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DIY power amplifier kit suggestions

Posted: 11 Jun 2019 14:18
by mvno_subscriber
Hi,

I'm looking at moving from pre+active speakers (Benchmark DAC1 HDR + Dynaudio BM12A) to pre+power amplifier+passive speakers.

I'm ok at soldering/repairing electronics (and love doing so!) so I wondered if perhaps a DIY kit for a power amp might be a good idea. It would give me a nice project and, it seems, a very well priced amp.

So far, these are the ones I've looked at:

Amp Camp Amp (solid state)
Akitika GT-102 (solid state)
Elekit TU-8600 (tube)

Of the three mentioned, the TU-8600 seems to have gotten the most praise.. but then again, is it worth it? I should mention I have no experience with tube amps, so that would be totally new to me.

I'm interested in building a high quality amp that should last for some time - so the price tag of the TU-8600 is bearable, should it be as good as they say (and I decide that going tube is ok - especially warmup-time and thus ease of use/availability is of concern).

Any thoughts or experiences are very welcome!

Re: DIY power amplifier kit suggestions

Posted: 11 Jun 2019 14:25
by georgesgiralt
I do not mean to sound rude, but the 300B used in the TU-8600 was obsolete before WWII ... IMHO and for a fraction of the cost, I would buy a current Dynaco kit with the improvements made by the people now selling them.
Time proven design, components easy to get, very good sound and easy to build... There is even an sca35 clone available which is an integrated preamp and amp.

Re: DIY power amplifier kit suggestions

Posted: 11 Jun 2019 14:47
by mvno_subscriber
You're not rude at all. I need input here! And especially for tubes, I have no idea what I should be looking for. Do you have any links to share? :)

Re: DIY power amplifier kit suggestions

Posted: 11 Jun 2019 16:42
by rewfew
If you went with tube or class A power, higher sensitivity loudspeakers are in order of at least 8 ohm. The two solid state amps might do you well. It's nice to do DIY kits, you can get high performance for the price on some kits. Then, you can think about making your own speakers too from many fine designs. My pre and power amps are DIY, and my speakers are home built. All have been working well for many years now.
My tube amps came from this outfit, https://www.transcendentsound.com/products-.html The model I use is no longer available. It has 16 output tubes for each monoblock, and in the 20 or so years of use, I've only replaced one output tube. Not bad for a tube amp, and outstanding for an OTL tube amp. So the products are solid and reliable. I use the grounded grid pre amp that's still in production. It's a stripped down, basic preamp with no frills and it's a giant killer. Built mine from a schematic.

Re: DIY power amplifier kit suggestions

Posted: 11 Jun 2019 17:09
by georgesgiralt

Re: DIY power amplifier kit suggestions

Posted: 11 Jun 2019 17:34
by DualSpinsMyVinyl
You might look at <www.tubes4hifi.com/bob.htm>. Tubes 4 HiFi are offering "Vacuume Tube Audio" retro Dynaco styled kits with improved and updated circuits ranging in power of 35wpc and 60wpc stereo amps, to mono block style power amps featuring 120wats each. I personally have the VTA ST120 amp(60wpc) that I purchased 11 years ago. It went together in about 10-11 hrs and is outstanding in performance. The instructions are similar in style to the original Dynaco/Heathkit instructions that make it easy for anyone. There is a support forum devoted to the original Dynaco kits as well as the new kit offerings <www.dynacotubeaudio.forumotion.com> that offers support to anyone who is having difficulty with their new amp kits and or original Dynaco kits. You will also find several testimonials from previous kit builders on the tubes4hifi site relating their experiences in VTA KIT building. (I have no connection whatsoever with these kits other than that I am a past purchaser/builder of one of their kits).

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 00:36
by bra10n
FYI,

https://www.kickstarter.com/projects/19 ... escription

Not a kit as such but you will need 3 Ways to satisfy your DIY itch.

