Fusing Monitors

Archived from groups: rec.audio.pro (More info?)

<< Is this a bad idea in general? >>

It does mean that your speaker cable is essentially a super tiny strand of
easily vaporised metal. I don't want my audio going through that.

Scott Fraser

Archived from groups: rec.audio.pro (More info?)

"e.maynard" <heartwood-erik@mindspring.com> wrote in message news:nz_vd.306$yK.24@newsread3.news.atl.earthlink.net...
> Hi.
>
> I've been using a pair of AR 18s speakers as nearfield monitors for many
> years, and I'd like to keep using them. The trouble is about every 9
> months or so, I have to replace a tweeter. I'm using a Hafler Pro2400
> amp (120 watts per side @ 8 ohms) and the speakers are rated "50 watts
> nominal/ 60 watts Maximum". I never monitor at too high a level, but
> there are those moments where loud source material will find it's way to
> them (Mr. Hi-hat when I'm not expecting it etc.).
>
> The AR manual suggests that when the speakers are going to be subjected
> to this kind of enviromnent, that you use a fuse. Their suggested fuse
> is a Bussman FNM 1 1/4, in a fuse block, on the back of the cabinet
> inline with either the + or - input. FNM 1 1/4 fuses are really hard to
> find! Can anyone suggest a substitute? Is this a bad idea in general?
> Guide me.........
>
> Many Thanks!

1 1/4 amp fuses can be ordered in large lots, but aren't as easy to
find in small packages.

I use a standard 240v, 1.5 amp, AGC Buss type fuse, in line, on the
positive lead to all near fields until the installs are running smoothly
and the operators have a grip on caution with levels. Sometimes I
leave them in and sometimes I remove them... it's a choice that has
to be based on need. There is a school of thought (a correct one,
I might add) that says if the monitors are pushed to a high level, the
heated filament of the fuse can change the sound. At nominal levels
it shouldn't be a problem.

The parts (holders and fuses) for these are readily available at Radio
Shack and other electronics shops, and the 1.5 amp fuses are very
common. The 2/10ths of an amp differetial between the 1 1/4 amp
fuse should make little difference when dealing with a spike and leave
a little more headroom before filament heating affects the sound when
monitoring normally.

--
David Morgan (MAMS)
http://www.m-a-m-s DOT com
Morgan Audio Media Service
Dallas, Texas (214) 662-9901
_______________________________________
http://www.artisan-recordingstudio.com

Archived from groups: rec.audio.pro (More info?)

If the max wattage rating is 60, then the current max would be I=P/R^2,
or 60/64, which would be just under 1 amp. Use an inline fuse holder
with a fast acting 1 amp fuse in line with the + lead. The voltage
rating is not as important, but anything of the typical 120/240 variety
is fine. 1 amp fast acting fuses should be available at Radio Shack or
even Home Depot or Lowes.

David Morgan (MAMS) wrote:
> "e.maynard" <heartwood-erik@mindspring.com> wrote in message news:nz_vd.306$yK.24@newsread3.news.atl.earthlink.net...
>
>>Hi.
>>
>>I've been using a pair of AR 18s speakers as nearfield monitors for many
>>years, and I'd like to keep using them. The trouble is about every 9
>>months or so, I have to replace a tweeter. I'm using a Hafler Pro2400
>>amp (120 watts per side @ 8 ohms) and the speakers are rated "50 watts
>>nominal/ 60 watts Maximum". I never monitor at too high a level, but
>>there are those moments where loud source material will find it's way to
>>them (Mr. Hi-hat when I'm not expecting it etc.).
>>
>>The AR manual suggests that when the speakers are going to be subjected
>>to this kind of enviromnent, that you use a fuse. Their suggested fuse
>>is a Bussman FNM 1 1/4, in a fuse block, on the back of the cabinet
>>inline with either the + or - input. FNM 1 1/4 fuses are really hard to
>>find! Can anyone suggest a substitute? Is this a bad idea in general?
>>Guide me.........

Archived from groups: rec.audio.pro (More info?)

