Thorsten Loesch
Member of the Trade: Studio RaumklanG, Studio Cocktail
Folks,
One of the last products I designed before leaving iFi/AMR was the original Zen Series. The aim was to make high value products. As a result some compromises were made. The biggest compromise was in the power supplies.
Still I liked them enough to keep a 6XX signature ZEN DAC & ZEN CAN set for myself when I left iFi. And external power supplies can be upgraded.
By making all power supplies 5V and external, very inexpensive switching chargers can be used as power source, keeping the cost of the final product down. The ZEN Dac even run's on USB power, though it can be supplied externally, with a number of benefits.
The actual IC used in the ZEN Can and the ZEN Phono to create +/-12V rails from 5V can handle 5A maximum. But the shipping power supply is limited to 2.4A, as shown in the Photo from Amir at audiosciencereview:
I had recommended a minimum of 4A to be included when I designed the ZEN Can, but what is shipped is 2.4A I guess to further lower production cost or in some bundles a iFi iPower with 5V/3A. Both are marginal and limit power into low impedances and to me also the subjective sense of dynamics and impact when driving medium impedance headphones.
The problem is that the ZEN Can idles at around 2A (10W) current draw, a little more when starting up cold. This means there is little extra power left to power low impedance headphones
So naturally Amir (and many others) complained that that ZEN Can struggles into low impedance headphones. The limit is supplied power adapter.
Driving my own heavily modified Fostex T50RP balanced from a ZEN CAN did show I was also running into power limits.
Additionally the ZEN DAC sounded ok on USB power but I expected more. An iFi iPower lifted up sound quality, but coming from a iFi Pro Set as daily driver I still felt I wanted more...
So of course, we can go and buy a 5V/5A power adapter. There are not that many readily available, what can be found is of unknown quality. While the double conversion system of the Zen CAN (Mains AC -> 5V DC -> +/- 12V DC) isolates the audio circuit from the noise of the AC Adapter, noise leakage from mains and/or pollution of mains for other gear may make problems.
Ok, so let's buy a 5V/5A linear power supply and another smaller linear supply for the Zen DAC. Something nice and audiophile. Quel dommage! We can drop a lot of money here. And ZEN line products were designed to be 99 to 199 USD... No way I'm dropping 200 USD on a power supply for a 129 USD DAC!
Do we have another option? For the DAC, we can get a basic linear PSU, like this one:
https://www.aliexpress.us/item/3256801490595838.html
It is very basic, but I got one from Aliexpress for 13 USD and modified it a little. Sadly this unit seems unavailable now, similar if more expensive supplies can still be found.
Testing it reveals a very low leakage capacitance between mains and output, at around 16pF, which is six times lower than even the iFi iPower at ~ 100pF and 137 times lower than a cooking switched mode adapter commonly showing 2.200pF. That makes a HUGE difference.
Inside are discrete rectifier diodes, there was a 2200uF filter capacitor and a 7805 equivalent Regulator IC with heatsink. What do you expect for 13 USD?
I changed the diodes to schottky diodes from my stock and added a number of capacitors for better high frequency noise stability and to make sure the regulator runs reliably stable.
The PSU worked fine on the ZEN DAC, it may have sounded slightly better than the iFi iPower, which sells by now at 69 USD, which is hardly cheap. So in this case, 13 USD and a little DIY is definitely saving us a decent chunk of cash.
But can we do better?
Well, when planning the ZEN line I had planned for ZEN module with Super Capacitor banks, to use existing supplies and create a "Super Capacitor Buffered Power Supply Unit", or SCBPSU, with lower noise and much increased peak current capability. This was never greenlighted, but we can do a very cheap and simple DIY Job.
We can DIY such supply easily and aliexpress has low cost Super Capacitors. I used CDA branded ones, they are now in short supply and expensive. Currently I might order from this store, which seems to have identical devices with different branding:
https://www.aliexpress.us/item/3256801165053418.html
Personally I used 20-pcs of 0.5F/5.5V to buffer the 1A linear power supply. There is a reason to use 20pcs 0.5F to make one 10F bank, instead of buying a single 10F device. Supercapacitors have fairly high Equivalent Series Resistance (ESR) meaning they cannot very effectively lower noise and will have limited current delivery.
