My latest project - KT88 SE tube amp

[PWR RYD]

Re: My latest project - KT88 SE tube amp

Oh wow, that's pretty nifty! I imagine you'll initially like the UL mode, because of the extra power and eventually settle on what you actually like best, haha.

What speakers and setup is this going with?

This amp will be sitting on the shelf right over my basement workbench driving the Wolf designed "Stances". The speakers are literally 2.5 feet in front of me. I've been listening to them for the last several months powered by a cheap garage sale Sony boom box. The speakers sound incredible! So I know this amp will only make them sound better!

[TN Allen]

Re: My latest project - KT88 SE tube amp

Your photos and descriptions make the amp circuits look rational, even comprehensible. Far more so than PCBs. Even though I've stuffed a few PCBs and hooked up the remainder of the components in a few amps, I hadn't a clue what I was really working with. The details of your tread are a great window into building an amp, what the components are, and how they work.

[Wolf]

Re: My latest project - KT88 SE tube amp

...driving the Wolf designed "Stances". The speakers are literally 2.5 feet in front of me.... The speakers sound incredible! So I know this amp will only make them sound better!

So this tube amp will do a 4 ohm load then... The impedance does rise into the tweeter range, so I wonder about FR differences from your amp to come, but the phase angle electrically is really easy to drive.
Thanks for the compliments!
Wolf

[PWR RYD]

Re: My latest project - KT88 SE tube amp

This amp shouldn't have any problem with the Stance's impedance. I finished the shielded cable input line level wiring this afternoon. All that is left is the small amount of wiring for the output transformers. They'll be here Monday. But I need to bead blast their end bells as well as the end bells for the power transformer. Look at the last couple of pictures of the power tranny... the Hammond power tranny's paint sucks! Edcor always has very nice finished end bells but I'm just not a fan of their blue. I like simple high temp semi-gloss black. Anyway, here are a few more pictures of some of the almost finished wiring (sorry for the couple of wood burn marks from the soldering iron :o ) :

[Æ]

Re: My latest project - KT88 SE tube amp

What an excellent thread, I'm enjoying it immensely, way better than the usual stuff that gets posted here. Nice that somebody can post and discuss a subject other than the usual drivel.

[mgrabow]

Re: My latest project - KT88 SE tube amp

Sweet Build...

[blair]

Re: My latest project - KT88 SE tube amp

Hi Craig,

Take a small file and scuff up the metal on your pot. Then run a short lead to your ground tabs on your pot. If not, when you reach for your volume pot, it might pick up ground noise. Just a precaution with the Alpha pots.

Blair

[PWR RYD]

Re: My latest project - KT88 SE tube amp

Great suggestion. I had done that on my K12 amp (per their instructions) but totally forgot about that on this one. Thanks! Done:



Also added a dab of RTV to make sure the signal lines stay put (nice a far away from everything high powered):



It's been great building this amp and sharing it via pictures. I was totally inspired by PassingInterest's T-60 bass horn build thread and thought others might like my build pics as much as I enjoyed his.

[50 watt head]

Re: My latest project - KT88 SE tube amp

Cool project + Excellent work = Great thread!

[Pete Schumacher]

Re: My latest project - KT88 SE tube amp

A little diversion. Taking DIY to the extreme . . .

[WernerM]

Re: My latest project - KT88 SE tube amp

Craig I just gotta say that I love this build, and thank you for posting it!

[[email protected]]

Re: My latest project - KT88 SE tube amp

It's been great building this amp and sharing it via pictures. I was totally inspired by PassingInterest's T-60 bass horn build thread and thought others might like my build pics as much as I enjoyed his.

you are correct.

[PWR RYD]

Re: My latest project - KT88 SE tube amp

The Edcor output transformers arrived this morning. Now I really wish I would have ordered the big ones instead :(

[PWR RYD]

Re: My latest project - KT88 SE tube amp

Is there a relationship between bandwidth and output power when sizing an output transformer? IOW these little Edcor's are rated at 15 watts 40-18kHz but I don't expect my amp to produce more than 5 watts in triode mode. Would the bandwidth be wider at third the power level?

[Sidi]

Re: My latest project - KT88 SE tube amp

core material, core saturation, winding inductances, interwinding capacitances, all play into the bandwidth. Those are all considerations when designing the transformer for a specific power level.