This unit was loaned to me to test by a friend.
Content and analysis made possible thanks to support from https://headphones.com, and https://patreon.com/goldensound supporters.
The AMP-23R is the successor to the Bakoon AMP-13R. A 25 watt speaker amp in a compact chassis, with headphone output included.
It has a few interesting design aspects, such as having a volume control that directly adjusts the gain of the amplification stage itself instead of simply attenuating the signal, and also it uses no negative feedback whatsoever.
Using no negative feedback inherently means that it’s not going for ultra-high measurements, but subjectively there are many who prefer the sound of amplifiers using little to no negative feedback.
Bakoon had a history of producing some quite unique products, even being one of the very few companies to produce a full current-mode amplifier, so it’s no surprise to see some quite interesting and unique design aspects here too.
Another interesting feature on the AMP-23R is its ‘JET2 Bias’ circuit, which uses a combination of an ADC and DAC to constantly monitor and correct the bias of the transistors in response to various external factors such as temperature. This means that the amp should perform identically from the moment it’s switched on and will not need warmup.
Test Setup:
– Audio Precision APx555 B-Series Analyzer
– Amplifier was warmed up for 6 hours before measuring.
– AudioQuest Mackenzie RCA interconnects
– Neurochrome Headphone Dummy Load
– Amplifier set to Low Gain for all tests
– Full reports containing additional data and test configurations are attached
– Exact analyzer configurations for each measurement are detailed in the full reports
– All measurements shown below are taken with a 32 ohm load in low gain unless otherwise specified
Full Reports:
Reports available here (These contain 4v unity gain, and 700mv test results, please check you’re looking at the right ones when comparing!):
Gain: 22.5dB (High), 7dB (Low)
Output impedance: 0.8 Ohm
Power:
Unfortunately I completely forgot to do a power test before the amp left. It is coming back to me later for a full review though so I’ll update this then.
Officially however, it can supply 25W into 8 ohms, and 6.25W into 32 ohms.
1khz 2V input 2V Output 32 ohm:
At 2V into a 32 Ohm load there’s a fair amount of harmonic distortion. Near equal amounts of 2nd and 3rd order.
As mentioned earlier, this amp employs zero negative feedback, low THD+N is NOT what it’s going for and NOT why people are buying this.
But….this performance is actually somewhat misleading, read on to see why.
1khz 2V input 2V Output 300 ohm:
Performance between a 300 ohm and 32 ohm load is extremely close.
Now what if we look at a realistic listening level of 700mV?
1khz 2V input 700mV Output 32 ohm:
What’s interesting is that at 700mV performance is practically identical to at the higher level of 2V. Whereas on many amps distortion level (and sometimes profile) will change depending on level.
This is likely because the Enleum AMP-23R volume control actually alters the gain of the amp, rather than attenuating the signal. This means that performance should in theory remain pretty much identical regardless of what volume you have the amp set to.
BUT, whilst testing, I did notice something unusual. The AMP-23R does not seem to perform quite so well with higher, or even standard 2V level RCA inputs. Its IMD vs input level graph for example looks like this:
This is pretty typical for a lot of amps. The higher the input level, the higher the output level. And at somepoint once the amp starts working too hard, performance starts to drop the more you push it. Crank the volume up too far and distortion might start to rise.
But on the 23R, this graph remained exactly the same even when I set the volume very low. Meaning it couldn’t be correlated to the amp output level, but instead the input level.
So I reduced the input signal to 0.3V and this is what we got:
1khz 300mV input 700mV Output 32 ohm:
Performance gets a big jump! And not only in absolute level, but notice the actual structure of the distortion.
Where we previously had equal 2nd and 3rd order harmonics, we now have a ‘triode-like’ profile with 2nd order prominence, then falling 3rd and 4th order. A profile which many would regard as subjectively preferable, as odd-order harmonics are generally agreed to be subjectively much less pleasing than even-order.
I try to avoid putting subjective commentary in the measurement posts unless I feel it’s necessary or appropriate, but here I think that’s the case.
To me the 23R sounded notably better when the DAC feeding it had about 8-10dB of DSP headroom/volume control applied, with things coming across less ‘dense’, slightly more neutral, and having better clarity of separation between elements.
If you have a 23R it’s worth playing about with this, you can pretty much ‘tune’ the amp by increasing/decreasing your DAC volume between -0dB and -10dB (assuming your DAC outputs about 2V on RCA).
The remainder of this post is showing tests with normal 2V line level, as that’s how most people are using it and I want to keep my test methodology consistent. But there is a PDF full report done with a 300mV input level instead of 2V if you are interested.
