Help with Bi-amping

Dale O'Bryon New member Username: Dale185 New York Post Number: 1 Registered: Apr-06	Posted on Monday, April 17, 2006 - 10:43 GMT I'm new to this board, I've been building my system for years now and i'm currently in the process of running two bryston 4B's to power a set of magnepan 3.6's. which way should I wire the amps? 1 amp for each speaker switched to mono or 1 amp powering the highs and the other powering the lows? If I go 1 to each speaker which is better, longer cables with short speaker wire setting the amp near the speaker or leaving the amps near the pre amp and going long speaker wires? Thanks
Jan Vigne Gold Member Username: Jan_b_vigne Dallas, TX Post Number: 8276 Registered: May-04	Posted on Monday, April 17, 2006 - 15:48 GMT Mono, close to the speakers.
Galactic Pot-Healer New member Username: Pothealer Post Number: 5 Registered: Apr-06	Posted on Tuesday, April 18, 2006 - 23:03 GMT Could I ask why have the amp close to the speaker rather than the pre-amp?
Jan Vigne Gold Member Username: Jan_b_vigne Dallas, TX Post Number: 8286 Registered: May-04	Posted on Wednesday, April 19, 2006 - 00:31 GMT To minimize the length of the speaker cables. Assuming the pre amp has an ouptut impedance of 600 Ohms or less, the pre amp can drive long (up to 200') cables without loss. The pre amp, however, deals with low level signals and any vibration/resonance in its circuitry could cause problems when the pre amp sits too close to the speakers.
Galactic Pot-Healer New member Username: Pothealer Post Number: 6 Registered: Apr-06	Posted on Wednesday, April 19, 2006 - 15:09 GMT Yeah I understand the pre-amp I was more interested in your views for the amp placement. Common wisdom has it that your shortest cables are ideally fitted on the input of the amp as noise that is introduced through the cable would be amplified and driven into the speaker. Assuming the cable on the output is just as susceptable to noise as the input then one would prefer to have the longest amp cable on the output as this would result in a lower noise level at the speaker. Are you relying on any filtering inside the amp to reduce the noise possibilities, or do you think the noise issue is too nominal to be of concern, in which case I would see your amp placement as the ideal?
Jan Vigne Gold Member Username: Jan_b_vigne Dallas, TX Post Number: 8290 Registered: May-04	Posted on Wednesday, April 19, 2006 - 16:09 GMT "Assuming the cable on the output is just as susceptable to noise as the input then one would prefer to have the longest amp cable on the output as this would result in a lower noise level at the speaker." I know what you mean but it doesn't make any sense. Why assume a cable is susceptible to noise when it isn't? What makes you think a shielded interconnect of good quality is susceptible to noise? And, if it is, then length wouldn't matter as it would pick up RF no matter how long or short the cable length happened to be. If you have a noisy interconnect, you should either repair it or replace it. And, ideally, you should have no interconnects or cables at all. That just isn't that practical.
Frank Abela Gold Member Username: Frank_abela Berkshire UK Post Number: 1313 Registered: Sep-04	Posted on Wednesday, April 19, 2006 - 16:49 GMT Interconnects are quite capable of picking up noise, and as they get longer they're more likely to act as aerials. This is why recording studios use balanced connections. This way they can mitigate the noise in their long runs (about 60 feet typically) as much as possible. That said, once the noise is reduced, placing the power amps close to the speakers is a very good idea. When driving long speaker cable lengths, there can be quite high losses due to the much higher power being driven down the speaker cables - higher by comparison to the low level signal travelling between preamp and power amp. Regards, Frank.
