Bi-amping - your advice, please

[Mr Nad]

It has been suggested in other threads (those relating to Mini-T amplifiers from amptastic.com/ebay) that bi-amping could be worth the effort.

I'd like to give this a try, but I'm a bit confused about what I need to do.

Looking up information on the net gives me some ideas, but still leaves me scratching my brains, so I turn to the knowledge of those here.

One article I read mentions active and passive bi-amping. In passive the left output from two (stereo) amps feeds the HF and LF drivers in one speaker, and the right outputs feed the two two drivers in the right speaker. It was advised not to try this as some amps could fry themselves due to the low impedance that may result from running drivers in parallel.

In an active setup, it was suggested that there is a crossover between the amps and the speakers (ie, outside the speakers).

So, as I don't want to fry my speakers, and as I don't have a crossover outside of the speakers, I'm wondering how I would go about bi-amping using two Mini-T amps.

I would be using a Caiman+ as a preamp, and wacking the volume control up to max on the Mini-Ts.

Would it be possible to use the Mini-Ts as 'monoblocks' if I used an RCA splitter to feed one with the left channel signal and the other with the right, then somehow combining the speaker outputs. Perhaps the attached diagram would help...

6145

Would that work or would I be assured of audio hell rather heaven.

I bow to your superior wisdom!

Lenny

[keiths]

Hi Lenny,

What your diagram (almost) shows, is what is generally referred to as "horizontal" passive bi-amping - using one amp for the left hand channel, the other for the right. Where your diagram looks a bit wrong, is that it shows the L & R speaker outputs of each amp connected together. What you actually would do is remove the connecting links from the terminals on the loudspeakers and run two pairs of speaker cables between each amp and speaker connecting (say) the left hand channel + and - speaker outputs on the amp to the bass + and - terminal on the speaker, and the right-hand channel's + & - outputs to those on the tweeter.

The other method of passive bi-amping is "vertical" bi-amping where one amp drives the bass units of both speakers whilst the other drives the tweeters. Again, you need to remove the speaker terminal links.

As long as the connections are made correctly and the links are removed, you won't blow anything up.

Hope this helps,

[bobbasrah]

Just as a point of interest Keith with regard to a dual T-amp configuration such as Lenny is proposing... Would the demand on the amplifier PSU stage not be less in the case of a single box driving the two amps, one to each of the LF and HF drivers in the same speaker?

[keiths]

Sorry Bob - not quite sure what you're saying? I guess with horizontal bi-amping the amps work more or less equally hard, whereas with vertical, the woofer amp probably does the bulk of the 'work'?

[Mr Nad]

Thank you, Keith.

I didn't think of connecting the drivers to different channels in this way. Or, if I did, I was wary of the words of warning regarding damaging the amp(s).

Does cabling in the way you suggest bypass the speaker crossover?

I can see I'll be needing to buy some more speaker cable, some of the biwiring stuff... which leads to another question - what would you recommend?

[Barry]

To Keith and Lenny

This might be of some interest:

http://theartofsound.net/forum/showthread.php?t=5818

Incidently Keith you have the designation "horizontal" and "vertical" reversed. What Lenny (Mr Nad) wants to try is vertical passive bi-amping.

Regards

[keiths]

To Keith and Lenny

This might be of some interest:

http://theartofsound.net/forum/showthread.php?t=5818


Thanks Barry :)



Incidently Keith you have the designation "horizontal" and "vertical" reversed. What Lenny (Mr Nad) wants to try is vertical passive bi-amping.
Regards

:doh:

[Rare Bird]

Why dont people just plug in a stereo & just listern to music for crying out aloud

:rolleyes:

[wee tee cee]

Lenny,
If you are happy with the T amp and have another amp you can use why not run the t amp on treble and the other on bass or vice versa. You can do a lot worse than belkin interconnects and van damme speaker cable to get you up and running. I found maplin rca splitters far more reliable than several e bay purchases that disintegrated very quickly.
You just balance both amps up using the volume pots.
My sons system uses a temple audio bantum and a 23 year old cyrus 1. The bantum is on the treble the cyrus on bass. Volume control via the lap top straight into a dac magic.....sounds lovely. Its great fun faffing about getting it set up right but very enjoyable.
Have some fun, the t amps are wonderfull.
If you get two I would love to know how you get on.....might even get a pair for myself to have a play...
Tony.

