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JC2- never seen the inside of a Linear Power? Well they haven't changed too much in 10 years or so. Bi-polar power supply and TO-3 output devices- all of which a Fosagte rep trashed at a RTTI meeting a couple of weeks ago. The High Voltage series of amps has quite a few hard wires running back and forth. They aren't as pretty as a surface mount Fosgate. I will let you see the insides of mine if you want. Or if you can't wait, go and open up a Mesa-Boogie guitar amp and you will start to have an idea on what they look like.
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Posts: 7996 | From: Charlotte,NC USA | Registered: May 1999
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Linear Power amplifiers are one of the most reliable amps on the market bar none, the use internal wiring jumpers to deliver power directly to or as close as possible to the components which need them because you can not generate the same current flow in a trace on the circuit board, if you flatten out the 14 gauge wire which connects the power supply transistors directly to the power source it would be near 2 inches wide of 4 mill thick copper on a circuit board, point in hand you cannot design an amp using traces to deliever the same current because you don't have the room! Also linear uses T-03 cased transistors because of their power dissapation per device, NONE higher in the industry, also fets are not linear enough to use as true high grade audio devices (excuse the pun)! Also Linear is not the same as it used to be, the problem with bi-polar devices is that they switch slow if left to switch at their own natural speed, fets are regulated devices that will not switch on thier own and require an ic to time or regulate them and they switch much faster and can pass current more quickly across the device but with the sacrifice of high reliability. thats why so many fet powered amps burn the power supply up so often. Linear has developed a hybrid power supply what they call a fet controlled bi-polar switching power supply on all the HV line of amps, this uses bi-polar transistors as the primary switching device but they use a regulator circuit to control 2 fets which set a switching speed for the bi-polars to switch at, this gives the reliability of the bi-polar at the switching speed of a fet, the best of both worlds. A typical T0-3 bi-polar device has specs of 250watts of power dissipation, at 25 amps of current and can carry voltages of up to 200 volts thru the device, this takes for less device numbers to make power, which also takes less supporting devices which increases efficeincy and reduces parasitic losses and phase shifts and anomolies. A typical fet in a To220 case can only generate 75 watts and handle only around 60 volts, thats why you see big amps with many many fets. Statistically you run a higher rate for failures. Also a TO-220 case tranisitor as less than 1/4 the thermal footprint of a TO-3 transistor, meaning the do not cool as well, and we all know that heat decreases efficiency, adds distortion and reduces the life of a transistor. Maybe thats why most original Linear amps are still on the road working after 10, 12, and 15 years of use, and thats not unusual! While most others that old are junked by now, or if they are still working make major news! Also surface mount technology is fine for computers or maybe in non-critical areas in amplifiers but in the audio chain they do nothing except save the manufactuers money by reducing the labor intensiveness, they are not good audio devices because of the narrow gaps internal in the small devices they are inheritly bad for crosstalk, which lower channel seperation, and the musicallity of the circuit, but I guess if you want to use mismatched positive and negative fet outputs any it does not matter, also using a offset network in order to use all negative fets in an output stage is a nasty way to make audio, for now bi-polar is the cleanest way to make audio, until fet technology changes. Of coarse if all you want to make is spl it really does not matter but amps are used more for music on a daily basis than for spl all the time. I like to have both and don't like having the amps fixed all the time, thats why I would choose Linear.
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Linear also uses jumper wires to move high voltage paths away from noise sensitive areas to make a more quite product, also this gives the amps a reduced noise floor, better channel seperation, image, stage, better dyanamic range and headroom. Some of the best in the industry. Thats why the editor for Stereo Review bought the Dynaudio Blazer from the president of Dynaudio because of its sound quality using the Linear 2.2HVs. He has now made them his reference amp for testing! Also, you are not going to get a honest report on a product from someone trying to sell another brand of product. The more someone talks against something the more he is scared of it. You never here anyone cutting down a pyramid. Prove a product by physics not how pretty something is, or by personal opinion. Facts should be the basis for dicisions not conjecture. People should sell their products on their on attributes not by talking against another product. This tells me alot about the person and his product.
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While I do give a nod to Linear to for reliability and performance I don't see much of an advantage for using TO-3's. Using a few more of the TO-220's and TO-3P's isn't an issue with me. They are easier to mount and the TO-3P's can handle high voltages just fine. I agree with mosfets not being the absolute best device for the final stage for SQ but this is by a small margin. I do feel that a pwm controlled mosfet power supply is currently the best thing going and if properly designed is the closest thing to bulletproof. (Needs to have a design allowing for increased drive voltage over the 12 volts the pwm ic is limited too.) By the way, my Power 1000 has been a very bulletproof design with no less than 56 TO-220 case style devices in it. wwuooughw Again, not bashing linear. It's good stuff. My amp is on hold since I can't compete with it except to demo. (and I want to compete for trophies) I going to have 2K saved in another month and that should let me tear into the new db drag car well enough to get it running and putting up some numbers.
