Reviews by labeelen
Hi All,
The default opamps of the FireStone Audio Bobby Class A fully balanced headphone amplifier are a quartet of OPA604s.
In this year of its 10th anniversary I wanted to see what potential is still in this decade old design by swapping the opamps with a discrete alternative by Sparkos.
I did several listening tests and would like to share my findings with Bobby owners and other readers.
My audio-chain consisted of:
As mentioned earlier Bobby's default opamps are the OPA604 which are ok but are a little veiled and lack some sparkle and detail.
In the past years, after numerous tests, I settled on Burson V5i and OPA627. The V5i giving more transparency, detail and better definition in the bass.
OPA627 was also a very nice upgrade option if you like a warmer fuller sound with subtle highs, detail and a little darker atmosphere.
When I swapped the above with the Sparkos ss3601 I was struck by the positive changes that this upgrade brought, it elevated and transformed the Bobby to a whole new level.
The sound was smooth, natural and very detailed and music was playing effortless and with great authority. Because of the pitchblack background you could hear new small details like subtle decays and get a better sence of space.
Sub-bass
The lowest frequencies are present but not as dominant as with the V5i's. For testing electronic sub bass I often use ‘Doin it Right’ by Daft Punk. With the ss3601 the lowest bass notes are presented with authority and confidence.
Bass
Bass is very punchy and clear. In Radioheads 'House of Cards' the ss3601 had better control and nicely prevented the lowest frequencies from smearing the midbase.
Mids
Male and female vocals sound natural and lifelike without any rough edges. Definition and placement of instruments is very good as can be heard in songs like ‘In Your Eyes’ from Peter Gabriel.
On ‘Man in the long black coat’ the voice of Dylan and his harmonica sound very natural. In my opinion harmonica’s are very challenging instruments to reproduce accurately. (that’s why this is also a good test-track to evaluate the subtle differences in linear power supplies, fuses and power cords)
Highs
The high frequency spectrum is well extended and airy but never sharp or piercing. In ‘I love Paris’ from Johnny Frigo this is nicely demonstrated with a high-hat that sounds very realistic and convincing, with a very nice and long decay.
in short:
The Sparkos ss3601 breathes new life in my Bobby Amplifier and really elevates it to new levels. Clarity, imaging and the richness of sound are second to none I really enjoyed rediscovering my music this way.
The default opamps of the FireStone Audio Bobby Class A fully balanced headphone amplifier are a quartet of OPA604s.
In this year of its 10th anniversary I wanted to see what potential is still in this decade old design by swapping the opamps with a discrete alternative by Sparkos.
I did several listening tests and would like to share my findings with Bobby owners and other readers.
My audio-chain consisted of:
- Qobuz (Hi-res streaming service)
- Roon (running on Synology NAS)
- HQPlayer (running on Intel Nuc12i5) for upsampling and EQ
- Raspberry Pi3 with TeraDak i2s hat running RopiEEE (NAA)
- Firestone Audio Tobby balanced 192k D/A Converter (via Glass Optical Fibre)
- VandenHull Integration Hybrid (single ended) RCA interconnect
- Firestone Audio Bobby Class A (fully balanced) Headphone amplifier
- Beyerdynamic T90 with balanced mod, tuning and custom cable by CustomCansUK2
As mentioned earlier Bobby's default opamps are the OPA604 which are ok but are a little veiled and lack some sparkle and detail.
In the past years, after numerous tests, I settled on Burson V5i and OPA627. The V5i giving more transparency, detail and better definition in the bass.
OPA627 was also a very nice upgrade option if you like a warmer fuller sound with subtle highs, detail and a little darker atmosphere.
When I swapped the above with the Sparkos ss3601 I was struck by the positive changes that this upgrade brought, it elevated and transformed the Bobby to a whole new level.
The sound was smooth, natural and very detailed and music was playing effortless and with great authority. Because of the pitchblack background you could hear new small details like subtle decays and get a better sence of space.
Sub-bass
The lowest frequencies are present but not as dominant as with the V5i's. For testing electronic sub bass I often use ‘Doin it Right’ by Daft Punk. With the ss3601 the lowest bass notes are presented with authority and confidence.