Henric Wiegenbroeker New member Username: Henrik Toronto, Ontario Canada Post Number: 2 Registered: Apr-06	Posted on Wednesday, April 19, 2006 - 18:11 GMT Hello, Wow. Excellent information in here. I'm just about to splurge on a new system. I'm planning to buy a pair of Dynaudio Focus 110s. I've also come across a used Exposure RC Superx amp. It's about 10 years old, doesn't come with a manual, and the seller wants Cdn$1000 for it (90 day warranty). I've listened to it driving the Focus 110s and like the sound. Can anyone give me advice on whether this is this a good amp and a good price? Do I need to worry about it breaking down? The reason I'm considering used, is that I can't afford new right now, otherwise I'd get the Arcam A80. H
Jan Vigne Gold Member Username: Jan_b_vigne Dallas, TX Post Number: 8291 Registered: May-04	Posted on Wednesday, April 19, 2006 - 23:27 GMT Frank - Once again I have to disagree with your post. A well designed and built interconnect cable of any length shouldn't pick up any noise unless its construction or installation are compromised in some manner. I consider a 100% shielded cable to be 100% shielded - if the manufacturer is being truthful. Length should have no relation to how the cable operates as an antenna once we get past about 31" or so - the length of a folded dipole. As to why studios use balanced lines, I've never heard it said the reason was due to the noise picked up by an interconnect. If that were the case, and the length of the cable affected how susceptible the cable was to RFI, there would be no way to establish a standard for proper operation of a circuit since the noise would vary with the construction and length of the cable. No competent designer would want to make the input to a piece of equipment a guessing game of which cable and which length were being used. No, I would suggest to you balanced lines are the result of balanced, complimentary operation of the equipment, not the interconnect. In this case, the chicken did come before the egg. Audio circuits were orignally designed for long cable runs since most of what we know to be standard operating procedure in audio came from the telephone industry which required long cable lengths, low loss and low noise. The first (telephone) cables were designed as balanced construction in order to minimize signal loss due to the impedance of the cable and the input/output impedance of the equipment. By maintaining twin conductors with a separate shield, the signal was transferred by similar conductors which could be either paralleled or twisted construction. But, the ground was kept separate from the signal by using a balanced line thereby ensuring the signal (hot) and return (neutral) were distributed on similar conductors. In the equipment of the day (and still now) this complimentary operation within the amplifiers resulted in an additional 6dB of signal to noise ratio by way of common mode rejection. When the broadcast industry was begun years later, the most logical way to operate the equipment was as a balanced system. There were no unbalanced lines at the time. The single ended, unbalanced system of operation and signal transfer was a result of the consumer audio market looking for a cheap way to manufacture equipment which didn't have to transfer signals across great lengths. This was the home situation as the typical radio, and later phonograph, in the home system was a single console. The single conductor connection, along with its accompanying RCA connector, was a way to use less materials in a situation where the advantages of balanced coperation were assumed never to be of consequence. To that end, so the story goes, the RCA connector and jacks were designed around scrap materials left over from making the better connectors for the professional market. At the time, there was no consideration for a consumer use where the interconnect would be made and broken repeatedly by the user. Or else the connector would never have been constructed in such a way the hot connection is made before ground and the ground connection is broken before the hot. I'm afraid I have to stick with my contention that a well made, 100% shielded interconnect should not be susceptible to noise pick up - unless its construction or installation are compromised. And, the length of the interconnect makes no significant difference to signal loss until we are talking very, very long lengths (professional sound reinforcement in stadiums or telephone systems), if the output impedance is sufficiently low, the input impedance sufficiently high and the cable and termination impedance are correct. Otherwise, I cannot understand how the first, hardwired, complimentary pairs of transcontinental telephone lines could have worked. If they acted as antennas based on their length, they would have been swamped by noise.
The Mortal One Bronze Member Username: Mortal_one Canada Post Number: 34 Registered: Nov-04	Posted on Sunday, April 23, 2006 - 01:56 GMT Jan take a look at this picture and tell me if these to cables are %100 sheilded, both say they are. Now tell me which one is the standard? http://www.lessloss.com/shields_lessloss_vs_100_percent.jpg Anouther one from some person on the www • NEVER use speaker cables shorter than 8'. Amazingly, 4' sounds much worse than 8'. Contrary to common belief, shorter interconnects (2 m or less) and longer speaker cables sound WAY BETTER than the opposite--based on extensive head-to-head tests. Also one to chech out http://www.rwonline.com/reference-room/wired-4-sound/2006.03.29-10_rwf_lampen_ma rch_29.shtml
Jan Vigne Gold Member Username: Jan_b_vigne Dallas, TX Post Number: 8310 Registered: May-04	Posted on Sunday, April 23, 2006 - 03:49 GMT "I consider a 100% shielded cable to be 100% shielded - if the manufacturer is being truthful." It's a shame so many aren't. Stick with Belden or better and you'll get what you pay for.
Frank Abela Gold Member Username: Frank_abela Berkshire UK Post Number: 1336 Registered: Sep-04	Posted on Wednesday, April 26, 2006 - 14:19 GMT Jan, very interesting, and I bow to your superior understanding - a bit. Regards, Frank.

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