THD+N / Frequency:
Total harmonic distortion does not change to any notable degree vs frequency.
SINAD/THD+N vs output level:
IMD (SMPTE) vs Output Level:
Crosstalk:
Crosstalk is quite high.
1khz Square Wave:
Multitone:
When input level is lowered to 0.3V the multitone is much much cleaner, dropping around 15dB in many areas.
I’m interested in purchasing the Enleum . I’m not a technical person but your measurements and observations aren’t inspiring me with confidence in regard to the Enleum’s technical performance? Perhaps I’m misinterpreted them ?
Can you clarify in layman’s terms .
Thank you ,
Drew
Basically, it seems this Amp was purposely designed to imitate a tube amp like response. So, measurements here do suck, so should sound great, though not accurate by any means.
I ended up purchasing the Enleum 23r . It’s sounds absolutely wonderful IMO despite the measurement concerns spoken about in this review .
Curious about your dac / source chain.
1. Reasonesence Labs Invicta Mirus Pro DAC
2. Lindemann Limetree Network Player in combination w/ the Sbooster LPS
Do you mean to say employing a preamp (that has a potentiometer to reduce DAC 2V constant signal) is the optimal set up/chain for a reduction in THD as you increase the gain/volume on the Enleum?
I thought the AMP-23R is a full current mode amp, so wondering why the Output impedance is only 0.8ohm. Is this value from OEM spec or something you measured?
I’m interested in why this amp is the first to bring our reviewer to the screen and why there are discrepancies between this and the video review e.g. in respect of dropping the input voltage. Here performance gets a “big jump”. On the video it’s “a bit better” and “not a massive jump”. Why?
My initial reaction to this channel was very positive but if you’re using the same measurements and listening tests but then posting contradictory outcomes that creates a credibility gap.
I’m absolutely thrilled with the sound of my Enleum 23r when listening to Jazz and Classical music music through my Falcon speakers. I certainly don’t hear the woolly sound the reviewer speaks about ? On the contrary. I have a different taste in music then the reviewer though . I’m also not a head phone listener so I can’t comment in that regard . Nevertheless, some of the damaging claims made by the reviewer about the Enleum 23r in the GoldenSound video review on YouTube are troubling . I’ll be reaching out to Enleum for comment .
I think your problem here is that our reviewer has been caught with his pants down a little. Asserting that the amp slides about but failing to mention it ships with something to prevent that as mentioned by Passion For Sound looks shoddy. Getting all worked up about DC offset looks silly in view of subsequent responses. Gets worse though. The assertion that it works marginally better at 2V gets thoroughly examined by PfS and the response from Lachlan and Soo makes GS look like he was looking for something to have a go at. The evidence suggests most have dismissed the GS and CMA reviews as being at best anomalous.
Some of the troubling statements made by Golden Sound in their rather cynical dismissive YouTube review of the Enleum 23r simply did not match up with the amazing listening experience that I and so many other Enleum owners have enjoyed . And, who have found themselves completely smitten with the sound of the little Enleum.
Not to mention the dozens professional reviewers who have been deeply impressed by the build quality and exceptional sound quality of the Enleum . The many stellar reviews and rewards the Enleum has received bear this out.
Of course the GS reviewer is entitled to his own opinion of the Enleum 23r – but not his own facts.
I decided to reach out to Enleum via email asked them to address some of the disturbing claims made by the GS reviewer . Enleum disputes many of these claims made in the GS review as either completely misinformed or blatantly untrue . Particularly the abjectly false insinuation that Enleum intentionally uses cheap or inferior parts as a cost saver and then disingenuously overcharges for their products. Their is also no evidence that the Enleum will damage headphones. This is a completely irresponsible claim by a reviewer and complete BS.
Enleum states the choice parts used in the Enleum are based solely on what makes it sound its absolute best . That and thousands of hours of meticulous listening and testing.
Certainly not on trying to save a few measly cents on the price of a capacitor or resistor as insinuated by GS.
Thankfully a recent well written and objective review of the Enleum 23r by Michael Lavorgna of Twittering Machines very effectively addressed and put to rest the falsities , misinformation and uninformed assumptions stated in the GS review.
According to Enleum the GS reviewer never reached out once to them with questions about Enleum’s design philosophy or the technical reasons behind the choice of parts employed in the Enleum before posting their review on YouTube .
For the money this is atrocious, like the Chord Dave,should sell the 2 together as the greatest snake oil products ever.
Thanks to Golden sound for exposing this piece of junk,Britains answer to ASR is really beginning to shine.