Greg Taylor wrote:
> If the max wattage rating is 60, then the current max would be I=P/R^2,
> or 60/64, which would be just under 1 amp. Use an inline fuse holder
> with a fast acting 1 amp fuse in line with the + lead. The voltage
> rating is not as important, but anything of the typical 120/240 variety
> is fine. 1 amp fast acting fuses should be available at Radio Shack or
> even Home Depot or Lowes.
>
> David Morgan (MAMS) wrote:
>
>> "e.maynard" <heartwood-erik@mindspring.com> wrote in message
>> news:nz_vd.306$yK.24@newsread3.news.atl.earthlink.net...
>>
>>> Hi.
>>>
>>> I've been using a pair of AR 18s speakers as nearfield monitors for many
>>> years, and I'd like to keep using them. The trouble is about every 9
>>> months or so, I have to replace a tweeter. I'm using a Hafler Pro2400
>>> amp (120 watts per side @ 8 ohms) and the speakers are rated "50 watts
>>> nominal/ 60 watts Maximum". I never monitor at too high a level, but
>>> there are those moments where loud source material will find it's way to
>>> them (Mr. Hi-hat when I'm not expecting it etc.).
>>>
>>> The AR manual suggests that when the speakers are going to be subjected
>>> to this kind of enviromnent, that you use a fuse. Their suggested fuse
>>> is a Bussman FNM 1 1/4, in a fuse block, on the back of the cabinet
>>> inline with either the + or - input. FNM 1 1/4 fuses are really hard to
>>> find! Can anyone suggest a substitute? Is this a bad idea in general?
>>> Guide me.........




Is there an advantage to the fast acting type? Other than the obvious
reason that it acts faster?

Archived from groups: rec.audio.pro (More info?)

e.maynard <heartwood-erik@mindspring.com> wrote:
>ScotFraser wrote:
>> << Is this a bad idea in general? >>

>>
>> It does mean that your speaker cable is essentially a super tiny strand of
>> easily vaporised metal. I don't want my audio going through that.
>
>Good point. But weren't there fuses in some of the large mains made some
>years ago?

There are fuses in lots of large mains. And yes, they are probably degrading
the sound, but they do so less than most of the other protection alternatives
out there. On the other hand, they are less effective than a lot of the
alternatives too. I would generally recommend avoiding them unless you know
you have a problem... and clearly the original poster does.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:
> e.maynard <heartwood-erik@mindspring.com> wrote:
>
>>I've been using a pair of AR 18s speakers as nearfield monitors for many
>>years, and I'd like to keep using them. The trouble is about every 9
>>months or so, I have to replace a tweeter. I'm using a Hafler Pro2400
>>amp (120 watts per side @ 8 ohms) and the speakers are rated "50 watts
>>nominal/ 60 watts Maximum". I never monitor at too high a level, but
>>there are those moments where loud source material will find it's way to
>>them (Mr. Hi-hat when I'm not expecting it etc.).
>>
>>The AR manual suggests that when the speakers are going to be subjected
>>to this kind of enviromnent, that you use a fuse. Their suggested fuse
>>is a Bussman FNM 1 1/4, in a fuse block, on the back of the cabinet
>>inline with either the + or - input. FNM 1 1/4 fuses are really hard to
>>find! Can anyone suggest a substitute? Is this a bad idea in general?
>>Guide me.........
>
>
> The FNM would be a good choice, but in a pinch you could just try a regular
> 3AG 1 1/4 amp fuse in series with the tweeter.
>
> You might also consider trying a larger amp.
> --scott


I thought I was on the right track using a 120wpc amp on the 60/65 watt
AR's. So do you think a higher headroom amp will help? Do you think it's
distortion and not "too much power" that's cooking the tweeters?


Thanks again.

Archived from groups: rec.audio.pro (More info?)

