Take the blind challenge! 300B SET vs. Straight Wire with Gain

[solderdude]

You can get very powerful bass with tube amplifiers if you pay attention to the load impedance where bass energy is made. It is nice to get away from that particular dependency though!

WRT your last comment: Yikes! If the SET was really that bad (rolled off in the audio band with a resistive load), I would regard it as a poor choice for this sort of comparison as its not typical of SETs, unless of the cheap variety that can be had for a few hundred dollars. Most of the SETs I get exposed to (mostly at audio shows) cost 4 figures at a minimum.

Yep, OTL should be linear over a very wide FR with a resistive load.
Most 'regular' tube amps usually have transformers in there limiting the FR, sometimes rolling off just within the audible band is what I was hinting to.
20kHz -4dB is kind of extreme even for Tx outputs, maybe done on purpose ? maybe the input transformers used are not loaded properly ? .. who knows why it measures the way it did.

 

[computer-audiophile]

maybe the input transformers used are not loaded properly ?

In fact, it's this signal transformer that I don't like at this point.

 

[atmasphere]

Yep, OTL should be linear over a very wide FR with a resistive load.
Most 'regular' tube amps usually have transformers in there limiting the FR, sometimes rolling off just within the audible band is what I was hinting to.
20kHz -4dB is kind of extreme even for Tx outputs, maybe done on purpose ? maybe the input transformers used are not loaded properly ? .. who knows why it measures the way it did.

I don't know of a tube amp that rolls off in the audio passband but I've no doubt they are out there.

This particular amplifier is so inexpensive that I could only imagine it made where labor isn't properly paid for. When I did a search on ebay, sure enough, they are made in China. I'm doubting very much that quality magnetics were used. Loading of the input transformer would be critical for performance. 6SJ7 (pentode) voltage amplifier tubes?? Yuck!! No self-respecting SET user would allow such a thing in an SET; I have to imagine the distortion and bandwidth would both be poor. Small signal pentodes tend to have very high output impedances so getting bandwidth out of them is really hard.

SETs don't measure that well, but usually they don't measure this badly either. IMO its a poor choice for doing a comparison like the focus of this thread.

 

[solderdude]

I don't know of a tube amp that rolls off in the audio passband but I've no doubt they are out there.

Of course there are also plenty of tube amps around that start to drop off above the 'audible range' and even ones, even with OP transformers that may even still work fine at 50kHz or higher.

 

[computer-audiophile]

I'm doubting very much that quality magnetics were used.

If you approach things with such scepticism, you won't come to any new conclusions. I sometimes simply try out such things and know a few experienced colleagues who do the same. I have a lively exchange with them. That's how I got to know this Raphaelite superficially. We do this simply because we want to try something new and are curious about the newcomers from China. Something is happening there. We know enough about the old manufacturers because we've been dealing with this topic for a long time. That's less interesting, I think.

 

[atmasphere]

Of course there are also plenty of tube amps around that start to drop off above the 'audible range' and even ones, even with OP transformers that may even still work fine at 50kHz or higher.

-And now I do... (nor does that surprise me about the Carver after the debacle around that mess), although .8dB down at 20KHz isn't likely to be heard. Not so at the other end of the band though, especially if your speakers are good down that low.

If you approach things with such scepticism, you won't come to any new conclusions. I sometimes simply try out such things and know a few experienced colleagues who do the same. I have a lively exchange with them. That's how I got to know this Raphaelite superficially. We do this simply because we want to try something new and are curious about the newcomers from China. Something is happening there. We know enough about the old manufacturers because we've been dealing with this topic for a long time. That's less interesting, I think.

If you want to hear what a good SET is about, I can point you to better examples. But they cost more.

I've been dealing with the 'newcomers' for a while. A local guitar amp company wanted us to do assembly for his product (a good-quality Marshall Plexi copy, made using Heyboer magnetics). But he was being challenged by other product entries that were built in China or made using Chinese parts. So he had us look at some parts he had collected for possible use in the amp. One of them was a 47uf 450V filter capacitor. Funny thing about that part- it had two insulated ends, where normally an axial lead electrolytic will have one insulated end and the other end the lead is welded to the body. So we cut the part open and lo and behold- inside was a 27uf 400V part!

You can get good things out of China like any country but you have to be careful. So I have skepticism based on experience. Any time I see stuff from China, it has to win me over.

 

[GXAlan]

This particular amplifier is so inexpensive that I could only imagine it made where labor isn't properly paid for. When I did a search on ebay, sure enough, they are made in China.

+1.

This is key. My hope was that the tubes would account for the biggest impact to the sound, which is why I chose to spend the money on US made tubes, where not only is labor properly paid for, but safety and environmental standards apply.

If you look at the review, you can see that the unit was dented even though the packaging was pretty reasonable and the unit shipped with tubes. I got the replacement transformer cover and the experience has me convinced that there is at least a 50% chance that the dent was done during assembly and the qa/qc was skipped, or as you point out, the labor involved opted to ignore it.

Based upon my email conversations with the retailer, I mentioned that I thought the RCA jacks needed to be removed in order to replace the cover and I was reassured that it wasn't the case. The vendor believed that there was just one PCB that needed to be removed.

The reality is that not only did I have to remove the RCAs, I also had to remove the IEC plugs. The big issue is that the design of the transformer cover is that it was 10 screws and the chassis itself fundamentally prevents you from screwing things in co-linearly in 6 of the 10 screws. That is, "line of sight" to the screw is impaired and you can only screw things a bit crooked. I'm not a novice with a screwdriver, and it's pretty clear that during assembly the screws are likely to be gently stripped. The original transfomer cover has some dynamat equivalent placed on it which the replacement doesn't. The replacement doesn't have the sticker either.

If the transformer cover was dented during original assembly, it is such a pain to replace the transformer cover that I can see that being skipped by the assembler.

Under the hood, I was able to identify the output transformers. The Raphaelite model is quoted as 5 Hz~60 kHz -1dB which makes me wonder if those 1:4.5K input transformers may be the culprit for the roll-off since those have no specifications.

Looking at "alibaba", those 1:4.5K input transformers are $160/pair. The output transformers are $300/pair. The power transformer is $135.
Then, looking at the tubes, probably $300. That's already $900 of the cost. Add the chassis and PCB costs and it gets pretty clear on the labor part. They also paid the German design firm to make it look pretty.

The unit measures worse than I would have expected. The unit also sounds better than I would have expected.

 

[computer-audiophile]

You can get good things out of China like any country but you have to be careful.

Good point.

 

[GXAlan]

Poll closes in a few hours. Files to be deleted and results revealed soon! Last chance if you were on the fence!

 

[JSmith]

I quickly went through the original files in the OP a few weeks back (when I voted) and did a comparison on a simple laptop with cheap earbuds... didn't get much time since to really analyse the audio files on better equipment or listen to the further matched files supplied by other members.

Still, since this is just for fun, these were my initial "results";

I didn't answer the bottom 3 questions, as I felt I heard a small difference between the two files.

I don't think some of the chosen soundbites lend well to this type of comparison either, i.e. quite distorted electric guitars etc.


JSmith

 

[GXAlan]

I don't think anyone else is going to vote in the next 27 minutes, so using this data:

Answer Key

Spoiler

1 vs 3
1 = Topping D90
3 = Raphaelite CS30-MkII

2 vs 5
2 = Raphaelite CS30-MkII
5 = Topping D90

4 vs 6
4 = Topping D90
6 = Raphaelite CS30-MkII

Commentary:
1) A group of audio enthusiasts at ASR was unable to detect the difference between the absolute worst amp ever tested here at 22 dB 5W SINAD amp and a theoretical straight-wire-with-gain. When you disagree [on the internet] with someone about the way things sound or criticize tube amplifiers about distortion factories, it's nice to keep this in mind. If this group of audio enthusiasts found it hard to hear the difference between the absolute worst amplifier ever measured here, you can imagine how hard it would be for an "ordinary" person to hear the difference.

Even if we are statistically underpowered, this also means that the "Effect Size" is small. The 300B is clearly not a distortion factory to everyone's ears even though it's a distortion factory to measurements.

2) Individual listeners who shared their votes while blinded were able to identify the same machine each time. In this case, doing statistics on repeated tests would show that the person was able to identify the correct amplifier. In an ABX test, or this case, a blinded A/B test, someone could take the test several times, choose the same vote, and show that they preferred an amplifier with statistical significance.

This is not a contradiction to #1. Not everyone will hear the same way you hear... individually, you may have a strong, reliable preference for a sound. #1 says that your opinion isn't shared by everyone.

@Axo1989 perfectly picked out the straight wire with gain
@JSmith perfectly picked out the 300B SET (using laptop and ear buds)

3) When comparing votes, the overall trend was in favor of the straight wire with gain. This supports the fundamental thesis of ASR. Choosing products that measure well is a safe/prudent choice, especially in a world where products that measure well can be found from manufacturers across the globe. For most people/most music, you'll be happy.

4) For the "jazz" track, 9 had no preference. This is a 26% margin for the 35 people who did express a preference. The straight wire with gain was preferred by 63%. This means that a solid 37% of listeners preferred the 300B tube in blind testing.

