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New member Username: R3cc0sCalgary, Alberta Canada Post Number: 7 Registered: Apr-08 | As entering the world of class "A" I am learning a bit about the differences between Triode and Pentode (ultra-linear) setups. However, what I want to know is what can be used to create a comparison between the wattage ratings are between a Class A vs. AB push pull? Most 300B amps run SET Triode only. Where as EL34 and the more powerful KT88 can run in pentode push/pull configurations, resulting in a far higher amount of peak power (at least rating). I've always found the KT88 to be a tube that never really sounded to me, what the "tube" sound should sound like. However the EL34s on the other hand, have a more lush and "creamy" midrange but has less punch. So anyways... A typical setup of an EL34 output w/ 12AX7 or 12AU7 input tubes generally produce power anywhere from 35-50 WPC and KT88 (which some amps are switchable) can run onwards of another 10 watts or so. However, most 300B intergrates, usually are rated at 6-12 Watts but in "Class A". I understand Class A is ineffecient, however how does ratings work for these kinds of Amps? Apparently a Class A amp can handle impedance loads better, which I'm looking for as my speakers are strange. However I was told that the 10Watt Class A amp I'm looking at (300B output tubes) have a non-rated type of "torque" which can move more current and voltage than what is rated in AB... I'm confused |
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New member Username: R3cc0sCalgary, Alberta Canada Post Number: 8 Registered: Apr-08 | A friend quoted me: in A you use 100% of the signal, so roots means square is calculated differently (lower RMS) in ab, your passing a low amount of current to the second amp via fwd bias of that transistors emitter, lower current, higher RMS I still don't understand, fcuking math lol |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 12444 Registered: May-04 | . You need a good search engine. Hate to say it but you've got it pretty well f'd up and there's not much that can easily straighten it out. "As entering the world of class "A" I am learning a bit about the differences between Triode and Pentode (ultra-linear) setups." Triodes and pentodes are types of tubes, they are not methods of operation. Single ended and push pull are conventional ways to operate an amplifier. UltraLinear is a connection technique as is "transformer coupled" and "Unity Coupled". UltraLinear and Unity Coupled amplifiers are always push pull types. A triode can be run in either single ended, paralleled single ended, push pull or parelleled push pull operation. The first two are the only modes of operation that make sense when using a triode output tube. A triode cannot be run in UltraLinear operation nor can it be connected in a Unity Coupled amplifier. You need to place "single ended vs. push pull amplifier" into a search engine. "However, what I want to know is what can be used to create a comparison between the wattage ratings are between a Class A vs. AB push pull?" A tube manual such as these; http://www.vacuumtubesinc.com/littub.html, will provide pertinent specifications for each tube type ever produced. The manuals will tell you how many watts can be dissipated by a specific type of tube running in class A, class AB, etc. Since most tubes are now obsolete and only a few tubes are used in consumer audio gear at this time, most people have no need for a tube manual. The information produced by most tube retailers should be sufficient for your needs. If you wish to know about a specific tube, place it's identifying number into a search engine. You need to place "class A operation" and "class AB operation" into a search engine. "Most 300B amps run SET Triode only. Where as EL34 and the more powerful KT88 can run in pentode push/pull configurations, resulting in a far higher amount of peak power (at least rating)." A 300B is a triode. You can't make a triode into a pentode. A EL34 is a pentode. Any pentode can be run as a triode though the benefits of such operation are debatable. A KT88/6550 is a pentode which is sometimes referred to a beam power tube. It can also be run as a triode since it and the pentode EL34 have more elements in their envelope which can be disconnected to form a semi-triode. A triode output tube can be run in single ended or paralleled operation. There is no logical reason to run a triode in push pull operation though you could if you just wanted to. A pentode has more component parts in the glass envelope than the simpler triode - which therefore makes a pentode a pentode and not a triode nor a tetrode- and therefore can produce more power. You need to read the information you will gather when you place "triode vs. pentode" into a search engine. "I've always found the KT88 to be a tube that never really sounded to me, what the "tube" sound should sound like. However the EL34s on the other hand, have a more lush and "creamy" midrange but has less punch."