[isuckedmandelsonslemons]

Why dont people just plug in a stereo & just listern to music for crying out aloud

:rolleyes:

Isn't that what iPods are for? No need to arse about with a hifi? Or maybe buy an old Ford Capri with a built in 8 track and listen to that? Hell's teeth I bet there are people listening to thise open reel tape recorder things.

[Mr Nad]

Why dont people just plug in a stereo & just listern to music for crying out aloud

:rolleyes:

"Fair point, well made, Barbera" :lol: (I quote from The Royle Family)... But what one person considers music, another considers tuneless sh!te.

Let's forget valves and DACs, and woofers, tweeters, subwoofers, midrange, interconnects and speaker cables. Lets just take an all-in-one box and make do with that. :ner:

Life wold be so much easier and cheaper. No fun!:steam:

I do accept your point. But I like to investigate.

[jaym481]

Active bi-amping puts the crossover (an active crossover, of course) between the preamp and the amps. The pre feeds full-range signal to the crossover (or "frequency dividing network") which splits it up according to the frequency and crossover slope desired. It is, some would argue (and I agree) the best way to bi-amp, and despite the additional component, it is almost always a sonic improvement over passive crossovers in the chain. It allows a lot of flex as well - you can use high powered SS for bass, a nice EL34 valve amp for mids and flea-watt (triode EL84s, maybe) valves for the top end. The differing output gets adjusted at the crossver so everything matches up.

[Pete The Cat]

I think I've said this on another thread but while bi-amping is regarded as a waste of time by some, with the right amps (eg where the cost of a second power amp is less than the difference in cost between the first amp and the next model up in the upgrade path) it can be worth it IMHO.

A while ago I ran Quad 405s together in my second system - passive vertical - and I still recall how great the change was. The soundstage broadened very noticeably and detail was sharper. In fact it was so good I began to take that system more seriously and succumbed to upgradeitis, eventually replacing them with a bunch of old Exposures instead :mental:

Pete

[seoirse2002]

:cool::cool:Hey Harry,
I still listen to those open reel things...its this sound that all the dacs are trying to achieve...analogue!

[DaveK]

FWIW, as I'm no acute eared audiophile by any means, I have tried 2 HK sourced Mini-T amps in both configurations, whichever is the correct description, and not damaged anything.
In order of preference, the use of one Mini-T on it's own was the least favoured and the most favoured was one amp driving each speaker (better than one driving bass on both and one driving treble on both) and each change was quite noticeable.
Hope this helps.
Dave.

[vouk]

I've dabbled with both active (Densen B200-B-300's and Saxo Xovers) and currently passive bi-amping (AA Bellini Pre - 2x Donizetti Centos') and, from the outset, must say that I did find it a worthwhile investment. Much obviously depends on pre and power gain, impedance, power amp design (dual mono etc) as well as speaker design and configuration. In your case, I would recommend going passive for the time being and see how it goes. There is much to say about which method provides the best results - all things being equal and if you have two identical power amps, (IMO) go vertical - with amps located close to each speaker you can also make some substantial savings on speaker cables.
If you make the connections properly, nothing to fear.

[vouk]

Connection wise, this might be of use:

http://audioanalogue.com/Download/Bridged&BiAmpingPA_TopClassConnectionExamples%28eng%29.pdf

http://audioanalogue.com/Download/Biwiring_Biamping%28ita%29.pdf


AA recommended horizontal bi-amping, but after AB comparisons I preferred the vertical set up.
Hope this helps!

[DSJR]

You have some speakers with passive crossovers. The T-amps don't offer a huge amount in reserve, even though the mean domestic levels don't usually need more than a very few Watts peak, but I feel certain that bi-amping, and giving each amp module less work to do, would be a good thing.

We used to just wire one stereo amp on the bass-mid and the other on the treble, but obviously, the T-amps are tiny enough to fit behind each speaker, one per channel, so, as long as the driving preamp can happily work with long interconnects and half the load per channel (effectively two amps in parallel), you should get quite an improvement I think.

[Mr Nad]

OK, I'm definitely going to give this bi-amping a go. I'm not permitted to run any additional cables, so I'll have to keep the T-amps together, and use existing speaker cable. I do quite like the idea of using longer interconnects (much cheaper), but the wife would be serious displeased.

I do need some decent interconnects, and I'm trying to lay my hands on a couple of sets of those Belkin Pure AV ones that come highly recommended. Can I find any...?