF). Any plinth that can absorb the motor rumble of a direct drive turntable should be pretty apt at dampening footfalls. Then again, it all goes out the window when you have a "slightly" warped record.
Perhaps I'll assemble the Bugle to spec and worry about increased capacitance when the Lenco replinthing (coupled with a modified Rega tonarm & MC cartridge) is a reality.

Best,
Benjamin

[avahifi]

Oh oh.   Changing 220 uF caps to .22 uF caps is changing pole points three orders of magnitude, and that is going to make significant low frequency changes.  I am not certain this is a good idea if the design is correct in the first place.  At least with plus and minus 9V DC rails, you won't need anything with more than a 25V rating which will keep the size and cost down.  Use non-polar types please.

Regards,

Frank Van Alstine

[Brinkman]

Frank,

The original value for each of the 4 capacitors we're speaking of is 220 nanofarads (nF), which as you know, can also be expressed as .220 microfarads (uF).
Jim said to keep the first two caps pretty close to this specification. If I read him correctly, one can vary between 100nF and 330nF (equal to .10uF and .33uF, respectively) on the second two. So the stock value of 220nF lies pretty close to the middle of those two values
The Sonicaps I plan on using would be non-polar, so we're both happy.

Best,
Benjamin