The 0.5F/5.5V types I paralleled have 0.3 Ohm ESR, 20pcs in parallel will produce a 10F/0.015Ohm (15mOhm) capacitor, at a cost of around 10USD. Yes, this nearly doubles our PSU Cost, but we are rewarded with ten times lower noise and the ability to sustain quite high peak currents by combining the cheap(est) modified linear power supply with cheap super capacitors. A total of under 30 USD for this power supply makes it a bit of a bargain.
After plugging in the new supply into the ZEN DAC and having a listen, I was like "now we are cooking with gas!". Certainly the distance to a Pro iDSD in solid state mode was much less. Enough less for me to not care. Which Firmware? I'm on the GTO one. Up to you though. Try and listen.
Personally, for mechanical arrangement I went full on coyote (ugly) and just soldered the capacitors directly together, cut the wire from the PSU and left a 5cm tail with plug after the super capacitor bank. A little electrical tape finished up the job for that "hardcore coyote ugly DIY look"!
Of course you can make nice boxes and add voltage indications and all that jazz? Why? I rather spend the time listening.
It's suitable for anything that needs 5V with no more than 1A continuous draw, realistically using a load tester the PSU crapped out at 900mA, well it is cheap. In the Zen lineup it's an obvious choice for pimping your Zen DAC or Zen Phono. Especially the ZEN Phono should get a significant boost.
Otherwise, anything that is normally powered from USB or needs 5V with < 900mA should be fine.
As for how ugly "Coyote Ugly DIY" can be here a picture. It also shows however how quick and easy it gets. The smaller bank at the bottom is the 5V/1A/10F SCBPSU.
One significant issue from the extreme simplicity, the 1A PSU needs around 10 Minutes to fully charge up from "cold" and there is very limited protection beyond the protection of the power supply itself. In practice this is no issue and the arrangement shown has been in use reliably and without degradation of the super capacitors for nearly 3 years, throughout covid lockdowns and all that jazz.
Sadly this PSU is not enough to power a ZEN CAN. I originally considered using 3pcs of these supplies in parallel or buying a relatively expensive (~ 50 USD) 5V/4A linear unit. But I happend to have the iPower(s) in 5V at hand and having designed them I knew just how good or bad they are.
Why spend money I don't have to? I think even the generic 5V/2.4A SMPS iFi ships will be fine to front the SCBPSU, but have not tried it. If I personally had the basic 2.4A PSU I would probably drop the 50 USD or so to buy something similar to this "40W" linear Power Supply (on 5V it really is only 20W):
https://www.aliexpress.us/item/3256801584320437.html
As is I used the iFi iPower 5V I had and added a truly massive Supercapacitor bank, 7.5F/5.5V/0.1Ohm X 20 adding 25 USD to the cost of the base power supply. This gives a 150F/0.005Ohm capacitor and prodigious peak current capability. It takes even longer to charge this bank from the 3A iFi iPower.
But once the super capacitor bank is full and plugged in, the difference is way bigger with my Fostex than on the DAC. I am not sure if the "supercapacitor charged" Zen or the Pro iCAN in solid state mode would win, on sonic memory it would be at least a fight.
Bottom line, Signature ZEN DAC and ZEN CAN with supercharged power supplies go a long way to bridge the gap in sound quality to the Pro Stack. Of course, the Pro Stack has many features and options the Supercharged ZEN Signature stack misses. They are nice to have but not essential for me.
Internally I modified the ZEN CAN from the 6XX EQ to have the perfect EQ for my Fostex T50RP (mod), this actually gives a better fit of LF EQ conture than the Pro iCAN has and of course there is no mid/treble EQ option on the Pro iCAN. I do miss the extra cream and caramel syrup tube mode gives a bit, but it's quite bearable.
Well, that's it. My take, if you have either standard or signature ZEN's, upgrade your power first.
After that, if you have the skills to work internally with surface mounted parts, upgrade the stock ZEN's to signature level. It's just replacing all SMD electrolytic Capacitors with either Panasonic Os-Con (power supplies) or Elna Silmic/Cerafine/Starget for the Audio section. These do make notable differences, but not as much as the power supplies.
After that the Zen CAN will do most Headphones I can think of justice and the stack will be a really high sound quality setup.
GOAT? Probably no. But who cares....
To para-quote Macklemore: "But sh!t, it was a hell of a lot less than 999 Bux!"...
Should you buy a ZEN set now, at the new prices?
Up to you, I would not be enthusiastic.
