KT88 SE UL Tube Power Amp: Testing and Final Thoughts

[@airgead5391]

Beautiful build, beautiful result. Congrats! (also for the happy owner)

[@nevillegoddard4966]

That's fantastic you got such great results with this KT88 amp! I'm so pleased! Perfect frequency response, quite high output power, & majority even harmonic distortion. What more could you want? Yep, you've definitely hit a home run with this one! 🎉🎉

[@warp2600]

Those graphs look wonderful. I wish I could hear what that beauty sounds like.

[@SkunkieDesignsElectronics]

It's pretty awesome + KT88 tubes are SO much cheaper than something like 300B tubes

[@snakeoilaudio]

Great work Skunkie! IMO the KT88 is the sweet spot of single ended designs. Obviously the mids are not as silky as a 300B and the top end is not that sparkly but in both disciplines it is still excellent. The KT88 in a SE config doesn't sound like a carnival like it does in most PP designs, it sounds like a proper SE amp but it has the additional power that you don't need these super efficient speakers and it woks a lot better with larger speaker driver units. IMO a 300B works best with 8inch drivers (if we forget these vintage super rare Altecs etc) a KT88 can easily drive a modern 12inch. Like you said, the bass is phenomenal. And at the same time I like the KT88 more than these giant 845, 805, 211 designs because you don't need these enormous transformers that mostly tend to slow down the amp. On top of it a KT88SE is dirt cheap. I really love 300Bs but in most cases the KT88 is the more versatile amp. Have you thought about pairing it with more conventional driver tubes like 6SN7?

[@SkunkieDesignsElectronics]

Don't think a single stage of a 6SN7 triode will develop enough voltage swing. You need 80Vpp min and the ability to drive a 250K grid leak resistor.

[@318ishonk]

Pretty impressive results. Congrats!

[@rogerayotte9503]

His ust might be my next amp.

[@neps4th]

Enjoy your topics, enthusiasm and technical demeanor. Neil

[@pascalou-x2c]

You have done a great job and the look is top 👍 very nice

[@SkunkieDesignsElectronics]

Thank you so much 😊

[@cobar5342]

Lovely result Stephe. Maybe one day you could consider doing a slow build for us to attempt to make

[@SkunkieDesignsElectronics]

I've done that on multiple amplifiers.

[@LeeBergerMediaProd]

Beautiful Amp! The output transformers are rated at 25 watts, is there any way to get more power with the alternate rectifier and output tubes your recommended? Just curious.

[@SkunkieDesignsElectronics]

Nope, that's all you're gonna get from a KT88 SE. The alternate drops 2-3 watts

[@christopherredfern6472]

Great seeing this , ive never given any thought to changing the rectifier in my ecc85 blueglow, so maybe I could try that with some el34 etc ? My opt are hammond 1628sea, I won't return to using edcor after experiencing their piss poor attitude to a factory failure I had , thank you for everything you do for us skunkie ❤

[@SkunkieDesignsElectronics]

Yeah I will never use their power transformers again.

[@christopherredfern6472]

@SkunkieDesignsElectronics yep same here, had one completely burn out due to very poor workmanship, was independently checked here and sent back to USA, they claimed it was the amp that caused the fault even though the amp was certified healthy by malvern audio, Edcor couldn't give a rats arse ! Hammond have proved bullet proof every time for yrs now !

[@NickP333]

Killer specs! The frequency response is just simply fantastic, surprisingly good even. No wondering where the low end punch is with this amp. What a beautifully designed amp. 12 wpc is just great at 80%. How many milliamps to achieve that in this amp?

[@SkunkieDesignsElectronics]

75ma on the plate which = 30W on a 35W tube.

[@SkunkieDesignsElectronics]

In push pull, you would set a KT88 in the 40-60ma range.

