Alright all?

Today we’re back to Hi-Fi 🙂

I have been experimenting with my Hi-Fi, as I have a 6-channel amp and Bi-wire/amp-able speakers, I have split my line-level signals with a Y-splitter cable and used 4 channels of amplifier to drive the speakers.

I think I like the sound, it’s just that the treble seems a little prominent now, clearer, with better imaging and separation, but maybe just a little peaky?

Could this be because the tweeter is too little load for the amp? Anyone tried this and found a similar problem? Can I hook an 12 Ohm resister in parallel with the tweeter inputs to suck a bit more power through, or will this bugger the crossover points up?

The speakers are 2.5 way, and have 2 pairs of terminals on the rear – one for the tweeter only, and one for the pair of bass/mids.

[12 Ohm chosen as speaker spec is min 6 Ohm and this gives 4 in parallel, amplifier is 4-8 Ohm compatible]

Speakers: AE 109
Amp: Cambridge azur 540r

Sound was a previously touch harsh in the upper registers, generally very good, but it’s the weak point now.

Eventually I plan on using an external crossover and then the amps after it, but not able to do that right now.

Any input?

It can be done but the amps really do need to be very similar.

I went the “comfortably overpowered” route, instead… 🙂

Rachel

I am lucky: In the Azur are 6 identical amps sharing a volume control. It does already work – but I’m a little taken aback by the “extra” treble.

To eliminate one factor, I used 2 of the 4 [!] previously unused channels for the bass, and kept the tweeters on the same amp channels as previously.

Still sounds odd, ish…

Are the crossovers still in the speakers?

edit – oops – re-read your post!

Do you want a bag on your head ?

scaredy – no, silly, I would not want that as then I can’t see and that would inhibit my riding.

Having said that, I would like some peril-sensitive sunglasses.

I did once ride down Oxford street with my eyes shut for 10 seconds, but I was a sh*t courier having a sh*t day and that was in 2008 which was not my best year. Aaaanyway

Double post?!

I have a pair of AE109s biamped with an Arcam Alpha 8/p75. First set it up years ago, so don’t recall exactly how it improved, but it was quite noticeable. I’d recommend it.

Looking to replace my gear with some AVI actives in the not to distant future.

When you biamp or biwire by taking the links out from the speaker posts the crossovers are still active but split – you need them and it is very unlikely indeed that you can better what the speaker manufacturer designed.
The multi channel amp normally needs to be told that it is running in biamp mode with X channels so that it can do the right thing in stereo direct mode or multi channel mode , my Arcam has a setting for biamp with
channel 6 and 7 . Does the Azur have a biamp mode?

In short, don’t.

There’s no doubt that in an ideal world using an active crossover and biamping can work very very well but biamping into a passive crossover gives you no headroom advantage because the treble amp still has to generate the same voltage swing and it’ll still be sending wasted current to ground through the shunt components in the highpass filter. Furthermore an amp driving a complete loudspeaker will be seeing a more consistent load impedance than an amp driving just the high or low half of the system. And what’s going to happen to the baffle step correction if you use an active crossover? What about notch filters on break-up peaks? Good passive crossovers are very cunning beasts (and some of the best appear extremely simple!)

I’m sure no-one cares but I had some prototype drivers I co-designed arrive this afternoon and got a quick and dirty enclosure (cannibalised old design) and very approximate crossover together and got to test it just before the close of play. In one word: Awesome! 🙂

you are changing the load impedence presented to your source using a Y split, you are also effectively connecting the inputs of the amp together as well.

drivers have an impedence not a constant resistance, and there should be no need to
alter the x over if it is a good bi ampable type.

i used 30amp twin and earth on a system once 😆 swear it sounded better…no really;)

If you want to drop the treble a bit, but a few resistors from say 2 ohms up, and when you’ve found what you like then buy the correct value to put across ther terminals to balance it out.

CGG who do you work for?

CGG who do you work for?

A very small pro-audio company – making arguably the best bass cabs on the planet. 🙂 PA and hi-fi speakers also in the works but we’re rather short of time and the critical design details require plenty!

My main source of info here is this:

http://www.halfgaar.net/bi-amping-acoustic-energy-120
– the 120 is a 109 with another network, another driver a little more MDF.

Also emails with Cambridge Audio – I am OK’d to use the 6.1 direct inputs in this fashion – I loose all tone/timing controls, but the volume still works. Switching inputs requires re-plugging the cables into the TT.

iffoverload – RE input impedance – tried the y cable with one source channel into 2 stereo inputs speakers still singlewired – sounded the same so I figured it was not an issue. I did worry the amp would explode, but it didn’t. Phew. You’re right about drivers not being resistance only – I am wondering if the driven load would be “easier” with a constant component [fixed resistor in parallel to passive x-over and driver]

Perhaps the speakers are not actually designed for bi-amping – only bi-wiring. AE never answer emails, so I am on my own here!

chiefgrooveguru – I am not after headroom [the CA is plenty loud] – I am looking for a little more refinement. bi-amped it’s more detailed, but the treble balance is a bit peaky. It may well be the load characteristics.

RE baffle step – is that important in a speaker with a flat front baffle? Notches – yes I can see the issue.

Looking at the x-over scematic for the 120 we “start” with a cap – doesn’t this mean the impedance rises below a certain frequency? I guess this may confuse the amp’s damping? Hence the resistor idea….

finishthat – as I just said above, I am just using the CA as “6-amps-in-a-box-with-a-volume-control” – I don’t need a mode setting, just select direct inputs.

Here’s an idea – can I use the existing crossover at line-level? I’d be inclined to think not, but only because no-one else does in these hacks! Can I not just copy the circuit with components designed for lower power levels?

cynic-al – Yes I guess I will be doing that, but I am afraid to go below 4 Ohms on the treble amps.

all – How close can I get to finding the MINIMUM value for impedance presented if I measure DC resistance across the driver? I want to calc the Min. value I can use in parallel without dropping below 4 Ohm load.

I am intending to work designing Hi-Fi some day, so feel free to get as tech as you like, I can just read-up on the bits I don’t get yet.

Thanks for the input guys – this is fun!

This is sooo far beyond my understanding that I’m just going to point and laugh, Ok? It’s right up there with double-dingles and beards.

😉

chiefgrooveguru – that gear looks mint. I think I trust you! Where did you learn the technical stuff to design speakers from the ground up?

http://forums.linn.co.uk/bb/showthread.php?tid=2887

Worth a read for the input from the Linn staff.

I think only floor standing speakers are designed from the ground up, stand-mounts start a couple of feet from the ground?

Excellent post from chiefgrooveguru.

Good passive crossovers are very cunning beasts (and some of the best appear extremely simple!)

I have some external crossovers for my LS3/5as designed by the chap who used to run Spendor and have witnessed what he can do with other designs, small tweaks around the midrange can change the perceived smoothness of the sound hugely.

As he pointed out, it is very likely that the original speakers would have been voiced using a single amp, non-bi-wired. So that is probably the best route to get the correct sound.

Psuedo-bi-amping like you suggest might work OK but you need to ensure that the amp sections are very well matched and that the volume control is accurate. But see chiefgrooveguru’s post.

I had some active crossovers built for a pair of Roksan Ojan speakers and bi-amped using 4 out of 5 channels from a huge Rotel 1095 amp.

Used the digital volume control in the DAC to go straight to the powers, missing out the pre-amp. Fantastic dynamics, if not too subtle.

Given the cost, the hassle, and the amount of boxes, then its not worth it, but it was fun.

I biamped a Linn system ages ago for a short while…it was expensive and offered little improvement over a single power amp. Going active was a big step up (i.e. bypassing the speaker crossover and using a dedicated amp for bass and treble).

I think the differences your hearing are more likely down to the effects of using the y-splitter…and those effects are not likely to be good 😉

Weeell.. I have a bi-amped system. I’ve got a pre-amp with two sets of outputs, and two identical power amps. They are all from the same set-up so are meant to work together.

The results were a lot better than just using one of the same amp. I have no idea why. I did of course remove the gold bar from the speaker terminals to disable the crossover, but the filters are still in place.

I biamped a Linn system ages ago for a short while…it was expensive and offered little improvement over a single power amp. Going active was a big step up (i.e. bypassing the speaker crossover and using a dedicated amp for bass and treble).

Hang on – what was the first bi-amping you did then because the second thing you call ‘active’ sounds like what I’ve done.. no?

No, I think you have done the first one. To do the second one you need an active crossover which splits the signal at line level and fit’s between preamp and poweramps.

Fair paly if it improved things in your system, to me, it didn’t make much difference.

Oh right, I see. Hmm.

The filter in the speaker would do something similar wouldn’t it?

you can get software to do the active crossovers, such as audiolense:

http://www.juicehifi.com/no/

I was about to write this, but discovered that chiefgrooveguru has done it for me 🙂

chiefgrooveguru – Member
In short, don’t.

There’s no doubt that in an ideal world using an active crossover and biamping can work very very well but biamping into a passive crossover gives you no headroom advantage because the treble amp still has to generate the same voltage swing and it’ll still be sending wasted current to ground through the shunt components in the highpass filter. Furthermore an amp driving a complete loudspeaker will be seeing a more consistent load impedance than an amp driving just the high or low half of the system. And what’s going to happen to the baffle step correction if you use an active crossover? What about notch filters on break-up peaks? Good passive crossovers are very cunning beasts (and some of the best appear extremely simple!)

The real point of biamping is headroom which you don’t get without an electronic crossover. But, as above, your passive crossovers will potentially have extra stuff like baffle step comp to make the best of your speaker design…

the treble seems a little prominent now, clearer, with better imaging

synthesia?

konabunny – Member
the treble seems a little prominent now, clearer, with better imaging

synthesia?

Not since I ate 24 grams of fresh psilocybin cubensis in ’02! Gosh that took a while to wear off….