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Oh and about the darlingtons. There is nothing wrong with the device. The configuration is very often in the final 2 stages of any amp anyway. I just don't like the fact that now they have created many more devices for final stages that are not substitutable with a conventional device. There are Tips,BD's 2N's,MT's that are interchangeable if you match the performance characteristics close enough. Hear you have a device where you get a power and driver transistor in the same case, possibly with a couple of resistors and maybe even a diode to further complicate service work. Why not just have the driver on the board? Performance doesn't suffer, I guess I'm just inconvenienced.
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I will also vouch for Linear Power....When I set a ground zero nuke of fire with a LP 4.1 it held together quite nicely considering it was connected to a sub that was on fire....LOL TJ
------------------ Metro Audio Dynamics Wrecking Crue Being unveiled on April 16 in Omaha NE.....The Crx....Treo and MMATS....
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power handling components such as audio amps and power supplies have changed little in the past 30yrs. however, i have come across something that seems to be showing promise in these arenas. it is called Digital Power Processing and was invented by tri-path TM. class "T" amps seem to have advantages over the class A, AB, and D amps that are most prevalent in todays market place. with the class A, and AB amps beening very ineffecient yet delivering high fidelity. class D amps beening very efficient yet having poor fidelity. Tri-path claims that the new class"T" design offers all of the benefits of the other type of amplifiers yet with none of their characteristic draw backs. tri-paths circuitry uses both analog and digital power processing algorythems that modulate the input siginal with a high frequency switching pattern. Tri-paths propriatory algorythems are dirivitives of both adaptive and predicted algorythems used in telecommunication processors.the modulation siginal is sent to output transistors then through a low-pass filter that demodulates it to recover an amplified version of the input signal. in a tri-path amlifier there is a input stage that provides analog input signal buffering. the output of this stage drives the "digital power processing" block. this block contains an adaptive signal conditioning processor, digital conversion function, mute control, overload handling, fault detection, predictive processing, and qualification logic functions. the output of the "DPP" block controls a power output stage that drives a speaker through a output filter. the class T amps switches the output transistors in a fashion similair to spread spectrum technology, at a varying rate up to 1.5mhz and averages 600khz to 700khz.the waveform for a tri-path class T amp would be a complex digital waveform of varying frequency before the final output filtering. if this technology proves to be as good as it looks to be it will be nice to pick up where the DSP's leave off. this should be enough to get people thinking and i would also like to mention that i do believe that this company offers 500X2 watts amplifier evalutation boards for around $150 dollars. the address for the company is www.tri-path.com if there is any of you that have the resources to do a complete eval. of this type of amp i would love to here of the REAL WORLD results. to say the least this does appear to be a very interesting technology and maybe also one to keep an eye on.
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Posts: 122 | From: St.Louis, MO | Registered: Feb 2000
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i wanted to list a few manufactors that use the tri-path technology. BEL CANTO CARVER ALPINE SONY PANASONIC these are just a few that offer new product using this technology. i have read reviews for product using class "T" amplification, yet still have not heard any first hand reviews from personal sources about the actual performance of these types of circuits. if any of you could look at this site www.tripath.com and just let the rest of us know what opinions you arrive at from looking and reading about this method of amplification. at least to me it seems to show the greatest amount ground breaking technology that IMO we will see an increasing use of the class "T" technologies. i am intrested to hear of others opinions especially any one who may currently be using product that uses this class "T" circuitry.