This "win" for the straight wire with gain over the worst amplifier tested here to date is smaller than the difference between the JBL M2 vs Revel Salon shootout, two very high performance speakers

Shootout between JBL M2 and Revel Salon 2

A blind listening test was organized and reported on AVS Forum. It ran this weekend and here are the results: http://www.avsforum.com/forum/89-speakers/2907816-speaker-shootout-two-most-accurate-well-reviewed-speakers-ever-made-12.html#post54628832 There are the details of tracks on the...

www.audiosciencereview.com

Imagine comparing the absolute worst speaker ever measured against the very best and having such a low margin for the win...

Take Home Points
If you are buying one system for the first time, go for audible transparency. It's a safe, popular choice and achieving audible transparency is not expensive.

When comparing a 22 dB SINAD amp and a straight wire with gain, this group didn't prefer the straight wire with gain with statistical significance. Therefore, if you have an existing audio product that you are mostly happy with, but it is not longer state-of-the-art in measurements, be careful before chasing after the next upgrade. As a group, we cannot even tell the difference between the worst amplifier ever measured here and a theoretical perfect one. INDIVIDUALLY, it may be possible.

Be kind to others who disagree with you about their audio preferences. For the jazz sample, among those who had a preference between the two, 37% of *this* group of listeners preferred the non-transparent audio source. The people responding to this survery have self-selected toward some degree of objectivism and audio science. You could imagine that in a forum of tube amp fanatics, the preference would swing in that direction.

The real differences between a tube amplifier and solid state amplifier in a system can be greater than the differences seen here (as measured by a resistor). The level dependent treble boost, which could correlate to the common description of "sweet treble" could swing your preference differently. Hopefully this experiment encourages to *try* out speakers with narrow rather than wide dispersion, tube amps or negative feedback amps rather than solid state amps...


Call to Action
I did my part. Who's next in setting up the next blind listening challenge for the readers?

 

[solderdude]

A: Picked the wire (Topping D90 out) as better sounding, based on 'smoother' sound so the amp (in this particular test) was simply reduced in SQ..
B: Picked the wire as best sounding based on knowing there is sibilance in the recording and should thus not be lowered. The treble roll-off was the most audible in this file.
C: Picked the wire as best sounding as it sounded 'smoother' (less gritty, so the amp added non-pleasant distortion).

 

[Sokel]

So I like 2/3 clean and 1/3 magic.
Sounds like me

 

[GXAlan]

So I like 2/3 clean and 1/3 magic.
Sounds like me

That is actually me too. Although I preferred the “magic” on the vocal track. . Which did you prefer the magic on?

 

[Sokel]

That is actually me too. Although I preferred the “magic” on the vocal track. . Which did you prefer the magic on?

The "1",I choose "3".
(I was the first to reply to your thread with my preference)

 

[JiiPee]

Desperately looking for an excuse... Got to maintain my street cred.... Think...Think... What are the perennial favorites... Yes - That's it!

The headphones I used were not revealing enough!

 

[Sokel]

Desperately looking for an excuse... Got to maintain my street cred.... Think...Think... What are the perennial favorites... Yes - That's it!

The headphones I used were not revealing enough!

I hear that the tar and feathers are already been prepared for the ones who choose any of the "wrongs"

*logs out*

 

[Keith_W]

So for full disclosure, this is how I voted:

1 vs 3: I picked the 300B SET.
2 vs 5: I picked "no difference".
4 vs 6: I picked the Topping.

So I guess your conclusion that "audio enthusiasts are unable to tell the difference" refers to me!

 

[Axo1989]

Desperately looking for an excuse... Got to maintain my street cred.... Think...Think... What are the perennial favorites... Yes - That's it!

The headphones I used were not revealing enough!

You jest, but I used two different headphones which were revealing ... of different things.

 

[Axo1989]

I don't think anyone else is going to vote in the next 27 minutes, so using this data:

View attachment 283429

Answer Key

Spoiler

1 vs 3
1 = Topping D90
3 = Raphaelite CS30-MkII
View attachment 283415

2 vs 5
2 = Raphaelite CS30-MkII
5 = Topping D90
View attachment 283414

4 vs 6
4 = Topping D90
6 = Raphaelite CS30-MkII
View attachment 283412

Commentary:
1) A group of audio enthusiasts at ASR was unable to detect the difference between the absolute worst amp ever tested here at 22 dB 5W SINAD amp and a theoretical straight-wire-with-gain. When you disagree [on the internet] with someone about the way things sound or criticize tube amplifiers about distortion factories, it's nice to keep this in mind. If this group of audio enthusiasts found it hard to hear the difference between the absolute worst amplifier ever measured here, you can imagine how hard it would be for an "ordinary" person to hear the difference.

