KT88 - Single Ended Tube Amplifier Build 2018 - Part 1

BG157 - New series on how to build a KT88 Single Ended Amplifier. Based on the works of Abdellah, Gendrano, & Kegger. This video will help you pick easy to find parts and yet maintain a high quality build. Circuit theory and parts selection will also be covered. Lets have some fun...

[@Animalhours]

Mark, thank you for putting so much effort into making this video series. I built this amplifier and absolutely love it. The build was a great experience and I learned a ton. And, I have a killer amp to show for it.

[@jakep8484]

I've been looking at this amp for a couple years myself, cant wait to see what you think. I'm finally building a 2A3 stereo. RIP Kegger, learned so much from his posts.

[@cathiestubes2820]

Hi I have built several SE amps and just a tip for your future SE designs. Since there is no Push Pull type noise cancellation, parts and tube, wiring and ground layout is more critically important. I notice that your input (6dj8) tube is close to the output trannys. The high magnetic flux of the OPTs can affect the input signal and so it is best practice if at all possible to have the input tube away from any of the magnetics and with as short an input lead from your input connector to the input tube as possible. Keep up the good work! Cheers.

[@grahampinkerton2091]

I built a Kt88 push pull amp back in the year of 1956. I´ve moved on a lot since then.

[@iansyme3535]

Mark, I have a long time passion for H-Fi and currently run a high end solid state (Chord SPM 1050 MK 2) and a Linn Streamer (Akurate DSM) but was quite beguiled and bewitched recently when hearing a demo on an Audio Research GSi75 amplifier..... This set me down the road of thinking about a self build of some sort and that is when the wheels basically fell off! I quickly discovered that power transformers of the voltage rating you prescribe in this circuit are as rare and hard to find as hens teeth -not to mention VERY expensive. Edcor wanted (from memory) $225 shipping. Factor in the cost of output transformers and choke and we are suddenly in to seriously large amounts of cash for just these parts alone. I was hoping to find a good sounding build for $300 dollars total but alas...Keep up the good work. I am much enjoying all the stuff on KZbin on self build but fear I will be putting the money towards a factory built amp from AR. Will follow with bated breath and see if you come up with changes to your initial design. If not you will be the VERY FIRST builder who dos not meet snags and change things along the way. You touched on this in the Part 1 video. Greetings from a 63yr old retired Telecommunications Technician from Scotland by the way. Ah, the power of the internet!

I thoroughly enjoyed your presentation. I felt like a student having a master class session! Thank you!

[@CraigHollabaugh]

Mark, you have been cranking so much excellent content. Thanks.

[@stephenhughes3422]

Hi mark keep them coming loved the 807 don’t know which one to build now might just have to be both and can’t wait for the pre-amp it’s going to be a busy year have a good one Steve from the uk

[@1959Berre]

The show must go on! Keep it coming.

[@turnersparadise8368]

Wow, thanks for jumping on this one. I am really looking forward to this build. BTW, I really like the new format with the second picture inset.

[@todddembsky8321]

Doing my "Happy Dance" will not put up a video of it, think of a bobber shaped jello item put into a paint mixer -- not pretty :-) I am sooo looking forward to this one, I have 4 matched sets of KT88's on the shelf that are just itching to make some noise !!!! Thank you for all the time and effort you put into these -- I just don't know who has the larger disclaimer that you will get killed if you do an oop, you or Mr Carlson's Lab!!

[@williamarchibald7629]

Thanks so very much for your detailed instructions and time. I'm just getting started on these series of videos, this something I'm going to try and build. I'm 187 n.c. on the 11 meter channel 1 holla back 😁

[@randyaloysius5838]

this guy is a tube amp Jedi. thanks for all this detailed info

[@tashpaug]

Mark, great videos. Looking forward to this build. Keep up the great work.

[@MrMannakin]

Excited about the new series. I have a KT88 push-pull amp and am interested in comparing it to the KT88 SET. I have x2 matched sets (4 valves) sitting on the shelf already :)

[@gallymendoza6773]

Thank you for doing this. Much appreciated.

[@angeloevangelou918]

Thank you for getting into it!!!, I have a question, what would be like to switch the KT88 s with 6c33 ? would it take a lot of tweeking? would it worth he effort?

[@THEtechknight]

8:00 This is what I call "noisy" threads. Threads that everyone has input but doesn't really go anywhere solid.

[@russellesimonetta3835]

Those edcors are reasonable actually!! For what you will have in the end awesome!!

[@SuperFredAZ]

I am looking back at these SET builds, one thing I don't quite understand is the use of a rectifier tube. 2 600 V diodes, and a PNP/NPN delay 20 second circuit would save cost, and at least 20 watts of wasted power, at no sacrifice to sound quality.

