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From: Meat Plow on 23 Jun 2010 10:59
On Thu, 24 Jun 2010 00:30:47 +1000, Grant ǝʇoɹʍ:

> On Wed, 23 Jun 2010 13:23:04 +0000 (UTC), Meat Plow <mhywatt(a)yahoo.com>
> wrote:
>
>>On Wed, 23 Jun 2010 08:48:22 +0100, N_Cook ??o??:
>>
>>> Just curious about these - how were they used? All that is known is
>>> they came from an audio lab.
>>> About 200 watt, 2.8 ohm vitreous resistors. 200watt estimated, by me,
>>> from surface area scaling of 2.5 and 6W ones, these are 210 mm long
>>> 35mm diameter. Some sort of multiple series and parallel for 2 ohm etc
>>> or with L and C for speaker simulation ?
>>
>>Most newer SS amps are rated to a minimum of 2 ohms.
>
> And cheapie meter leads might account for the extra 0.8 Ohms? --
> Grant.

They'd have to be very cheap. Mr. Kook is a talented technician so I
think that we can rule out that factor.

I use a pair of finned 300 watt 8 ohm resistors mounted on a giant power
supply heat sink to raise their continuous rating. Got them from Yamaha
way back in the 80's when I did warranty work for their pro-audio line.
They aren't branded Yamaha. They sent them to our warranty station along
with some other equipment they required to authorize us. If I recall the
total startup cost was a couple thousand bucks but we also had a credit
line with their service/parts dept.
From: AZ Nomad on 23 Jun 2010 12:10
On Thu, 24 Jun 2010 00:30:47 +1000, Grant <omg(a)grrr.id.au> wrote:
>On Wed, 23 Jun 2010 13:23:04 +0000 (UTC), Meat Plow <mhywatt(a)yahoo.com> wrote:

>>On Wed, 23 Jun 2010 08:48:22 +0100, N_Cook ??o??:
>>
>>> Just curious about these - how were they used? All that is known is they
>>> came from an audio lab.
>>> About 200 watt, 2.8 ohm vitreous resistors. 200watt estimated, by me,
>>> from surface area scaling of 2.5 and 6W ones, these are 210 mm long 35mm
>>> diameter. Some sort of multiple series and parallel for 2 ohm etc or
>>> with L and C for speaker simulation ?
>>
>>Most newer SS amps are rated to a minimum of 2 ohms.

>And cheapie meter leads might account for the extra 0.8 Ohms?

You'd need at least 90' of them (at 20 AWG)

or 8' of 30AWG, but I've never heard of such slim wire
being used for probes.
From: GregS on 23 Jun 2010 12:28
In article <slrni24cf9.uu4.aznomad.3(a)ip70-176-155-130.ph.ph.cox.net>, AZ Nomad <aznomad.3(a)PremoveOBthisOX.COM> wrote:
>On Thu, 24 Jun 2010 00:30:47 +1000, Grant <omg(a)grrr.id.au> wrote:
>>On Wed, 23 Jun 2010 13:23:04 +0000 (UTC), Meat Plow <mhywatt(a)yahoo.com> wrote:
>
>>>On Wed, 23 Jun 2010 08:48:22 +0100, N_Cook ??o??:
>>>
>>>> Just curious about these - how were they used? All that is known is they
>>>> came from an audio lab.
>>>> About 200 watt, 2.8 ohm vitreous resistors. 200watt estimated, by me,
>>>> from surface area scaling of 2.5 and 6W ones, these are 210 mm long 35mm
>>>> diameter. Some sort of multiple series and parallel for 2 ohm etc or
>>>> with L and C for speaker simulation ?
>>>
>>>Most newer SS amps are rated to a minimum of 2 ohms.

CAR AMPS

>>And cheapie meter leads might account for the extra 0.8 Ohms?
>
>You'd need at least 90' of them (at 20 AWG)
>
>or 8' of 30AWG, but I've never heard of such slim wire
>being used for probes.

I typically get .3 ohms on the Fluke.

I have a couple dummy loads. One with 8- 50 watt gold
chassis resistors attached to sink with fan.
I have four more separate sinks without fan.
I either choose 8 ohms or 4.

greg
From: Cydrome Leader on 23 Jun 2010 13:20
N_Cook <diverse(a)tcp.co.uk> wrote:
> Just curious about these - how were they used? All that is known is they
> came from an audio lab.
> About 200 watt, 2.8 ohm vitreous resistors. 200watt estimated, by me, from
> surface area scaling of 2.5 and 6W ones, these are 210 mm long 35mm
> diameter. Some sort of multiple series and parallel for 2 ohm etc or with L
> and C for speaker simulation ?

the ones I used were just large (hundreds of watts) ceramic wirewound
resistor mounted in heatsinks. They had to have been 8 ohms or something
really close as to not blow up 1970s and 1980s equipment.

you could hear the music though them if you got close enough.


From: Gareth Magennis on 23 Jun 2010 13:51


"GregS" <zekfrivo(a)zekfrivolous.com> wrote in message
news:hvtck7$hc9$1(a)usenet01.srv.cis.pitt.edu...
> In article <slrni24cf9.uu4.aznomad.3(a)ip70-176-155-130.ph.ph.cox.net>, AZ
> Nomad <aznomad.3(a)PremoveOBthisOX.COM> wrote:
>>On Thu, 24 Jun 2010 00:30:47 +1000, Grant <omg(a)grrr.id.au> wrote:
>>>On Wed, 23 Jun 2010 13:23:04 +0000 (UTC), Meat Plow <mhywatt(a)yahoo.com>
>>>wrote:
>>
>>>>On Wed, 23 Jun 2010 08:48:22 +0100, N_Cook ??o??:
>>>>
>>>>> Just curious about these - how were they used? All that is known is
>>>>> they
>>>>> came from an audio lab.
>>>>> About 200 watt, 2.8 ohm vitreous resistors. 200watt estimated, by me,
>>>>> from surface area scaling of 2.5 and 6W ones, these are 210 mm long
>>>>> 35mm
>>>>> diameter. Some sort of multiple series and parallel for 2 ohm etc or
>>>>> with L and C for speaker simulation ?
>>>>
>>>>Most newer SS amps are rated to a minimum of 2 ohms.
>
> CAR AMPS
>
>>>And cheapie meter leads might account for the extra 0.8 Ohms?
>>
>>You'd need at least 90' of them (at 20 AWG)
>>
>>or 8' of 30AWG, but I've never heard of such slim wire
>>being used for probes.
>
> I typically get .3 ohms on the Fluke.
>
> I have a couple dummy loads. One with 8- 50 watt gold
> chassis resistors attached to sink with fan.
> I have four more separate sinks without fan.
> I either choose 8 ohms or 4.
>
> greg



My highest power dummy load is a (hacked) 3KW fan heater.



Gareth.

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