Record breaker: Raphaelite CS30-MKII tube amplifier review and measurements

[tomchr]

Thanks for the photo. Nice to see! I used to have a HP voltmeter exactly like that, and I also used 300B tubes from JJ.

The JJ 300B is incredible value. I tried some Shugang mesh plate ones that I found on ePay as well. They were really nice except one of them had a nasty tendency for thermal runaway even at 360 V, 60 mA. Back to the vendor they went.

It's clear that you should have high sensitivity speakers for a 300B SET, then the amp is in a low distortion range and doesn't lose track of large orchestral classical material.

There are many 'knobs' to turn. Speaker sensitivity is one. Size of listening space and distance to speakers is another. Desired SPL is a third.

Tube amps require more care and feeding than I'm willing to accept. But your preferences may be different than mine. I'm completely at peace with that.

And ... no Class D amp will ever provide the cool glow-in-the-dark look of a mesh plate 300B.

Tom

 

[computer-audiophile]

Just for fun, I'll show pictures of speakers that go particularly well with 'low-power' SET. They are not from me, but from a former friend. Me and my wife know some nice people in the audio-world who have such outstanding equipment. But for reasons of discretion I can not always show all the pictures.

 

[tomchr]

A for Ara | FS-2 Collection

A for Ara makes the finest high fidelity loudspeakers for your home. State-of-the-art-engineering meets meticulous craftsmanship. Our aim is to restore the lost art of active listening.

www.aforara.com

Tom

 

[computer-audiophile]

A for Ara | FS-2 Collection

A for Ara makes the finest high fidelity loudspeakers for your home. State-of-the-art-engineering meets meticulous craftsmanship. Our aim is to restore the lost art of active listening.

www.aforara.com

Tom

The design looks very similar to Oswald Mill Audio.

Oswalds Mill Audio | OMA

OMA can't change the world, but we do make the world's best audio equipment. Equipment without a peer, made for those who understand that the finest things in l

oswaldsmillaudio.com

 

[sarumbear]

If you know your preferences you can choose an amp that caters to those. If you prefer squeaky clean, you can choose an amp with low THD, low IMD, low mains hum, ample power, etc. But if you prefer the sound of an SET you could choose an amp with a harmonic distortion structure that caters to that preference. You'd want something with low-order HD where H2 > H3 > H4.

I thought the whole aim of High Fidelity as in Hi-Fi was as clear cut as it gets for an audio equipment manufacturer but it is obvious I was wrong.

Who on their right mind wants to add distortion to their audio system? — Other than a musician who is trying to create a new sound using an effect unit…

 

[GXAlan]

That good graphs and bad graphs do not necessarily reflect what we call enjoyable music coming out of a system.
What I see is an amp with insufficient filtering for PSU, but then again it is a SET! so there is no rejection.
Also I see an amp that could be in clipping.

I do agree that the amp in this review has been driven well into clipping. 10% THD is pretty hard clipping. A fair review would test the amp within its design limits.

I have the 1/2 watt data. Clearly better, but not much better.

Post in thread 'Record breaker: Raphaelite CS30-MKII tube amplifier review and measurements'
https://audiosciencereview.com/foru...er-review-and-measurements.44020/post-1565746

The power supply noise is the biggest issue for sure.

I published the 5W data just to set the record but also because in the blind test, it really shows that horrible SINAD is not horrible in sound.

If you look at Figure 6, that’s probably what I am seeing with this unit too but at lower powers since it doesn’t have the MOSFET SCS tech.

Western Electric Type No.91E integrated amplifier Measurements

Sidebar 3: Measurements I performed the measurements of the Western Electric 91E with my Audio Precision SYS2722 system. I carefully installed the tubes following the instructions in the excellent manual, and after turning on the amplifier, waited for the 91E to optimize the bias for the 300B...

www.stereophile.com

 

[tomchr]

I thought the whole aim of High Fidelity as in Hi-Fi was as clear cut as it gets for an audio equipment manufacturer but it is obvious I was wrong.

I've tried both and prefer the squeaky clean approach. But others have different opinions. Nelson Pass sells many amps. His philosophy appears to be to aim for a certain level of harmonic distortion with a particular distribution. I don't think it has to be an US vs THEM situation here. We can all coexist. I just wished more manufacturers would publish measurements and specs so consumers can know up front what they're buying. That's why I publish tons of measurements for my products. I was one of the first to publish multi-tone tests, for example.

Who on their right mind wants to add distortion to their audio system? — Other than a musician who is trying to create a new sound using an effect unit…

Or people who have different preferences than you. They're allowed to have their opinions and preferences too...

Tom

 

[tomchr]

Post in thread 'Record breaker: Raphaelite CS30-MKII tube amplifier review and measurements'
https://audiosciencereview.com/foru...er-review-and-measurements.44020/post-1565746

The power supply noise is the biggest issue for sure.

Yeah. The supply noise is pretty high here. But the -32 dBc THD at 0.5 W isn't exactly stellar either. Even for a 300B amp. Here's the DG300B (1 kHz, 1 W) for comparison. You'll notice much, much fewer (if any) IMD products from the supply noise.

Tom

 

[Ken Tajalli]

I thought the whole aim of High Fidelity as in Hi-Fi was as clear cut as it gets for an audio equipment manufacturer but it is obvious I was wrong.

