henry4841

If you correctly measure AC signal voltage at speakers you will be shocked at the watt or watts you are truly using. I dare say the average listener listens at around 80db to 85db loud at most. At least sensible people. Our speakers at minimum are 95db or better at just one watt 1 meter. Just plain old common sense will apply if used. And the rating is a continuous 1 watt which we never listen at in real life. Give it some thought. Even peaks are just a few watts with horn speakers. PWK said many years ago that what is needed is a good 5 watt amplifier, with his speakers of course. Nothing has changed what a genius electronic engineer found decades ago. There are always going to be skeptics and it's their money to waste in unused watts if they want to. It is the hype propagated by those trying to sell amplifiers we have been hearing since taking an interest in this hobby. More is better, right. Invest your money is a good quality amplifier instead of a high wattage one with horn speakers. Horn speakers are very unforgiving and require quality watts not quantity.

Just thought I would mention that big screen TV decided to go dark yesterday afternoon. Took the back off to see if it had any bad caps in the power supply, looked good, and then tightened the screws that hold the two boards that also make ground and the picture came back. I now hope a bad ground of the boards was the problem. Something I learned from watching youtube video's of tech's repairing TV's. Bad ground of boards a common problem.

Up and running but not finished. Also picture of my man cave. Not polished ***** and span as some of our members listening room but suites me just fine. Details and problems encountered with this build forthcoming in a few days. Still waiting on some parts I ordered last Monday from Mouser. Mouser's service leaves a lot to be desired of late.

I started the SET 300B thread a few weeks back but just now got the dang thing to work. More on what and why on that thread in a few days. https://community.klipsch.com/index.php?/topic/214318-set-300b-project/

Quite a collection of 12AT7's Tiger. I have a few of them myself. There was a lot of tube swapping by the producers when tubes ruled. When they tooled up to make a run they made many more than they needed to sell to others at a later time without any lettering.

And a lot of it. The big 200 watt per channel amp woke those things up. Now instead of little speakers with big amps I prefer big speakers with less power needed amps. Just listened to my new SET 300B amp build last night with probably 6 watts, have not tested it yet. Filled the room with glorious sound. And loud with less than a watt usage. Unlike most I have many amplifiers to back up my claim of a few tube watts is all that is need with our speakers. The last retail amp I bought, Yamaha a decade or more ago, with 60 watts per channel did not make bass like this new SET 300B with expected 6 watts.

Did some checking on data sheets and it appears to be a no go. Not a lot of info on the CV593 but I found it to be a GZ32. I have not looked that carefully at the charts but this is what I found glancing at the numbers. http://www.r-type.org/exhib/aaa1104.htm http://www.r-type.org/pdfs/gz32.pdf https://frank.pocnet.net/sheets/093/5/5AR4.pdf Compare the numbers yourself. Data sheets tell the story in electronics. The VRD is pushing any rectifier pretty hard so you need a really good one. You should have no trouble getting rid of those tubes you cannot use. Tube prices have really increased of late.

Just watched a HBO movie about how diamonds are hyped by telling big lies to make big money. We music lovers are taught early on that more watts equals better when the truth is it is nothing more than BS sugar coated. One is much better of buying a quality amp with moderate power. But decades ago when I bought some of the first Bose 901's I could tell a big difference going from a 75watt per channel to a 200watt per channel. But they only had 9 cheap but good little speakers trying to make bass and they could be power hungry trying to do this. I would never use inefficient speakers for my main listening ever again.

Absolutely nothing wrong with buying so many watts you are never going to use as long as the amp sounds good at 1 watt. That is where you sound is going to live. I did much the same when young with my LaScala's. Used a 200watt per channel monster amp for over 20 years. I now know I was like the old man on the freeway driving a 200mph car 50mph. Five tube watts are perfect for me in my room, average size I would say. Like 10 or more SS watts, class A of course, when it comes to SS amps. This is not to say I do not have big watt amplifiers. Have one of the best 150watt class A/B PP SS amplifiers ever designed that sounds outstanding. Why so many watts when I know I am just using a few watts. Because I can. But to set the record straight I do have this SS amp biased where it is in class A where all my music lives with my speakers.

No way for you to know exactly what the meters are saying. They are eye candy at most. Get out a decent VOM to get numbers for an accurate amount of voltage you are getting to the terminals of your speakers. Measure across the speaker terminals the peak AC voltage on peaks then use ohms law to get an more accurate number of the watts you are truly using. Do this on the loudest you listen at. Nelson Pass has an oscilloscope set up to show a 1 watt window in his testing listening room on 95db full range speakers and people are always telling him to turn the volume down and the signal is no where near the limit range of the scope. Real measurements and not hype audiophiles are subjected to so much of. Members on our forum using Klipsch speakers should think quality watts over quantity and not listen to false claims from those trying to sell something.

So many misconception of power needs of real efficient horn speakers. The truth is most never use more than a couple of watts period with our speakers. One question, if a $25K Japanese SET 300B amplifier with 5 to 7 watts is not good enough for our speakers just what in the world could they be good for. 5 Watts with tube, slightly more quality watts with SS is what one truly needs. An amp that sounds great at millwatts not watts is a major concern as well.

