Newest Amplifier Design by Kang Su Park - The Allnic M-2500 Monoblock

ketcham

Industry Expert
Feb 29, 2016
126
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115
DSC09257.JPG

Anthony Kershaw of Audiophilia recently posted a review on the new Allnic M-2500 and I wanted to post my impressions and summarize what it offers. I have owned many tube amplifier designs over the years and historically the push-pull type has never been my favorite. Each design approach has its strengths and weaknesses. As my speakers became more efficient, the micro detailing of single bulb, low wattage amplifiers presented huge benefit without any detriment to my evolving and, admittedly, more mellow listening style -- a lateral move where I remained content for some time. When I learned of these new amplifiers, I requested KS Park to make a set specific to the PX25. This enabled me to do a direct comparison using the same PX25 tubes and rectifiers.

This new amp design has hit the sweet spot between SET and typical push-pull amplifiers. The M-2500 maintains the micro detailing, texture and overall finesse across the midrange SET designs are known for while improving the dynamics, slam factor and extended and focused bass. This improvement was further accentuated by replacing my 1937 production OSRAM PX25 and 1950 production GEC (OSRAM) U52 with modern Kron tubes. There was an unexpected and pleasantly surprising profound change in clarity, as if donning eyeglasses first thing in the morning. Frequency extension in both directions. Deeper, broader soundstage and improved imaging with a new emphasis on the delicacy of decay particularly noted in percussion. To emphasize, this change was not subtle and I anticipate these amplifiers being a tube rolling delight while adhering to the manufacturer specifications.

I suspect the SET characteristics can be attributed to the direct-heated vacuum tube rectification. The 5U4G full-wave rectifier tube replaces the semiconductor diode in the rectification circuit of the M-3000 mkii and other traditional push-pull amplifiers.

With the individual tube biasing, pairing is not necessary. Historically, I find Allnic circuit design does not overdrive their tubes and they tend to last a very long time. The M-2500 appears to retain this benefit.

The M-2500s are now my go-to amps with no issues presenting with any genre at any volume. My amps are the PX25 20W continuous triode, set at 8 ohm driving Daedalus Zeus Speakers with 99 dB efficiency at a VERY flat impedance curve (+/- 1 ohm above 100hz) and most of the time are spot on at 6ohms. I have had customers prefer the micro-detailing and improved bass inherent to the PX25 and drive their Daedalus speakers at 96 dB.

m2500 front.jpg

The 300B/PX25/KT150 circuits are each unique and, therefore, tubes are not interchangeable. Amplifier design is established on order and hand built in Korea.


PX25 - 1st Stage 5654, 2nd Stage 6S4, U52/5U4G Rectifier and PX25 x2. 20W Continuous. Triode

300B - 1st Stage 6485, 2nd Stage 12A4, 5U4G Rectifier and 300B x2. 30W Continuous. Triode

KT150 - 1st Stage 5654, 2nd Stage 6S4, 5U4G Rectifier and KT150 x2. 100W Continuous. Pentode


Technical Specification

Output Power:

PX25 : 20W Triode
300B : 30W Triode
KT150 : 100W Pentode

Distortion 0.01% at 1kHz at 10W
Frequency Response 20Hz to 50kHz flat
S/N Ratio -100dB (CCIR, 1kHz)
Damping Factor 8 at 8Ω load at 1kHz
Voltage gain less 0.03% +26dB
Input Impedance 100kΩ (single-ended, unbalanced)

Tubes (per monoblock pair):
PX25 x 4, 5654 x2, 6S4 x 4, 5U4G x 2
300B x 4, 12A4 x 4, 6485 x 2, 5U4G x 2
KT150 x 4, 5654 x2, 6S4 x 4, 5U4G x 2
(Substitute with equivalent direct-heated rectifiers only)

Fuses 3A/230V, 5A/120V
Dimension 440mm (W) x 370mm (D) x 260mm (H)
Weight 20kg


Anthony Kershaw's M-2500 Review

Allnic Audio Korea

DSC09263.JPG
 

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ketcham

Industry Expert
Feb 29, 2016
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How to choose which circuit design remains the $14K question. I have both the PX25 and the K150 on loan and from feedback, the amplifiers certainly handle the demands placed on them, so far. The 20W continuous triode PX25 has no issues driving speakers at 96 dB efficiency at 6 Ohms. The 30W continuous triode 300B has no issue driving speakers at 90 dB efficiency. Any less efficient speaker, consider the KT150 100W continuous pentode. To date, I have not received feedback of soft clipping, or hardening of the presentation typically in the lower frequencies.

Regarding the sonic characteristics for each power tube, this is an entirely subjective preference. Those that never have heard the father of 300B should audition a PX25 before purchase. The modern production 300B is more prevalent and like the 1940's original WE300B, the Osram PX25 of the 1930's are increasingly rare with the retail market at $1400 per tube today. I believe only Kron and Emission Labs makes modern PX25 tubes. I certainly would love to learn about other manufacturers. Albeit with less power, the PX25 has more bass extension and certain swagger not witnessed in 300B along with improved the micro detailing and layering across the midrange.

Other factors to consider are room size, listening style, the genre of music and listening level.
 
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Hyperion

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How to choose which circuit design remains the $14K question. I have both the PX25 and the K150 on loan and from feedback, the amplifiers certainly handle the demands placed on them, so far. The 20W continuous triode PX25 has no issues driving speakers at 96 dB efficiency at 6 Ohms. The 30W continuous triode 300B has no issue driving speakers at 90 dB efficiency. Any less efficient speaker, consider the KT150 100W continuous pentode. To date, I have not received feedback of soft clipping, or hardening of the presentation typically in the lower frequencies.

Regarding the sonic characteristics for each power tube, this is an entirely subjective preference. Those that never have heard the father of 300B should audition a PX25 before purchase. The modern production 300B is more prevalent and like the 1940's original WE300B, the Osram PX25 of the 1930's are increasingly rare with the retail market at $1400 per tube today. I believe only Kron and Emission Labs makes modern PX25 tubes. I certainly would love to learn about other manufacturers. Albeit with less power, the PX25 has more bass extension and certain swagger not witnessed in 300B along with improved the micro detailing and layering across the midrange.

Other factors to consider are room size, listening style, the genre of music and listening level.

In terms of overall potential and flexibility, the KT150 would certainly be the weapon of choice. The 300B would probably be the sweetspot though where I do have several speaker choices here where 30W output would be sufficient including Cube Audio, Stenheim and Apertura.

/ Marcus, www.perfect-sense.se
 

ketcham

Industry Expert
Feb 29, 2016
126
57
115
Marcus. Yes you do represent some excellent manufacturers. At what point would you direct your clients from the 300B to the KT150 or believe the PX25 would be a good fit?
 

advanced101

VIP/Donor
May 3, 2017
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Looks like a nice offering at a good price. Would be interesting to compare the PP PX25 with a comparably priced 845 SET. Looks like all the Allnic gear is getting some nice upgrades.
 
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parsifalcor

New Member
May 30, 2020
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Ketcham, can you compare your thoughts on the M-2500 vs. the M-3000 MK. II?
 

ketcham

Industry Expert
Feb 29, 2016
126
57
115
The Titan M-5000 was based off the M-3000 mkii. Both amps are complete powerhouses and if your system goes to rock concert level, feel your organs resonate, these are the amps for you. The M-2500 is a newer circuit design that does a great job marrying the qualities of push-pull with a single-ended triode. While less powerful than the M-3000 mkii, I have not found any discernable sense of being left wanting with the M-2500 KT150, which will drive any speaker on the market. Dynamics and Slam are palpable without any soft clipping. The M-2500 shines in being able to tailor each individual system and realize new qualities in familiar recordings. The three tube types (KT150, 300B, PX25) were intentional. This quiver address everyone's needs.
 

parsifalcor

New Member
May 30, 2020
2
1
3
33
Thanks so much for your response! I got a great deal on a very lightly used pair of the baby Titans (M-3000 mk. II) and could not be more pleased. Allnic components have really taken my system and ENJOYMENT to the next level!
 
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Dante Choi

Well-Known Member
Feb 26, 2016
28
26
93
Buenos Aires,, Argentina
View attachment 65315

Anthony Kershaw of Audiophilia recently posted a review on the new Allnic M-2500 and I wanted to post my impressions and summarize what it offers. I have owned many tube amplifier designs over the years and historically the push-pull type has never been my favorite. Each design approach has its strengths and weaknesses. As my speakers became more efficient, the micro detailing of single bulb, low wattage amplifiers presented huge benefit without any detriment to my evolving and, admittedly, more mellow listening style -- a lateral move where I remained content for some time. When I learned of these new amplifiers, I requested KS Park to make a set specific to the PX25. This enabled me to do a direct comparison using the same PX25 tubes and rectifiers.

This new amp design has hit the sweet spot between SET and typical push-pull amplifiers. The M-2500 maintains the micro detailing, texture and overall finesse across the midrange SET designs are known for while improving the dynamics, slam factor and extended and focused bass. This improvement was further accentuated by replacing my 1937 production OSRAM PX25 and 1950 production GEC (OSRAM) U52 with modern Kron tubes. There was an unexpected and pleasantly surprising profound change in clarity, as if donning eyeglasses first thing in the morning. Frequency extension in both directions. Deeper, broader soundstage and improved imaging with a new emphasis on the delicacy of decay particularly noted in percussion. To emphasize, this change was not subtle and I anticipate these amplifiers being a tube rolling delight while adhering to the manufacturer specifications.

