In Reply to: Effects of Chassis material choice for input signal shielding ? posted by drummerwill on September 17, 2009 at 07:56:26:
For this discussion, I am assuming a Single-Ended RCA input into your amplifier.
Your input to your amplifier will come from a "hot" wire, and a "cold" wire. In some setups, the "cold" wire is a shield around the "hot" wire, or in some cases, there are two wires, with a shield around both. In some cases, the two wires are both not connected to the shield, in other cases, one wire-- the "cold" wire, may also be connected to the shield.
Once your amplifier's input sees the "hot" and a "cold"-- you have your complete single-ended input signal into the amp.
Now, what? Assuming that you're using an RCA male to connect into your amplifier, once inside the amp-- in good amp design-- the "hot" WILL NOT be shielded inside the amp, rather, the "hot" lead from the input jack will go directly to the input grid on your first stage of amplification. In some amplifiers, you may wish to have a D.C.-blocking capacitor in series with this "hot" input. In this case, the cap becomes the short unshielded wire-- from the RCA jack "hot" pin-- to the input tube's grid.
This "hot" lead should-- ideally, be under one inch long-- that is, the input jack should be located very close to the input tube's grid.
In this way, your "shield" or "cold" side of your input jack can, and should, go to the amplifier's central, or "star" grounding system, BUT this ground wire from the RCA jack should have an inch or two of length-- a little separation-- from the "star" system before it connects to it. This is your input tube's ground reference point, relative to that tube's grid. It needs a little separation from the other grounds in the amplifier.
The primary reason that shielding should be avoided inside an amplifier is because shielding acts as a pickup device and injects distortions found inside the amplifier's chassis into the shielded wire's "hot" lead from induced radiation found within the wire's shield.
The basic rule is easier to understand-- shields go OUTSIDE the amp-- NO shielding for inside the amp.
Amp chassis materials are ideally chosen for their PHYSICAL sonic properties-- that is-- whether they "ring" or "deaden" sound. Ideally, they absorb very little energy (so they do not dull the life out of music), but they also do not ring like a Bell (and so, do not add colorations to music).
Aluminum adds a "whitish" coloration that is evident no matter where or how it is used in an amplifier.-- or even in wire.
Copper attends to a dulling, slowing down effect on music, but it does not lose introspective or depth of image if it is single-crystal, and oxygen-free. Copper is greatly improved by cryogenic treatment.
Copper use in chassis can provide a decent ground-plane for circuit designers to build upon, but it will also dull sound quality. Large-gauge silver wire, placed exactly and only where it belongs, outperforms copper ground plates in spades-- as a grounding system.
The use of woods and plastics in amplifier design is fraught with problems-- unwanted resonances, and sounds that are not found on your record or CD! With that said, it is still possible to use these materials wisely and come up with decent (but not the best possible) sound quality.
Steel is also not without its problems. It is magnetic, and therefore, layout and mounting of components is critical with steel, as is the steel's thickness..
For steel chassis, brass should be used for all fasteners, and all magnetic components mounts (transformers, chokes, etc., which are also steel should be mounted on brass standoffs).
Brass is THE best material for working with steel chassis.
If you are considering working with steel chassis, its thickness is critical, as this determines how it manifests its magnetic properties, and this also determines the actual physical, sonic signature of the completed chassis.
If a steel chassis is painted, or Powder-Coated outside, then it must receive the same treatment inside.
Truly advanced amplifier builders will choose to work with steel chassis because if its thickness and dimensions are correct, and if component layout and mounting are all correct, the finished piece will not dull music, and further-- it will not add colorations either.
Steel is hard to work with at the top level of performance, but when done right, nothing else can touch it sonically.
