Nice!
Kegger/blueglow kt88 project
- Thread starter Tubeglowpio
- Start date
Tubeglowpio
Active Member
Glad all is fine, so you would be getting about 12 watts rms into a 8 ohm load, that sounds good. I was hoping to get about 16 clean out of the 120's with a bit higher current and voltage of course.
Ruidoso Bill
Active Member
I continue to appreciate all of you, your patience especially as I get back into this hobby.
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JohnT123
Super Member
Looks like a great build Bill. Mine does not have that kind of output power because my power supply provides a lower B+ voltage. The small advantage is that I've run KT88, KT66, 6550, 6L6GC and EL34 tubes without changing the bias and get good results out of all of them. On the next build I'm going to use the EF86 drivers as pentodes instead of triodes just to see what happens in terms of output. I keep forgetting that my build is very different than what everyone else has done. It's 2 different Blueglow amps plus my power supply and drivers, but big picture, the amp itself is very much like Marks' KT88 build. I have a long background in QA and project management so I'm always asking myself how could I improve this, or what could I have done better. My guitar amps typically go through several revisions before I'm happy.
Ruidoso Bill
Active Member
I really can't decide what to do next, I haven't found a tube preamp yet I'm interested in building or do another power amp and correct some things I'm not satisfied with. I have a lot of leftover parts from the first build and have a second power transformer coming, so another chassis and a few more ransformers and I'm there. Maybe some vu meters and concentrate on quality.
I have learned a ton, got my test equipment in place, built a new power supply, dummy loads etc and really enjoy the actual building.
JohnT123
Super Member
I'm going to try a toroidal power transformer in the near future. Primary reason is cost. I've never worked with one but Antek has one that should provide 425 volts @ 450 ma with 8 amps of 6.3 volts and it only cost $39 USD. The shielding cover cost $37 USD. That's about 25% of what I pay in Canada for a traditional transformer with the same specs. I have friends that want me to build them one of these things but they go cross-eyed when I tell them how much it will cost.
I know that Mark talked about an El Cheapo project over on his site and I'm thinking that the toroidal could push things in that direction. I also want to do a tube pre. I have a Dynaco PAT4 SS pre that I'm prepared to use as a donor. It already has all the I/O and controls so really it's just a case of building the power supply and main board to install in the chassis. It should save me a lot of money on the build cost.
I know that Mark talked about an El Cheapo project over on his site and I'm thinking that the toroidal could push things in that direction. I also want to do a tube pre. I have a Dynaco PAT4 SS pre that I'm prepared to use as a donor. It already has all the I/O and controls so really it's just a case of building the power supply and main board to install in the chassis. It should save me a lot of money on the build cost.
Ruidoso Bill
Active Member
That's my main gripe about the preamps I've looked at, I want switchable inputs and controls, my Pat 5 is completely redone so don't want to sacrafice it but you've given me a good idea.
Ruidoso Bill
Active Member
Just looking at another project, I enjoyed this last one. I'm also considering a restoration.
JohnT123
Super Member
I have 3 SS pre amps and the Dynaco PAT4 is by far the worst. Somebody gutted it and installed VanAlsteine (sp) boards. It's horrible and has cross talk between inputs. I suspect the person that did the work messed up some stuff. I believe that the pre amp is the heart of the sound and I do want an all tube signal path.
Heffa
New Member
Whohooo!
It's alive, and it sounds AMAZING!
I have yet to test it with my "real" horn speakers, so far I have only used my crappy test speakers in my man-cave, but even here I am mesmerized.
No hum whatsoever, dead silent between songs. Couldn't be happier I think.
However, I only measure like 3V p2p on the output, where others get several tens of Volt here
What p2p voltage is a "normal" line signal? Perhaps my in signal of 400mV was to little? Come to think of it now, I don't think I tried to increase that
Could it be that I need a pre amp as well?
It's alive, and it sounds AMAZING!
I have yet to test it with my "real" horn speakers, so far I have only used my crappy test speakers in my man-cave, but even here I am mesmerized.
No hum whatsoever, dead silent between songs. Couldn't be happier I think.
However, I only measure like 3V p2p on the output, where others get several tens of Volt here
What p2p voltage is a "normal" line signal? Perhaps my in signal of 400mV was to little? Come to think of it now, I don't think I tried to increase that
Could it be that I need a pre amp as well?
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JohnT123
Super Member
WOOT! Another satisfied customer. I think you've already answered your own question re. output voltage. A CD player is going to send it 1 - 2 volts and a pre amp more than that. Enjoy your success.
EDIT: I have to use a pre for phono, phone and tuner but I can run my CD direct with no issues.
EDIT: I have to use a pre for phono, phone and tuner but I can run my CD direct with no issues.
Ruidoso Bill
Active Member
Whohooo!
It's alive, and it sounds AMAZING!
I have yet to test it with my "real" horn speakers, so far I have only used my crappy test speakers in my man-cave, but even here I am mesmerized.
No hum whatsoever, dead silent between songs. Couldn't be happier I think.
However, I only measure like 3V p2p on the output, where others get several tens of Volt here
What p2p voltage is a "normal" line signal? Perhaps my in signal of 400mV was to little? Come to think of it now, I don't think I tried to increase that
Could it be that I need a pre amp as well?
View attachment 1465670 View attachment 1465679
Congrats, nice to see it reversed, fun to hear your comments, I feel the same.
I think Mark said it would need a preamp, my signal generator puts out more than the amp could handle all the way to clipping.
Maybe we should get hats or t-shirts!
Ruidoso Bill
Active Member
Not on the High Holidays
Ruidoso Bill
Active Member
Took some things apart, still curious why one channel had a little more output than the other, did a better job matching the led's, replaced them, put some rubber washers under the mounting brackets on the ps transformers, and found yet another pinched wire (heater wire), pulled the transformer out and re ran the wires, now it's all nearly as perfect as I can make this one, channels scope nearly identical.
I better start another project before I screw this one up.
I better start another project before I screw this one up.
Ruidoso Bill
Active Member
Hi
I built one of these a few years ago but I sold it to trade up to a new Lux integrated.
Im missing it so much that I think I may build the parallel version with KT 120 as I seem to have most of the parts
I wonder who has it now?
Like that chassis! I had asked someone about those cool looking vent holes around the tube sockets, not sure if it's functional but looks really nice. I think if you take pride in what you build, looking great is a big +, your's my friend looks great!
Attention to detail is a big deal in the long run.
I just ordered the transformers to build a second one, you know that first one has some issues and heck why not go for perfection. Mine is pumping some Van Morrison as I type.
santa
Well-Known Member
Thanks very much.
Vent holes in both the top and bottom covers really help to lower operating temps especially over the course of a long session here in sunny Ca. central valley.
The ones around the kt88 are spaced properly, the ones around the rectifier should be closer to the tube.
Vent holes in both the top and bottom covers really help to lower operating temps especially over the course of a long session here in sunny Ca. central valley.
The ones around the kt88 are spaced properly, the ones around the rectifier should be closer to the tube.
Ruidoso Bill
Active Member
Yes to Edcors, I did order the non painted end bells, have a little different scheme in mind this time. They are actually local for me, doesn't save me time but nice to support local and their quality is super. I do like the holes, not sure I can pull it off that perfect. I'm also doing meters this time, only ultra linear, not sure if a gain control is needed either, preamp input only for me.
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