[Tribbs]

Regarding R18 values:
 
I will be using the 12BH7 low mu tubes with my Grado cans.
Is 150Ω too high or should I pick a lower value?
 
Also;
I'll be using the small Hammond enclosure (black).  I've seen some nice, uhm, donuts (?for a lack of a better word) to decorate the tube hole in the top of the enclosure.  What are people using to make that hole look better?  I'm thinking something in chrome, brushed alum or gold finish.

 

[cfcubed]

>  Regarding R18 values
Someone using a CTH with (your model?) Grados would have to chime in.  If all you have is 100R you can try it, just solder 'em a bit up off PCB (or use SIP sockets) so they're easy to change.  BTW at one time IIRC we said 120R max for them.
 
> decorate the tube hole in the top
The plastic (black) ones tend to be called grommets & somewhere I'd part number(s) for at least the middle one below.  Don't ask me for that now
These came from my local electronics store:

 
For metal/chrome I've used a single plate out of a (search"tube protector" off ebay.
 
Cutting the hole is tricky, I use a greenlee step drill in a cheapo HF drill press but there are other ways.  And using any kind of perforated sheet for the top is easier then drilling neat ventilation holes like that in my avatar pic.

 

[runeight]

Quote:

Regarding R18 values:
 
I will be using the 12BH7 low mu tubes with my Grado cans.
Is 150Ω too high or should I pick a lower value?
 
Also;
I'll be using the small Hammond enclosure (black).  I've seen some nice, uhm, donuts (?for a lack of a better word) to decorate the tube hole in the top of the enclosure.  What are people using to make that hole look better?  I'm thinking something in chrome, brushed alum or gold finish.

If you'd like to experiment you could try 50R first. This will drop the power in the headphones a lot. If not enough then move to 100 or 120R.
 
 

 

[Tribbs]

I thought I had read somewhere that R120Ω was large enough with Grado (32Ω Z) but am not sure.
I'll use SIPs and experiment with different values - thanks.
 
"Tube Protectors" - Oh man, you can tell this is my first tube amp <lol> - thanks.
 
Next query;
 
Which specific Dual 50K POT to order?  It's not listed in the Mouser shared BoM cart.
I may have to order the long Hammond enclosure to accomodate?
 
 

 

[cfcubed]

10k->50k log/audio taper dual/stereo volume pot is fine.  Little one like RK097* for small case, larger case for bigger pots like ubiquitous RK27.

 

[BK_856er]

You can also just barely fit a nice TKD pot (small 601 series) in the small case....
 
BK
 

 

[Tribbs]

I was just scoping those TKDs out but can't find a 50K.
Where did you find your 50K(?) TKD?

 

[BK_856er]

I believe mine is a 10K.  When I was looking 50K were only available from ebay/asia and I wasn't in a position to gamble on the potentially long shipping time.  You might check with the US TKD distributor (sellmark electronics).  My 10K seemed to work fine.
 
BK
 

 

[Forte]

Quote:

Also;
I'll be using the small Hammond enclosure (black).  I've seen some nice, uhm, donuts (?for a lack of a better word) to decorate the tube hole in the top of the enclosure.  What are people using to make that hole look better?  I'm thinking something in chrome, brushed alum or gold finish.

Try searching you local hardware store for a "Flush Draw Pull", something like this http://www.knobsandhardware.com/pulls/linnea-llc-rpr-65-flush-pull_g588762.html?af=1615&cse=1615
I found one when looking for some desk draw handles, you just need to find one the right size and remove the plate at the back

 

[Mullet]

Quote:

> decorate the tube hole in the top
The plastic (black) ones tend to be called grommets & somewhere I'd part number(s) for at least the middle one below.  Don't ask me for that now
These came from my local electronics store:

 
For metal/chrome I've used a single plate out of a (search"tube protector" off ebay.
 
Cutting the hole is tricky, I use a greenlee step drill in a cheapo HF drill press but there are other ways.  And using any kind of perforated sheet for the top is easier then drilling neat ventilation holes like that in my avatar pic.

Those black donut thingies are actually called bushings according to eagle plastics. I was recently looking for a few extras for future CTH builds and decided to look at the part # on one of my current CTH's bushing. For a 1.5 inch diameter hole you could get this one at Mouser: 561-MP15018. They have other sizes as well. Just download the spec sheet and find the right size.
 
I agree that drilling the hole is a pain. I have found great success in finding scrap perf metal around the office. In fact my latest incarnation came from a broken space heater. You'd be amazed at what you can find if you know what to look for. I ended up using a metal hole punch found in a tool chest in my machine room at work. If I understand correctly, metal hole punches are kind of expensive.
 
 

 

[Mullet]

On another note... anyone know where I can get some of those Hammond screws? Somehow I lost mine for a build I'm doing and searching the web came up with a few results that required spending more than $10 on a credit card ie Element14 (aka Newark/Farnell) I might try going to a hardware store, but I kind of want black screws; plus I want them to be the self tapping type screw. I would need 8 of 'em.

 

[cfcubed]

Thanks for the grommets bushings correction & part #.    WRT extra black Hammond case screws, I may very well have them as I've used Allen heads in some builds.  Will look tonight & PM either way.

 

[jdkJake]

 
Quote:

On another note... anyone know where I can get some of those Hammond screws? Somehow I lost mine for a build I'm doing and searching the web came up with a few results that required spending more than $10 on a credit card ie Element14 (aka Newark/Farnell) I might try going to a hardware store, but I kind of want black screws; plus I want them to be the self tapping type screw. I would need 8 of 'em.

Do you have a ACE hardware locally? They have them, just not sure if they are black (I think they do). They also have a selection of bushings.
 
For sure the best local source for small hardware in all materials and sizes. 
 

 

[Tribbs]

Man, the U.S. markup on some of this stuff -
http://www.goodcomponent.com/tube%20ring.html
http://www.goodcomponent.com/tube%20protector.html
http://www.goodcomponent.com/9-pin%20tube%20socket.html
 
Quote:

 
To BK_856er:
Were those AuriCaps a worthwhile upgrade to your CTH?
Did you replace the C4L/R output pair? With the same values (220n)?
What other CTH component upgrades did you find worthwhile?
 
 
 

 

[BK_856er]

I built it as a gift - didn't try the stock configuration/never got much time with it.  I'll defer to others regarding what's worthwhile.  Can't really go wrong with the stock setup.
 
Next one will be all mine!
 
BK