} Ideally you should be striving for a neutral amplifier with no tube or transistor colorations. However, you should not characterize any particular tube as "sounding" a certain way. Any tube will sound like the circuit surrounding it and the transformers in front of and behind it. "So anyways... A typical setup of an EL34 output w/ 12AX7 or 12AU7 input tubes generally produce power anywhere from 35-50 WPC and KT88 (which some amps are switchable) can run onwards of another 10 watts or so." It would depend on the number of output tubes employed in what mode of operation with what transformers. Gather enough tubes and you can make a 250 watt tube amp without too much trouble though it will be very heavy, very large and produce lots of heat. "However, most 300B intergrates, usually are rated at 6-12 Watts but in "Class A". I understand Class A is ineffecient, however how does ratings work for these kinds of Amps? " A 300B triode output tube is normally run in single ended operation which can only be class A. I don't understand the other sentence. "Apparently a Class A amp can handle impedance loads better, which I'm looking for as my speakers are strange." Whoever told you that is wrong. The class of operation has little to nothing to do with the ability of an amplifier to deal with oddball loads. It is advised to avoid combining "strange" speakers and tube amplifiers. Strange speakers are a product of the transistor age and should be kept as far from tubes as possible. "However I was told that the 10Watt Class A amp I'm looking at (300B output tubes) have a non-rated type of "torque" which can move more current and voltage than what is rated in AB... " That literally makes no sense. Torque is synonymous with current. They both do the work. Horsepower and voltage are synonymous. They represent the potential to get work done but actually do none of the work themself. Tubes are current operated devices which act as a voltage source for the loudspeaker. It has nothing to do with class A or class AB other than a 300B triode is typically found in a single ended amplifier (S.E.T. - single ended triode) which must operate in class A. Speakers requiring large amounts of current should not be paired with tube output stages. "A friend quoted me: in A you use 100% of the signal, so roots means square is calculated differently (lower RMS)" If that's all he said, don't speak to him again. "in ab, your passing a low amount of current to the second amp via fwd bias of that transistors emitter, lower current, higher RMS." I assume you heard that from a friend. "I'm confused" NOSHIT!!! Use a search engine. . |
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Platinum Member Username: NuckPost Number: 10051 Registered: Dec-04 | I entered all of the above quotes into a search engine, but came up empty...why? r3, keep looking...this is a science, but a well defines one. A course in tubes is a well advised time eater...but dust off your high school math and physics for best results. |
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Silver Member Username: WattsssupBarrie, ON Canada Post Number: 239 Registered: Aug-06 | Straight Shooter! |
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New member Username: R3cc0sCalgary, Alberta Canada Post Number: 10 Registered: Apr-08 | Jan Thank you so much for clearing everything up, and I know that there was an on-going thread about tubes tubes and everything surround them. You've been very informative and has helped me decide on not going to a SET tube setup (aka 300B). Talking with Greg from Jolida, had mentioned that the way Pentode tubes work, is that for the first 12 watts of their potential 40 to 60 (Dependant on whether a EL34 or KT88) generally runs on the triode circuits of the tube first, and only when the current is required, will it utilize the rest. (his analogy was having a V8 engine with a turbocharger, and not requiring to engage it whilst at low RPMs) Just.. if I may have on more question, generally what are the sonic characteristics of output tubes? I was told by Jolida that if I like the sound of 300B amps or SET amps, but require the power... the KT66 is the "premier" solution, compared to EL34 or KT88 setups |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 12460 Registered: May-04 | . "Talking with Greg from Jolida, had mentioned that the way Pentode tubes work, is that for the first 12 watts of their potential 40 to 60 (Dependant on whether a EL34 or KT88) generally runs on the triode circuits of the tube first, and only when the current is required, will it utilize the rest. (his analogy was having a V8 engine with a turbocharger, and not requiring to engage it whilst at low RPMs)" I'm not currently familiar with the Jolida line to comment on that concept. Typically the switch from pentode to triode (and back) is made with a physical switch and is not something the amplifier automatically accomplishes on its own. Maybe Joilda has something new. "Just.. if I may have on more question, generally what are the sonic characteristics of output tubes? I was told by Jolida that if I like the sound of 300B amps or SET amps, but require the