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Posts: 122 | From: St.Louis, MO | Registered: Feb 2000
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just a little more of info to feed on. tri-path offers fundamentally a novel and proprietary DSP IC that control high voltage circuits instead of low level signals or data. proprietary algorithms provide the computing power, incorperate protection schemes and feature a unique adaptive mechanism whereby the DSP engine learns the non-linearities of the individual output transistors and compinsates automatically for perfect behavior. this self corrective function address imperfect switching, ground bounce,output transistor mismatches, cross-over distortion between output device on-off cycles, and residual energy from the oscillator in the audio band. it forces the output stage to operate at peak performance at all times. this stuff is cool....just a little mind blowing to me....have fun people that is what it is all about http://www.soundstage.com/yfiles/yfiles200002.htm
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Posts: 122 | From: St.Louis, MO | Registered: Feb 2000
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http://www.chipcenter.com/analog/product_reviews_400-499/prod491.htm i figured i could send the interested parties here instead of re-typing all the info. this is a chip-set for class "D" amplification that seemed intresting to me also.....just wanted to share.... the chip-set are the LM4651 and LM4652
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Posts: 122 | From: St.Louis, MO | Registered: Feb 2000
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getting to the nidy gridy. At my shop we concentrate on the best sound we can get and not break peoples pocket. I love amps the have THD .0014%, we can do a lot with those. We are more involve with Hifonics amps. Even the low class hifonics can out do many rock fords amps. the low class uses a Bipolar Mosfet config. which is good, because to amp can handle a higher currenty than other amps in it;s class. We even bridge the amp 2 ohm mono and ran it for 3 hours and the amp didn't cut off. plus it was rated at 849 watts rms. We had to put a fan on it but, after 3 hours of abuse we could understand. This amp cost less and put out more than some so call brands (rockford, audiobahn, kicker, sony, etc. We sell the amp for 260 here and everyone loves it. Z600 check it out
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getting to the nidy gridy. At my shop we concentrate on the best sound we can get and not break peoples pocket. I love amps the have THD .0014%, we can do a lot with those. We are more involve with Hifonics amps. Even the low class hifonics can out do many rock fords amps. the low class uses a Bipolar Mosfet config. which is good, because to amp can handle a higher currenty than other amps in it;s class. We even bridge the amp 2 ohm mono and ran it for 3 hours and the amp didn't cut off. plus it was rated at 849 watts rms. We had to put a fan on it but, after 3 hours of abuse we could understand. This amp cost less and put out more than some so call brands (rockford, audiobahn, kicker, sony, etc. We sell the amp for 260 here and everyone loves it. Z600 check it out
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Crystal, that was the whole point of me starting this thread! I wanted all the new guys, not to mention myself, to get a little more insight on the amplifiers topology and engineering, pros/cons, personal opinions, whatever! Thanks to all that have given input on the subject!!
------------------ Sometimes the majority only means that all the fools are on the same side.
Use your ears to judge components, NOT your wallet! K.I.S.S.
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I just read over some of the stuff on the Tripath chips. The amps have a THD that is quite a bit worse than Class AB, but really should still be inaudible. They make a point on their site to say that people prefer a tube amp that has more distortion than a transistor amp, so the extra distortion of the class T amp shouldn't matter. They also state that the Class T amps have some issues when it comes to comes to clipping, one reason people prefer tube amps. The power supply has to have special considerations also, but should be easily fixed. The output filters should be easier to implement than the ones in class D since you can have a much higher filter point. Their efficiency spec makes sense since the outputs are basically on or off, and 80% is more realistic than the claims of 99% for some class D amps. I think I am going to have to design a power supply and get one of the 500 watt evaluation kits. Don't know what I would do with 2000 watts though, maybe get 3 more Illusion 12's.
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http://www.soundstage.com/yfiles/yfiles.htm the above link is one that i found very interesting to read. Breifly....it speaks of distortion MATCHING amps and speakers and how THD of a any giving component may be perceived by the ear completely different than measured by test equipment. it focuses on real world performances basically of SET amplifiers both tube and solid state and for the most part is based upon theory.... this may be some what of an advanced topic for some....but one that i thought all the TECHIES would enjoy reading.... oh, and by the way if you dont have the above sight book marked you should, cause the have released some very good articles.
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Posts: 122 | From: St.Louis, MO | Registered: Feb 2000
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http://www.soundstage.com/yfiles/yfiles200002.htm here is the Bel Canto roll at class"T".... i know some of you wonder why i post so much home audiophyle stuff....but just keep in mind that all that they do in that areana does make it to this one eventually.... have fun most importantly and if you get frustrated take a break, cool down, catch your calm, and try again, and then again if need be
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Posts: 122 | From: St.Louis, MO | Registered: Feb 2000
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I don't know, I haven't seen any 500 pound monoblock class A amps in a car yet
I just downloaded and printed all the tech papers from tripath and will post on that when I get through reading them all.
Test equipment and ears are two different things. There are reasons why in some cases a THD analyzer is better than your ears, and cases where your ears are better. It all depends on what results you are looking for.
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The class T designs look real promising. The efficiency is easily understood and the increased fidelity over Class D is easy to understand. But I have some reservations about some things they say in their white papers. I definately want to either get a chip from them or an evaluation board. They are very simple to use and design with all I need is a power supply design, a heatsink, and a 2000 watt 4 ohm speaker. I'm normally a SQ guy but high power amps get me all nerdy.
It seems the auto industry has adopted a 36 volt setup, I've got some papers at work about some new batteries and other technology for future cars.
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e-man - The future is not 24 volt. It is believed that 42 volt is the next and upcoming thing. Check the link out: http://www.carsound.com/news.shtml#News1
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