I finished building my TU-8600S amp over the weekend. I very carefully followed the instructions in the manual and the tips that Victor gave me. I double-checked all solder joints and component placements.
It worked the first time that I powered it up. It is dead quiet when the volume is turned all the way up with no music playing.
This is my first tube amp and is by far the best sounding amp I have ever owned.
I ordered all the upgrades. I have attached pictures of the Takman resistor preparation, orientation of the V caps, wire routing of the primary connection on the Lundahl OPTs, and tubes used.
I will be rolling tubes in a few weeks, after I have gotten familiar with the sound of the amp.
Thanks again to Victor for the great service he provided to me and his great dedication to our hobby. I appreciate that he brought this 300B amp kit to us and made it so easy to get the upgraded components.
Allan
Round Rock, Texas
It worked the first time that I powered it up. It is dead quiet when the volume is turned all the way up with no music playing.
This is my first tube amp and is by far the best sounding amp I have ever owned.
I ordered all the upgrades. I have attached pictures of the Takman resistor preparation, orientation of the V caps, wire routing of the primary connection on the Lundahl OPTs, and tubes used.
I will be rolling tubes in a few weeks, after I have gotten familiar with the sound of the amp.
Thanks again to Victor for the great service he provided to me and his great dedication to our hobby. I appreciate that he brought this 300B amp kit to us and made it so easy to get the upgraded components.
Allan
Round Rock, Texas
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Hello Rock Ball,
It seems from one of the pics that you installed a TKD CP60x pot in your build.
What is the length of the hex spacer you used between the main PCB and the pot PCB?
Thanks,
Peter
It seems from one of the pics that you installed a TKD CP60x pot in your build.
What is the length of the hex spacer you used between the main PCB and the pot PCB?
Thanks,
Peter
The TKD upgrade came with the hex spacers needed for the install. I did not measure them with a ruler so I can't answer your question specifically. The next time I open the cover, I'll measure that for you if someone hasn't answered the question by then.
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So Vcap CuTF is the upgrade cap option instead of Mundorf silver/gold for 8600S?
Also, the value used to be 0.22 uF, now 0.1 uF. So 0.1 uF in the 8600 circuit does not result in any loss of bass?
Also, the value used to be 0.22 uF, now 0.1 uF. So 0.1 uF in the 8600 circuit does not result in any loss of bass?
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I can't speak to the comparison between the previous version and this version, but I was surprised at how good the bass was. I listened to my amp without my subs turned on for quite a while and there was plenty of fantastic full-sounding bass.
I was under the impression that 300B tube amps weren't supposed to have the amount of bass that a class D amp has, so I wasn't expecting much. But this amp is not lacking bass.
Also, I built the Amp Camp Amp 1.8 a few weeks ago and was enjoying it until I built the TU-8600S. ACA is 8 watts (?) and TU-8600S is 9 watts (?). The TU-8600S is a lot louder than the ACA. I don't know if its appropriate to compare the wattage spec for loudness in this case, but that is my observation.
That is really cool to know that you've got the DIY bug. I've been holding off on the TU-8600 since I already have a TU-8200 that is heavily modified but your posts might get me to ask VK if he has any 8600s left. Really, really nice work and great job taking the photos.
Thank you. Yes, I was bit by the DIY bug back in January. I bought speaker and subwoofer kits. Next, I want to build the SunValley phono amp.
Glad to hear 0.1 uF works fine for bass. That opens up some options for future cap experiments in terms of cost and space available under the board.
FYI, those VCap CuTF teflon caps take FOREVER to break in IME, probably longest of any caps I've tried, so if you think the amp sounds good now, i would wait quite a bit longer for some real treat 🙂
My Elekit 8600R with Jupiter Copper Foil caps has more bass quantity and apparent oomph in midbass than my 2A3, EL84, 45 tube amps and even my class AB solid state or IceEdge 1200AS2 amp. Bass isn't as drum-skin tight or "neutral" as ICE but quite shocking for a 300B SET, lending great foundation for that rich, lively 300B vocals.
I did notice that Dannie Richie of GR Research modified his 8600R and demo's some of his upper tier speakers with it. I don't care to install tube connectors, but bypassing the extra long input board traces (and even volume pot) with good wire seems like something worth trying...
"1. I wired the inputs straight to the boards with some OCC wire, and by-passed the volume pot and board traces.
2. I removed the binding posts and replaced them with tube connectors.
3. I replaced the input caps with Miflex Copper foil caps."
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I have the tube connectors on my speakers so I am considering using them on the amp, but I'm waiting to see if I don't need the original connectors for any possible reason before I make the final decision.
Same with the volume control. I may want to use it in the future for something, so I will probably wait a long time before I decide to make that change.
What stops me from going onboard with tube connectors is that it still introduces connector metal and solder joint in the signal path. If I'm going to go through the trouble of bypassing binding posts, I figure I would go all the way and go for wire-to-wire contact For example, I saw this once..
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That's a really interesting picture. I see your point and like the idea of using what's in the picture. That seems like an easy mod.
Average speakers tend to have more but less controlled bass with single-ended tube amps than with solid state amps due to the much lower damping factor, which puts emphasis on the low-bass resonance.
What do you mean by the Elekit being louder? Is it louder before noticeable distortion kicks in? If the TU-8600 is louder at the same volume settings then you are comparing input sensitivity not the output power.
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I bought the V Cap capacitor upgrade from Victor. I don't have anything to compare them with since that's all that I have used. They sound great to me.
I did end up installing Electra Cable Tube Connectors on the amp. I have a thread on AudioCircles that shows the installation.