Amp for B&O speakers
April 8, 2005
I have a pair of '70s B&O Beovox 3800 speakers. The
sticker at the back says they are 4-ohm 50W speakers. Unfortunately, I am not very well
versed in hi-fi and I would like to ask for your opinion on what kind of amplifier would
be good to drive these speakers. I have options of buying a second-hand Rotel 820 or 920
(which is only 25W), but I am not sure if they are powerful enough. Can you please suggest
to me what the main features of a good amp (for these speakers) would be? Any idea for a
second-hand model would be highly appreciated.
Ede
The main feature you need to look for is the ability to
drive low impedances. Specifically, make sure the amplifier you're considering is rated by
the manufacturer to drive a 4-ohm load. Looking at the unit's specifications (you can find
these in the back of the owner's manual for most amplifiers) you'll almost always see a
power rating into 8 ohms. For example, the Rotel you're looking at might be specified to
produce 25W in 8 ohms. You want to make sure that there is also a 4-ohm rating. Typically
the amp should produce more power into the 4-ohm load than into 8 ohms. I suspect the
Rotel will produce at least 40Wpc into 4 ohms. With your speakers it is imperative that
the amplifier you buy have this rating. I suspect the Rotel does and would therefore be
fine for your situation. Rotel usually builds pretty beefy amplifiers.
DIY subwoofer
April 7, 2005
I have subwoofer speaker, 10'', and I want to make a box
for it, but I don't know how. Could you tell me how to make it?
Gede
I suggest you do some reading on the website www.diysubwoofers.org. There seem
to be quite a number of do-it-yourself designs detailed there, and I'm sure you can pick
up some helpful tips. I'd also suggest you plan to power the unit with a built-in
amplifier. Google "plate amps" and you'll come up with a plethora of options at
all different price points. These amps will recess right into your enclosure and include
crossover functions too. Lastly, you can buy pre-finished boxes from many online vendors
such as www.madisound.com if you
decide that constructing your own box is too much trouble. It's surprising just how
cost effective these enclosures are.
Integrated amp high end?
April 5, 2005
Is an integrated amplifier considered "high end"
or do you have to have a separate amp and preamp to be considered truly high end?
Franco
"High-end" as a concept is related more to
sound quality and ultimate performance than any system or component type. If a
manufacturer has sound quality as an ultimate goal, the component is considered high end
regardless of the cost or product genre. So the answer is that, yes, an integrated
amplifier can be considered a high-end component. In fact, there seem to be more and more
integrateds populating some outstanding systems. On April 15th you'll read about the Blue
Circle CS right here on GoodSound!, a decidedly high-end integrated amplifier
from a specialist manufacturer.
Summing the output of two amps?
April 1, 2005
I have two power amps (one Kenwood, the other Sansui). I
was wondering if I can use both to increase the power to my speakers? Is there a device I
can buy to sum their power?
You have a great website.
Donald
It's not possible to sum the output of the two power
amplifiers you have, nor is there a commercial product, at least that I'm aware of, that
will allow you to do this. There is a way to use both power amplifiers at the same time
with one set of speakers, however: biamplify. Your speakers must be set up for
biamplification, though, and there's no guarantee that biamplifying will actually sound
better than using just one amp. It's something you simply have to try to know.
You can easily check if you can biamplify by looking at
the back of your speakers. If there are two sets of binding posts (i.e., four
connectors), then you're in luck. What these connectors allow you to do is connect one
amplifier to one set of inputs/connectors (likely labeled "high frequency" or
similar) and the other amplifier to the second set of inputs/connectors (likely labeled
"low frequency" or similar). One amplifier drive the highs, and the other
amplifier drives the lows. To accomplish this you would also need two sets of outputs on
your preamplifier (or you would need to use a "Y" adapter to split the output
you have into two runs) and two sets of interconnects to run to each amplifier.
The one problem with biamping that you should be aware
of is matching the relative output levels of each amplifier so one is not louder than the
other. If it is, this can cause the highs to play back louder than the lows, or vice
versa. Hopefully, one or both of your amps have a level/gain control that would help you
level-match the output.
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