A correctly designed amplifier is biased for a specific tube. This is not to say other tubes will work but not to top performance unless re-biased. Most of the adjustments of bias from factory is a narrow range for the specific tube that came with the amp. My experience is for an EL-34 amp a 6L6, KT-77, KT-88 and others of the EL-34 family will work but one has to be careful of glowing plates. Changing to a big KT-150 is another matter. Will not harm the amp or tubes but the 150 will be just run lets say half speed for an example and not to full potential. Could be wrong. There could be enough bias range built into the amp but unlikely. Doubtful the PS transformer is rated high enough for the added current those big tubes require if re-biased correctly. Craig needs to respond for correct answers.

Would those tubes be RCA clear tops? If so the getter, silver, is on the sides not the top as most tubes. Check the sides of those tubes. Very rarely does a pre tube fail. Most of the tubes that get tired are the power tubes. Correct me if I am wrong but is not the VRD a takeoff of the Dynaco ST-70? Most of these PP EL-34 family of tube amps have similarities to the Dynaco.

As the chart says possible, depends on your PS transformer and how it is rated. I am working on a 300B amplifier right now and the PS transformer is rated for 6 amps. You add the current all the tubes need to operate from the data sheet and as long as you do not exceed the PS transformer rating you are good. Craig would know the rating of the transformer used to be able to answer you question. When changing tubes, different type as in this example, one should dig into the data sheets of the tubes and the PS transformer. The tranny I am using right now is the Hammond 274BX. Check the data sheet for this tranny and it gives all the ratings. Those big 150's run a lot of current as well and one must check to see how much current you have from your transformer to see if able to change. For instance this trans is rated for 750V's at 201ma. You then check the tubes you plan on running to be sure you do not exceed this rating or you will have a hot buzzing transformer if not a destroyed one. https://www.mouser.com/datasheet/2/177/200-1390014.pdf I am running my KT-88s at around 120ma a pair so my Hammond 274BX is more than capable at 201ma. I was not sure if you had an electronic background of which you do so this video is the best I have seen explaining the function of all the graphs and figures in data sheets for tubes. Technical and kinda dry but very from one of the best. https://www.youtube.com/watch?v=1pU3jNquDUo&t=229s Roger does an excellent job for those that are interested in such things. Sounds like you would make a great diy'er. Jump into the water.

The correct bias for a KT-88 would be very different from the KT-150. There is a guy on the PrimLuna thread saying he thinks it has an automatic bias circuit. Not so sure myself but if so it would have to involve some SS components to my way of thinking to achieve that along with some sensing devices. One really needs an electronic background to understand the info on a data sheet. That being said though most of the info provided is for someone designing an amplifier. What we are discussing is bias so there are a few things that are important to us. To simplify this lets use this tube for an example. https://frank.pocnet.net/sheets/163/e/EL34.pdf This JJ EL34 tube is rated for 25 watts. To make for a long tube life we only want to use around 80% of that value, lets say 20 watts to make it simple. There are only two things we can play with to achieve running this tube at 20 watts, volts V and amps, milliamps in this case ma. On this data sheet the typical characteristics is shown. They quote 250V's and 100ma of current. Using ohms law you will find using those figures a wattage rating of 25 watts, the limit of the tube. Ug3 is negative so no voltage typical. G2 typical is 265V so with a plate voltage of 250v G2 is plenty good enough. G1 has to be more negative than ground to put the brakes on the tube. Ia is the typical current of 100ma which is much higher than I would run any EL34 but that is what is on the data sheet. What try to run on my SET EL34 builds is around 400V on the plate and run approxiamantly 52ma of current for 20.8 watts. Decrease the current run more voltage. Increase the voltage run more current. As long as one does not go over 25 watts for the JJ EL34 the tube should be OK but as I said most do not run a tube at max. If you compare the two tubes the KT88 is a 40 to 46 watt tube whereas the KT150 is rated at 70 watts. Pretty big difference is you want to get the most out of the KT150. I hope this helps some but if really interested an online electronic course is the way to go. I do not see where it will hurt anything to try the KT-150 in the VRD without changing a thing but if the amp is biased correctly for the KT-88 tube one should re-bias the amplifier to run more current for the KT-150. Also the KT-150 is going to drop the plate voltage some as well.

Am I correct that the VRD is a EL-34 PP amplifier? Kt-150's might work but not to it's their full potential. This is from just looking quickly at the data sheets the pinout is much the same except for G3 which is tied to the cathode internally on the KT-150. The KT-150 should at least make some music. Both are true pentodes with much the same pinout. For the KT150 to work the best it is capable of the current in the tube should be increased. That is if the plate voltage is close and the PS transformer is capable of producing enough ma. https://frank.pocnet.net/sheets/084/k/KT150.pdf https://frank.pocnet.net/sheets/030/e/EL34.pdf

I found this very interesting. Thanks for posting.

First for me. Would love to see that circuit.

Are you saying you can change the bias in this amplifier easy enough to run KT150's? If so that is a nice touch.

They tried their best to wear you out. Kudo's for not giving up.

The last tube amp I built, SE-KT88, cost me over $350 just for the iron and the price of iron is only rising. Fast, too.

Caps can do that, not saying they are the problem though.

This has been stored for decades in a closet having been bought in the 80's I believe. If not mistaken one of the first DCX's offered to the public. Worked much better than Dolby for tape enthusiast.

The schematic is still floating out in interspace so all one has to do is some surfing so no big deal.

Just wanted to say welcome to the tube section. We need more new members like yourself posting on Maynard's tube section. Nice seeing new members participating. Tubes still rule when it comes to sound.