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Boyuu tube amps


celestial_sound

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^I am far from experienced with tube rolling.  Just sharing what I've learned so far about the A12.  I think you'll enjoy the amp.  The midrange is very nice out of the box.  I think the EH 12AX7's improved the sound, particularly the highs and center image.

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  • 2 months later...
On 10/18/2021 at 2:00 PM, bmoran said:

^I am far from experienced with tube rolling.  Just sharing what I've learned so far about the A12.  I think you'll enjoy the amp.  The midrange is very nice out of the box.  I think the EH 12AX7's improved the sound, particularly the highs and center image.

You guys are where I was at a couple of years ago after I bought my Cornwall Is. I decided to skip dipping my toe in tubes and just went for it with a Jolida Fusion 3502P...which is a great amp, albeit push-pull. That Tubecube7 has me thinking about SET again. 

Here's what I've learned: 

When it comes to 12ax7/ECC83 tubes, NOS is king. SOOOO much better than anything being made today. I hate to say it, bmoran, but those Electro Harmonix just scratch the surface. It's both been an adventure and a curse searching for the best sound. 

When it comes to power tubes, I've found the best sounding current issue tubes are all made by Gold Lion. I've tried everything else, except NOS, which are prohibitively expensive and have a minimal impact on sound compared to your 12AX7s. 

What's worked for me, in MY system, with MY preamp, and MY amp, and MY Cornwalls, in MY room, with MY ears (because all of those come into play when it comes to sound quality), is a set of Gold Lion KT88s with either Tungsram or Matsushita 12AX7s...and I'm still testing to find the best set of 12AT7s in that combo. 

It's wonderful, it's exhausting, it's obsessive, it's rewarding, it's cool, it's amazing, it's a gigantic time suck...but welcome to the world of tube rolling. 

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On 1/4/2022 at 1:10 PM, JohnW said:

It's wonderful, it's exhausting, it's obsessive, it's rewarding, it's cool, it's amazing, it's a gigantic time suck...but welcome to the world of tube rolling. 

 

I did the Skunkie Designs mods to the A12 (see YouTube) and added Miflex 600V coupling caps to the project.  The amp is now a capable SET.  Still putting hours on it, but the improvement is dramatic.  The original design was pretty bad...Might have to look at a set of gold lion 12AX7's or maybe some NOS.  The A12 is competing for center stage with a VTA ST-70 in triode mode, which is superior in all aspects, but the SET A12 has a sweetness that I hope improves over time.

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The Gold Lion 12ax7s are fine, and I'm sure it depends on the amp, but all the NOS 12AX7s I've tried best the GLs. 

Trouble is, you have to buy a bunch just to find the ones you like, then sell the ones you don't. 

But hey, that's TubeLife.

 

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  • 2 weeks later...
On 10/19/2021 at 5:08 AM, Area 51 said:

Thanks for your input, bmoran. I have zero experience with tubes so you're that much ahead of me. I hope you'll continue to post.

Area 51: stick with your 6P1. It's a "balanced single ended" design made famous by AtmaSphere. The Reisong's (A10 or A12) won't improve your sound (had and compared the A10 to the 6P1) and will sound better if you make the following low cost suggestions: (a) get a voltage regulator (about $50); (b) replace the tubes: 6P1P (Russian) for 6P1; 6SN7 for 6H8C; and 5AR4/GZ34 or 5U4GB for 5U4C. 

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On 1/21/2022 at 7:26 AM, epictetus21 said:

Area 51: stick with your 6P1. It's a "balanced single ended" design made famous by AtmaSphere. The Reisong's (A10 or A12) won't improve your sound (had and compared the A10 to the 6P1) and will sound better if you make the following low cost suggestions: (a) get a voltage regulator (about $50); (b) replace the tubes: 6P1P (Russian) for 6P1; 6SN7 for 6H8C; and 5AR4/GZ34 or 5U4GB for 5U4C. 

Thank you epictetus21! I really appreciate your suggestions.

 

I have been looking at voltage regulators. Is the Tripp Lite ($94), which also claims to be a "power conditioner" and has 6 outlets, worth almost  twice as much money as the APC LE1200 Line-R ($57) with 4 outlets? Can I use an extension cord or power strip for more outlets?

 

Due to some unexpected delays I haven't even opened the boxes yet so my own A/B comparisons (6P1 vs. A10, A12, A20, A50 and MT-34) won't begin until next week when I have to decide what to keep. The 6P1 does have one advantage already, though: cost. They're cheap. In fact, I picked up two at bargain prices. So, I'm wondering if they might be used bi-amping. Any thoughts? 

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 On 1/21/2022 at 10:26 AM, epictetus21 said:

Area 51: stick with your 6P1. It's a "balanced single ended" design made famous by AtmaSphere. The Reisong's (A10 or A12) won't improve your sound (had and compared the A10 to the 6P1) and will sound better if you make the following low cost suggestions: (a) get a voltage regulator (about $50); (b) replace the tubes: 6P1P (Russian) for 6P1; 6SN7 for 6H8C; and 5AR4/GZ34 or 5U4GB for 5U4C. 

Thank you epictetus21! I really appreciate your suggestions.

 

I have been looking at voltage regulators. Is the Tripp Lite ($94), which also claims to be a "power conditioner" and has 6 outlets, worth almost  twice as much money as the APC LE1200 Line-R ($57) with 4 outlets? Can I use an extension cord or power strip for more outlets?

 

Due to some unexpected delays I haven't even opened the boxes yet so my own A/B comparisons (6P1 vs. A10, A12, A20, A50 and MT-34) won't begin until next week when I have to decide what to keep. The 6P1 does have one advantage already, though: cost. They're cheap. In fact, I picked up two at bargain prices. So, I'm wondering if they might be used bi-amping. Any thoughts?

