bi wire,is there much point????????

Hello again folks,
I've had a dig around to find out the voltage gains of the NAD and Naim gear and both seem to be 29 db.

I think most of the improvement in the sound appeared to be the matching of the grunt and welly of the NAD with far superior treble ablilites of the Naim. We did try swaping the amps round (i.e Naim for Bass duties and NAD for treble) but the results were distinctly poor in comparison and not to be recommended.

I can comment that the timing was perfectly accecptable and certainly no worse than my standard TEAC VRDS T1, Nad setup.

It could be that we just happended to stumble upon a very good ,but strange match. It certainly wasn't a "boombox" presentation, just silky smooth, detailed and nicely integrated. I agree that more extended listening would have been nice, but over the cousre of the 2 hours or so that we had the system in this set-up it sounded good with a wide variety of listening material.

I'll try it out again soon with the sole intention of evaluating the relative merits of Bi -Amping, but with more extended listening. When I tried it the last time it was during an equipment comparison session between my friends system and my own that lasted two days and alot of mixing of source, cables, amps and speakers.


Oh well, I suppose more experimentation is required.

 

so how do you go about bi amping? do you ned power and pre outs on the amps?



cheers,



Rob.

 

rob,
bi-amping involves using 2 stereo amplifiers to drive the mid/bass and treble speaker cones seperately.
you can have either vertical or horizontal bi-amping.
horizontal biamping is where one amp drives both speakers low frequencies and the other amp drives both speakers high frequencies.
vertical bi-amping is where one amp uses one channel to drive the low frequencies and the other channel to drive the high frequencies of one speaker and the other amp is used in the same manner to drive the other speaker.
the differencies are usually just one of cabling. improvements are usually quoted to be better spaciality and detail. there is also the assertion that timing and coherence can suffer.
if you have an integrated amp with pre-outs (most do) and a matching power amp (e.g. arcam's a85 and p85) connect them together as explained in the manual. then remove the link wire / bars on the back of your speakers (these are usually wires or flat bits of metal). run the bass speaker cabled runs from the power amp to the lower binding posts on the back of the speaker (usually, again check the manuals). run the treble speaker cables
from the integrated to the top speaker terminals (again check the manuals). this is horizontal bi-amping.
one further way of using 2 amps is bridging. not all amps are capable of this but some are. this means using both channels of the amp to create 1 much more powerful channel. i.e. turn a 100 wpc stereo amp into a 300 wpc monoblock. this is fine however you cannot bi-amp in the traditional way like this and there may be speaker matching problems as the amp now sees 1/2 the impedance i.e. instead of seeing an 8 ohm speaker it now 'sees' a 4 ohm speaker so if the amps psu is a bit weedy distortion will set in quickly.
hope that helps.
cheers

julian

 

Unless you're using four mono-blocks, you're only going to have one channel per side aren't you? I mean it is the same amp channel driving the LF and HF of each speaker isn't it?

 

is it possable to bi amp using the tape rec out of one amp and running it to aux on another?



cheers,

Rob.

 

Rob, honestly mate I wouldnt bother with bi-amping... even more so if your amp doesnt have pre-out.

If you have 2 amps why not flog them both and get a better one?

I biamped with 2 x valve powers and a valve pre for over a year, and I'd never do it again.

Others MMV of course.

Cheers
Chris

 

The answer is yes but not easily. The problem is that the tape output is at a fixed level. Every time you wanted to adjust the volume, you would need to adjust both amps in order to balance the bass and treble.

The pre-out on the other hand is volume controlled so the power amp needs no volume control. Both amps must have the same gain for this to work properly. For example, all the Arcam Alpha amps had the same gain so you can pair any Alpha integrated with any Alpha power amp and bi-amp.

Chris

 

martin,
no, you feed both channels of 1 amp the left signal and both channels of the other the right - you may need to make up splitter leads for this though and it may not be possible if you are using an integrated amp without external bridging between the pre and power sections (naim definately and nad i believe do this, any others?)
there may be benefits to this if you don't have a dual mono power amp as the transformer is having to supply the same current to both channels at the same time.
cheers


julian

 

If you're talking about using two integrated amps like this then you're going to end up with seperate volume controls for the LF and HF aren't you? Although I guess this could be fun to play with I don't think it's really very practical is it If you took the tape loop output and fed it into a dedicated power amp then this wouldn't be any good either, because then you'd have NO volume control for whatever the power amp was driving.

 

Tape rec output is fixed as it is not controlled by the volume control of the pre-amp.

 

Just in case you didn't get the message yet no, because the tape rec output is fixed and not volume controlled.

Michael.

 

Which is better? Bi-amp or separate pre-amp and power amp?

For instance Arcam A85/P85 combination is capable or either.
But experts seem to recommend using them as pre/power.

 

You can use both, I used to run A32/P35 horizontal bi-amped, first using the A32's Throu line straight to the p35, with matchoing (no R/A i/c's ).
Then using the built in preamp in the dac (to far better effect) then switching the A32 into power amp mode, and using the 'throu line' to give the P35 it's signal
Bi-amping, gave me a monster stage and image, with big bass, sort of painted the wall with sound (Some do remember the feeling), mono blocking, some feel you lose the total dynamics and openiness, they may be right, but I feel you gain more naturaliness and depth and realisum, this is based on my findings only WM

 

Right, I see what you mean. I kind of thought you'd only ever vertically bi-amp using single channel amps (mono blocks or bridged stereo amps), what you're talking about is using two stereo amps right? Is that common? I must confess I've never heard of anyone doing this although I can now see it's possible, although if you have to use some sort of signal splitter I'd naively wonder if this would obviate any gains you might achieve by the biamping?

 

You would only need a signal splitter if the pre hase one set of outputs. This applies to vertical or horizontal bi-amping.

There are a few reasons some people go for vertical bi-amping.

Imagine you have two identical power amps that don't use a dual mono power supply.
Consider horizontal bi-amping. The power amp supplying the mid/bass is under more stress as it has to provide more current than the power amp supplying the tweeters.
Now consider vertical bi-amping. In each amp one channel drives the bass and one channel drives the treble. Potentially this means that there is more current available for the bass as the treble is not taxing the power supply.
Another possible advantage of vertical bi-amping is that there no chance of cross talk within the power amp.
With vertical bi-amping you could also place your amps closer to their respective speakers.

 

Vertical biamping with mono blocks would only require one pair of pre-amp outs I believe, although most people worrying about biamping are going to have a good enough pre amp to have at least two pairs anyway. Right now I'm trying a Densen preamp that has four pairs of pre-amp outs, which seems rather excessive...

Would there not potentially be even more current available for the bass if the amp was bridged (since I assume significantly less than half the current would be needed for the HF)? You would though of course loose the benefit of isolating the LF and HF parts.

Is vertical biamping using two stereo power amps common?

 

Four pairs of pre outs does seem excessive.

I agree that vertical bi-amping does not seem to be very common.
If you have the facility to try then I don't see any reason not to give a go at least once.

I suppose that bridging offers even more current to the bass.
The only problem is if your speakers are low impedance. Bridged amps are not always happy about low impedance speakers.

 

Have you guys ever seen a 'Y' lead before ?, saves a lot grief

 

denson are, i believe, advocates of active operation and are going to bring out an active crossover. if you have a 3 or 4 way speaker system you may need this many pre outs to split the signal as close to the source as possible. naim do a similar thing on the rear of their psu, which for earthing reasons have the signal running through the psu.]

some power amps intended for use with integrated amps have a signal through allowing you to daisy chain amps how you like i believe arcam and cyrus do this but i could be wrong?
cheers


julian