Orders are now open for Abbado III NOS DACs - DM me and be sure to mention your preferred payment method (Wise or Paypal) and location so I can quote you inclusive of fees and shipping. Abbado III is based on Abbado II architecturally but also includes an aspect of Celibidache's design hence is perhaps best seen as the merging of Celibidache and Abbado themes. Its DAC supply rails regulated by discrete transistors fed from IR LED voltage references but has a lower noise floor owing to the use of more paralleled TDA1545 DAC chips (24) and improved dynamics from a plug-in filter module which in stock form is 9th order (11th order by request). There is also the option to include an analog volume control to allow direct drive of a poweramp in systems with only digital sources. Use of an analog volume control beats a digital one in terms of SNR at lower listening levels. The physical footprint remains the same as Abbado II albeit slightly taller at 100mm * 70mm *24mm high - the fixing hole positions have moved though. We are using a 4 layer PCB and the DAC requires a single power rail of 9V at 270mA. Design wise, it's non-oversampling (i.e. there is no digital filter on-board) and the input format is I2S (three signal wire) at 44k1/16bits active within a 32bit frame. BCK is required to be 64fs (2.82MHz at 44k1 sample rate), MCK isn't required. Output is nominally 1.5VRMS with a 6dB gain reduction option on-board and a limited range of overall gain from a multi-turn trimmer. The gain reduction comes in handy when you want to use a pair of Abbados to create balanced outputs, the balanced output level can be kept the same as when unbalanced. In this configuration, the trimmer allows interchannel matching of output levels. Our I2S splitter board provides the functionality to run a pair of Abbados in balanced mode.
Preferred payment method is via Wise which typically adds a 2% fee. Our receiving currency is CNY, alternatively USD or Euro. PayPal may also be used, in USD but will attract higher fees, 5.5%.
Price for Abbado III built and tested, 9th order filter, with volume control : 1320RMB
11th order filter option : +120RMB
Omit volume control : -140RMB
Shipping is in addition and depends on your location and speed of service. Courier (FedEx, TNT, DHL) typically takes 8 - 10 days and e-packet four to eight weeks. Not all locations can be serviced by e-packet though.
FAQs
What else is needed to turn Abbado III into a fully operational DAC?
First, you'll need a well regulated low noise power supply of 9V rated at 270mA or higher. An LM317-based board set to the correct voltage will suffice if you already have an unregulated supply (like a typical wall-wart). The LM317 will need adequate heatsinking. I don't recommend switching supplies due to issues with common-mode noise, its very hard to filter out. That disrecommendation doesn't apply though when both the DAC and amp are within the same box as in our example below, in that case the CM noise isn't a worry. We have a suitable LM317-based board which takes in an AC feed from a mains transformer at 18V and down-regulates with a buck converter prior to the linear regulator. The use of the buck means it runs cool as the linear regulator is operated with just enough voltage drop to ensure good line rejection.
Second - you may need a digital interface card. I say 'may' because some digital sources produce I2S directly (like Raspberry Pi, dedicated SDcard players) but most sources will either output USB (like a PC or laptop) or S/PDIF coax (a CD or DVD player) or Toslink. We can supply a card for interfacing one (or more) of those sources to Abbado's I2S input. A CM6631A-based card for USB input is the premium choice as it operates under 'async USB' and offers up to 192k sample rates. However in stock form it isn't suitable because at 44.1kHz it outputs a 128fs BCK - when we supply such cards we upgrade the firmware for you to support a standard 64fs BCK. Async USB has the lowest jitter however given it operates under high-speed USB it needs a fairly expensive isolator to protect your DAC and amp from common-mode noise. A TE7022-based interface has the advantage of only needing a $5 full-speed USB isolator while still offering up to 96k sample rates and is normally cheaper than a CM6631A board. For S/PDIF inputs, the board we recommend handles both coax (two inputs) and Toslink. Further, it has a switched I2S input - this can accept I2S from the USB source. A single pole switch acts as source selector, cycling through the inputs. An OLED screen is an option to indicate the selected input. This board needs a 5-12V supply, so it is fine being run direct from the DAC's 9V rail.
Third you'll be wanting some output sockets, typically RCAs so you can connect your finished DAC to your amp or preamp. We can supply these and we also have a PCB to mount them to make outputting Abbado to your system easier. XLRs would be the recommended way to output in balanced mode.
Lastly, and this is obviously optional for a DIYer, is a case. We haven't supplied cases in the past because they're so heavy (i.e. expensive to ship).