---Dennis---
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Follow Ups
- RE: Effects of Chassis material choice for input signal shielding ? - tube wrangler 09/17/0913:18:42 09/17/09 (107)
- Much of this is junk science .... the rest is phantasy - Ray Moth 05:17:17 09/18/09 (106)
- chassis materials - Donald North 16:11:55 09/18/09 (3)
- True, but not in this context: - gusser 16:21:39 09/18/09 (2)
- RE: True, but not in this context: - bfranchuk@jetnet.ab.ca 15:26:41 09/19/09 (1)
- RE: True, but not in this context: - tube wrangler 21:59:48 09/19/09 (0)
- The same was said about Einstein - rickmcinnis@dogwoodfabrics.com 12:01:28 09/18/09 (19)
- RE: The same was said about Einstein - finnman500@hotmail.com 21:29:02 09/24/09 (3)
- RE: The same was said about Einstein - Ray Moth 18:13:16 10/2/09 (0)
- RE: The same was said about Einstein - PakProtector 13:27:49 09/28/09 (1)
- RE: The same was said about Einstein - finnman500@hotmail.com 19:00:41 10/2/09 (0)
- RE: The same was said about Einstein - JimL 17:59:41 09/18/09 (1)
- RE: The same was said about Einstein - GEO 19:20:56 09/18/09 (0)
- RE: The same was said about Einstein - Ray Moth 16:22:43 09/18/09 (4)
- Advancing the Emperer's Wardrobe - Cleantimestream 09:33:12 09/23/09 (3)
- Prolly on the wrong track... - FenderLover 06:03:53 09/29/09 (0)
- RE: Advancing the Emperer's Wardrobe - PakProtector 05:29:31 09/26/09 (0)
- Heisenberg, Schmeisenberg! - Ray Moth 18:23:40 09/23/09 (0)
- Your ignorance is profound - GEO 13:05:13 09/18/09 (3)
- one more - PakProtector 15:43:26 09/18/09 (2)
- RE: one more - tesla 20:01:46 09/18/09 (1)
- RE: one more - PakProtector 03:50:49 09/19/09 (0)
- Big Difference with Einstein - gusser 12:49:25 09/18/09 (3)
- RE: Big Difference with Einstein - tube wrangler 21:40:58 09/18/09 (2)
- RE: Big Difference with Einstein - PakProtector 05:24:38 09/21/09 (0)
- Big Difference with Edison - drlowmu 23:15:35 09/18/09 (0)
- RE: Much of this is junk science .... the rest is phantasy - tube wrangler 08:04:14 09/18/09 (13)
- RE: Much of this is junk science .... the rest is phantasy - audiobag 10:13:29 09/24/09 (0)
- RE: Much of this is junk science .... the rest is phantasy - bfranchuk@jetnet.ab.ca 10:09:35 09/18/09 (1)
- I agree - tesla 20:06:06 09/18/09 (0)
- RE: Much of this is junk science .... the rest is phantasy - Ray Moth 08:46:54 09/18/09 (9)
- RE: Much of this is junk science .... the rest is phantasy - tube wrangler 22:06:09 09/18/09 (0)
- Ray...................... - drlowmu 09:57:53 09/18/09 (7)
- RE: Ray...................... - PakProtector 15:48:05 09/18/09 (6)
- RE: Ray...................... - tube wrangler 22:36:12 09/18/09 (5)
- IF you looked it up, you ought to know how to spell it - Ray Moth 18:27:22 10/2/09 (0)
- RE: Ray...................... - Tre' 12:53:33 09/19/09 (1)
- RE: Ray...................... - tube wrangler 14:46:07 09/19/09 (0)
- RE: Ray...................... - PakProtector 12:15:25 09/19/09 (1)
- RE: Ray...................... - tube wrangler 14:52:41 09/19/09 (0)
- Ray, - drlowmu 06:45:22 09/18/09 (67)
- RE: Ray, - Ray Moth 08:16:45 09/18/09 (66)
- RE: Ray, - drlowmu 09:49:52 09/18/09 (65)
- Let's not let education and scientific theory get in the way. - GEO 13:14:02 09/18/09 (6)
- RE: Let's not let education and scientific theory get in the way. - drlowmu 07:44:17 09/29/09 (5)
- RE: Let's not let education and scientific theory get in the way. - PakProtector 08:24:57 10/5/09 (0)
- Name-dropping again? - Ray Moth 18:35:05 10/2/09 (3)