"e.maynard" <heartwood-erik@mindspring.com> wrote in message news:41C07D93.3040700@mindspring.com...
> David Morgan (MAMS) wrote:
> > "e.maynard" <heartwood-erik@mindspring.com> wrote in message news:nz_vd.306$yK.24@newsread3.news.atl.earthlink.net...
> >
> >>Hi.
> >>
> >>I've been using a pair of AR 18s speakers as nearfield monitors for many
> >>years, and I'd like to keep using them. The trouble is about every 9
> >>months or so, I have to replace a tweeter. I'm using a Hafler Pro2400
> >>amp (120 watts per side @ 8 ohms) and the speakers are rated "50 watts
> >>nominal/ 60 watts Maximum". I never monitor at too high a level, but
> >>there are those moments where loud source material will find it's way to
> >>them (Mr. Hi-hat when I'm not expecting it etc.).
> >>
> >>The AR manual suggests that when the speakers are going to be subjected
> >>to this kind of enviromnent, that you use a fuse. Their suggested fuse
> >>is a Bussman FNM 1 1/4, in a fuse block, on the back of the cabinet
> >>inline with either the + or - input. FNM 1 1/4 fuses are really hard to
> >>find! Can anyone suggest a substitute? Is this a bad idea in general?
> >>Guide me.........
> >>
> >>Many Thanks!
> >
> >
> > 1 1/4 amp fuses can be ordered in large lots, but aren't as easy to
> > find in small packages.
> >
> > I use a standard 240v, 1.5 amp, AGC Buss type fuse, in line, on the
> > positive lead to all near fields until the installs are running smoothly
> > and the operators have a grip on caution with levels. Sometimes I
> > leave them in and sometimes I remove them... it's a choice that has
> > to be based on need. There is a school of thought (a correct one,
> > I might add) that says if the monitors are pushed to a high level, the
> > heated filament of the fuse can change the sound. At nominal levels
> > it shouldn't be a problem.
> >
> > The parts (holders and fuses) for these are readily available at Radio
> > Shack and other electronics shops, and the 1.5 amp fuses are very
> > common. The 2/10ths of an amp differetial between the 1 1/4 amp
> > fuse should make little difference when dealing with a spike and leave
> > a little more headroom before filament heating affects the sound when
> > monitoring normally.
> >
>
> "until the installs are running smoothly and the operators have a grip
> on caution with levels"
>
> So what you are saying is..........I should get a grip on the levels in
> the room instead of fooling with an inline fuse. I can handle that. It's
> just that the old AR tweeters are getting harder to find.
>
> Thanks.

Everybody makes mistakes, and it sounds to me like your ARs may
not have replacement tweets available forever. I'd opt for the fuses....
if you can hear degradation (my bet is you won't) remove them. But
someday perhaps, there will be someone working in your place other
than you.... maybe it's his/her ass you need to cover. ;-)

DM

Archived from groups: rec.audio.pro (More info?)

e.maynard <heartwood-erik@mindspring.com> wrote:
Kludge wrote:
>>
>> The FNM would be a good choice, but in a pinch you could just try a regular
>> 3AG 1 1/4 amp fuse in series with the tweeter.
>>
>> You might also consider trying a larger amp.
>
>I thought I was on the right track using a 120wpc amp on the 60/65 watt
>AR's. So do you think a higher headroom amp will help? Do you think it's
>distortion and not "too much power" that's cooking the tweeters?

Maybe. I assume that you are blowing the tweeters when you are doing
something silly, like repatching live? And you aren't actually blowing
them when monitoring, right?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:
> e.maynard <heartwood-erik@mindspring.com> wrote:
> Kludge wrote:
>
>>>The FNM would be a good choice, but in a pinch you could just try a regular
>>>3AG 1 1/4 amp fuse in series with the tweeter.
>>>
>>>You might also consider trying a larger amp.
>>
>>I thought I was on the right track using a 120wpc amp on the 60/65 watt
>>AR's. So do you think a higher headroom amp will help? Do you think it's
>>distortion and not "too much power" that's cooking the tweeters?
>
>
> Maybe. I assume that you are blowing the tweeters when you are doing
> something silly, like repatching live? And you aren't actually blowing
> them when monitoring, right?
> --scott


Yup......It's never happened while monitoring, just when I do something
stupid like patching

Archived from groups: rec.audio.pro (More info?)

On Wed, 15 Dec 2004 12:30:33 -0600, "jakdedert"
<jdedert@bellsouth.net> wrote:

>e.maynard wrote:

>>>
>>>> Hi.
>>>>
>>>> I've been using a pair of AR 18s speakers as nearfield monitors for
>>>> many years, and I'd like to keep using them. The trouble is about
>>>> every 9 months or so, I have to replace a tweeter. <snip>

Well, knowing Hafler amps, it's not clipping that's destroying the
tweeters...it's over powering. Cut back on the gain a bit. Sounds
like you're trying to push these heat sinks more than 4 dB above their
rating. Either that, or dump them for some JBLs.

dB

Archived from groups: rec.audio.pro (More info?)

In article <PJ0wd.278$Z47.15@newsread2.news.atl.earthlink.net> heartwood-erik@mindspring.com writes:

> Yup......It's never happened while monitoring, just when I do something
> stupid like patching

Well, then DON'T DO THAT!

