• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

APPJ PA0901A anyone?

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After posting my first ever post (first ever thread), I have resorted to getting a least expensive tube amp just to try out, to me, this new region of music reproduction.

I did had a nobsound ms 10d mkii hybrid tube amp which I gave to my brother.

My first thread didn't go well since it people were talking about very techical stuffs and end up me spending hours on wiki to understand which didn't fully address my question. And now the thread got closed by the moderator.

So simply put. A $10000 first watt SS monoblock would sound better than a $200 APPJ pa0901a which sounds better than my $200 ten year old panasonic SA-HE7 av receiver?

I have been reading about tube operation. So I know what's a heater a cathode grid screen plate triode tetrode pentode SET push-pull class A A1A2 AB Ultralinear etc.

I would like to ask if this combo would be the best for me to get a taste of a true valve amp sounds like.

APPJ PA0901A with a pair of power tube EL84 and a 12AX7 small signal driver tube?

And a pair of 4.5 inch or 5.5 inch Fostex full range drivers? I just saw a post mentioned tangband.

I know there are a lot of famous tubes like the e EL34 300B etc. So I hope to find the right least expensive way to try out the best entry level configuration.
 
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Hi

Having recently travelled the path to discovering valves, what I have done is bought a Douk audio EL34 amp kit. I really enjoyed building it and fault finding until it worked. It is surprisingly good. I have bought some alternate valves to see the differences and have played with feedback resistor values to see what happened. I have now bought a messed about second hand KT88 single ended amp that is being modified with switches to try different screen wiring and different feedback values more directly than ripping the thing apart to resolder connections every time.

There is a lot of learning to do but I have Ben really surprised at the nicer quality of vales as opposed to transistors for power amplification.


Avo111
 
The real question here is: do you know what you like when you hear it? Listening to professional or audiophile grade equipment is an art all in its own. To really tell whether gear is worth the time and/or effort and/or purchase price, depends on your intentions. If you intend to show off to people who may not know any better, go ahead and buy whatever looks good. It may or may not sound superlative but it will definitely command a hefty price tag.

OTOH, if you are just getting started, and want to get deeper into both the fidelity and DIY aspects of audio, assembling a personal reference system or two is an essential first step, as well as assembling a collection of listening material. The Panasonic receiver is not a horrible first piece to start with, as long as your source unit has acceptable quality. I believe it will do dolby digital and pro logic, but not dts. Matching it up to a set of speakers with sufficient quality to hear nuance and details in the material will put you in a place where you can begin to train your ears.

The hybrid amp you mentioned is not really much better than a clock radio as far as quality or fidelity goes. Not much (if any) louder, either. You could quite probably build an all-tube amp of better quality for less than the price of a new xbox or playstation. Besides the danger of electric shock, tubes are much more forgiving than solid-state devices for entry-level builds. Especially if you are not well-trained in things like handling static-sensitive devices, soldering techniques, routing of wiring and such. Even better, many tubes share the same pin configuration, so once you have a working circuit, it is a trivial matter to swap out tubes and compare them against each other in the same circuit.

The APPJ amp you question is basically a Miniwatt N3 clone built in China. You could definitely help yourself out and build the same thing for cheaper, or buy something better off someone reputable. It would not be an overly complicated project to attempt. Again, it depends on whether you want a sanitary looking piece to show off or if you are trying to develop skill and experience. This forum is chock full of build guides, tips and tricks, and chronicles of others' quests. There are literally hundreds of simple, decent designs to choose from, and many of the original builders are still here (virtually in person) doing what they do. If you already have a formidable skill set, I would definitely go for something more complicated than a silicon regulated power supply and a 2 stage design.
 
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I have been listening to at receiver for 20 years and I just couldn't fall in love with their sound. It's not that they are bad. It's just that something is missing. I listened to that hybrid amp and it seems more lifelike. But I did listened it in another room with same set of speakers. I have tried listening to FLAC lossless 32bit 192Hz with a very good sound card that able to produce the proper signal to my HE-7 at highest bit rate. I have been moving my speakers back and forth and doing lots of EQ and but it just does not cut it. I need more fidelity into what I hear. I have looked at the Douk audio kit. For $32 USD it's definitely something I can do and it seems easy to assemble. I assume I got the right kit.

Douk Audio EL34 OR KT88 Single Ended Class A Stereo Tube Amplifier KIT DIY 10W 2 | eBay
 
Bchiu, That kit is missing most the bits you need! You have to add on power transformer and 2 output transformers not to mention a chassis or case for the thing. It is also circuit board based which takes away a lot of the flexibility for mods.

