Another idea for volume control on the FP III+

[tuffy_puppy]

thank you sir doc!!  greg,  my email is hosed up again.  let's do what the good doctor advocates!!  moving on to the channel attenuators. i do not like such largely spaced units and wonder about goldpoint units.  the way to go or not?  i do apologize for hijacking jim's topic and would like to wrap this up and to get out of the way.  please, put me out of my misery and get rid of me!!!!  don

[Jim R.]

John,

You wrote:

"The
Khozmo attenuator looks as though it uses similar surface mount resistors, Resistors:
1% 100ppm , 1/10W, low noise, non-inductive. The surface mounted resistors used on
the standard Goldpoint Mini-Vs are 0.1% Nichrome THIN film with a thermal noise specification
(TCR) of 25 PPM or 50 PPM. Thin film as opposed to metal film."

That's only one kind of Khozmo attenuator.  Look at the Khozmo web site and look at the "ladder" attenuator link.  This type uses through-hole dale vishay rn55 and caddocks as standard -- though there are other choices at higher prices.  They also have 48 steps instead of 41.  Should be easy to replace the caddocks with nude vishays.

I ordered mine directly from Khozmo as PCX did not have the 25k stocked in this ladder configuration.

Don, I've purchased my attenuator and after figuring out my wrong assumption on how the attenuator was wired, I'm all set, have my attenuator ordered and have a plan, so I'm done with this thread.

-- Jim

[4krow]

You guys have tempted me with these things long enough, but I found a surprise in the basement from years ago. A Shalco stepped attenuator project that, at the time, I didn't have the skills to deal with(and besides, seems to me, it was a balanced config). It'a real mess, as I wasn't able to neatly cut the leads the way that would work best. Anyway, it does offer yet another possibility for the new project I will starting in the near future(no Don, not yours, these things are giant).

[VoltSecond]

That is an interesting idea:

However, I wonder about a stepped system that uses two 6-position rotary switches for a total of 36 steps -- one coarse and one fine) and wonder if anybody has done this and what type of attenuator you built -- series, ladder, or hybrid?

With two - 2 pole 6 position switches we could consider for the second switch an "inverse" "Single Series, Single Shunt, Stepped attenuator" to generate a "fine" control.  An inverse S5 attenuator keeps one resistor in the ground leg and switches a resistor to he input.  The inverse attenuator has the benefit of not "popping" when switching volumes even if a non-shorting switch is used.  The inverse attenuator has the disadvantage of wide input resistance swings, but for 6 steps, it can be made controllable.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.siteswithstyle.com%2FVoltSecond%2F12_posistion_shunt%2FSHUNT_MODE_POT_CONFIG_B.gif&hash=be09b45456c58fc2ee86cda6dbdc97e67a0dbef8)

The question would be what would be best for the first stage? I'm thinking a standard stepped attenuator would work.

What is to be considered is if an "impedance leveling" resistor between the first and second stage is needed.

------------------------------------------------------------------

I'm thinking 2 db steps for fine control and 10 dB for coarse as a goal.  One step of fine would over lap with the coarse settings giving about a 60 dB adjust range.

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Another thought:

A single pole single throw center off switch could be also be added for a 1 dB balance adjust. The center off would be used for a "mute" switch.

[Paul Joppa]

For what it's worth, none of the current products were laid out with the Khozmo, Shallco, or other large attenuator in mind. I don't know what will fit in which product, (The Goldpoints are mostly similar in size to the stock and should fit.) I did a layout for an upcoming version of the Crack which does fit the large attenuators but I don't know if that aspect made it into the latest production design. I'll certainly push for it in the 300B preamp though!

[Jim R.]

Paul,

Well, if it's of any help, I certainly believe BH gear to be totally worthy of these boutique parts for those who want to make that choice.  The stock kits are a superb value as they come -- and the engineering and sonics are there for sure, and will satisfy a large percentage of listeners, but with a couple upgrades in intelligent places, a lot of the products can hang with the big boys for sure.  Does it make any sense to put Duelund silver foil CAST caps in a Quickie?  Perhaps not, but a good attaenuator in just about any product that uses one is definitely going to be a nice upgrade for a lot of people.  You can't undo the damage to the signal done in a pot but you can minimize it with a higher quality one.

-- Jim

[4krow]

Well said indeed.

[earwaxxer]

Paul,

Well, if it's of any help, I certainly believe BH gear to be totally worthy of these boutique parts for those who want to make that choice.  The stock kits are a superb value as they come -- and the engineering and sonics are there for sure, and will satisfy a large percentage of listeners, but with a couple upgrades in intelligent places, a lot of the products can hang with the big boys for sure.  Does it make any sense to put Duelund silver foil CAST caps in a Quickie?  Perhaps not, but a good attaenuator in just about any product that uses one is definitely going to be a nice upgrade for a lot of people.  You can't undo the damage to the signal done in a pot but you can minimize it with a higher quality one.

-- Jim

Hey Jim - cant agree more! Duelund CAST is a bit over the top, not sure where they would be 'worth it' to tell you the truth. Not that I dont think that they are worth the money. Just not sure where you would justify it. You could easily say 'not in a Quickie' but then where? I guess you could spending $2-3K on caps is in a component that costs upwards of $20K. But then you are forced to deal with the issue of why did a $20K component not have them already? I would feel pretty ripped off if my $20K component didn't have the pinnacle of boutique part already on board, and here I was hacking out some $2 parts. The sad thing is that most of them dont have the good stuff. You are paying for someones supposed 'genius'. I personally think that is idiotic. There are many smart folks out there. Many of them involved with Bottlehead. For those that are too lazy to put some personal sweat and toil into their kit, and have money they dont know what to do with, there are the big bucks vendor. For the other 99% there is Bottlehead and others. My personal opinion is that China has had a good effect on this industry. They have made due with common electronics and produced great sounding kit for practically nothing. We (the USA) can, and we are doing the same. It has taken an awakening. In the past we have defined this industry. We will continue to. Use the KISS principle.

[porcupunctis]

I shouldn't but I will say it anyway, fitting a khozmo in yor Crack is a lot like, well fitting a khozmo in your crack.  It can be done but you gotta dremel out the base.

[Grainger49]

Randall,

How did you keep from going through the outside of the base?  Those notches look deep!

[Laudanum]

I shouldn't but I will say it anyway, fitting a khozmo in yor Crack is a lot like, well fitting a khozmo in your crack.  It can be done but you gotta dremel out the base.

I shouldnt say it either but, since you provided the mental graphic ... I probably wouldnt mind Dremeling out my Crack base if I wanted a Khozmo bad enough but I wouldnt want to Dremel out my Crack 

[Jim R.]

Desmond,

Maybe you've just discovered a whole new, untapped market for dremel accessories .

Sorry, couldn't resist.

-- Jim

[Laudanum]

Desmond,

Maybe you've just discovered a whole new, untapped market for dremel accessories .

Sorry, couldn't resist.

-- Jim

I don't know,  I think Randall would have to get the credit for those accessories.  He kinda started it. 
That said, it's a strange world and I dont think I'd be surprised to read about folks who have found "creative" uses for the Dremel tool somewhere other than the work bench.   

[John Roman]

Dremel tools a great for DIY. I've pretty much worn mine out using it on all manner of things. Pressing it beyond it's design limits for sure. Time for a new one or just replace the bearings.

[4krow]

Though I own two dremels, the 'multi-saw' can be handy as well. But for the brave hearted, the die grinder tops them all.