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

"DeserTBoB" <desertb@rglobal.net> wrote in message news:h391s096b9spc6lc0rn8q8fpbnev31qdas@4ax.com...
> On Wed, 15 Dec 2004 18:41:26 GMT, "e.maynard"
> <heartwood-erik@mindspring.com> wrote:
>
> >> You might also consider trying a larger amp.
> >> --scott
> >
> >
> >I thought I was on the right track using a 120wpc amp on the 60/65 watt
> >AR's. So do you think a higher headroom amp will help? Do you think it's
> >distortion and not "too much power" that's cooking the tweeters? <snip>
>
> Not clipping. You're overpowering them because of AR's legendary
> shitty efficiency. Dump 'em and get something more efficient.
>
> dB


I dunno.... I'd give good money to have back some of the AR models
I've been through over the years.

Archived from groups: rec.audio.pro (More info?)

True, but the HF power component of most program material is at that
degree lower anyway. If you want to use this approach then you would
use a lower amperage fuse, say .25-.30 amps and wire it inline with the
tweeter ONLY, which means opening up the box, etc. Putting a fuse of
that rating inline with both woofer and tweeter will always blow
prematurely because of the higher bass and mid power levels.

James Perrett wrote:

> If they're going in series only with the tweeter would it be a good idea
> to use a slightly lower current rating? I understood that if a speaker
> system is rated at 60W then the tweeter itself is usually rated at a
> lower power (say 15-20W continuous).

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:
> In article <41C19C48.A9F35E7C@soc.soton.ac.uk>,
> James Perrett <James.R.Perrett@soc.soton.ac.uk> wrote:
>
>>Scott Dorsey wrote:
>>
>>>The FNM and FLM fuses blow more slowly than the AGC types, but they do
>>>not have as high series resistance before blowing than the MDR slow-blow
>>>types. They are about the same as the 593-series military fuses.
>>>
>>>If the tweeter failures are caused by slow heating effects, these fuses
>>>are going to be more effective than AGC fuses for the same probability of
>>>false blowing. If they are caused by rapid effects (like dome tearing,
>>>coil tearing from the dome, etc.) they will be less effective.
>>>
>>>I would tend to try the AGC 1 1/4 fuse. If you get a lot of random blowing
>>>during normal operation, then I'd investigate more. If you don't, don't
>>>worry about it.
>>
>>If they're going in series only with the tweeter would it be a good idea
>>to use a slightly lower current rating? I understood that if a speaker
>>system is rated at 60W then the tweeter itself is usually rated at a
>>lower power (say 15-20W continuous).
>
>
> I gathered the manufacturer recommended 1 1/4 in series with the tweeter.
> You _always_ want to fuse the drivers seperately and not put the thing
> in front of the crossover. If the manufacturer indeed recommended something
> of 1 1/4A before the crossover, you probably want a much smaller fuse on
> the tweeter itself.
> --scott


The AR manual suggests installing the fuse block on the back of the
speaker cabinet. One lead (-) would attach directly to the normal input,
and the (+) lead would run through the fuse and into the speaker input.
All of this is pre-X-over.

Scott, if my only problem seems to be with the tweeter(s), do you think
it'd be a better idea to fuse just the tweeter (post x-over)?

Archived from groups: rec.audio.pro (More info?)

I love my AR91's...

"David Morgan (MAMS)" <mams@NOSPAm-a-m-s.com> wrote in message
news:6S4wd.7558$E_6.4132@trnddc04...
>
> "DeserTBoB" <desertb@rglobal.net> wrote in message
> news:h391s096b9spc6lc0rn8q8fpbnev31qdas@4ax.com...
>> On Wed, 15 Dec 2004 18:41:26 GMT, "e.maynard"
>> <heartwood-erik@mindspring.com> wrote:
>>
>> >> You might also consider trying a larger amp.
>> >> --scott
>> >
>> >
>> >I thought I was on the right track using a 120wpc amp on the 60/65 watt
>> >AR's. So do you think a higher headroom amp will help? Do you think it's
>> >distortion and not "too much power" that's cooking the tweeters? <snip>
>>
>> Not clipping. You're overpowering them because of AR's legendary
>> shitty efficiency. Dump 'em and get something more efficient.
>>
>> dB
>
>
> I dunno.... I'd give good money to have back some of the AR models
> I've been through over the years.
>
>

Archived from groups: rec.audio.pro (More info?)

"e.maynard" <heartwood-erik@mindspring.com> wrote in message
news:Rriwd.1362$yK.1064@newsread3.news.atl.earthlink.net
> Scott Dorsey wrote:
>> e.maynard <heartwood-erik@mindspring.com> wrote:
>>
>>> The AR manual suggests installing the fuse block on the back of the
>>> speaker cabinet. One lead (-) would attach directly to the normal
>>> input, and the (+) lead would run through the fuse and into the
>>> speaker input. All of this is pre-X-over.
>>>
>>> Scott, if my only problem seems to be with the tweeter(s), do you
>>> think it'd be a better idea to fuse just the tweeter (post x-over)?