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 02:25
by theclosetguy
There is a mysticism surrounding the WE 300B. Unlike the response posted above. Its not obsolete. It's just not for everyone. Very Low power. Incredible Sound. Your speakers need to be 90 db to 95db rated. So Horns are the primary choice for those who love these tubes. I'd stick to an el34/6ca7 or a 6550/Kt88 amp. Most are capable of 35 to 60 watts which can drive most speakers to a good volume. Refew mentioned kits with a good amount of tubes. More tubes, more power. The st-70 was 35 watts a side.
The VTL kits are good. Updated Dynaco st-70's. If you buy a chinese kit make sure you get it from a reputable dealer and that it has a warranty. Cheap parts equal quick failure if you use the amp regularly.
Kits are fun. Just take your time and check all cap directions before soldering
Mike M

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 06:44
by georgesgiralt
Well, my late elder brother had a couple of mono blocks based upon 300B, driving Klipsch Aria boxes.
I was very far from impressed. During some time he had the old setup and the 300B setup in parallel (then he sold the old setup). I can't remember the brand of the amps, but clearly, the 300B was definitely not worth a penny IMHO.
Yes, there is unicorn dust on them being so old, but tube design has gone a looong way since the days the 300B has been designed. You milleage may vary ;-) and that's just my 2 ยข worth.

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 13:53
by mvno_subscriber
Thanks for the tips! Any more experience with the actual kits would be most welcome. Also, I'm very much on the fence when it comes to using tube amps. Apparently it means I have to be very picky regarding speakers, and depending on the model a warm up might be mandatory (sometimes I have the time for a warm up, but mostly I would like to play immediately - if a cold amp = poor sound then tubes might be too much a practical hassle for me). Then again, most high end DIY power amp kits seem to be tube based. Or am I missing something?

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 14:13
by Jim Leach
If you don't want to wait for tubes to get hot, solid state is probably for you.

You can go class-A solid state, and warm-up is still a very good idea for best sonics, but it can start amplifying almost immediately. Maybe add a one minute output mute circuit (similar to Counterpoint) and go with that.

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 15:47
by pivot
I would say you need to decide on what speakers you are interested in before locking yourself into an amplifier topology.

The speakers that will work best with a directly heated single ended triode amp based on the 300B may not be the choice for a chip amp gain clone with 50 watts a channel.

All tube amps are "obsolete" by current measures and that should not concern you as a vinyl listener. With the right speakers the 300B brings it's own pluses to the party.

For tubes, have you looked at Bottlehead gear? I have built a couple pieces, not power amps, and the manuals and support forums are first rate.

https://bottlehead.com/

Re: DIY power amplifier kit suggestions

Posted: 12 Jun 2019 16:27
by rewfew
For tubes if you want to explore that end then a preamp based on valves may be a easier way to start. That's what first involved me in tube equipment. You can readily use a tube pre with solid state amps. A really good preamp can bring out the best of any amplifier's topology. Some want great flexibility with remote control selection and volume control. I wanted great sound. I'm not infirmed that I can't get up and change the volume if wanted. Tube amps though have a tendency to need a higher ohm speaker load and sensitivity to get enough volume out of lower available watt production. The exception to this is an upcoming product from the link I provided of a transformer coupled tube amp that can work well into 4 and even 2 ohm loads, (higher current), that many lower sensitivity speakers present to the amplifier. So, if you were still keen on tube amplification, your choice of passive speakers would be increased. I've been a kit builder since the mid 80's. I built a solid state amp that I still use today. The Hafler 220 amplifier. Like I mentioned, you can reap very good price per performance doing a bit of soldering. And a sense of pride you did it you r self. Study up on your choices, you can figure out what you want. Then buy a good solder iron and a good multimeter and go for it.

Re: DIY power amplifier kit suggestions

Posted: 13 Jun 2019 02:44
by aardvarkash10
that's three very different amps.

The Amp Camp is low power output Class A producing prodigious amounts of heat and not a lot of output power. Speakers would need to be efficient(92 - 95dbm), but the mosfets in the amp will tolerate speaker impedance curves that are challenging.

The Akitika is a Class AB and at 50W output moves well into the "robust power" category. Speaker choice widens considerably - 85dbm or better, and any tortuous impedance profile you like.

The Elekit uses tubes in SE format, so needs VERY sensitive speakers (95dbm or better) with VERY flat impedance curves. These speakers don't come cheap and tend to misbehave if you are into EDM, metal or prog or other dense, high volume material. Like Nelson's Amp Camp design, this amp will warm your house effectively while producing, aaaaah, modest outputs of music.

The Nelson design runs at low voltages and has less risk of stopping your heart if you touch something in error. The others escalate from that in order.

The Elkit has the lowest parts count and, once you've got your head around hollow-state electronics, its the simplest design by far.

Make informed choices and then dive in.