Members Chrisjd Posted October 21, 2008 Members Share Posted October 21, 2008 I want to purchase one of these. I see there are a few different models on the website. What are the differences? Some of the tech talk is a little foreign to me. Which one should I purchase? https://taweber.powweb.com/biasrite/br_page.htm Link to comment Share on other sites More sharing options...
Members EdgeOfDarkness Posted October 21, 2008 Members Share Posted October 21, 2008 you do not have to use all the heads on them..I am getting the BR4 next month.I dont think I need a 9 pin head for preamp tubes.but you can get a octal to 9 pin adapter from GT. Link to comment Share on other sites More sharing options...
Members Johnny Z Posted October 21, 2008 Members Share Posted October 21, 2008 Get the cheapst one. Link to comment Share on other sites More sharing options...
Members fridgit Posted October 21, 2008 Members Share Posted October 21, 2008 I have a BR-4 that I'm looking to sell. Hardly been used & works perfectly. I would sell it via Paypal for $100 shipped. I'll get some pics going. PM me if interested. My eBay id is salcidofam, if you want to check out my score. Link to comment Share on other sites More sharing options...
Members tommythelurker Posted October 21, 2008 Members Share Posted October 21, 2008 If it's so foreign to you that you can't even figure it out from reading the website, maybe you shouldn't be dicking around with this sort of thing. Or at least let us know specifically what you aren't following so we can inform you a little rather than simply telling you "which one to buy" which will probably end up with you spending money on something you can't figure out how to use. Link to comment Share on other sites More sharing options...
Members Chrisjd Posted October 21, 2008 Author Members Share Posted October 21, 2008 If it's so foreign to you that you can't even figure it out from reading the website, maybe you shouldn't be dicking around with this sort of thing.Or at least let us know specifically what you aren't following so we can inform you a little rather than simply telling you "which one to buy" which will probably end up with you spending money on something you can't figure out how to use. What is the difference between the "Octal" and "9pin", and which one would I want for my amps? Link to comment Share on other sites More sharing options...
Members tommythelurker Posted October 21, 2008 Members Share Posted October 21, 2008 What is the difference between the "Octal" and "9pin", and which one would I want for my amps? Octal has 8 pins and 9 pin obviously has 9 pins. Most 50W+ amps use tubes that require the octal socket. Tubes like EL34's, 6L6's, 6550 etc. are all octal tubes. Tubes like EL84 are 9 pin. So you choose the adapter based on the amp you plan to use it with and what type of tube that amp uses. Based on the amps in your sig, you should be good with the octal socket. Link to comment Share on other sites More sharing options...
Members sah5150 Posted October 22, 2008 Members Share Posted October 22, 2008 What is the difference between the "Octal" and "9pin", and which one would I want for my amps? So... you are going to buy this and work on your own amps and don't know this? Please be careful, ok? Steve Link to comment Share on other sites More sharing options...
Members Shiny_Surface Posted October 22, 2008 Members Share Posted October 22, 2008 I want to purchase one of these. I see there are a few different models on the website. What are the differences? Some of the tech talk is a little foreign to me. Which one should I purchase? https://taweber.powweb.com/biasrite/br_page.htm Most of your amps are 100 watters to my knowledge, so get the br-4 octal. Link to comment Share on other sites More sharing options...
Members mhenson42 Posted October 22, 2008 Members Share Posted October 22, 2008 I have a BR-4. A BR-2 would be fine since most 4 powertube amps I've owned are biased with one bias pot any way. Link to comment Share on other sites More sharing options...
Members magh8 Posted October 22, 2008 Members Share Posted October 22, 2008 awsome tool to have and I agree with matt on the br2 that's what I have.buy one.the only con is you still have to take the chassis out of the head box if you just want to check the bias but you can buy 90 degree adapters for them. Link to comment Share on other sites More sharing options...
Members tommythelurker Posted October 22, 2008 Members Share Posted October 22, 2008 I have a BR-4. A BR-2 would be fine since most 4 powertube amps I've owned are biased with one bias pot any way. It's got nothing to with with having one bias pot and everything to do with the fact that tubes vary. But you could survive with just one adapter if you don't mind swapping it to each tube. Having more adapters just makes it more convenient. Link to comment Share on other sites More sharing options...
Members Chrisjd Posted October 22, 2008 Author Members Share Posted October 22, 2008 awsome tool to have and I agree with matt on the br2 that's what I have.buy one.the only con is you still have to take the chassis out of the head box if you just want to check the bias but you can buy 90 degree adapters for them. Why would you have to take it out of the headshell? Link to comment Share on other sites More sharing options...
