[NiToNi]

I thought it could be interesting for a lot of people that want to get their feet wet with classic SET DHT NFB amps on a budget (say max. $1K), including myself, to try to narrow down those 300B amplifiers (8W) available online (eBay, Aliexpress, DH Gate, DealExtreme etc) that seem they could hold a lot of potential based on specs (circuit, transformers, tubes, components etc) and visual build quality (inner and outer) alone. Then by narrowing down the selection using an objective engineering hat, members may be encouraged to try out the various alternatives, at which point we could also benefit from subjective feedback.

Perhaps it's a stupid idea, but let me kick off with a few links to amps that seem to represent what's available at this price point, in this case from Aliexpress and eBay:

Douk/Lingyun 300B

Yaqin MS-300B

Music Hall 300B

Shugang SG-300B

Raphaelite CS30

Raphaelite CSK30

Rivals 300B Classic Wood

Rivals ALU-300B-SP

Rivals 300B

Rivals Luxury-ALU300B

Paiyon 300B

Meixing Mingda MC300-A

Aiqin Psvane 300B

Raphaelite Sinovt 45    (45 not 300B but still )

I'd be very interested to hear some opinions from those who know their 300B's which of those amps above that deserve or DO NOT deserve further consideration.

[sonicboom]

Then by narrowing down the selection using an objective engineering hat, members may be encouraged to try out the various alternatives, at which point we could also benefit from subjective feedback.

Perhaps it's a stupid idea, but let me kick off with a few links to amps that seem to represent what's available at this price point, in this case from Aliexpress and eBay:

While I wouldn't be so harsh as to call this proposal stupid, I don't see the point. All these no-name Chinese companies are in it to make a quick buck and nothing more. There are many instances found on the net, were knowledgeable and experienced DIY'ers had to modify amps (such as Music Angel, Yaqin etc) to correct circuit design deficiencies.That's not to say anything about the quality of the passive parts used, that according to many SET-heads, are of prime importance in these simple circuits. How about the most important part of the SET, the output transformer? I'm sure that the Chinese "winders" are very knowledgeable in the art of transformer design as well as very meticulous in their winding operations.

Of course there are the exceptions where Chinese companies can and do manufacture good quality products such as Allnic, Consonance, Antique etc. You do however pay for what you get and the products from these better Chinese companies aren't cheap.

All this to say, that if you're willing to spend up to $1K for a DHT amp, why not ask around and try to find and commission an experienced person to build you a very nice SET of a known and well regarded design, with components including OPT's that you may specify. I'm almost certain that the end result will be way better than any of the amps you listed above.

[Bemopti123]

Be very leery.  I also second all the anecdotes of people purchasing these sort of amps and encountering tons of problems with them.  You are better of purchasing second hand amps from proven designers rather than risk the aggravation of spending your hard earned 1000 $ on a product that may look good on paper but will bring you aggravation in the end.  At the very least, buy something from a brick and mortar internet store that you can talk to in case that things go South. 

[raindance]

I tried the Shuguang. It is quite heavy and looks well built. However the volume knob was held on by insufficient friction and tended to fall off.

Sound quality: I just didn't find it "special". Once I opened it up and looked inside, I realized why - it uses global negative feedback. I tried disconnecting it and the amp became dull sounding with overblown bass. I put this down to cheap output transformers and moved on.

The el-cheapo 6P3P kit I built recently actually sounds better after a few tweaks...

The Meixing Mingda stuff seems to use quality parts, but they need extensive work as the circuitry is copied from old gear that has far too much gain.

[NiToNi]

Thanks for sharing your experiences, raindance - very interesting indeed.

Yes the problem is knowing if there are any diamonds at all out there in what seems like a pretty vast rough.

[FullRangeMan]

There is the Nirvana at $1550:
http://www.commonsenseaudio.com/nirvanaamps.html

[raindance]

Thanks for sharing your experiences, raindance - very interesting indeed.

Yes the problem is knowing if there are any diamonds at all out there in what seems like a pretty vast rough.

I guess the moral of my story is that you'd probably be able to get a decent single ended pentode amp for the money,  but not 300b. Why not build something? I find SEP using EL34 to be quite nice.

[FullRangeMan]

There is the Decware ZenTriode EL84 2W Stereo for $1K or the Rachel SE-EL34 6W Stereo at around $1300.
Much better than Sino amps.

[raindance]

Here are some cheap amps I have tried, mostly not single ended, but you may find it interesting:

1. Yarland fv 34 CIII - this is an EL84-based PP amp that sounds better than it has a right to. The output power is around 5 or 6 watts per channel despite what the manufacturer says. Not much bass, but decent mids and sweet highs. It is sold under many different names. Cheap as dirt. Watch out for safety - they didn't always connect the earth.

2. Yarland fv 34 BIII - this is an EL34 based PP amp that is an utter disaster. Absolute rubbish. Watch out for safety - they didn't always connect the earth. But it sucks so bad I wouldn't even buy it as a modder.

3. Jolida JD102B - Lovely example of an EL84 UL PP amp. About 15 watts per side. Great out of the box. You can mellow it out a teeny bit by clipping off a power supply bypass cap.

4. Shuguang S300i - 300B single ended with global feedback - doesn't really sound like a 300B amp, but if you get one cheap, might be fun to try it 

5. 6P3P kit from doukmall on ebay - not good out of the box, but a few tweaks and some EL34's and it is pretty OK. You can upgrade this thing all day long with better transformers, etc. The way I have it wired now I get only 4-5 watts per side, but I use it many hours each day in my office with a pair of big Athena speakers.

6. Meixing/Mingda MC-34-A - too much gain; I did modify the heater arrangement to run 12AX7's in place of the 6N2's and it sounded quite nice, but a bit treble-heavy indicating possible oscillation. I didn't have a scope at the time to verify. They had stupid tube cages that caused them to overheat, fortunately they were removable.

7. Cayin TA30 - if you can find an unmodded one, this is the amp that Primaluna now uses as a basis for some of their product line. It is manual bias - a fantastic amp. Very extended top end, tight bass, great mids. Unfortunately people "modded" these and ruined them. They were the best built hand-wired amps I have ever seen. I've heard a bigger Cayin and it didn't have the same magic.

If you want to go SET, you should really consider building. The transformers (expensive) and circuit topology are key to success. I'd build a SEP first to get the idea and some practice, then try an SET.

[FullRangeMan]

Sino amps usually dont have soft start or separated switches for Heating and HV, even MingDa big triodes 211/845/805.
So tubes last few hours.

[raindance]

Sino amps usually dont have soft start or separated switches for Heating and HV, even MingDa big triodes 211/845/805.
So tubes last few hours.

It amazes me how this feature is left out. An NTC thermistor on the output of the B+ rectifier costs very little and works quite well. I've seen a well known amp designer in the USA who placed an NTC on the mains input. Completely pointless. It's not only the Chinese who don't understand this stuff 

[FullRangeMan]

How much seconds it delay?

[raindance]

You have to look at the specs - they have a time constant that is dependant on circuit parameters. They work great for class A amps due to the constant current nature of said amps. They introduce a small voltage loss but it is negligible.

[FullRangeMan]

Hmm, my mains wall is 220V.

[raindance]

I'm talking about B+, not mains. Are you in the UK?

[FullRangeMan]

OK, I undestand you. Iam in Brazil.
I would add B+ and grid.