power... the KT66 is the "premier" solution, compared to EL34 or KT88 setups" You're still not getting the point. While some people would - and have - ascribed a "sound" to a particular type of tube it is almost impossible to do so IMO. I don't believe you could listen to a group of five or more amplifiers all using the same tube type, say EL34's, and by way of comparison to another group using 6550's make a definitive assessment of the "sound" of each tube. Some would like you to think an EL34 is "sweeter" than a 6550 and a triode will always be more detailed and harmonically rich than a pentode. Like most generalized "stereotypes" there is some truth to that but like most stereotypes the rules are meant to be broken. The same tube will sound very different in a different circuit and with different transformers around them. The exact same tube will sound "different" if you run the amp in class A, AB1, AB or C. Within a class of operation such as AB a tube will sound different when it is biased up or down. There is no such thing as the sound of a type of tube only the sound of that tube in that circuit. Ideally the tube has no sound of its own and you are only aware of the music. KT66/6L6's are tetrode type beam power tubes that are the forgotten heroes of consumer audio. Thousands of guitar amplifiers use either EL34's or 6L6's for their particular sound in conjunction with a particular instrument speaker. But the sound is "Marshall" or "Fender" more than it is KT66. Instrument and consumer amps do not strive for the same virtues but 6L6/KT66's are a very nice tube in my estimation. I run them in my power amplifiers. But that is because they "sound good" - to the extent they "sound" at all - in the circuit around them. The American version, the 6L6, was developed in 1936 while the European version, the KT66 was a later development intended to remove a technical glitch, a slight "kink" (therefore the Kinkless Type 66), in the response of the 6L6. The tubes are mostly interchangeable along with a few other tubes meant as direct drop in replacements for these tubes. However, you must check the bias requirements for any power tube you wish to use before placing it in operation in any amplifier. Some KT66's will not sound as good as a 6L6 if the circuit is not correct. The same works in the opposite direction. . |
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Gold Member Username: Frank_abelaBerkshire UK Post Number: 2893 Registered: Sep-04 | r3cc0s For your information, people talk about a 'tube sound' and usually mean it as a warm pleasant relaxed presentation. They say this because in the old days (50's through to 70's) most tube amplifiers were based on the same circuits such as Mullard or Williamson, so they had a common sound. Nowadays, most tube amp manufacturers have evolved the earlier designs so the amps don't sound quite so sweet and have less of that warmth. the circuits have evolved and so has the sound. Some tube amplifiers sound positively un-tube-like. Regards, Frank. |
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Bronze Member Username: R3cc0sCalgary, Alberta Canada Post Number: 12 Registered: Apr-08 | Jan/Frank... in my journey to find the ideal amplifier to drive inefficient speakers, I would like to get some insight as to what "circuitry" I should be looking for in a quality Tube amp? As I posted in another topic, I had spoke to my friend's dad who happens to own a lab which fixes all types of electronics, his experience is that the key area surrounding a good "tube" amplifier is it's transformers and supporting circuitry. In his years past, he had actuality managed to make a transformer less 300B amplifier, but it was mated specifically for a DIY speaker he was designing which was a 98db effeciency. He said that in the past, when Bob Carver had his own brand, he had a "silver" line of products which included a tube hybrid amp, which used a very well spun silver coil. So essentially, are there any specific transformers, capacitors etc.. that I should be looking for a manufacture to use to provide better quality characteristics in both sound and reliability? p.s. As my buddy's dad is from HK, he has alot of favorable experiences with Sansui transformers and had made that recommendation. |
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Silver Member Username: HawkbillyNova Scotia Canada Post Number: 227 Registered: Jul-07 | I'm sure transformers and capacitors are important to the sound of an amplifier, but I'm equally sure there are 100 other elements to the design that are equally important....most of which I wouldn't understand. If you are looking for a tube amp which will drive inefficient speakers you should plan to demo any amp with those speakers cuz just knowing the manufacturer of the transformers and capacitors isn't going to tell you that. |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 12463 Registered: May-04 | . You are still not seeing the forest for wishing desperately to know about the leaves on the trees. Yes, transformers are the heart and soul of any tube amplifier. Even