Members Illuminatus Posted October 22, 2008 Members Share Posted October 22, 2008 Why would you have to take it out of the headshell? because its too big baby! Link to comment Share on other sites More sharing options...
Members PaoloJM Posted October 22, 2008 Members Share Posted October 22, 2008 I dont get this product. It measures plate voltage and cathode current. Cathode current includes screen current and plate current so using the cathode current and plate voltage does not give you the actual plate dissipation. Using these values will always have you biased slightly lower than you need to be. What gives, am I missing something? Link to comment Share on other sites More sharing options...
Members tommythelurker Posted October 22, 2008 Members Share Posted October 22, 2008 it's only a few mA difference, no big deal. If you're really concerned about it you can determine the screen current and subtract it from the cathode current, but correct bias isn't necessarily about a specific plate current anyway, the calculated figures from the formula you see floating around are more of a ballpark. Link to comment Share on other sites More sharing options...
Members the_bleeding Posted October 22, 2008 Members Share Posted October 22, 2008 dude, buy the special heads meant to be used in partner with multimeters. You'll save a bunch fo cash. Link to comment Share on other sites More sharing options...
Members Zozobra Posted October 22, 2008 Members Share Posted October 22, 2008 They more often then not dont read the plate voltage though. Link to comment Share on other sites More sharing options...
Members PaoloJM Posted October 22, 2008 Members Share Posted October 22, 2008 it's only a few mA difference, no big deal. If you're really concerned about it you can determine the screen current and subtract it from the cathode current, but correct bias isn't necessarily about a specific plate current anyway, the calculated figures from the formula you see floating around are more of a ballpark. I get that, I just think it would be more logical if it measured plate current instead (assuming the amp designer got his screen dissipation calcs right the first time!!). Thinking about it for a sec; measuring plate current then would cause problems measuring the plate voltage, right, so this is probably the best comprimise, screen current is usully about 1/8th of plate current anyways.I'm a bit slow today, please dont be too hard on me!! Link to comment Share on other sites More sharing options...
Members Mr Songwriter Posted October 22, 2008 Members Share Posted October 22, 2008 Alright PaoloJM! OP: I bought one of these from a company called Amp-Head, I bought the one with just one head, no multimeter (I alrady have one) and a switch to toggle between plate voltage and bias current reading. With the amp I was using it on, I didn't have to take the chassis out because a) there was enough clearance above the power tubes and b) there was an access hole for the bias pot, that may not be the case with all of your amps. Link to comment Share on other sites More sharing options...
Members boytbpc Posted October 22, 2008 Members Share Posted October 22, 2008 Go to Duncan Amps and read the bias article by Lord Valve. To a point, if you don't understand it, you shouldn't bias your amp. You can a.) screw your amp up or b.) kill yourself. As far as what you need, go to EuroTubes and get their $25 Bias Probe and their cheap VOM. With the info and the bias probe, you'll be ok. Matthew Link to comment Share on other sites More sharing options...
Members magh8 Posted October 22, 2008 Members Share Posted October 22, 2008 Why would you have to take it out of the headshell? so far every amp I have tried to check the bias the probes are to big almost the size of a tube.so if your head can fit a pair of tubes stacked on top of one another you're all set...lol imo only design flaw.hopefully they will go to a more compact probe. Link to comment Share on other sites More sharing options...
Members tommythelurker Posted October 22, 2008 Members Share Posted October 22, 2008 I get that, I just think it would be more logical if it measured plate current instead (assuming the amp designer got his screen dissipation calcs right the first time!!). Thinking about it for a sec; measuring plate current then would cause problems measuring the plate voltage, right, so this is probably the best comprimise, screen current is usully about 1/8th of plate current anyways.I'm a bit slow today, please dont be too hard on me!! The reason they don't measure the plate current directly is it's dangerous. The plate is typically at 400V-500V which can bite you if you're not careful. The cathode is at ground potential so it's very safe. You put a 1 ohm resistor between the cathode and ground and you only have a few milivolts across it which can be easily measured to determine the current without danger of shock from high voltage Link to comment Share on other sites More sharing options...
Members Chrisjd Posted October 22, 2008 Author Members Share Posted October 22, 2008 Yeah, I am completely lost in all this, I better just have someone do it for me. I have never had any amp tech training. Link to comment Share on other sites More sharing options...
Members mhenson42 Posted October 22, 2008 Members Share Posted October 22, 2008 Yeah, I am completely lost in all this, I better just have someone do it for me. I have never had any amp tech training. It's super easy. Just read the instructions on the Weber site and don't touch anything on the inside of your amp (except the bias pot - use a screwdriver with a rubber handle if you are concerned). That's all I did - retubed all three of my amps in about an hour without any prior biasing experience or knowledge. Link to comment Share on other sites More sharing options...
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