 

This is a great post, I am new to tube amps and looking for my first so I am anxious to hear how the tests go, good luck.

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1 hour ago, sbcoffey42 said:

This is a great post, I am new to tube amps and looking for my first so I am anxious to hear how the tests go, good luck.

Yeah, me too, thank you. There are a lot of people here with a lot of good experience. I'm hoping somebody with some electronics knowledge can educate me about voltage regulators.

Like: can I use a power strip to add more outlets?

 

And, the bi amping thing is interesting. I wonder if a pair of my bargain Chinese amplifiers would work well with my high efficiency Klipsch speakers?  

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47 minutes ago, Area 51 said:

Yeah, me too, thank you. There are a lot of people here with a lot of good experience. I'm hoping somebody with some electronics knowledge can educate me about voltage regulators.

Like: can I use a power strip to add more outlets?

 

And, the bi amping thing is interesting. I wonder if a pair of my bargain Chinese amplifiers would work well with my high efficiency Klipsch speakers?  

I would think you could add a power strip as long as you don’t exceed power handling of the regulator. I certainly wouldn’t use an extension cord and power strip on one of those. Just remember you probably don’t use everything at once and most stuff is low wattage anyway. Except for class a amps.

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I have the Reisong A10 EL34 based SET and Boyuurange A50. These have been in and out of my system for about 6 months.

 

The A50 (300B) has had some issues. First of all there is some ripple from the power supply causing audible 60Hz hum. And then there's the usual low level noise. Initially, the left channel would make a fairly loud pop a few seconds after turn-on. Swapping the original input tubes (crap) made the pop sound go away. The bass, for me, I must say is lousy. Some of this is probably due to the speakers I'm using. I don't think they are a good match for this amp, and probably most (all?) 300B SET amps due to the impedance curve which has some low drops at the low end. For a more technical and in-depth possible explanation of this phenomena see https://www.x3mhc.no/dokumenter/SE-v-PP-Part1.pdf  I replaced the original input tubes with mid 1950's Sylvania JAN 6SN7 "chrome dome bad boys". This somehow tamed the lousy bass response to some extent. More recently it seems one of those tubes may be giving me some trouble (see my post "Strange Fae-Out Problem". The 300B tubes themselves seem to require a fairly long burn-in time (several hundred hours). The bass response has been gradually getting better but it "swings" back & forth between "acceptable" (barely) to still fairly lousy. However, it does have *some* of that mid-range magic 300B SET amps are known for - at the expense of hum, noise, soft overhanging puffy loose bass which absolutely requires my use of the tone control to reduce it. A few days later it seems to go back to somewhat OK and then gets funky again. The mid-range, albeit somewhat addictive, is a trade-off, IMO.

The Reisong A10 is more stable. It doesn't have that midrange that makes me want to keep coming back for more, but the bass is not as annoying. However, I'm pretty sure this amp is not really a true SET zero negative feedback amp. I believe it has some ultralinear application of negative feedback. I've also tried 12AX7 (GE) for the input tubes (with adaptors). I didn't really care for the so-called improvement. The 12AX7 are what is used in the Reisong A12. Nice little amp though for $400.

 

For the front-end (source) I'm using a NAD M32 with BluOS in preamp mode, so it is basically performing the role of streamer, player, DAC and preamp/control center. Speakers are Danley SH50 & four Epik Empire subs.

 

My long time reference tube amps are Luxman MB3045 which I don't want to fire up at the moment because they really need a restoration after 45 years and I can't get the parts right now due to supply chain issues. I'll also be comparing the Decware SE84UFO when I get them (on order) at which time I'll also probably get Cary CAD-805.

 

But, for the price, the A50 & A10 are a bargain so don't be afraid to get your feet wet if this picks your curiosity.

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10 minutes ago, artto said:

But, for the price, the A50 & A10 are a bargain

Thanks for your input, artto. It's the bargain aspect of these amps I find appealing as I am forced to feed this new audio addiction on a shoestring budget (I spent all my money buying Klipsch speakers). On paper the A50 looks pretty good. I'm sorry to learn your experience with this amp hasn't been better.

The A10 is interesting even if it's not a "true SET zero negative feedback amp". I have ordered some adaptors so I can try some 12AX7 tubes. I the A12 is the same as the A10 wired for 12AX7 tubes, isn't it? Do you know anything about the A20 or MT-34? The MT-34 is push-pull. The A20 blurb reads: "uses no big loop feedback technology". I don't know how reliable any of these claims may be (the A10 is described as "Single-end Class-A") but there you are; 8w per channel. 

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Area 51, the A50 is basically a design that’s been floating around on the internet for decades. It has known flaws (see all the YouTube mods).

 

I bought some 12AX7 adaptors for the A10. I have some old GE 12AX7 & RCA 7025 that I like in my Audio Research preamp. Quite honestly, I preferred the original 6N2P in the A10. I’ve since also purchased NOS Soviet Voskhod 6N2P-EV Silver Shields but haven’t tried them yet. And yes, the A12 is an A10 wired for 12AX7.

 

I have no experience with the A20 or MT-34. Being push-pull they will probably sound more powerful and are probably a better match for most speakers and people’s preferences.

 

The A20 propaganda “uses no big loop feedback technology” is pretty much meaningless. As usual, it all depends on how it’s implemented. Keep in mind these are all OLD designs. There’s nothing new and ground breaking here.

 

As far as power output claims on these inexpensive Chinese SET amps – take it with a grain of salt. The actual usable power output is probably about ½ or less of what is claimed. OTOH, that translates to -3dB less SPL. Not that big of a deal. More will depend on your speaker’s sensitivity, the size & acoustics of your room, musical preferences, and of course how loud you like it.

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