[@NickP333]

@@SkunkieDesignsElectronics Apologies for yet another comment, but my last one is gone. Thx, YT… 😡 Anyway, as a tech, I had learned enough to do my job. I’m not sure I’d have the subjective opinions based on what I hear vs. objective data and a thought of, “if two parts measure the same, they’ll sound 5he same”. Obviously not true. Mike Sanders who owns the amplifier company, Quicksilver, of which I own his PP Mid Mono Monoblock amps. It came with EL34’s, but I tried KT88’s as well, which of course necessitated a bias adjustment. Mike says this: “Maximum bias is 50 ma for EL34s and 75 ma for the KT series tubes”. I think this is why I’m confused….

[@SkunkieDesignsElectronics]

Biasing PP amps is a completely different deal from single ended.

[@NickP333]

@@SkunkieDesignsElectronics Ahhh…ok! 💡 🧠 That makes perfect sense. Most guitar amps are PP, as are my PP monoblocks. The only SET amp I have is my Elekit 300B amp which has auto bias, as do most SE guitar amps. Thanks very much, Stephe! 🔊😊🎶💜

[@davidatrakchi2707]

If one day I'll kick away my solid state Pass F6 and switch to tubes it will be thanks to you!!

[@chrislj2890]

I have two systems and each has both a solid state and tube integrated amp. I just use a switcher for the speakers and it works well for me.

[@davidatrakchi2707]

@@chrislj2890 sounds amazing for one like me suffering from limited space and my wife carefully watching over

[@chrislj2890]

@@davidatrakchi2707 I'm in a small house with not a lot of room also, and my wife's mantra is "where are you going to put it?" They can be so negative sometimes, lol.

[@lysippus]

I cannot find details on this amp on your website. What brand cathode resistors are those? I have some 500R wirewound ones but having trouble finding the chassis mount type

[@SkunkieDesignsElectronics]

It's because I haven't put it together, I JUST finished this amp a couple of days ago! Those resistors were probably off ebay or might even be off amazon lol.

[@lysippus]

@@SkunkieDesignsElectronics ok I misunderstood I thought you said it was on your website. no worries, thanks. also there are some odd posts like "great info" when a question was asked, or someone saying to take mushrooms, lol! thats the internet, i guess

[@SkunkieDesignsElectronics]

Probably will be later this month.

[@RobertKohut]

Nice!! 🙂

[@vitalip1955]

Super!!!!

[@MrMersh-ts7jl]

Have you ever desired to venture into push pull? An el84 maybe. Solid power with quite low distortion. By the way I really like the look of this unit.

[@SkunkieDesignsElectronics]

I have some projects in the future. Going class AB extremely complicates everything.

[@MrMersh-ts7jl]

@@SkunkieDesignsElectronics looking forward to it. My journey began with push pull and I have yet to do anything with a single ended setup. Your videos have definitely got me off on the right foot for single ended setups. Thank you

[@MrMersh-ts7jl]

@@SkunkieDesignsElectronics I'd also say that if you look into the classic Williamson design the only thing I ever ran into was getting the phase splitter to output a perfectly mirrored signal and in my specific application which was a mono amp It came down to using a very cheap decade resistance box.

[@SkunkieDesignsElectronics]

I see tuning the GNFB to specific output transformers being a challenge and even sizing the coupling caps isn't straight forward to keep the amp stable.

[@MrMersh-ts7jl]

@@SkunkieDesignsElectronics In my experience like the Williamson design I mentioned earlier, starting with a known great and stable design and then moving from there worked extremely well for me. And like I mentioned before it helped me basically skunkie up the reisong MT34 mk2. I will be sending pictures of that over to you is including the audio analyzer suite measurements

[@middleearthltd]

For me that is a beautiful power amplifier Add the Color Preamplifier And the EAR Clone Phono Stage Perfect, in my opinion, for a turntable sourced analog Skunkie Stack As it should be

[@SkunkieDesignsElectronics]

Skunkie Stack :)

[@orwhat24]

Pls remind us which Klipsch? Do you mean the 600M?

[@SkunkieDesignsElectronics]

Listened with RP600M and also Fyne Audio F500

[@jchborg90277]

Is this the amp you're selling?

[@SkunkieDesignsElectronics]

This was built on consignment for a customer.