Even if we are statistically underpowered, this also means that the "Effect Size" is small. The 300B is clearly not a distortion factory to everyone's ears even though it's a distortion factory to measurements.

2) Individual listeners who shared their votes while blinded were able to identify the same machine each time. In this case, doing statistics on repeated tests would show that the person was able to identify the correct amplifier. In an ABX test, or this case, a blinded A/B test, someone could take the test several times, choose the same vote, and show that they preferred an amplifier with statistical significance.

This is not a contradiction to #1. Not everyone will hear the same way you hear... individually, you may have a strong, reliable preference for a sound. #1 says that your opinion isn't shared by everyone.

@Axo1989 perfectly picked out the straight wire with gain
@JSmith perfectly picked out the 300B SET (using laptop and ear buds)

3) When comparing votes, the overall trend was in favor of the straight wire with gain. This supports the fundamental thesis of ASR. Choosing products that measure well is a safe/prudent choice, especially in a world where products that measure well can be found from manufacturers across the globe. For most people/most music, you'll be happy.

4) For the "jazz" track, 9 had no preference. This is a 26% margin for the 35 people who did express a preference. The straight wire with gain was preferred by 63%. This means that a solid 37% of listeners preferred the 300B tube in blind testing.

This "win" for the straight wire with gain over the worst amplifier tested here to date is smaller than the difference between the JBL M2 vs Revel Salon shootout, two very high performance speakers

Shootout between JBL M2 and Revel Salon 2

A blind listening test was organized and reported on AVS Forum. It ran this weekend and here are the results: http://www.avsforum.com/forum/89-speakers/2907816-speaker-shootout-two-most-accurate-well-reviewed-speakers-ever-made-12.html#post54628832 There are the details of tracks on the...

www.audiosciencereview.com

Imagine comparing the absolute worst speaker ever measured against the very best and having such a low margin for the win...

Take Home Points
If you are buying one system for the first time, go for audible transparency. It's a safe, popular choice and achieving audible transparency is not expensive.

When comparing a 22 dB SINAD amp and a straight wire with gain, this group didn't prefer the straight wire with gain with statistical significance. Therefore, if you have an existing audio product that you are mostly happy with, but it is not longer state-of-the-art in measurements, be careful before chasing after the next upgrade. As a group, we cannot even tell the difference between the worst amplifier ever measured here and a theoretical perfect one. INDIVIDUALLY, it may be possible.

Be kind to others who disagree with you about their audio preferences. For the jazz sample, among those who had a preference between the two, 37% of *this* group of listeners preferred the non-transparent audio source. The people responding to this survery have self-selected toward some degree of objectivism and audio science. You could imagine that in a forum of tube amp fanatics, the preference would swing in that direction.

The real differences between a tube amplifier and solid state amplifier in a system can be greater than the differences seen here (as measured by a resistor). The level dependent treble boost, which could correlate to the common description of "sweet treble" could swing your preference differently. Hopefully this experiment encourages to *try* out speakers with narrow rather than wide dispersion, tube amps or negative feedback amps rather than solid state amps...


Call to Action
I did my part. Who's next in setting up the next blind listening challenge for the readers?

Thanks again for setting up!

Now that I can elaborate without spoiling the fun, some of it depended on familiarity. I don't listen to prog rock or mainstream jazz so found the third pair hardest (the first pair had a tell) and the second pair easiest (I do listen to spoken word stuff, like Laurie Anderson or La Dispute). The opposite of the group as a whole, where most differentiated the third (jazz) pair and fewest differentiated the second (spoken word).

I used two pairs of (non-cheap) headphones (wireless Air Pods Max and wired Sony Z1R) to hear everything. The Sonys gave the bass definition and AirPods the treble (for the first and second listening choices respectively) to hear the relevant distortion. The AirPods were best to hear the noise (both choices). For the third pair I found both noise and distortion were masked so differentiated via treble roll-off. So while I already knew the answers and couldn't do it blind again I don't know I would have differentiated the third pair with the treble-adjusted files (edit: added by @solderdude, thank you) that I listened to later.

I reckon @JSmith may be a hero for getting it on earbuds. Also, I did get why some would prefer the tube sound especially on the second pair (where it had more 'warmth and character' but less 'clarity'). For those of you with high SINAD gear who didn't differentiate (as opposed to preference) at least the first two—wasn't the hum unmistakable?

And finally, yes a taste of 300B SET sound but not the whole picture. Hopefully someone can do that next.