Sunfire Sub Hum Elimination
Joe Adams
Have a Sunfire True Subwoofer? Does it hum? Have you tried lifting
the ground and reversing AC power polarity and hum still exists? Then
do what I did: install an AC line isolation transformer (there are
many good ones available surplus from the computer industry) and your
hum problem will be solved. I used a 1kVA high isolation type and and
the hum simply disappeared.
WWWires
I heard one Humming quite loudly at a dealer (who will go nameless)
the sales person passed it off as a problem in the setup it was hooked
into the "subwoofer out" of a AV reciever, yuch. Given its
capabilities and my trust in my setup abilities and its crosover
controls I bought one and to my chagrin it was dead quiet, so I do not
have any first hand experience geting rid of the hum but I think it
should be known that the thing can run silent, and I am sure Bob is
not very happy at your brute force solution, that transformer probably
cost as much new as the sub. I think you should look at the ground on
the interconnect-s try reversing the interconnect (it the shield, I
hope it has a shield, that should be grounded on one end only, and you
thought the electrons wanted to flow that way by design.
Fred W.
Joe Adams
WWWires wrote:
[ cut -- rgd ]
> cost as much new as the sub. I think you should look at the ground on
> the interconnect-s try reversing the interconnect (it the shield, I
> hope it has a shield, that should be grounded on one end only, and you
> thought the electrons wanted to flow that way by design.
The Sunfire subwoofer is *much* more susceptible to hum pickup due to
ac grounding problems than any other subwoofer I have tried. Several
reviews of this unit also bear this out. The isolation transformer
approach is not the only way to eliminate the hum, but it's easy and
works great. Besides, these transformers can be obtained surplus for
less than $100. I did not mean to imply that this subwoofer cannot
run silent. Just unplug the input cable and the hum goes away. But
tracking down ground loops in some complex setups can be a very time
consuming and frustrating affair.
Joe
donahue
Lets see here, using a 1K watt transformer in series with an amp which
draw 2400+ watts of power. Does this idea seem very bright? Any body
buying the Sunfire amp should consider a dedicated high current
(20+amps) AC circuit(s).
I have personally put a 2K watt isolation transformer in series with
my entire stereo system. The higher series impedance presented by the
transformer robbed the music of dynamics and punch.
BTW, I personally auditioned this subwoofer and was not impressed. The
unit was in the left corner of the room. This caused the soundstage to
become unbalanced. You really need two units and who knows how much
wall current. The woofer also buzzed.
The bottom line here is that the special high current needs of this
unit must be provided for before any high-end performance can be
realized.
I can just imagine the sound of your present system. The road is
longer and winding to real music.
uh....OH!
On 6 Jan 1997 10:31:46 -0500, MEE...@prodigy.com (Thomas Garcia)
wrote:
>I believe you may have errored when you proposed that the Sunfire sub
>draws 2400+ watts from a 120v source. The enclosed amp will deliver
>appx. 2700w to the drivers(per specs) but requires far less wattage
>at 120v to drive the amp. Additional research into the manufacturers
>specs. or white paper may clear some of the confusion.
I'm sorry. I missed something in this. What? Do you mean that the
amplifier requires far less power than 2700 watts while delivering
that amount to the drivers? What? Must be a syntax error on my part.
What? Can anyone post the white paper? This confuses the hell out of
me.
colin
Michael Ford
In article <5ar5t2$g...@eyrie.graphics.cornell.edu>, MEE...@prodigy.com
(Thomas Garcia) wrote:
> I believe you may have errored when you proposed that the Sunfire sub
> draws 2400+ watts from a 120v source. The enclosed amp will deliver
> appx. 2700w to the drivers(per specs) but requires far less wattage
> at 120v to drive the amp. Additional research into the manufacturers
> specs. or white paper may clear some of the confusion.
Looking at the AC line input fuse or the UL power spec is a safe way
to check the power requirements. How much the amp can output will not
exceed the input amount for more than the power supply capacitors can
store, and that isn't very long. The last time I checked a typical
wall socket it was good for continous 13 amps and 120 VAC, or about
1500 to 2000 watts. Those are a LOT of watts, with a LOT of heat
needing to go someplace.
So I think the question is backwards. Sure the amp can output 2700
watts for some short period, and maybe even well over 1000 watts
continously, but where is all that heat going to go?
I think the answer is, stay away from the higher power limits except
for VERY short periods of time.
Joe Adams
At maximum output, driven by a 20 Hz continuous signal, the Sunfire
subwoofer might draw 2.7kW, per spec, but in practice, integrated with
normal speakers of average efficiency in a typical 12x15' room, the
sub's level pot is only up 1/4, so I didn't feel the necessity to
install a 3kW isolation transformer, which by itself would probably
have more mechanical hum than the subwoofer! This system sounds quite
fine and needs no apologies, considering the total investment in it.
BTY I never said it was a high-end system, and if it was, I probably
wouldn't use a subwoofer in the first place, and certainly not the
Sunfire. The Sunfire subwoofer's unique asset is its small size and
high performance ratio, which cannot be touched by any subwoofer
currently on the market.
Todd Jenkins
co...@iofr.com (uh....OH!) writes:
>MEE...@prodigy.com (Thomas Garcia) wrote:
>>I believe you may have errored when you proposed that the Sunfire sub
>>draws 2400+ watts from a 120v source. The enclosed amp will deliver
>>appx. 2700w to the drivers(per specs) but requires far less wattage
>>at 120v to drive the amp.