- RE: Name-dropping again? - PakProtector 08:34:13 10/5/09 (2)
- RE: Name-dropping again? - Ray Moth 17:57:44 10/6/09 (1)
- RE: Name-dropping again? - drlowmu 22:17:59 10/15/09 (0)
- disagree. - PakProtector 13:07:18 09/18/09 (57)
- RE: disagree. - drlowmu 13:36:42 09/18/09 (56)
- "The same was said about Einstein" (to quote another inmate) - Ray Moth 16:39:14 09/18/09 (4)
- RE: "The same was said about Einstein" (to quote another inmate) - bfranchuk@jetnet.ab.ca 23:31:34 09/19/09 (0)
- don't forget Teller...:) - PakProtector 17:31:16 09/18/09 (2)
- RE: don't forget Teller...:) - GEO 17:32:31 09/18/09 (1)
- and...:) - PakProtector 18:36:51 09/18/09 (0)
- RE: disagree. - PakProtector 15:38:07 09/18/09 (50)
- RE: disagree. - Ray Moth 21:32:41 09/19/09 (49)
- RE: disagree. - tube wrangler 22:25:00 09/19/09 (48)
- RE: disagree. - Ray Moth 23:11:39 09/19/09 (47)
- RE: disagree. - tube wrangler 10:52:20 09/20/09 (19)
- RE: disagree. - Ray Moth 18:40:26 09/20/09 (10)
- RE: disagree. - tube wrangler 19:25:42 09/20/09 (9)
- RE: disagree. - Ray Moth 21:51:15 09/20/09 (8)
- RE: disagree. - tube wrangler 22:29:42 09/20/09 (7)
- RE: disagree. - Ray Moth 04:34:54 09/21/09 (6)
- RE: disagree. - tube wrangler 21:41:17 09/21/09 (0)
- RE: disagree. - PakProtector 06:20:36 09/21/09 (4)
- RE: disagree. - tube wrangler 21:45:47 09/21/09 (3)
- RE: disagree. - GEO 20:04:27 09/22/09 (0)
- Childish? Pot calling the kettle black - Ray Moth 08:26:32 09/22/09 (0)
- RE: disagree. - PakProtector 03:18:17 09/22/09 (0)
- RE: disagree. - PakProtector 13:10:45 09/20/09 (7)
- RE: disagree. - tube wrangler 19:32:54 09/20/09 (6)
- RE: disagree. - Ray Moth 04:22:34 09/21/09 (5)
- RE: disagree. - tube wrangler 21:59:54 09/21/09 (4)
- Closed mind? - Ray Moth 08:58:27 09/22/09 (3)
- RE: Closed mind? - tube wrangler 14:10:18 09/22/09 (2)
- No turf war - sorry! - Ray Moth 05:59:22 09/27/09 (1)
- RE: No turf war - sorry! - tube wrangler 20:19:02 09/27/09 (0)
- RE: disagree. - Ron Oehlert 09:16:52 09/20/09 (1)
- interesting.... - FenderLover 00:02:11 09/21/09 (0)
- RE: disagree. - PakProtector 07:33:57 09/20/09 (24)
- RE: disagree. - Ray Moth 19:16:21 09/20/09 (23)
- RE: disagree. - tube wrangler 19:37:02 09/20/09 (22)
- RE: disagree. - mach1 00:00:40 09/21/09 (21)
- RE: disagree. - tube wrangler 22:22:21 09/21/09 (18)
- RE: disagree. - PakProtector 09:16:30 09/22/09 (17)
- RE: disagree. - tube wrangler 14:27:48 09/22/09 (16)
- RE: disagree. - PakProtector 16:16:14 09/22/09 (15)
- RE: disagree. - tube wrangler 19:05:21 09/22/09 (14)
- RE: disagree. - PakProtector 03:37:02 09/23/09 (4)
- RE: disagree. - tube wrangler 11:14:36 09/23/09 (3)
- RE: disagree. - PakProtector 14:38:42 09/24/09 (2)
- RE: disagree. - tube wrangler 18:42:46 09/24/09 (1)
- Monster Cable are 'good people'? - PakProtector 06:10:11 09/25/09 (0)
- Praise be! - Ray Moth 20:58:50 09/22/09 (0)
- RE: Lost marbles - mach1 20:09:01 09/22/09 (7)
- RE: Lost marbles - tube wrangler 11:40:51 09/23/09 (6)
- Very imaginative - PakProtector 14:56:55 09/23/09 (5)
- RE: Very imaginative - tube wrangler 19:23:35 09/23/09 (4)
- RE: Very imaginative - PakProtector 14:43:37 09/24/09 (0)
- RE: Very imaginative - GEO 20:30:34 09/23/09 (0)
- RE: Very imaginative - Ray Moth 20:10:52 09/23/09 (1)
- RE: Very imaginative - mach1 21:16:47 09/23/09 (0)
- LOL - exactly! How greatly improved? - Ray Moth 18:53:26 09/21/09 (1)
- RE: LOL - exactly! How greatly improved? - tube wrangler 19:35:45 09/23/09 (0)