This is the kit I bought

Single Ended Class A EL34 5Z3P 110V 220V Tube Audio Amplifier DIY Amp Kit 1set | eBay

Check with seller about shipping rates these seem to change from time to time. Once you get into this there is no end to the possible fiddling. Apart from trying different tubes it is easy to modify feedback and also play with screen connections to change modes from triode to pentode for example. The more you do the more you learn!
 
I hear what you're saying. I grew up listening to both SS and tube-based systems. I can tell you this: many SS amplifiers are designed and "doctored up" to emulate the sound of very basic tube-based circuits. Very few tube-based circuits are modified to sound like SS amplifiers. While a whole lot of SS units test better in a lab environment than comparable tube amps, they have a sterility to them due to this flawless reproduction. This difference is noticeable to the critical listener. What is good to a distortion analyzer may not translate to your ears and brain so directly. This is the difference between absolute fidelity of SS devices and the deviance from it that tubes "color the signal".

The kit you cited is a skeleton to be filled in with your choice of major "organs and skin". It basically consists of the pc board, tube sockets, and lots of the cheapest parts in the world that mount to the board. You would need to find all of the iron and glass, as well as a chassis, connectors, and hardware to make it whole. Even if you go with the iron pictured in the listing and some cheap chinese glass, They will be more expensive than the "kit". Expect to spend another 200 dollars or more on iron and glass alone. If you want 20 - 20K bandwidth, expect to pay dearly for sufficient iron.

Here's a whole kit you won't have to go fish for any parts:
tu-8200-parts.jpg

DIY Audio Projects - Hi-Fi Blog for DIY Audiophiles: Elekit TU-8200 Tube Amplifier Kit (SE 6L6)
Only $700

An almost equivalent chinese ebay kit:
$(KGrHqR,!i4F!MKS5EPqBQGS04N0eg~~60_57.JPG

6L6 SE 12AX7 AND 6L6 Valve Tube Amplifier Complete DIY KIT Stereo | eBay
Only $400 plus chassis and jacks. What you see is what you get.

Most ebay sellers will offer a finished product of their kits for maybe $50 extra or less.

A pic of the kit mentioned in the post before this, assembled:
s-l1600.jpg

Only $330 shipped

Main difference is in the engineering and quality of parts in the kit.

While we are on the ebay subject, it is an immensely huge source for dirt cheap project chassis like you are after. People rip organs and vintage radios down and sell the parts every day. Here's a good example:

$_57.JPG

Conn Stereo Amplifier Vintage Stereo HI FI 12V6 12BH7 12AX7 Tubes | eBay
Currently about $60 shipped, 3 days left on auction.

Chances are good that this thing will sell for the cost of a couple of new 6L6 tubes and one transformer. It came out of a WW2-era stereo organ with tremolo. Maybe it would plug in and work, but if not, it would take less time to get it to make noise than building a scratch kit. Extra money to buy silver caps and a variety of tubes to roll through it. Then some more for a case build.
 
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I built the Elekit TU-8200 several years ago..it is the best kit you could ever imagine...if you can solder you can build this great kit...components are super and Victor can provide upgrades. I have had so much fun playing my Elekit 8200 with a full variety of power tubes.6l6gc, Kt77(my favorite), KT88, EL34, KT66, etc. I have since built the Elekit 8500 preamp, my system sounds so great, my vinyl from back in the 70's sounds so good...Don't hesitate to get in touch and I will give you details on the build...
 
Hi bchiu2000, I'd been in your shoes but somewhat in more radical way: if someone told me 25 years ago that one! day! I will be listening all! on tubes only! I laughed at "that idiot" enormously ))

Eventually, not long ago, I decided to give it a try with similar to APPJ - Miniwatt 6J1 / 6P1 3W+3W. Cant say I'd been blown away with, of course, its luck of power, but the speakers were sensitive enough to make the impression. The whole thing sounded darn well and my GAS started spinning. (GAS - gear acquisition syndrome)

I sold it and purchased an awesome branded bigger one, quite modded it (a little not finalized yet), but... something is itching in me about building one of my own.

I advise you not to hurry. Without great deal of practical experience with tubes and understanding how it all works it will be a pain to build one from scratch. Just buy that APPJ, and while enjoying it you start gathering the knowledge and, more importantly, the ideas on what you want it to be.

Though, assembling one of those kits would be some fun too. For the EL34's sake, why not have two? ))

PP. If you are in my area we could meet sometime.
 
Thanks all u guys for the valuable inputs and the links to awesome kits. The Douk kit is pretty good but the shipping really kills the value to it. The elekit would definitely not be my first build since it's a $700 kit and I don't know if I can get it done without blowing up anything lol.