[@NotMarkKnopfler]

Mine was like number 5 :-) Greets from Aberdeen, Scotland.

[@jeffreyjhouser]

I like the initial onset of this video, but is there a link to the other amp that is described in the beginning? I'd like t check that out, as well!

[@electricwally]

Hi Mark, can you please help me to understand why you did not choose to include the all important split-rail circuit in the power supply of this KT-88 SE amp build? I noticed you included it in your previous SE amp build using the 807 tubes. Extremely helpful video series. Thank you very much.

[@makiddo]

Hello, I enjoy your videos, what I like to ask you about all these new Chinese amplifiers such as the Willsenton R8 Tube Integrated amplifier, as well as the others that are on the market these days? What would be expected as far as the longevity of tubes and parts and for the unit itself?

[@BenPrevo]

Would you consider doing a budget s/e 6BQ5/6AQ5 build -- I have a set of transformers from an old magnavox stereo amp -- thanks.

[@alaingingras7224]

What is 200k ohms on the plate of driver tube to plate of power tube.That is high voltage bypassing the coupling .22uf coupling cap... Please a brief shout.

[@marinosavraam]

Hello. ! ! ! Nice design for construction. I would like to ask. What resistors and what components do I need to put in the preamplifier stage tube so that I can have a signal Line in. For CD players, mixer e.t.c.

[@litzdog911]

Awesome! I might just build this one! Thanks Mark!

[@jostop7059]

Hello mijn vraag is in het NEDERLANDS... DUTH waarom moet de voeding van de versterker met een grote transfo ...kan dat niet met een ...Elecktronishe voedieng .en waarom niet .dank je bij voorbaat Jos

[@denniskonieczny138]

I have a pair of Transcender 017 Transformers with 3.5K primary to 4/8 ohms. Would these be ok for KT88 or 6550 output tubes?

[@tongordebeke1355]

Nice project I will follow this for sure, PS your bom stated 1 KT88 and 2 ECC83 that is not correct I think.

[@nightfurynova]

Im getting ready to build this and realizing that most of the parts nearly doubled in price since 2018.

[@robhall2570]

Love all the build video's but some of the parts are very hard to source in the UK, and when you can find them they are very expensive, mostly due to shipping costs. I will keep looking though.

[@rickg8015]

Robert Hall There are usually counterparts on your side of the pond.. Like for OPT’s, there’s Sowter transformers. You just have to give the same specs for custom ones.

[@redtopc20xe]

Hi Robert. If you find a supplier could you also let me know as I'm also in the UK. thanks

[@hakanberg8670]

Same problem here in Sweden, but I was thinking on building something with Hammond transformers instead - the 369HX as power and perhaps the 1628SEA as output transformers. Need to read up more on them before ordering something though. Thoughts on this anyone?

[@alexanderstefanov6474]

@@hakanberg8670 Lundahl are vastly superior to Hammond or edcor and they are made in sweden, but the Japanese brands Hasimoto and Iso (old Tango employees) are even better

[@hakanberg8670]

@@alexanderstefanov6474 Lol, thanks but I finished this build 3 years ago - and it sounds fantastic with my Hammond transformers 🙂

[@danielthomas3057]

The power switch should be after the fuse on the hot side.

[@MrTanknz]

Hi Mark, have been toying with the idea of doing one of these builds for a while... your videos are amazing! However i am in Australia, do you think the XPWR144 from Edcor would be a suitable 240V alternative to the XPWR033??

[@Drgorst]

What’s a suitable option for 230V countries? WPWR114?

[@Blueglow]

check out part 9 for this info

[@alexanderstefanov6474]

Edcor and hammond are basic El core transformers, Hashimoto and ISO are leagues ahead, expensive but not even comparable in performance

[@skularatna8136]

Can this be substituted with EL34

[@gregj.gotham4402]

I’d love to build a SE using my 6550 1958 Tung-Sol smooth black plate tubes. I’ve only recapped 3 amps with zero electrical knowledge in theory. Can you direct me to a post of a build you have done I do belong to AK for 10 years now. I do have soldering as I have work in engineering as a lab tech, retired now. Thank you for any reply.

[@russellhamner4898]

What's the advantage to using tube rectification? Or more to what I want to know, what's WRONG with solid state? Also: is it ever feasible to have the power supply completely separate, in a "remote" chassis? No one ever does this as far as I've seen, and it seems like it would be a good way to isolate noisy AC systems from the signal circuits. I'm still learning, please don't laugh at these amateurish questions! Or do, it really doesn't matter as I no longer have feelings that could be hurt; side effect of decades of listening to solid state audio.