Bass
Bass is very punchy and clear. In Radioheads 'House of Cards' the ss3601 had better control and nicely prevented the lowest frequencies from smearing the midbase.
Mids
Male and female vocals sound natural and lifelike without any rough edges. Definition and placement of instruments is very good as can be heard in songs like ‘In Your Eyes’ from Peter Gabriel.
On ‘Man in the long black coat’ the voice of Dylan and his harmonica sound very natural. In my opinion harmonica’s are very challenging instruments to reproduce accurately. (that’s why this is also a good test-track to evaluate the subtle differences in linear power supplies, fuses and power cords)
Highs
The high frequency spectrum is well extended and airy but never sharp or piercing. In ‘I love Paris’ from Johnny Frigo this is nicely demonstrated with a high-hat that sounds very realistic and convincing, with a very nice and long decay.
in short:
The Sparkos ss3601 breathes new life in my Bobby Amplifier and really elevates it to new levels. Clarity, imaging and the richness of sound are second to none I really enjoyed rediscovering my music this way.
Attachments
Several years ago I built myself a HP amplifier based on the Texas Instruments TPA6120A2 headphone amplifier chip.
This is a compact powerfull device that combines very well with a variety of headphones.
I experimented with different opamps in this design and for those interested I would like to share some of my experiences.
Recently I replaced the current OPA1611 opamps with Sparkos ss3601 which improved the sonic performance in several key areas.
I did several listening tests and would like to share my findings with other owners of TPA6120A2 based headphone amplifiers and others interested in swapping opamps.
My audio-chain consisted of:
Default opamps of the TPA6120A2 are the JRC5534 which are decent musical sounding opamps with a natural be it somewhat subdued sound.
In the past years, after numerous tests, I settled on the OPA1611 which improved the performance of the TPA6120A2 significantly with a more detailed better defined sound that had real synergy with the T90 headphones.
Other opamps that I liked in this amplifier where the OPA1641, OPA602BP and ADA4627 each having there strenghts and a few weaknesses. OPA1641 was very dynamic but lacked a little finesse; OPA602BP was very natural sounding, a little dry and less dynamic; ADA4627 is very detailed but somewhat analytical sounding.
When I swapped the OPA1611 with the Sparkos ss3601 I was pleasantly surprised with the improvements in soundstage, sense of space and increased detail.
The sound was engaging, controlled & natural and this upgrade made me really rediscover the TPA6120A2 amplifier.
Sub-bass
In Doin' it Right by Daft Punk the low frequencies are well presented if you have a bass-heavy (of V-shaped headphone) it might even be a little too much, but it was a perfect match for my T90.
Bass
In Never Look Back by Chicane the TPA6120A2/ss3601 combination proves it can produce some serious punchy low frequencies with good control.
Mids
Vocals sound very natural, Olivia Vedder's voice sounds crisp in my Father's daughter. The percusion is also very clear and maybe a notch on the dry side.
Dynamics are also on a very high level as could be heard at the end of Angus & Julia Stone’s ‘Draw Your swords’.
Highs
The upper frequencies are extended and delivered in a very subtle and sparkling way.
On Peter Gabriel's 'In Your Eyes' you can nicely hear the extended decay's slowly fade away.
Conclusion:
Overall I was happily surprised that I could still squeeze some extra musical performance out the TPA6120A2.
With the ss3601 I was able to hear new levels of detail combined with a very pleasant fluid emmersive smooth, forgiving and addicting sound with well separated instruments and a wide realistic soundstage.
In short I have been very happy with the OPA1611 but the Sparkos ss3601 does have the edge in more refined highs, sense of space and a more pitch black background and makes it easier to hear deeper into the recordings.
[Update]
I discovered that the sound of the Sparkos ss3601 further improved after 30+ hours of burn-in.
The bass was reduced somewhat in volume (in a positive way) and became even better defined and controled.
This resulted in a balanced, coherent, very detailed and smooth sound.
Apparently you should give these discrete opamps time to settle in order to show their full potential.
This is a compact powerfull device that combines very well with a variety of headphones.
I experimented with different opamps in this design and for those interested I would like to share some of my experiences.
