[MusicMtnMonkey]

I'd appreciate any input as I consider this project, Thanks for any help in advance!

My experience so far is building pair of interconnects and a Bugle.  I have an older Technics TT which I'm working on a tonearm wire job, but it's not right yet (that's what cheapy practice machines are for   The Bugle is running happily now, but my soldering skills are still weak.  I can't really read a circuit diagram yet, but I think I understand polarity and get the idea behind the basics for the resistors and capacitors and what they do (I had a few Radio Shack 200 in 1 kits as a kid and had the most fun with the the light sensor projects like the motion detector).  Kind of like knowing the individual letters of the alphabet, but not knowing how to form words from those letters.

Neighborly peace has led me to purchase and start spending a lot of time listening to headphones, plus now I can jam out at night after quiet hours!  I'm currently using my Golden Tube SEP-1 (a 70's mullard tube) for a HP Amp and it sounds great!  My sources would mainly be the Squeezebox and Bugle.

My goals with the project would be to have:
better sound (of course!)
Place the HP Amp closer to my desk/listening chair so I can use the volume on it.  A remote volume control add on would be bonus!
Enjoy another project.  Even my wife acknowledged, I got a lot of enjoyment out of soldering the Bugle together.
Would this be an upgrade to my existing Pre Amp?

My Concerns:
High voltage??
How hard is this kit?
Will the upgrade in sounds going from a "6922" to a "6H30" be worth the cost, should I just keep using my Preamp which I think is some kind of SET circuit??
My budget is $300 to around $500, I think I could get the circuit board/half kit for my birthday to help.


My final question, "of so many", is why so many transformers in the Castanet design??  How many of the transformers are really in the signal path?

[hagtech]

The CASTANET should be a big upgrade.  And it is not the difference between 6922 and 6H30, it's a whole different circuit.  Only one transformer per channel in the signal path, plus a choke.  The rest are power supply. 

Why so many?  That's what it takes to do it right.  Anything less is a compromise.

jh

[MusicMtnMonkey]

So R11x is directly in the signal path??
C10X is parallel to R12, C8, and C9, all part of the signal path?

I'm wondering if upgrading these components would affect sound the most?

[hagtech]

Yes, they are all in signal path.  Each would likely affect sound in some way.

jh

[MusicMtnMonkey]

Yes, they are all in signal path.  Each would likely affect sound in some way.

jh

Thanks for your replies JH!  I anticipate ordering a board soon, enjoying researching the project!

PS.  Your designs do seem so short of audio path, minimal in components, and elegant

[MusicMtnMonkey]

C8x  ??
C9x  BLackGATE- 58659 Std 470uf 50v 16 x 36 (mm?)
C10x  Obbligato Film Oil 4.7 uf 630 V  55x40 mm
 
For C10x does the capacitance need to be exactly 3.0 - 3.3 or can it be slightly higher or lower?

(my post is a little premature here, still researching specifics, I'll keep updating..)

In the manual "three 3.3uF film capacitors with Hovland 3.0uF 200V capacitors from AES (#C-H3-200), although this may not necessarily be a sonic upgrade. Alternately, you can add smaller bypass films to
these, such as your favorite audiophile 0.01uF to 0.1uF capacitor."  Is C7 in the signal path?  Is there a reason to bypass and upgrade C7?

[hagtech]

3.3uF can be higher or lower.  No big deal. 

jh

[MusicMtnMonkey]

So now I'm thinking of upgrading to these components:
C9x  Nichicon Muse KZ 470 uf 25V (polarized for this position?, is this the correct variety of cap?)
C10x  Mundorf Supreme 3.3 uf  800V

R11x and R12x  TX2575  Texas Components nude Vishay type
R10  Alps Blue Velvet pot  (any other suggestions that aren't too pricey??)

Should I upgrade C8x?
Are the other caps and resistors parts of the "power supply" and maybe unecessary to upgrade??  (or suggestions?)...

Thanks for any help in advance!!

[hagtech]

Yes, those are nice upgrades (if you like those brands / versions).  C8 is upgraded with C9.  You might want to try the teflon caps that folks are talking about in other threads.  The blue velvet pot is quite good for the money.

jh

[MusicMtnMonkey]

I feel bad that I keep asking soo many questions.  I swear I've searched here and other forums, but there is little discussion of CASTANET.  I may have to organize a consulting fund for Jim's time spent helping.  Currently, I can only hope that other's will see my thread and it will provide good researching.

The good news is, I did order a few of those FT3 caps.  Tubes was nice enough to let me make a small order of 4.  I really didn't know where I would use them (at the time and I was busy with RL when it all went down) but figured for the price of a handfull it was a tiny risk, they would go in my parts bin if nothing else.  Also I ordered a few 2575 resistors from Texas Components. 

So what's the problem? Well It's gonna be a month probably or so before those parts show up.  Now I have more time to think about the project and find funding for boutique high performance parts (bling!).  I'm probably all too hung up on the C9 location (electrolytic's affect sound right?).  That little voice in my head is telling me to "just get the nice parts" the first time, resoldering or a second kit will be too far in the future (really hoping this all goes well and I'm onto a Coronet next  )  I'm back to thinking about Black Gates. 

What I'm wondering is for
C9x  220uf 25V FK  Black Gates (pair?) or
C9x  1000uf 50V FK  Black Gates

instead of the Standard? (do I need to use the standard and get a 470uf 25V cap for the C9 position) 
The Choke Filtered Supply equation does not apply to C9 does it??