[@silvionovais2504]

Which are the best valves for single ended?

[@ericmillot71]

ELECTRO-HARMONIX EL34 / 6550 / KT88 👌👌👌

[@renegrondin8162]

Burning question,why we dont see 6ohms output transformer and what if i only have 6 ohms speakers?

[@belotan4218]

Hi all. I want to build this one but where can i order the parts? Please somebody help post the link.

[@michaeldashnaw9631]

I would really like to know how to get the English version of single-ended. I can only get the Japanese versions. What am I doing wrong! Thanks.

[@AUDIOETRADIOATUBES]

wonderfull I use almost the same design but with a EL34

[@andrewmccarter2476]

I've noticed in both builds that you have done, and others on the internet, that the B+ = 400V. Why is it that the B+ needs to be that high, could you not also do a design using 120Vac out of the wall, ie ~170V? I ask only because I am wanting to do a SET that doesn’t have transformers except for the audio, this is due to using a small chassis.

[@Blueglow]

Sadly, these are the voltages tubes were designed to work at. They are high voltage devices.

[@stuarticusrobinson9319]

I'm not sure it's wise to show the power switch on the neutral wire?

[@paulengelder2601]

OK to do this if you interrupt BOTH sides of the line

[@silasfatchett7380]

A single pole power switch should be in the hot line. In many jurisdictions this is a legal requirement.

[@dennisclarke4632]

Hello Blueglow The Led dome in you're list has the wrong number. 516-1397-ND is a HLMP-Q150 645nm This is the right number by you're specs 516-1396-ND 655nm Just one number makes a different. I am building this amp in the Netherlands and have ordered the choke and speaker output and power transformer at AEEtransformers dot com. I hope it's going to work. I shall send you some pictures. Greet Clarkesound

[@johnsweda2999]

Why go for a valve rectifier than solid state, keep it original put both in and swap between the two see which is better. You have this guy's KZbin channel?

[@Radio478]

Valve tube rectifier always 👍

[@vcp93]

Is this something a "n00b" could tackle or would this be even too advanced for a novice? Cheers!

[@russellhamner4898]

IMO single ended is definitely the best starting point for no0bz but bear in mind that the output iron and usually the output to0bz as well will be much costlier than pull-push or shove-yank setups. My first power amp was based on the schematic from the output section of a Fisher integrated amp that used EL84 (or actually 6BQ5) tubes, and the iron literally only cost me $20. But these big scary single ended trannies - yes I called them "trannies," live with it - can get way up there, especially ones that handle massively high power levels like 25 watts.

[@piotrwojna269]

what power anode resistors ???

[@RobertKohut]

Nice!! Very excited!!

[@markyoung7470]

Ok here is the stupid question is this a stereo or mono amp?

[@marinosavraam]

Line in input or Phono (turnetable) ?

[@marinosavraam]

Hello. ! ! ! Nice design for construction. I would like to ask. What resistors and what components do I need to put in the preamplifier stage tube so that I can have a signal Line in. For CD players, mixer e.t.c.

[@lego40404]

Mark, for the shipping cost of those Edcors why not just use that money for different OT's. I have never used the One Electrons but these seem to fit this bill and reviews have been good and they are accessible here in the U.S. www.one-electron.com/Trans/UBT2_10.pdf

[@Trex1268]

Will This Also Run The 6550?

[@Blueglow]

Yes

[@blacktoothgriner]

Denice kegger?

[@moodyga40]

6SN7 work well as drive tube

[@HoangManhCuong2677]

0,22uf/400v or 22uf/400v hình ảnh mờ quá không nhìn rõ, thanks

[@Waltkat]

If you're talking about the coupling capacitor between the driver tube and the output tube then it should be 0.22uf/400v.

[@erwinflores6364]

Why not build a Fixed Bias SE amp

[@judges69]

Thanks Mark.

[@tasoulisvavaroulis515]

Really thank you!

[@redtopc20xe]

Can anyone give me the list of what's needed/ or email it to me? Thank you

[@FlorianVincze]

❤8dojaras

[@kaybax4623]

Is this project dead?

[@Blueglow]

Far from dead, just was waiting on parts and now waiting on free time...

[@kaybax4623]

Glad to hear. Looking forward to an experienced and understandable breakdown of the build.

[@dhpbear2]

Nice start to a new series! I really wish you'd retire that horrible out-of-tune intro music, though:)

[@domingoarmesto7590]

Traducir a espñol

[@johnsimms3957]

I think tube rectifiers are obsolete.

[@erwinflores6364]

Tube power amp and pre amp a lot better sounding with tube rectifiers

[@radicalaudiodesign]

Is it possible to build this as a mono-block?