But pick up an original set second hand, haggle like a rug seller and make the seller cry, upgrade it and you be like:
"I'm gonna pop some tags
Only got few dollars in my pocket
I, I, I'm hunting, looking for a come-up
This is f...ing awesome"
Thor
One of the last products I designed before leaving iFi/AMR was the original Zen Series. The aim was to make high value products. As a result some compromises were made. The biggest compromise was in the power supplies.
Still I liked them enough to keep a 6XX signature ZEN DAC & ZEN CAN set for myself when I left iFi. And external power supplies can be upgraded.
By making all power supplies 5V and external, very inexpensive switching chargers can be used as power source, keeping the cost of the final product down. The ZEN Dac even run's on USB power, though it can be supplied externally, with a number of benefits.
The actual IC used in the ZEN Can and the ZEN Phono to create +/-12V rails from 5V can handle 5A maximum. But the shipping power supply is limited to 2.4A, as shown in the Photo from Amir at audiosciencereview:
I had recommended a minimum of 4A to be included when I designed the ZEN Can, but what is shipped is 2.4A I guess to further lower production cost or in some bundles a iFi iPower with 5V/3A. Both are marginal and limit power into low impedances and to me also the subjective sense of dynamics and impact when driving medium impedance headphones.
The problem is that the ZEN Can idles at around 2A (10W) current draw, a little more when starting up cold. This means there is little extra power left to power low impedance headphones
So naturally Amir (and many others) complained that that ZEN Can struggles into low impedance headphones. The limit is supplied power adapter.
Driving my own heavily modified Fostex T50RP balanced from a ZEN CAN did show I was also running into power limits.
Additionally the ZEN DAC sounded ok on USB power but I expected more. An iFi iPower lifted up sound quality, but coming from a iFi Pro Set as daily driver I still felt I wanted more...
So of course, we can go and buy a 5V/5A power adapter. There are not that many readily available, what can be found is of unknown quality. While the double conversion system of the Zen CAN (Mains AC -> 5V DC -> +/- 12V DC) isolates the audio circuit from the noise of the AC Adapter, noise leakage from mains and/or pollution of mains for other gear may make problems.
Ok, so let's buy a 5V/5A linear power supply and another smaller linear supply for the Zen DAC. Something nice and audiophile. Quel dommage! We can drop a lot of money here. And ZEN line products were designed to be 99 to 199 USD... No way I'm dropping 200 USD on a power supply for a 129 USD DAC!
Do we have another option? For the DAC, we can get a basic linear PSU, like this one:
https://www.aliexpress.us/item/3256801490595838.html
It is very basic, but I got one from Aliexpress for 13 USD and modified it a little. Sadly this unit seems unavailable now, similar if more expensive supplies can still be found.
Testing it reveals a very low leakage capacitance between mains and output, at around 16pF, which is six times lower than even the iFi iPower at ~ 100pF and 137 times lower than a cooking switched mode adapter commonly showing 2.200pF. That makes a HUGE difference.
Inside are discrete rectifier diodes, there was a 2200uF filter capacitor and a 7805 equivalent Regulator IC with heatsink. What do you expect for 13 USD?
I changed the diodes to schottky diodes from my stock and added a number of capacitors for better high frequency noise stability and to make sure the regulator runs reliably stable.
The PSU worked fine on the ZEN DAC, it may have sounded slightly better than the iFi iPower, which sells by now at 69 USD, which is hardly cheap. So in this case, 13 USD and a little DIY is definitely saving us a decent chunk of cash.
But can we do better?
Well, when planning the ZEN line I had planned for ZEN module with Super Capacitor banks, to use existing supplies and create a "Super Capacitor Buffered Power Supply Unit", or SCBPSU, with lower noise and much increased peak current capability. This was never greenlighted, but we can do a very cheap and simple DIY Job.
We can DIY such supply easily and aliexpress has low cost Super Capacitors. I used CDA branded ones, they are now in short supply and expensive. Currently I might order from this store, which seems to have identical devices with different branding:
https://www.aliexpress.us/item/3256801165053418.html
Personally I used 20-pcs of 0.5F/5.5V to buffer the 1A linear power supply. There is a reason to use 20pcs 0.5F to make one 10F bank, instead of buying a single 10F device. Supercapacitors have fairly high Equivalent Series Resistance (ESR) meaning they cannot very effectively lower noise and will have limited current delivery.
The 0.5F/5.5V types I paralleled have 0.3 Ohm ESR, 20pcs in parallel will produce a 10F/0.015Ohm (15mOhm) capacitor, at a cost of around 10USD. Yes, this nearly doubles our PSU Cost, but we are rewarded with ten times lower noise and the ability to sustain quite high peak currents by combining the cheap(est) modified linear power supply with cheap super capacitors. A total of under 30 USD for this power supply makes it a bit of a bargain.
