My latest project - KT88 SE tube amp

[bkeane1259]

Re: My latest project - KT88 SE tube amp

Craig should put a sticker inside the amp with the URL of this thread so future owners can see how it was meticulously handcrafted.

LOL....we're selling Craig's amp before he's even done building it.

[greywarden]

Re: My latest project - KT88 SE tube amp

Craig should put a sticker inside the amp with the URL of this thread so future owners can see how it was meticulously handcrafted.

LOL....we're selling Craig's amp before he's even done building it.

And 100 years from now :P

[PWR RYD]

Re: My latest project - KT88 SE tube amp

That ground conductor is solid 10 ga. copper. This forms my main system ground. I like the "star grounding" concept, but it is really not practical to have every single component that is grounded go to one single point. So this ground "bus" is where all group grounds go back to. Each channel of the driver stage will have a home run ground wire back to this bus. And each channel of the output tube cathode RC will have a home run back to this ground bus.



Totally not necessary at such low current levels but I used the same solid 10 ga. copper to tie the two big film caps' B+ together:



You can see the high voltage and ground wires heading over to the LC filter for the driver stage. Eventually the B+ leads for the output transformers will be landed on the B+ bus too.

[Pete Schumacher]

Re: My latest project - KT88 SE tube amp

You've got enough space in there. Why not use all film type capacitors and dump the electrolytics?

[PWR RYD]

Re: My latest project - KT88 SE tube amp

Hi Pete. Good question. The only electrolytic is the first cap in the LCL. I believe that because it is in front of the rather large choke it doesn't really make much sonic difference. All the other power supply caps are film. It is just another compromise I made in this build. This amp is going to be my "work bench" amp, not the center piece of my main system. That is also why I chose to cheap out on the output transformers. If I really like how this SET amp sounds then maybe I will build an all out amp.

[blair]

Re: My latest project - KT88 SE tube amp

I've built a few SE KT88 amps in my day, and I will bet you get better OPTs after you listen

The build looks awesome!

Regarding some previous posts, there are a bunch of tube builders here from what I've learned over the years, but most of us don't post the projects here. Here are a few projects of mine. Not to thread jack!









The list goes on....

Keep us posted on your project!

Blair

[PWR RYD]

Re: My latest project - KT88 SE tube amp

I've built a few SE KT88 amps in my day, and I will bet you get better OPTs after you listen

The build looks awesome!

Regarding some previous posts, there are a bunch of tube builders here from what I've learned over the years, but most of us don't post the projects here. Here are a few projects of mine. Not to thread jack!


Keep us posted on your project!

Blair

I'm afraid you are right and I will want the big boy output transformers :o

I wonder if building tube amps is supposed to be a secret addiction

Your amps all look fantastic Blair! I love the green tinted wood on the first one pictured.

[TN Allen]

Re: My latest project - KT88 SE tube amp

I've built a few SE KT88 amps in my day, and I will bet you get better OPTs after you listen

The build looks awesome!

Regarding some previous posts, there are a bunch of tube builders here from what I've learned over the years, but most of us don't post the projects here. Here are a few projects of mine. Not to thread jack!


The list goes on....

Keep us posted on your project!

Blair

It's great to see other tube projects, yours are distinctive! I've spent about 1/2 hour carefully looking over your photos. Any chance you'd elaborate a little about these amps, or send links if you posted descriptions on other forums? Also, I'm curious about what looks like a woofer in the background of the third photo down. And, that's a nice piece of Curly Maple in the last photo, nice placement of knobs and grain.

[blair]

Re: My latest project - KT88 SE tube amp

I'm afraid you are right and I will want the big boy output transformers :o

I wonder if building tube amps is supposed to be a secret addiction

Your amps all look fantastic Blair! I love the green tinted wood on the first one pictured.

I don't think it's a secret addiction. The topic used to come up here quite a bit, but almost always ended in flame wars about SS vs. tube gear like it really changed anyone's perspective. Like a line array guy arguing with a point source guy

If you do get bigger output iron, I highly suggest Transcendar. Gerry will get you transformers to you in about 1/3 the time of Edcor, and they are wider bandwidth.

Good luck on the build even though it looks like you don't need it.

Blair

[Sidi]

Re: My latest project - KT88 SE tube amp

I have a crap tonne of CDE 600V and 450V electrolytics if you need any. I tried to sell them at one point but got no interest... just pay shipping if you need a few ;-)

[blair]

Re: My latest project - KT88 SE tube amp

Hi TN,

Did you get your amp biased? The green fella is a tinker toy really. Fisher 500B iron, since that image, I switched to 7591 outputs, and drilled out another set of holes for a proper VA/CF stage. It's torn apart yet again. Supposed to be a quick flip that turned into a project;)

The Mahogany and Maple amp is a concept project I built using monster Baldwin power transformers, the second transformer from the back is actually a choke, and the two transformers up front are Dynaco A-470s. Both pairs of EL34s are fed through a single driver and the secondaries are in parallel for ~70W. There are two of these even though I'm too lazy to wire the second one. LOL!

I build preamps like the curly maple one you see to keep my addictions in audio going. Now that I know people may want to see these types of projects, I will post my next build. Sowter 200W output iron, Western Electric KS-8878 power transformers and Hammond 193Q chokes. I think they will house 3 -4 pairs of KT88s per amp.

Image of one KS-8878 and chokes for size reference:



I cannot find my thread on the speakers, but here is an image:



Blair

[TN Allen]

Re: My latest project - KT88 SE tube amp

Hi TN,

Did you get your amp biased? The green fella is a tinker toy really. Fisher 500B iron, since that image, I switched to 7591 outputs, and drilled out another set of holes for a proper VA/CF stage. It's torn apart yet again. Supposed to be a quick flip that turned into a project;)

The Mahogany and Maple amp is a concept project I built using monster Baldwin power transformers, the second transformer from the back is actually a choke, and the two transformers up front are Dynaco A-470s. Both pairs of EL34s are fed through a single driver and the secondaries are in parallel for ~70W. There are two of these even though I'm too lazy to wire the second one. LOL!

I build preamps like the curly maple one you see to keep my addictions in audio going. Now that I know people may want to see these types of projects, I will post my next build. Sowter 200W output iron, Western Electric KS-8878 power transformers and Hammond 193Q chokes. I think they will house 3 -4 pairs of KT88s per amp.

Image of one KS-8878 and chokes for size reference:



I cannot find my thread on the speakers, but here is an image:



Blair

All of this is very interesting to me. I'll send you a personal message as I don't want to deviate too far from PWR RYD's thread.

[PWR RYD]

Re: My latest project - KT88 SE tube amp

I totally appreciate everyone's input/replies so far. Blair your amp pictures are an inspiration. Even if this thread turned into a SS vs tube flame war I would just continue to post my project progress pictures and just ignore that stuff

[PWR RYD]

Re: My latest project - KT88 SE tube amp

Got home a bit earlier than expected and was able to sneak in 30 minutes of fun before dinner. Nothing really picture worthy. Just added a bleed resistor across the power supply caps and two dabs of RTV to hold the high voltage twisted wires up tight to the top aluminum plate thus further away from the big choke. It only keeps them a 1/2 inch further away... But two dabs of silicon cost nill.

[PWR RYD]

Re: My latest project - KT88 SE tube amp

Here is the bleed resistor: