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Old 6th July 2010, 09:20 AM   #321
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by regiregi22 View Post
What will be the differences compared to a resistor or just nothing? Or even a plain wire?
all exposed conductive parts must be connected to Safety Earth.

Do not use "just nothing" nor use a "resistor" alone.


This connection MUST be able to pass thousands of amperes and survive long enough for the mains fuse to rupture and the arc to extinguish.

It Must be:
a direct wire link,
or
a pair of high power inverse parallel diodes,
or
a high power Thermistor.
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Old 6th July 2010, 10:11 AM   #322
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Sorry for being unclear. I was meant to state (or ask?) that the CL-60 behaves similar to a ground breaker without the capacitor. See the attached schematic.

When there's no voltage present, both will act as a 10ohm resistor tying chassis and ground. When voltage increases, it becomes a closed circuit
.
In the case of the ground breaker, it will close the circuit when there is a voltage over 1.5-2v (the diode voltage drop). When applied that voltage, the diodes conduct thus bridging the resistor, giving a result of 0 ohms.

In the case of the CL-60, as soon as voltage starts to increase, resistance decreases until it reaches (theorically) 0 ohms. We would need to know the graph curve to see how effective it is.
With a diode bridge breaker, it suddenly changes from 10 ohms to 0 ohms as soon as it reaches those ~2v.

I hope now it is clearer

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File Type: jpg ground breaker.JPG (9.1 KB, 304 views)
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Old 6th July 2010, 10:17 AM   #323
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Quote:
Originally Posted by AndrewT View Post
all exposed conductive parts must be connected to Safety Earth.

Do not use "just nothing" nor use a "resistor" alone.
And what about the outputs binding posts? it is an exposed conductive part.
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Old 6th July 2010, 11:24 AM   #324
AndrewT is offline AndrewT  Scotland
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Originally Posted by regiregi22 View Post
And what about the outputs binding posts? it is an exposed conductive part.
if the conductive parts are exposed then they must be connected to Safety Earth. That's why the shrouded speaker terminals came about. But they are very unpopular.

Similarly the input RCA barrel is exposed as soon as the interconnect is removed.
The RCA hot input is exposed at the remote end of the interconnect, if it is left unconnected. That's the really dangerous one if youngsters are still sucking on anything they investigate.
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Old 6th July 2010, 11:28 AM   #325
AndrewT is offline AndrewT  Scotland
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I do wish ESP would re-draw that post322 diagram.

It should show the Protective Earth wire (third wire in the mains cable) directly and permanently connected to conductive chassis.

The Disconnecting Network will connect from any other part of the conductive chassis to the Main Audio Ground. It does not have to coincide with the PE connection. I believe the "permanent" requirement implies that these two connections to chassis should not coincide.
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Last edited by AndrewT; 6th July 2010 at 11:34 AM.
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Old 6th July 2010, 11:59 AM   #326
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Quote:
Originally Posted by AndrewT View Post
I do wish ESP would re-draw that post322 diagram.
In fact, this one is the re-drawn one by me. This is the original one:
http://sound.westhost.com/earth-f4.gif
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Old 6th July 2010, 01:09 PM   #327
troystg is offline troystg  United States
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This thread was started for the Mauro My Ref Rev_C so I will try to stay on topic.

The amp was designed with a floating pwr supply. That's how I use it and have no issues.

However, the PGND connection between the two pwr supply caps can be tied to the chassis if desired.

I (personal opinion) would NOT use a direct link or straight wire.
I (personal opinion) would use a CL-60 and may just try that to see if it has an affect.
I (personal opinion) don't think there would be anything wrong with the Rodd Elliot diagram for the DC blocker circuit but a single CL-60 is simpler.
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Old 6th July 2010, 01:36 PM   #328
AndrewT is offline AndrewT  Scotland
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Originally Posted by troystg View Post
The amp was designed with a floating pwr supply. That's how I use it and have no issues.

However, the PGND connection between the two pwr supply caps can be tied to the chassis if desired
most regulations do not give you this choice.
"A floating pwr supply" and exposed conductive parts is quite simply not allowed.

If there are any exposed conductive parts then one MUST connect them to Safety Earth, irrespective of how the amplifier was designed or intended to be used.
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Old 6th July 2010, 02:24 PM   #329
troystg is offline troystg  United States
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Quote:
Originally Posted by AndrewT View Post
most regulations do not give you this choice.
"A floating pwr supply" and exposed conductive parts is quite simply not allowed.

If there are any exposed conductive parts then one MUST connect them to Safety Earth, irrespective of how the amplifier was designed or intended to be used.
In DIY one can CHOOSE to do whatever he / she desires.

There are no rules, but hopefully common sense.

I recommend professional training / education / mentoring or a whole lot of questions to the forum and patience waiting for answers back.
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Old 7th July 2010, 11:57 PM   #330
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Well, it's time to give some preliminary results about my tests:

C5 (diodes filtering):

No cap is a very important improvement, I'll try some 10nF MKP10 (Lead spacing 7.5mm, prefect fit). (D2 and D3 must be soft recovery diodes!!)

C7 (LM318 bypass):

In C7 I've tried Evox SMR5, Wima MKS2 and MKP2 in 220nf and 100nF values, 10nF FKP2 too;

MKP2 (included in kit) is a very nice upgrade versus the MKS2 but compared to SMRs and FKP2s is closed.

SMRs have gorgeous high and medium range but lacks some bass, FKP2 a bit less gorgeous but much more equilibrated.

Best of all is no C7 cap at all but stability could be a concern...

C6, C11 (Zeners bypass)

Tried Wima 4.7uF MKS2XL in place of the Silmics, it seems a nice upgrade but at 2x the cost. Waiting them burning in...

C10 filtering

Tried a Silver Mica and there's a subtle improvement, a bit more refined high range.

C12 filtering

A FKP2 here make a big difference: RECOMENDED and DEFINITIVE!

C34 LM318 compensation

Tried a Silver Mica and there's a not so subtle but neither so big effect, more refined high range and tighter bass.

R13 input shunt resistor

Tried a single swap between PRPs and Caddocks MK132, after that one of the legs broke (@#!)

There's a nice but subtle improvement: a bit more refined high range, more body and harmonics.

If cost is no object the Caddock is the clear winner but a cost conscious build probably would drop it for a Takman Carbon Film.

R3 output resistor

Tried the standard Xicon of the previous GB, the Caddock MP915 and a Mills MRA-5.

The Caddock is better than the Xicon, more refined and open but difference is not so big for 6x the cost...

The Mills is strange, is the more refined of all three but is somewhat dinamically challenged... and directional (!)

If cost is no object the Caddock is the winner but a cost conscious build probably would drop it...

LM318

Mounted and burning in the metal can version, it seems a nice but a bit subtle upgrade.

Disclaimer: All those test could change results with burn-in of components and further listening sessions.

The unique exception is the 220pF FKP2 in C12, IMHO a definitive and suggested mod.
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