Recently I replaced the current OPA1611 opamps with Sparkos ss3601 which improved the sonic performance in several key areas.
I did several listening tests and would like to share my findings with other owners of TPA6120A2 based headphone amplifiers and others interested in swapping opamps.
My audio-chain consisted of:
- Qobuz (Hi-res streaming service)
- Roon (running on Synology NAS)
- HQPlayer (running on Intel Nuc12i5) for upsampling and EQ
- Raspberry Pi3 with TeraDak i2s hat running RopiEEE (NAA)
- Firestone Audio Tobby balanced 192k D/A Converter (via Glass Optical Fibre)
- VandenHull Integration Hybrid (single ended) RCA interconnect
- Custom built (DIY) TPA6120A2 based headphone amplifier
- Beyerdynamic T90 with balanced mod, tuning and custom cable by CustomCansUK
Default opamps of the TPA6120A2 are the JRC5534 which are decent musical sounding opamps with a natural be it somewhat subdued sound.
In the past years, after numerous tests, I settled on the OPA1611 which improved the performance of the TPA6120A2 significantly with a more detailed better defined sound that had real synergy with the T90 headphones.
Other opamps that I liked in this amplifier where the OPA1641, OPA602BP and ADA4627 each having there strenghts and a few weaknesses. OPA1641 was very dynamic but lacked a little finesse; OPA602BP was very natural sounding, a little dry and less dynamic; ADA4627 is very detailed but somewhat analytical sounding.
When I swapped the OPA1611 with the Sparkos ss3601 I was pleasantly surprised with the improvements in soundstage, sense of space and increased detail.
The sound was engaging, controlled & natural and this upgrade made me really rediscover the TPA6120A2 amplifier.
Sub-bass
In Doin' it Right by Daft Punk the low frequencies are well presented if you have a bass-heavy (of V-shaped headphone) it might even be a little too much, but it was a perfect match for my T90.
Bass
In Never Look Back by Chicane the TPA6120A2/ss3601 combination proves it can produce some serious punchy low frequencies with good control.
Mids
Vocals sound very natural, Olivia Vedder's voice sounds crisp in my Father's daughter. The percusion is also very clear and maybe a notch on the dry side.
Dynamics are also on a very high level as could be heard at the end of Angus & Julia Stone’s ‘Draw Your swords’.
Highs
The upper frequencies are extended and delivered in a very subtle and sparkling way.
On Peter Gabriel's 'In Your Eyes' you can nicely hear the extended decay's slowly fade away.
Conclusion:
Overall I was happily surprised that I could still squeeze some extra musical performance out the TPA6120A2.
With the ss3601 I was able to hear new levels of detail combined with a very pleasant fluid emmersive smooth, forgiving and addicting sound with well separated instruments and a wide realistic soundstage.
In short I have been very happy with the OPA1611 but the Sparkos ss3601 does have the edge in more refined highs, sense of space and a more pitch black background and makes it easier to hear deeper into the recordings.
[Update]
I discovered that the sound of the Sparkos ss3601 further improved after 30+ hours of burn-in.
The bass was reduced somewhat in volume (in a positive way) and became even better defined and controled.
This resulted in a balanced, coherent, very detailed and smooth sound.
Apparently you should give these discrete opamps time to settle in order to show their full potential.
Attachments
Recently I upgraded my Zishan Z1 Digital Audio Player (DAP) with the Sparkos ss3602 discrete opamp.
In this short overview I would like to share my opinions and experiences with this upgrade.
Used headphones where AKG K712 Pro and Philips Fidelio X2
NE5532 is the default opamp of the Z1 DAP.
A few years ago after several tests and opamp swaps (including Muses8920, Muses8820, Burson V5i and LT1028) I settled on the Linear Technology LT1028. As these are single channel in a soic package you had to mount two on a dual 8 pin SOIC to 8 pin DIP PCB.
Compared to the default NE5532 the LT1028 gave the Z1 a much more refined, musical, warm and detailed sound. It should be stated however that the Z1 by default is on the warm side and it's bass can be a little uncontrolled and overwhelming.
Recently I upraded the prefered opamp (LT1028) with the Sparkos ss3602 which brought improvements in smoothness, detail retrieval, spaciousness and somewhat tamed the loose bass.