I suspect the SET characteristics can be attributed to the direct-heated vacuum tube rectification. The 5U4G full-wave rectifier tube replaces the semiconductor diode in the rectification circuit of the M-3000 mkii and other traditional push-pull amplifiers.

With the individual tube biasing, pairing is not necessary. Historically, I find Allnic circuit design does not overdrive their tubes and they tend to last a very long time. The M-2500 appears to retain this benefit.

The M-2500s are now my go-to amps with no issues presenting with any genre at any volume. My amps are the PX25 20W continuous triode, set at 8 ohm driving Daedalus Zeus Speakers with 99 dB efficiency at a VERY flat impedance curve (+/- 1 ohm above 100hz) and most of the time are spot on at 6ohms. I have had customers prefer the micro-detailing and improved bass inherent to the PX25 and drive their Daedalus speakers at 96 dB.

View attachment 65316

The 300B/PX25/KT150 circuits are each unique and, therefore, tubes are not interchangeable. Amplifier design is established on order and hand built in Korea.


PX25 - 1st Stage 5654, 2nd Stage 6S4, U52/5U4G Rectifier and PX25 x2. 20W Continuous. Triode

300B - 1st Stage 6485, 2nd Stage 12A4, 5U4G Rectifier and 300B x2. 30W Continuous. Triode

KT150 - 1st Stage 5654, 2nd Stage 6S4, 5U4G Rectifier and KT150 x2. 100W Continuous. Pentode


Technical Specification

Output Power:

PX25 : 20W Triode
300B : 30W Triode
KT150 : 100W Pentode

Distortion 0.01% at 1kHz at 10W
Frequency Response 20Hz to 50kHz flat
S/N Ratio -100dB (CCIR, 1kHz)
Damping Factor 8 at 8Ω load at 1kHz
Voltage gain less 0.03% +26dB
Input Impedance 100kΩ (single-ended, unbalanced)

Tubes (per monoblock pair):
PX25 x 4, 5654 x2, 6S4 x 4, 5U4G x 2
300B x 4, 12A4 x 4, 6485 x 2, 5U4G x 2
KT150 x 4, 5654 x2, 6S4 x 4, 5U4G x 2
(Substitute with equivalent direct-heated rectifiers only)

Fuses 3A/230V, 5A/120V
Dimension 440mm (W) x 370mm (D) x 260mm (H)
Weight 20kg


Anthony Kershaw's M-2500 Review

Allnic Audio Korea

View attachment 65319
Many tks for your post. Just for your reference I own several equipment of Allnic H-5000, L-8000, etc...). Five or six years ago, I visite Allnic head office in Korea and purchased A-8000 monoblocks, this is KR 1610SE version, half size of A-10000 (KR-1610 SP). At that time, I went to purcahse 300B amp (because I have several original WE-300A) but when I tested A-8000 (I guess that Mr.Park made only 3-4 pairs of this model), it's beat all Allnic 300B, AD1, etc... so was easy to take the desicion. But as I have several WE-300A, I'd like to use them, but unfortunatelly I could never find any amp that could compete against Allnic A-8000 to drive my Tannoy Autograph with Silver Monitors (16 ohms). Now I am very interested on this new Allnic. How do you think? Can these amp compete against T-1610SE?
 

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bonzo75

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Many tks for your post. Just for your reference I own several equipment of Allnic H-5000, L-8000, etc...). Five or six years ago, I visite Allnic head office in Korea and purchased A-8000 monoblocks, this is KR 1610SE version, half size of A-10000 (KR-1610 SP). At that time, I went to purcahse 300B amp (because I have several original WE-300A) but when I tested A-8000 (I guess that Mr.Park made only 3-4 pairs of this model), it's beat all Allnic 300B, AD1, etc... so was easy to take the desicion. But as I have several WE-300A, I'd like to use them, but unfortunatelly I could never find any amp that could compete against Allnic A-8000 to drive my Tannoy Autograph with Silver Monitors (16 ohms). Now I am very interested on this new Allnic. How do you think? Can these amp compete against T-1610SE?

Wow Allnic and Tannoy autograph with silver drivers, I would love to hear that.

When you tested the various Allnic amps, which speaker was used for the test?
 

Dante Choi

Well-Known Member
Feb 26, 2016
28
26
93
Buenos Aires,, Argentina
Wow Allnic and Tannoy autograph with silver drivers, I would love to hear that.

When you tested the various Allnic amps, which speaker was used for the test?
Tks for your comment. Also Tannoy Autogaph but with Red Monitors. In that time Mr.Park loved Tannoy, but now apparently his favorite speaker are JBL Hartsfield...
 
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bonzo75

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Feb 26, 2014
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Also Tannoy but with Red Monitors. In that time Mr.Park loved Tannoy, but now apparently his favorite speaker are JBL Hartsfield...

