I am not a vacuum tube guy. I never build any vacuum tube audio system, either it is a pre-amplifier, buffer stage, a vacuum tube output DAC, or anything related to vacuum tube from ground up.
You might already know this if you following my blog for quite some time. The Bottlehead Crack is the only vacuum tube amplifier that bought in the used condition. Then I just upgrading it. The others vacuum tube amplifier is a hybrid with an op-amp and operate in low voltage. Yes I made it but it doesn't count as a pure vacuum tube amplifier I guess.
I am not hate it, but instead I loved how the vacuum tube sound. It is very musical, detail with lots of energy and dynamic. The vocal from vacuum tube amplifier are sweet and more bodied. It feels like you are covered with the soul of the music played. Unlike the solid-state that some times feels cold and edgy, but I still doesn't want to swim it deeper to this vacuum tube world. I know my limitation when building an audio gear, it must be great and using the best possible components available. So I love at this point where my audio system run from the more affordable solid-state components instead the vacuum tube. I hope it is a good excuse for me:)
So if I want a vacuum tube amplifier for driving my speakers, I prefer to bought it. Like today post, this is a review of others built vacuum tube amplifier. This amplifier is in second hand condition and the cost is about US$200! So let's take a look.
The package arrived at my house which in a very large and heavy wooden box. I think it is more than 20 kilos. I am not sure what condition when I bought this amplifier, I also don't know how it sound because I cannot test it directly. The price is very okay, cheap in my opinion and I am pretty sure I cannot build the amplifier like this with the same amount money I bought.
The finishing of this amplifier in my opinion is very good. Although I found many scratch on the side wooden panel and the steel top panel, but it is all common for used amplifier like this.
The vacuum tubes are safely stored on different box. They are secured individually and all in good shape.
The power tube is China made KT88 and I am not complaining at all since the price for this amplifier is unbelievable cheap.
There is also a tube rectifier using 5U4, then 2 piece medium size 6H8C and the small 2 piece of 6DJ8.
But before I powering ON this amplifier, I better check what inside this amplifier first.
Once I open the bottom plate of this amplifier, I just glad I didn't power it ON yet.
Gosh!
This is the most ugliest point-to-point connection and it is dangerous! I give you a tour to take a look what I mean by saying this ugly.
First, this small cable is breaks. It should go to the capacitors next to it. This might be the signal cable from the anode to the coupling capacitors and it is a high voltage since the cable is taken from the positive high voltage. Why it cannot soldered correctly?
Second, why using series capacitors for signal? This might worsen the sound quality compares to using single capacitors with the same value in total.
Third, the glue are everywhere.
Another cold joint solder found when I inspecting the amplifier connection is on the power capacitor. Again it is scary if short-circuit to the ground and it is dangerous.
The glue are messy and many components wire are short already then extended with additional wire. Those components are all in used condition when use in this amplifier. Theoretically the used components shouldn't reuse to any new project except for testing only.
This inspection turn become a small repair. I should remove few components, then tidy up the cables connection a little bit and correct many solder joints.
Another sight of ugliness is this unused grounding cable. What the builder think when he or she let the cable like this lying around inside a working unit. I am speechless.
Luckily this amplifier goes to me. I can repair it easy.
After all the repair I made, I am confident that this amplifier is safe enough to operate, then I can put all the vacuum tubes into the sockets and this amplifier is ready to test in my home audio system.
Surprisingly it sound amazing:)
I love how detail and large sound stage from this amplifier.
The vocal is warm, although for some music, it feels a little bit thin, but it is still okay.
The treble are open and smooth. It is also very extended, creating the additional high frequency micro details. This what I cannot hear in most solid-state amplifier.
The only matters is the bass are still lacking the punch and cannot going deep enough.
For sure, I like this vacuum tube amplifier at the first time I listen the music from it.
While at the first time I am quite disappointed with the internals components, but when I listen from this amplifier, I really like it.
This vacuum tube amplifier is hot like oven. I test it for an hours then I turn the power OFF. This is because I still unsure about the internal safety yet.
I will make another post about tidy up this whole amplifier and upgrading the components. I will also share the schematic of this amplifier which in my opinion is unique and I am sure there is a story behind this build that I can capture when I draw all the lines.
Disclaimer: Any statement and photos in this article are not allowed to copy or publish without written permission from the writer. Any injury or loss from following tips in this article is not under writer responsibility.
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