I was wondering is there any tutorials and instructions on this site teach me how to build something like a APPJ/ miniwatt. Cuz I do have a local electronic store I can go to to grab parts and avoid paying hefty shipping fees for the kits. I have been building phototype cell phone at my last job mainly soldering smds and 30 pins smd ICs. So I guess I can do a little soldering.

Man cave, your Alpair 7 is at 86spl. Isn't not sensitivity enuf for valve amps?

Hey Shef, I live in Richmond! Definitely I can come over to your place for a visit someday!
 
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Thanks all u guys for the valuable inputs and the links to awesome kits. The Douk kit is pretty good but the shipping really kills the value to it. The elekit would definitely not be my first build since it's a $700 kit and I don't know if I can get it done without blowing up anything lol.

I was wondering is there any tutorials and instructions on this site teach me how to build something like a APPJ/ miniwatt. Cuz I do have a local electronic store I can go to to grab parts and avoid paying hefty shipping fees for the kits. I have been building phototype cell phone at my last job mainly soldering smds and 30 pins smd ICs. So I guess I can do a little soldering.

Man cave, your Alpair 7 is at 86spl. Isn't not sensitivity enuf for valve amps?

Hey Shef, I live in Richmond! Definitely I can come over to your place for a visit someday!

Yes, the MarkAudio CHN-70 is rated at about 86.6db, the Elekit 8200 is rated at about 8watts/channel with 6l6gc in pentode mode (less in Ultralinear and Triode). Plenty of power to run the CHN-70 to very loud levels. I have some Fostex FE206en drivers in the double bass reflex cabinets which are much more efficient and really sound good too. I think that the Elekit 8200 is a real bargain at ~$700 when you compare to similar quality kits. I didn't find it difficult to build as the instructions are very detailed and complete. It was a really fun build and fired up on the first try. Victor Kung provides outstanding customer service and is always available to provide support. I added the little USB DAC and matching Elekit 8500 preamp which has given me a really outstanding/versatile low cost tube system. Good luck with your project whatever you decide to build!
 
I have one of mine in an enclosure that you can buy directly from the manufacturer, I like it. Search the site and you can get some good ideas about home made enclosures. Some DIY's have made some really interesting ones.
Not sure why the design doesn't have separate preamp tubes, maybe one of the circuit design gurus can answer that one.
 
Usually the preamp will have things like source selection, eq, volume control, etc. built into it. The separate power amp will just have gain controls to match the amp output to the preamp signal. This configuration allows you much more flexibility to change some parts of your rig without having to change others.

To answer the sensitivity question, it all depends on the finished rig. You can either go with a more sensitive speaker and a less powerful amp, or a less sensitive speaker and a more powerful amp, to achieve the same sound pressure level. For every 3dB of extra speaker sensitivity, the amp power halves, and vice versa. In your case, a few extra dB of speaker sensitivity could allow you to get the volume you want without having to run a push-pull power amp.

Rolling tubes is a super subjective endeavor. Besides the fact that no two tubes are exactly the same, the more common audio tubes have been in production for 50 years or longer. This is in addition to the less-subtle differences in characteristics between manufacturers of the same basic model number. The retail industry picked up on these factors long ago, and started using vague terms like shiny, glassy, fizzy, chimey, creamy, dark, etc. to market their brands. Just because a particular tube carries a heavenly price tag doesn't mean it will drop into your rig and sound awesome.

None of the concepts discussed in this post translate to cheap, fast or simple. If you wanted that, there are plenty of pieces at best buy that satisfy those specs.
 
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That ebay chassis ends tonight, and has topped out at 36 bucks plus shipping. Doing a little googling says this thing came out of a 1959 Conn Caprice 426M. Schematics available online if you hunt. Stereo 12AX7 / PP 12V6 channels with input gain controls, plus a couple extra tubes for a tremolo circuit. Not a bad chassis to start off with, super common socket pinouts make for tube rolling heaven. Good platform for a vintage rat rod. If something smokes and you give up on it, list the thing on ebay and someone will buy it for what you paid. Very little financial risk, big bang for the buck if you can bring the thing to life.

Buying new, I believe in general you get what you pay for. Doing a little research (or more) helps to narrow the many choices. An inexpensive integrated preamp/power amp is going to be harder to find than separate components. If you can't afford something like the Elekit, the Nobsound / Douk units cited previously come premade for half that price, and come with big volume knobs and peg meters and such. Going this route, I would rather get a pre-tested unit, as problem solving one of these rigs is going to be supported by people like us. The manufacturer is pretty much done with you once the unit arrives in working condition.
 
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