Who on their right mind wants to add distortion to their audio system? — Other than a musician who is trying to create a new sound using an effect unit…

And I thought the whole aim of pants was to keep ones legs protected and warm, yet I prefer those skin tight leather pants on ladies with the right figure!
I know, I know, they are not comfy, nor all that warm, even wrinkles in some areas! but I like them.
Purely a subjective preference, I admit - I am sure a pair of robust jeans would objectively have better performance and passes more tests.
Don't shoot me.

 

[tomchr]

LOL <snort>

Tom

 

[pma]

And I thought the whole aim of pants was to keep ones legs protected and warm, yet I prefer those skin tight leather pants on ladies with the right figure!

I am afraid that in case of amplifiers such comparison does not work. Non-linear distortion of any kind does not add anything warm, sweet or protecting. Once it becomes audible, it sounds horrible, disharmonic (remember it creates all sort of non harmonic tones by intermodulation, as you never listen to a single note). To me it is not understandable why these debates are so popular and why people need to protect their toys.

 

[Ken Tajalli]

In an SET the ripple on the B+ supply is attenuated by the output transformer. That's typically not much attenuation. 25:1 for 5 kΩ -> 8 Ω. Compare that with 50+ dB (300:1) in a typical chip amp. So you need a squeaky clean power supply. It's also susceptible to hum injection through the filament supply. It's not trivial to design a good SET. I do agree that the amp in this review has been driven well into clipping. 10% THD is pretty hard clipping. A fair review would test the amp within its design limits.

Err? did I not just say all of that? in a concize manner?

 

[Ken Tajalli]

I am afraid that in case of amplifiers such comparison does not work. Non-linear distortion of any kind does not add anything warm, sweet or protecting. Once it becomes audible, it sounds horrible, disharmonic (remember it creates all sort of non harmonic tones by intermodulation, as you never listen to a single note). To me it is not understandable why these debates are so popular and why people need to protect their toys.

Smiley faces passed you by! ha!
A valve amp is not always a purely utilitarian device. A Hifi device.
Some tolerate the distortions, knowing well they are distortions, because they look cool and retro - perhaps even sexy! (tight leather pants?)
And they can sound reasonably good. Just look at the measurements! from the results, it must a dog, but the OP says it sounded good - so even with an objectively terrible results, it does not mean a terrible sound sometimes. I am not arguing that the amp sounds Sweet or Warm or anything magical. No way. What I am saying is "Look at the whole package", the look of the amp, its retro, it is warm (literally!) reminds you of your grand pa, so what if its got bad SINAD? it still manages to do enough to justify its keep.

 

[tomchr]

Actually, even-order harmonic distortion is supposed to add warmth. It can also add a sense of space. SETs generate mostly even-order distortion as they tend to clip harder in one direction than the other.

Whether you believe it's OK for an amp to add warmth is another story - and a reflection of your personal preference. I like the temperature in my house set to 19 ºC. Some may prefer 22 ºC.

Tom

 

[sarumbear]

This tread is as subjective as it gets. Soon there will be talk of Holly water…

 

[tomchr]

Oh? Why is that? Does every discussion have to devolve into US vs THEM? I think there's room for more nuance like that.

All I (and others) have said is that personal preferences play into the choice of audio gear. I've designed well-regarded tube amps and state-of-the-art solid state amps. While I would personally prefer a clean Class AB solid state design I'm completely at peace coexisting in a world that contains people who swear by tubes. I make my design decisions based on measurements (plural!) not listening tests. I intend to get the best measured performance out of the parts as possible. But that's me. Others are different. That's fine.

Tom

 

[BlackTalon]

This tread is as subjective as it gets. Soon there will be talk of Holly water…

Is she the woman in the leather pants?

 

[GXAlan]

I fixed the dented transformer cover. While I had it opened, I threw ferrite chokes over all sorts of random wires for no rational reason except that I live in a high EMI environment. I played with the hum pots putting my ears to the speakers and stopping when it seemed the quietest.

With my new multimeter, I checked the output. There's no DC, and my 20,000 count multimeter insists that AC voltage at idle is 0.6 to 1.0 millivolt which is pretty good. As I play with the volume potentiometer, the mismatch between the residual noise improves/worsens but it is generally in that range which seems pretty good to me?

@tomchr

 

[tomchr]

I bet the hum is worst when the volume pot is turned to the 2 o'clock (-6 dB) position. That's when its output impedance is the highest.

Tom

 

[Waxx]

The best 300B SET i know (subjective best off course) is the Sophia Electric 91-01. I never measured it, but I had one for a while in consignation from the owner who was abroad for a year for his job, and did put it next to some way more expensive (Audio Note, Shindo labs) owned by a friend. SET amps are high harmonic distortion, that is nothing new, but the Sophia Electric had a less distorted sound than those in my experience. I had to give it back to the owner when he returned, but i did enjoy those. Would i ever pay those prices? Probally not (maybe if i win the big lot of the lottery or so, but otherwise...) but they do sound nice to the ears. But i cosign, don't use them as your main amp, they are a niche of very coloured amplifiers, not for everybody. That Sophia Electric would be interesting for an ASR test i think.

I also heared some chinese builds of 300B SET amps, and they all but one were terrible, even from popular brands like Cayin. The only one that stood out on western level was Line Magnetic. The rest were noting more than distortion boxes. I don't know this one tested here, but i would not be surprised if they are not better than a Cayin or Nobosound SET that i heared. The Line Magnetic is also very expensive altough, way beyon what i would pay for one.

But at the end, i prefer PP tube amps, not SET amps. And they are in general cheaper and more powerfull, so...