After plugging in the new supply into the ZEN DAC and having a listen, I was like "now we are cooking with gas!". Certainly the distance to a Pro iDSD in solid state mode was much less. Enough less for me to not care. Which Firmware? I'm on the GTO one. Up to you though. Try and listen.
Personally, for mechanical arrangement I went full on coyote (ugly) and just soldered the capacitors directly together, cut the wire from the PSU and left a 5cm tail with plug after the super capacitor bank. A little electrical tape finished up the job for that "hardcore coyote ugly DIY look"!
Of course you can make nice boxes and add voltage indications and all that jazz? Why? I rather spend the time listening.
It's suitable for anything that needs 5V with no more than 1A continuous draw, realistically using a load tester the PSU crapped out at 900mA, well it is cheap. In the Zen lineup it's an obvious choice for pimping your Zen DAC or Zen Phono. Especially the ZEN Phono should get a significant boost.
Otherwise, anything that is normally powered from USB or needs 5V with < 900mA should be fine.
As for how ugly "Coyote Ugly DIY" can be here a picture. It also shows however how quick and easy it gets. The smaller bank at the bottom is the 5V/1A/10F SCBPSU.
One significant issue from the extreme simplicity, the 1A PSU needs around 10 Minutes to fully charge up from "cold" and there is very limited protection beyond the protection of the power supply itself. In practice this is no issue and the arrangement shown has been in use reliably and without degradation of the super capacitors for nearly 3 years, throughout covid lockdowns and all that jazz.
Sadly this PSU is not enough to power a ZEN CAN. I originally considered using 3pcs of these supplies in parallel or buying a relatively expensive (~ 50 USD) 5V/4A linear unit. But I happend to have the iPower(s) in 5V at hand and having designed them I knew just how good or bad they are.
Why spend money I don't have to? I think even the generic 5V/2.4A SMPS iFi ships will be fine to front the SCBPSU, but have not tried it. If I personally had the basic 2.4A PSU I would probably drop the 50 USD or so to buy something similar to this "40W" linear Power Supply (on 5V it really is only 20W):
https://www.aliexpress.us/item/3256801584320437.html
As is I used the iFi iPower 5V I had and added a truly massive Supercapacitor bank, 7.5F/5.5V/0.1Ohm X 20 adding 25 USD to the cost of the base power supply. This gives a 150F/0.005Ohm capacitor and prodigious peak current capability. It takes even longer to charge this bank from the 3A iFi iPower.
But once the super capacitor bank is full and plugged in, the difference is way bigger with my Fostex than on the DAC. I am not sure if the "supercapacitor charged" Zen or the Pro iCAN in solid state mode would win, on sonic memory it would be at least a fight.
Bottom line, Signature ZEN DAC and ZEN CAN with supercharged power supplies go a long way to bridge the gap in sound quality to the Pro Stack. Of course, the Pro Stack has many features and options the Supercharged ZEN Signature stack misses. They are nice to have but not essential for me.
Internally I modified the ZEN CAN from the 6XX EQ to have the perfect EQ for my Fostex T50RP (mod), this actually gives a better fit of LF EQ conture than the Pro iCAN has and of course there is no mid/treble EQ option on the Pro iCAN. I do miss the extra cream and caramel syrup tube mode gives a bit, but it's quite bearable.
Well, that's it. My take, if you have either standard or signature ZEN's, upgrade your power first.
After that, if you have the skills to work internally with surface mounted parts, upgrade the stock ZEN's to signature level. It's just replacing all SMD electrolytic Capacitors with either Panasonic Os-Con (power supplies) or Elna Silmic/Cerafine/Starget for the Audio section. These do make notable differences, but not as much as the power supplies.
After that the Zen CAN will do most Headphones I can think of justice and the stack will be a really high sound quality setup.
GOAT? Probably no. But who cares....
To para-quote Macklemore: "But sh!t, it was a hell of a lot less than 999 Bux!"...
Should you buy a ZEN set now, at the new prices?
Up to you, I would not be enthusiastic.
But pick up an original set second hand, haggle like a rug seller and make the seller cry, upgrade it and you be like:
"I'm gonna pop some tags
Only got few dollars in my pocket
I, I, I'm hunting, looking for a come-up
This is f...ing awesome"
Thor
Last edited:
