Choke specs for the Crack

JamieMcC · 27842

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Offline captain widwiki

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Reply #30 on: April 12, 2014, 03:17:18 PM
Are there any problem if I put two chokes instead of the two 270ohm 5w resistors on the top of the chassis like the SEX ?



Offline Paul Birkeland

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Reply #31 on: April 13, 2014, 06:21:24 AM
It's more of a space issue - you may find it difficult to fit them up there.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Grainger49

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Reply #32 on: April 13, 2014, 07:05:26 AM
If you opt for dual chokes don't mount them side by side.  If they must be close mount them at 90 degrees to each other.  But if you put them on opposite sides of the amp that should suffice for isolation.



Offline captain widwiki

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Reply #33 on: April 13, 2014, 01:56:17 PM
OK thanks.

another question:  What are differences between the Triad C7-X and the Hammond 193C ? Is there a better one ?
As I plan to put the two choke on the top of the chassis, the Hammond  will look better...



Offline mcandmar

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Reply #34 on: April 13, 2014, 02:27:05 PM
The C7-X is a direct replacement for one of the resistors, where as the 193C would need a bit of a circuit tweak to work, though the 193C is the equivalent of two C7X's in terms of inductance.

M.McCandless


Offline Paul Joppa

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Reply #35 on: April 13, 2014, 04:30:50 PM
...
another question:  What are differences between the Triad C7-X and the Hammond 193C ? Is there a better one ? ...
Well they are both chokes LOL ...  The 193 weighs more than three times as much, has twice the inductance and a similar current rating, has 2/3 the DC resistance, it's enclosed instead of open frame, and it's mounted vertically. Costs a lot more, too.

Incidentally, I believe the current-production C7-X is in fact made by Hammond, to the original Triad specs (more or less). The original was chosen back in the days of the original S.E.X. amp (we are fast approaching the 20th anniversary of that seminal product!) because it was available from Allied at significantly less cost than other chokes of similar specs. It's been a go-to workhorse for Bottlehead in several applications, mostly because it works and we know its foibles.

Fortunately, a power supply choke is not usually a critical component. For Crack, you want a current rating of 70mA or more, and probably a DC resistance of 200-350 ohms to keep the power supply voltage pretty close to original. I don't think either PB (the designer) or I have actually modeled a choke power supply for this application, so no comment on the best inductance. There have been discussions on how to model power supplies, and what behavior is best, at the Tube-DIY Asylum. But go there with your cynicism intact and post wiht your flame suit on - there is a LOT of misinformation surrounding the good stuff, and people get pretty excitable on the subject.

Paul Joppa


Offline captain widwiki

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Reply #36 on: April 14, 2014, 01:08:04 AM
Thanks Paul I think I'll opt for the Triad C7-X and search for some transformer covers



Offline JamieMcC

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Reply #37 on: April 29, 2014, 05:55:37 AM
Hi all, just wanted to say thanks to all those who helped hold my hand with the choke installation details and share a couple of pics of how its turned out. Keeping the fasteners out of sight behind the transformer worked well I intend to go back over the connection with some better insulation or shrink wrap to make the connections look a bit more tidy at a later date.   

(https://www.head-fi.org/image/id/5980074/width/900/height/900/flags/LL)

(https://www.head-fi.org/image/id/5980075/width/900/height/900/flags/LL)

(https://www.head-fi.org/image/id/5980078/width/900/height/900/flags/LL)

(https://www.head-fi.org/image/id/5980079/width/900/height/900/flags/LL)
« Last Edit: April 29, 2014, 09:05:13 AM by JamieMcC »

Shoot for the moon if you miss you will still be amongst the stars!


Offline NightFlight

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Reply #38 on: May 08, 2014, 07:56:11 AM
Well, that cleared up all my questions. Thanks everyone.



Offline modestmeowth

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Reply #39 on: May 20, 2014, 04:50:05 PM
The C7-X is a direct replacement for one of the resistors, where as the 193C would need a bit of a circuit tweak to work, though the 193C is the equivalent of two C7X's in terms of inductance.

What kind of circuit tweak is needed for the 193c?



Offline Paul Birkeland

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Reply #40 on: May 21, 2014, 07:28:38 AM
Add a 100 Ohm 3W resistor as a series component in the power supply to drop the voltage that the 193C doesn't.

This is kind of a moot point though, finding a place to mount that choke will be the tough part.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline modestmeowth

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Reply #41 on: May 21, 2014, 06:16:27 PM
Add a 100 Ohm 3W resistor as a series component in the power supply to drop the voltage that the 193C doesn't.

This is kind of a moot point though, finding a place to mount that choke will be the tough part.

I'm working on making a different base plate and box, something along the line of 12" x  12". Couldn't I mount the choke up top if I go this route?



Offline Paul Birkeland

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Reply #42 on: May 22, 2014, 04:55:31 AM
Yes indeed.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline modestmeowth

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Reply #43 on: May 23, 2014, 08:55:01 PM
Yes indeed.

Just to clarify before I order, I want two right?



Offline Paul Birkeland

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Reply #44 on: May 24, 2014, 06:39:23 AM
Yes indeed.

Just to clarify before I order, I want two right?
I don't know, I could see situations where 1, 2, or 3 of these chokes could be used.  The specifics are up to you.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man