an output transformerless amplifier will be extremely dependent upon the quality of its power transformer. In the Golden Age of tube amplifiers the leading companies were those that knew transformers and typically designed and wound their own in house. Dynaco began as a transformer company. Today far more attention has been lavished on passive parts such as capacitors and connectors. It is widely acknowledged that the higher quality of such components, even when duplicating original designs from fifty years past, has been responsible for the generally higher sound quality available today when compared to the "average" tube amplifier of fifty years ago. (You might be interested to know I run two McIntosh tube amplifiers from the early 1960's as my main amplifiers.) You can rest assured that highly respected companies have always used parts that live up to and deserve their reputation. When I was selling audio there were many times I wished I could rip off the top plate of an amplifier and show the uncomprehending client the quality of the power supply and its attendant parts in the product I was selling vs. the one he could find for a few bucks less elsewhere. But I couldn't and no one is going to place their transformers on display for you. Even if they did, they are still just parts. People who care about parts argue about parts. If that's where you wish to go, I am not your tour guide. Pick up a copy of any of the review magazines that offer subjective evaluations of amplifiers and they will typically provide the laundry list of "audiophile approved" parts that can be found in high quality components. But, if your argument for one amplifier is Auracaps, Hovland or even UltraLinear, you are not undersatnding what it is you should be buying. I would highly suggest you temporarily forget about parts and tube types, circuit topologies and modes of operation. Concentrate on the music you hear passing through a component. A good manufacturer will take care of the parts for you. Listen to the music, not the tube type nor the capacitor values. You are buying something that will allow music into your home. Let the music be what you choose. There is no "ideal" amplifier. That's why there are lots of amplifiers to choose from. As a rule, tubes are not a good combination with inefficient or low sensitivity speakers. There are exceptions of course to that statement but tubes prefer high sensitivity, high impedance speakers. With the general attitude of the speaker industry being "watts are cheap", the trend in speakers with low sensitivity specifications is to make highly reactive loads that can benefit from high "power" amplification. It's well outside of the discussion here to explain all of the reasons a tube amplifier doesn't suit the average 2008 low sensitivity speaker. Just take my word that you are probably going to be disappointed if you force a tube amplifier to do duty in a situation that it was not meant to face. . |
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Gold Member Username: Frank_abelaBerkshire UK Post Number: 2898 Registered: Sep-04 | Indeed, in essence what you're asking is akin to choosing the best brand of car by which engine manufacturer is best. There's more to a car than just an engine... |
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Bronze Member Username: R3cc0sCalgary, Alberta Canada Post Number: 17 Registered: Apr-08 | Well, I bit the bullet and picked up an Amplifier from Grant Fidelity www.grantfidelity.com The A-88 which is a classic KT-88 designed chinese amplifier using Grant's tweaks and transformers for our 110v market. Using the stock Grade 6 Shuguang tubes (4 x KT-88-98 outputs (bias'd 5.8), 4 x 6N7S drivers and 2 x 12AX& pre-amp tubes It sounds phenomenal with my setup! This is a "dual monoblock design" with 2 x power and output transformers. Dual circuitry & it's very balanced. Runs 32wpc Triode & 65 wpc Pentode (UL) @ 8ohm So what differences has it made? Well in triode, it gives me the tubey warmth without being surpy like my CAV-50 Better everything: Imaging Width/Depth, Resolution, Air, and Bass Running in Pentode, I lose a bit of stage but gain a more "solid" state sound with a ton of swing and effortless power My speakers are inefficient 4ohm Totem Arros, but in Triode 32watt class A, there is more than enough power to drive them well, and even if there was any distortion, well hey it's harmonic. The CAV-50 EL34s, no matter the Bias & tubes i've rolled, it just much more mellow and surpy.. To me, that's not involving and not what Hi-Fi is about Present setup (Musical & Resolved) Totem Arros & Hawks (Arros preffered) Tara Labs RSC Prime 1000 Bi-wire (8ft runs) Grant Fidelity A-88 w/ stock Shuguang tubes Grant Fidelity Power Cable PC 1.5 (Fantastic cable... much better than my Volex and Kimber i've used) Eichmann eXpress 6 Series 2 Interconnects Jolida JD100A stage 1 mods w/ Electro Harmonix gold (12ax7) w/ Grant Fidelity Power Cable finally... the sound I wanted |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 12514 Registered: May-04 | . Congratulations and good luck. |