>I'm sorry. I missed something in this. What? Do you mean that the
>amplifier requires far less power than 2700 watts while delivering
>that amount to the drivers?
I don't have a copy of the white paper here at home, but suffice to
say that a great deal of it is rather humorous. But to the question
at hand, it appears that Carver claims 2700W into the 3.3 ohm dcr of
the voice coil (100 volts p-p into 3.3 ohms x 1.15 = REIA is about
2650W). However (and I don't know if this is standard practice
because I don't design amplifiers) this is into the dcr of the coil,
and nowhere is the impedance of the system anywhere close to 3.3 ohms.
My guess (from typical loss factors in the PR system and knowledge of
where the impedance peaks are) is that the minimum impedance is likely
to be around the 20-35hz range and be around 6 ohms. This is then
roughly 1650W peak. Over the range of the amplifier, considering the
inevitably very high peak in impedance in the 40-70hz range, the
average impedance is likely to be in the range of 12-15 ohms...650W.
Most heavy-duty drivers will take this kind of peak power fairly
easily...a pro driver rated at 400W with a 6dB crest factor will
handle 1600W, and one of 600W will take 2.4kW peak. We test drivers
like this for 8 hours continuous on a regular basis, so there's
nothing unusual here except for a fairly high impedance over the
midbass range. I don't particularly like the idea of an amplifier
rated at 2700W when it can't deliver anywhere close to that to the
loudspeaker's load. I can see the amp drawing 2700W from the wall for
very short periods (read *very* considering the fuse), but the shmucks
in the magazines saying that they measured 2700W into the driver
probably didn't realize they had to measure V*I*cos(theta) for true
power...
Cheers!
Todd Jenkins
Project Engineer - EV/Altec Pro
The opinions expressed herein do not represent those of my employer.
APEX...@aol.com
[ Moderator Note: the reply after an initial rejection -- rgd ]
Greetings:
First. I would like to address the issue of my post lacking
substance. Carver Magnetic Field Amplifiers were a "gimmick". Not
getting too deep into the technical aspects of the amplifiers, they
have a very cheap power supply that has serious design limitations and
flaws. I was selling audio components at one time and when a customer
had repeated break downs he wrote Bob Carver. His response was
arrogant, rude, and basically "You bought it, I don't care if it
works, it's your's now". After reading the letter the customer sent
and Bob Carver's response, the owner of the business gave the customer
a new, higher cost amplifier of a different make and dropped the
Carver line from his store.
Second. Obviously Bob Carver is at it again performing his "audio
miracles" with his new Sunfire company. By the nature of the
discussion "Re: Sunfire Sub Hum Elimination" he once again is
designing equipment with serious flaws. My statement that "it's
design flaw is the fact that it was designed by Bob Carver" has very
serious merit and was not intended as a "put down" to those who
purchased his equipment. I sold the stuff, which is in my estimation
is worse than buying a product that is inferior.
Third. I only participate in open discussions that are uncensored
where a free exchange of ideas and opinions can be exchanged. You
should change the name of your discussion "What I think is relevant to
the high end audio world, all opinions other than my own will be
omitted" Obviously I will not be participating anymore and with my
audio experience (just about 20 years now) I'm sure there is much
substantive information I can add (well, maybe not if you don't happen
to agree with what I have to say). I will end by saying this: "To
have bought a Bob Carver product is a mistake. To defend his cheap
designs and marketing gimmicks is stupidity"
Ronald Schneider
On 10 Jan 1997 APEX...@aol.com wrote:
-----< snip >-----
> Carver Magnetic Field Amplifiers were a "gimmick". Not
> getting too deep into the technical aspects of the amplifiers, they
> have a very cheap power supply that has serious design limitations and
> flaws. I was selling audio components at one time and when a customer
> had repeated break downs he wrote Bob Carver. His response was
> arrogant, rude, and basically "You bought it, I don't care if it
> works, it's your's now".
A cheap power supply? I own the Carver PT-2400 Magnetic Field
Amplifier. It definitely does not have cheap power supplies. If never
driven to clipping, then it is an astounding amplifier.
----- <snip >-----
> Second. Obviously Bob Carver is at it again performing his "audio
> miracles" with his new Sunfire company. By the nature of the
> discussion "Re: Sunfire Sub Hum Elimination" he once again is
> designing equipment with serious flaws.
It is a great little sub considering size, price, and
performance. I don't understand why people who are looking for this
sort of combination would ever pass it up.
-----< snip >-----
> I will end by saying this: "To
> have bought a Bob Carver product is a mistake. To defend his cheap
> designs and marketing gimmicks is stupidity"
I admit that I never liked much from the old Carver line exept
for the Amazing Loudspeakers and the PT-2400. So I bought both and it
was no mistake. I would defend them because they sound beutiful and I
don't think that I am stupid. A lot of people bought the mass market
products with the Carver name on it just for the status symbol that
they could put in their stereo rack. It kind of reminds me of when
some people bought Porche 914 just so they could own a Porche. That
did not mean that Porche only produced bad vehicles. They still had
the awsome 911.
I am considering purchasing the new Sunfire Cinema Grand for
home theater. It looks very elegant and is a great little performer. I
think small, elegant ,performers seems to be the trend with the new
Bob Carver Sunfire product designs. So far, I like them.
Tyson Schneider