[hagtech]

470uF is just a nominal value.  220uF to 1000uF will work ok.  Choked supply does not care about C9, however, C9 cares about the choked supply.  That is, the output impedance of the tube (depends on C9) sees the load reflected through the output tranny in parallel with the choke plate load, which is in series with the power supply impedance at B+.  Below 20Hz this starts to become significant.  That is, the B+ impedance rises and has a damped resonance.  With a different tuning on the prototype (less B+ capacitance, I think), it actually resonated with a 0.5dB boost at 20Hz.

jh

[tubesforever]

I have been using a Dale Vishay stepped attenuator on my Clarinet with superb sonic results.  I cannot find them anymore on ebay.  However the replacements are listed as DACTs and sport surface mounted resisors for the ladder.  You can get these as Vishays but I am not sure what the equivalent resistor type would be?  Meaning is that a Dale film resistor or a Vishay foil resistor?

I have not tried the DACTs personally. 

I have at least 2 of the Dale Vishay 10k ohm stepped attenuators if you want to try one.  Ask Jim what loading you might have to change on the board to allow these 10k attenuators to maintain circuit balance. 

For anyone reading this thread I hope you understand just how great Jim is for us DIY types.  Here he is describing for us what we need to consider in terms of maximizing our projects.  He does not need to do this.  He does this because he LOVES it!

Thanks Jim for being such a great DIY resource. 

Cheers!

[Theo]

What is the optimal resistance rating attenuator to use for the Castanet?  The stock Panasonic pot is 50kOhm.  I would like to know what kind of adjustments are required when I use different rating pots or attenuators, say for 10k and 100k?
   

[MusicMtnMonkey]

I'm curious about the variation possible in volume control also Theo.

I saw positive postings about this over on Head Fi:
http://cgi.ebay.com/DACT-Type-23-Stepped-Attenuator-Potentiometer-50K-2a3_W0QQitemZ300258424361QQihZ020QQcategoryZ3280QQtcZphotoQQcmdZViewItem

I'm pretty close to ordering one, but since it was being discussed I thought I'd post the link and see if anyone has comments about this ebay stepped attenuator (care to share a better source in this price range??).  I was thinking the size may require case modifications?

And to second Tubey, Jim has been incredibly helpfull, Thanks again!!

[hagtech]

You can use any value audio pot.  1k, 10k, 500k.  The CASTANET will run fine.  The question is whether or not the previous component can handle the loading.  Oftentimes a tubed DAC or phonostage will compress a bit when driving 10k or lower volume pots.  I like 50k as a compromise between loading and bandwidth.  With very high value pots (say 1Meg), the circuit becomes more sensitive to leakage currents, noise, and the input RC low pass filter might become audible.  The treble then becomes a function of volume.

jh

[Theo]

I'm curious about the variation possible in volume control also Theo.

I saw positive postings about this over on Head Fi:
http://cgi.ebay.com/DACT-Type-23-Stepped-Attenuator-Potentiometer-50K-2a3_W0QQitemZ300258424361QQihZ020QQcategoryZ3280QQtcZphotoQQcmdZViewItem

I'm pretty close to ordering one, but since it was being discussed I thought I'd post the link and see if anyone has comments about this ebay stepped attenuator (care to share a better source in this price range??).  I was thinking the size may require case modifications?

Hm nice, but it definitely requires case mod or even a larger case altogether.   The stock Panasonic pot is very compact and very tightly fit onto the Castanet circuit board.  I would have to seriously plan before ordering parts.

[tubesforever]

I have gone full width rack size lansing cases for my projects for two reasons.  To use a higher end phono selection switch (Carsten Electrnics) and use Dale Vishay attenuators. 



Here is a picture of the Dale Vishay stepped attenuator with my first revolution Clarinet.  The new vishay resistors are 1/2 watt and I am not sure if they are metal film.  The Dales were sweet pieces!

I am hoping the Vishay DACTs sound as good or better.  If not buy some Dales and get a shallco switch from Percy Audio.   

BTW I could not have run front power switches with the smaller casework.  I would have had hum and noise galore.  I took this into account when I planned my build.  I also use double braided shield on these lines!   You can never be too careful or too shielded!

Cheers

[Theo]

I have gone full width rack size lansing cases for my projects for two reasons.  To use a higher end phono selection switch (Carsten Electrnics) and use Dale Vishay attenuators. 



Here is a picture of the Dale Vishay stepped attenuator with my first revolution Clarinet.  The new vishay resistors are 1/2 watt and I am not sure if they are metal film.  The Dales were sweet pieces!

I am hoping the Vishay DACTs sound as good or better.  If not buy some Dales and get a shallco switch from Percy Audio.   

BTW I could not have run front power switches with the smaller casework.  I would have had hum and noise galore.  I took this into account when I planned my build.  I also use double braided shield on these lines!   You can never be too careful or too shielded!

Cheers

Jim, I wish to have learned from experience DIY foes like you earlier.  When I built my Cornet2 and Castanet I didn't do any planning for expansion and upgrades, because I didn't envisioned that I would enjoy upgrading parts.  After hearing so many good stories of part upgrades, I tried my first upgrade by replacing the three stock 3.3uF caps with Obbligato Premium in the Castanet.  Boy, did that opened my eyes to possibilities.  The sonic improvement was beyond believe and turned me to a believer of using better parts.  Now I'm hooked.  Looking for bigger cases is my next step.