Was the higher power of the Allnic 8000 part of the reason for preferring it? Because both silver and red are 16 ohms and quite sensitive, so just wondering why the lower powered ones didn't do as well, maybe 8000 is just better
 

Dante Choi

Well-Known Member
Feb 26, 2016
28
26
93
Buenos Aires,, Argentina
Was the higher power of the Allnic 8000 part of the reason for preferring it? Because both silver and red are 16 ohms and quite sensitive, so just wondering why the lower powered ones didn't do as well, maybe 8000 is just better
Mr.Park designe A-8000 with 3 differents valves of 1st stage. Choosing differents valves you can adjust the output power to 12W or 25W or 50W x Ch. I tested differents valves and now I am using with KR-242 delivery 50W x Ch. This is hugh power for Tannoy, so I am tryng to listen at low volume. The sound of A-8000 is like electric storm. Very flat, very etended in high as low freq and very transparent. From the technical view, this is right amplifier, but I'd like some more gentle, warm tone of amplifier without resigning transparency or extension.
 

bonzo75

Member Sponsor
Feb 26, 2014
15,394
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940
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Mr.Park designe A-8000 with 3 differents valves of 1st stage. Choosing differents valves you can adjust the output power to 12W or 25W or 50W x Ch. I tested differents valves and now I am using with KR-242 delivery 50W x Ch. This is hugh power for Tannoy, so I am tryng to listen at low volume. The sound of A-8000 is like electric storm. Very flat, very etended in high as low freq and very transparent. From the technical view, this is right amplifier, but I'd like some more gentle, warm tone of amplifier without resigning transparency or extension.

Oh wow that's my favorite tube in the Lampi. I completely understand why you like it so much, and you must have a dream system. Once after covid clears and we start traveling far again, I would like to visit you sometime
 

Dante Choi

Well-Known Member
Feb 26, 2016
28
26
93
Buenos Aires,, Argentina
I am reading reguarly your post in Zero Distortion. Also I'd like to listen your system. I'm living in Argentina. You are wellcome to visit me in any time. I have Clearaudio Statement/TT1/Thorens 124 MK II with German Norma Plinth & Norma Tonearm connected to Allnic H-5000 and EMT-927 with SME V/12, Ortofon RF-297 connected to EMT-139ST. Have two systems, one is Allnic L-8000 with Allnic A-8000 to drive Tannoy Autograph and the second system is Krell Evo-1/2 to drive Wilson Alexx. I changed the Xover of Tannoy using Duelund Cast Pio Condensers and also changed all internal cable with Duelund. The sound is very different now.
 

bonzo75

Member Sponsor
Feb 26, 2014
15,394
4,870
940
London
I am reading reguarly your post in Zero Distortion. Also I'd like to listen your system. I'm living in Argentina. You are wellcome to visit me in any time. I have Clearaudio Statement/TT1/Thorens 124 MK II with German Norma Plinth & Norma Tonearm connected to Allnic H-5000 and EMT-927 with SME V/12, Ortofon RF-297 connected to EMT-139ST. Have two systems, one is Allnic L-8000 with Allnic A-8000 to drive Tannoy Autograph and the second system is Krell Evo-1/2 to drive Wilson Alexx. I changed the Xover of Tannoy using Duelund Cast Pio Condensers and also changed all internal cable with Duelund. The sound is very different now.

If you have any videos playing classical, and vocals, please post
 

ketcham

Industry Expert
Feb 29, 2016
126
57
115
This is the first I have heard of the A-8000! What is the tube complement and does it use tubed rectifiers? Kang Su offers custom 8/16 ohm matched output transformers. Does your amplifier have spec transformers to match your speakers?

They certainly are beautiful!
 

Dante Choi

Well-Known Member
Feb 26, 2016
28
26
93
Buenos Aires,, Argentina
This is the first I have heard of the A-8000! What is the tube complement and does it use tubed rectifiers? Kang Su offers custom 8/16 ohm matched output transformers. Does your amplifier have spec transformers to match your speakers?

They certainly are beautiful!
Tks for your comment. These are really great amps.
I know that Park made 3 pairs of A-8000, one pair is in his home driving Cessaro Horns, the 2nd pair is my home and one of my friend is using also. This amp is exactly same than A-10000 bue with single KR T-1610 instead of 2 per channel. I specially asked to use with my Tannoy, so my amp is prepared for 8 & 16 ohms.
 

Wrm57

Well-Known Member
Oct 30, 2012
21
9
233
John,

Any thoughts on how the rectifier might hold up in the KT150 version? A 100w power amp would seem a different story than 20w or 30w, placing quite demand on a single rectifier. Any lag? Bass response hold up?

Bill

PS - I'm the guy breaking in your A2000 25th Anniv!
 
Last edited:

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