>> Yes, it is always better to fuse the drivers individually. You want
>> the fuse to be seeing what the load it is protecting sees, not a
>> combination of that and stuff from other loads. Each load should
>> have an individual fuse.

Agreed.

There are issues with thermally-induced IM in fuses serving a full-range
driver.

The same thermal effects might cause THD for woofers. However woofer fuses
are usually much more massive, and thermal effects are lower for
higher-current fuses.

> So if I just want/need/chose to fuse the tweeters, would you
> recommend a fuse value to use. Do you think it'd be a good idea to
> use a fuse holder like this:
> http://www.partsexpress.com/pe/sho [...] er=070-630


> Or a nicer version of it.

Looking at

http://www.partsexpress.com/pdf/catalog05/110pec05.pdf

I'd pick pn 071-510, which is probably no nicer, but for the cost
differential...

If a fuse holders like this didn't work reliably and well, a big chunk of
the world of electronics as we know it would stop operating.

Archived from groups: rec.audio.pro (More info?)

"e.maynard" <heartwood-erik@mindspring.com> wrote in message
news:41C1BAD9.4010100@mindspring.com
> Arny Krueger wrote:
>> "e.maynard" <heartwood-erik@mindspring.com> wrote in message
>> news:Rriwd.1362$yK.1064@newsread3.news.atl.earthlink.net
>>
>>> Scott Dorsey wrote:
>>>
>>>> e.maynard <heartwood-erik@mindspring.com> wrote:
>>>>
>>>>
>>>>> The AR manual suggests installing the fuse block on the back of
>>>>> the speaker cabinet. One lead (-) would attach directly to the
>>>>> normal input, and the (+) lead would run through the fuse and
>>>>> into the speaker input. All of this is pre-X-over.
>>>>>
>>>>> Scott, if my only problem seems to be with the tweeter(s), do you
>>>>> think it'd be a better idea to fuse just the tweeter (post
>>>>> x-over)?
>>
>>
>>>> Yes, it is always better to fuse the drivers individually. You
>>>> want the fuse to be seeing what the load it is protecting sees,
>>>> not a combination of that and stuff from other loads. Each load
>>>> should have an individual fuse.
>>
>>
>> Agreed.
>>
>> There are issues with thermally-induced IM in fuses serving a
>> full-range driver.
>>
>> The same thermal effects might cause THD for woofers. However woofer
>> fuses are usually much more massive, and thermal effects are lower
>> for higher-current fuses.
>>
>>
>>> So if I just want/need/chose to fuse the tweeters, would you
>>> recommend a fuse value to use. Do you think it'd be a good idea to
>>> use a fuse holder like this:
>>> http://www.partsexpress.com/pe/sho [...] er=070-630
>>
>>
>>
>>> Or a nicer version of it.
>>
>>
>> Looking at
>>
>> http://www.partsexpress.com/pdf/catalog05/110pec05.pdf
>>
>> I'd pick pn 071-510, which is probably no nicer, but for the cost
>> differential...
>>
>> If a fuse holders like this didn't work reliably and well, a big
>> chunk of the world of electronics as we know it would stop operating.

> Any suggestions on which fuse to use? Hey that rhymes.

I'd start out with one that I thought was a bit small, and replace it as
needed until the required size was so large that I was starting to get
afraid.

In the case of a tweeter, I'd start with a 1 amp fuse, and get very scared
around 3 amps, unless this was something like the large horn tweeter in a
stage monitor.

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:
> e.maynard <heartwood-erik@mindspring.com> wrote:
>
>>So if I just want/need/chose to fuse the tweeters, would you recommend a
>>fuse value to use. Do you think it'd be a good idea to use a fuse holder
>>like this:
>>http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=070-630
>>
>>Or a nicer version of it.
>
>
> Sure. Whatever your local auto parts store has in stock.
>
> I'd say start out with a 1/4 amp, then work up until it isn't blowing
> during normal use.
> --scott



Thanks a lot for all of the advice. I wish I could find a fuse holder
similar to this (that would hold an ADC type fuse):

http://www.bussmann.com/library/bifs/2114.pdf

The reason being that it would be easier to install on the back of the
cabinet (due to the "ear" type design).