Hi, guys. The simple se is my first amp build and my first tube amp. I have all of my parts including edcor gxse output transformers. I just can't seem to make up my mind on output tubes. So many choices. I listen to mostly rock music but also some jazz and folk. I currently have a pair of infinity primus p150s for speakers (for now). As a generalization I have read that kt88s excel in the bass and treble and the el34 has the better midrange. The speakers have a fairly detailed midrange but lacking in the top and bottom end. I am not sure if the kt88s would help in the bass department or if I should just try and enhance their best quality and go with the el34s. And the next question of course is what brand? I am only going to be able to buy one set for now because I am already gonna go a little over budget (what project doesn't) Thanks ahead of time for any help. I have learned some much from this forum in the last few months.
I've got a pair of Electro-Harmonix KT88s and a pair of Winged C EL34s. As much as I want to like the EL34s, I've found that I almost always prefer the KT88s.
For reference, I'm using the Edcor GXSE15-6-5K output transformers. My power transformer is the Edcor XPWR155. If I recall, B+ is around 420 volts. I'm using a 560 ohm cathode resistor.
I've currently got the amp paired with Pi Speakers 4 Pis, but I've also used it with Two Pis and with Overnight Sensations MTMs.
--TWH
For reference, I'm using the Edcor GXSE15-6-5K output transformers. My power transformer is the Edcor XPWR155. If I recall, B+ is around 420 volts. I'm using a 560 ohm cathode resistor.
I've currently got the amp paired with Pi Speakers 4 Pis, but I've also used it with Two Pis and with Overnight Sensations MTMs.
--TWH
I have the identical setup as timhowell and have used JJ 6550; EH KT88; RCA 6L6GC (NOS)... Of the three, the RCA are my favorite (rummage sale - $1 for the pair). IMHO, it won't matter what tube you use until you upgrade to better speakers. My son has the same speakers and we tried them with several of my tube amps... not real impressive at 88db sensitivity. I had built him an EL84 PP amp with the understanding he would acquire better speakers and he did... a pair of Klipsch like dad uses.
Thanks to both of you for your opinions. I got the allied 6k7vg power transformer and I plan to use only a tube rectifier 5ar4. I think I'm gonna give the eh kt88s a shot to start. As far as the speakers go, just trying to get what I can out of them for now with possibly some diy full rangers in the future. I don't think volume will be a problem because I live in a town house and rarely get to really crank it unless both neighbors are not home. Another question. What 12at7 are you guys using and how much of a difference does it make? Thanks.
Thanks for that information! I didn't realize cfb made that much difference in power output. I plan on making mine switchable
Like Tim Howell, I have 4 Pis and have used 2 Pi Towers. I tried EH 6CA7s which are great value, Shuguang EL-34s which are not (but cheap), OS Svetlana 6550s and now Gold Lion KT-88s.
The 6CA7s are OK all around, the 6550s have better bass but a little grainy in the treble. The GL KT-88s are from another planet. Awesome. $120 but you'll spend almost half of that and more on mediocrity.
The 6CA7s are OK all around, the 6550s have better bass but a little grainy in the treble. The GL KT-88s are from another planet. Awesome. $120 but you'll spend almost half of that and more on mediocrity.
In my experience, at least with mine, a big difference... I started out with a JJ, but shortly after picked up Amperex Bugle Boy. Much better than the JJ. Then I tried a NOS RCA black plate and thought I had found the sound I was looking for until I bought a NOS Sylvania Gold Brand (6201) black plate...Great sound/soundstage. It'll be awhile before I buy another 12at7, unless it's another Sylvania Gold Brand.
Bill,
I'm pretty sure that I'm doing the measurement correctly... But I am pretty new to the QA400 audio analyzer, so there is a possibility that I made a mistake.
Both of the measurements were made at 5% THD. With cathode feedback on, that 5% happens at a higher wattage. If max power is measured with and without feedback, they will both come up to around 13 watts -- if you increase the gain until it no longer rises significantly on the fundamental frequency, and the harmonics rise disproportionately to the fundamental.
Does my methodology make sense here?
-- Pete
I'm pretty sure that I'm doing the measurement correctly... But I am pretty new to the QA400 audio analyzer, so there is a possibility that I made a mistake.
Both of the measurements were made at 5% THD. With cathode feedback on, that 5% happens at a higher wattage. If max power is measured with and without feedback, they will both come up to around 13 watts -- if you increase the gain until it no longer rises significantly on the fundamental frequency, and the harmonics rise disproportionately to the fundamental.
Does my methodology make sense here?
-- Pete
Ok, thanks. Looks like nos for the 12at7 is the way to go. Tubedepot has some nos jan Phillips for 15.00. I wonder if these would be good to start out with?
I can see the wisdom in going right for the gold lions right away instead of trying several different ones only to end up with them anyway. Could cost less in the long run. Nice to hear things from real people instead of just reading hype from tube dealer websites. Speaking of, where do you buy your tubes? From the usual tubedepot, AES, etc?
Right now AES has 10% off everything until July 31, 2015 and Parts Connection is giving 20% almost everything until July 31 as well.
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