To my ears the ss3602 is the best sounding opamp for the Z1 but I am a little reluctant to advise this upgrade without reservations because the Z1 is a nice little DAP but has it's limitations that even a great sounding opamp like the Sparkos ss3602 cannot fully overcome.
On the other hand if your only concern is to get the best sounding opamp upgrade for the Z1 then the ss3602 should be on your list.
In this short overview I would like to share my opinions and experiences with this upgrade.
Used headphones where AKG K712 Pro and Philips Fidelio X2
NE5532 is the default opamp of the Z1 DAP.
A few years ago after several tests and opamp swaps (including Muses8920, Muses8820, Burson V5i and LT1028) I settled on the Linear Technology LT1028. As these are single channel in a soic package you had to mount two on a dual 8 pin SOIC to 8 pin DIP PCB.
Compared to the default NE5532 the LT1028 gave the Z1 a much more refined, musical, warm and detailed sound. It should be stated however that the Z1 by default is on the warm side and it's bass can be a little uncontrolled and overwhelming.
Recently I upraded the prefered opamp (LT1028) with the Sparkos ss3602 which brought improvements in smoothness, detail retrieval, spaciousness and somewhat tamed the loose bass.
To my ears the ss3602 is the best sounding opamp for the Z1 but I am a little reluctant to advise this upgrade without reservations because the Z1 is a nice little DAP but has it's limitations that even a great sounding opamp like the Sparkos ss3602 cannot fully overcome.
On the other hand if your only concern is to get the best sounding opamp upgrade for the Z1 then the ss3602 should be on your list.
Attachments
Recently I upgraded my Zishan Z3 Digital Audio Player (DAP) with the Sparkos ss3602 discrete opamp.
In this short overview I would like to share my opinions and experiences with this upgrade.
Used headphones where AKG K712 Pro and Philips Fidelio X2
LM4562 is the default opamp of the Z3 DAP.
Over time I have tested and swapped numerous opamps in the Z3 with mixed results:
Opa1641, Lt1028 and Muses8820 each have their strengths and weaknesses but are overall not better than the default LM4562.
The opamps that I valued better than the default opamp where: LME49720HA, Muses02, Muses8920, Opa827, Opa1612 and Opa2604. They improved dynamics, tranparency, high frequency extension and where ovarall more natural sounding.
These aspects were further improved by switching to the LT1057, Opa627, Opa2107, Burson V5i or AD825 and I finally settled on the latter (i.e. Analoque Devices AD825) for serveral years.
Recently I upraded my prefered opamp (AD825) with the Sparkos ss3602 which brought improvements in smoothness, detail retrieval and spaciousness.
Although the ss3602 is (in my opinion) the best sounding opamp for the Z3 in honesty I find it a little overkill because the Z3 has its limits and therefore does not utilize the full potential of ss3602.
On the other hand if you want the best possible sound quality the ss3602 deserves to be auditioned.
In this short overview I would like to share my opinions and experiences with this upgrade.
Used headphones where AKG K712 Pro and Philips Fidelio X2
LM4562 is the default opamp of the Z3 DAP.
Over time I have tested and swapped numerous opamps in the Z3 with mixed results:
Opa1641, Lt1028 and Muses8820 each have their strengths and weaknesses but are overall not better than the default LM4562.
The opamps that I valued better than the default opamp where: LME49720HA, Muses02, Muses8920, Opa827, Opa1612 and Opa2604. They improved dynamics, tranparency, high frequency extension and where ovarall more natural sounding.
These aspects were further improved by switching to the LT1057, Opa627, Opa2107, Burson V5i or AD825 and I finally settled on the latter (i.e. Analoque Devices AD825) for serveral years.
Recently I upraded my prefered opamp (AD825) with the Sparkos ss3602 which brought improvements in smoothness, detail retrieval and spaciousness.
Although the ss3602 is (in my opinion) the best sounding opamp for the Z3 in honesty I find it a little overkill because the Z3 has its limits and therefore does not utilize the full potential of ss3602.
On the other hand if you want the best possible sound quality the ss3602 deserves to be auditioned.
Attachments