USB CM6631A card examples : https://www.aliexpress.com/item/32874113831.html www.aliexpress.com/item/1005004083748180.html
TE7022 interface example : https://www.aliexpress.com/item/1005005388553366.html
USB isolator, full speed : https://www.aliexpress.com/item/1005001369085297.html
USB isolator, high speed : https://www.aliexpress.com/item/1005001379930133.html
Multi-input S/PDIF card : https://www.aliexpress.com/item/1005002923079600.html
Coax/Toslink S/PDIF card : https://www.aliexpress.com/item/1005002772984954.html
What's supplied with the DAC?
The inputs and outputs of Abbado use Molex type 2510 4pin connectors which mate with a shell containing crimp-terminated wires. We supply those wires pre-crimped with shells along with the DAC. If you buy an input board through us we'll also provide the I2S cable ready-made to suit that board. If you buy our PCB mounted RCAs we'll include the 4 wire cable to interface to that.
What, if anything, is unique about Abbado's design?
Commercial NOS DACs typically have minimal filtering after the DAC chip itself whereas Abbado has a steep (9th or 11th order) low-pass passive filter afterwards. By strongly attenuating the NOS image frequencies this LC filter improves dynamics and makes the aural picture more clearly delineated with acoustic instruments having a well defined position in space. Passive filters like this are extremely difficult to implement using off-the-shelf inductors as no commercially available ones have sufficiently close tolerance. So Abbado's inductors are custom, hand-wound using gapped ferrite P14 cores. Having a passive filter prior to any active analog stage means the downstream discrete buffer stage no longer 'sees' a step waveform out of the DAC chip, rather a continuous signal. The volume control option uses the lowest resistance ALPS pot available (5k) so as to add the least extra noise, its driven directly from the I/V resistor which is only possible because of the substantial output current from the array of TDA1545s. Abbado's DAC chips are 'multibit' but they're not strictly speaking 'R2R' as internally they use no resistors. Instead, capacitors are used as elements in the DAC which have their charge constantly refreshed (similar to the DRAM in your computer) to compensate for any drift. By paralleling 24 of these devices and running them at higher current levels than typically used, the noise floor is considerably lower than with a single chip - this translates in practice to a 'warmer' sound where the acoustic ambience captured on a recording is more easily perceived. In order to achieve retrieval of these low-level ambience cues, the DACs' power rails need to be extremely clean and this is achieved through use of a pair of discrete series regulators fed from an IR LED derived reference voltage.
The development of Abbado III has taken place over several years and it builds on and improves prior designs, most particularly it draws its heritage from Celibidache. While Celibidache used an array of 20 TDA1387s, Abbado swapped the DAC chips to TDA1545 because each chip has a 3dB improvement in SNR compared to TDA1387. Thus Celi's already black background has been darkened further. Celi used a pair of current sources to 'steer' the current into the I/V resistor whereas on Abbado I've been able to delete one of those CCSs with the aim of further lowering the noise. The last improvement over Celibidache has been made in the output stage - its now fully discrete whereas Celi used a very low noise opamp. The discrete nature of the output stage seems to contribute a more relaxed sound, particularly in the higher frequencies.
Abbado III is well-suited to the creation of a convenient 'all-in-one' box - aka a 'DAC-AMP' using its volume control option. Here's a picture of an Abbado (green PCB bottom right), minus filter to reveal the DAC array, in such a configuration. There are two power supplies - a 24V SMPSU top left for the amps (our own monoAMPs) and a hybrid linear-buck for the Abbado DAC. The input board (yellow colour bottom left) supports USB, Bluetooth and S/PDIF - switching of sources is done with a push-button on the front panel with LEDs for indication.
Preferred payment method is via Wise which typically adds a 2% fee. Our receiving currency is CNY, alternatively USD or Euro. PayPal may also be used, in USD but will attract higher fees, 5.5%.
Price for Abbado III built and tested, 9th order filter, with volume control : 1320RMB
11th order filter option : +120RMB
Omit volume control : -140RMB
Shipping is in addition and depends on your location and speed of service. Courier (FedEx, TNT, DHL) typically takes 8 - 10 days and e-packet four to eight weeks. Not all locations can be serviced by e-packet though.
FAQs
What else is needed to turn Abbado III into a fully operational DAC?
First, you'll need a well regulated low noise power supply of 9V rated at 270mA or higher. An LM317-based board set to the correct voltage will suffice if you already have an unregulated supply (like a typical wall-wart). The LM317 will need adequate heatsinking. I don't recommend switching supplies due to issues with common-mode noise, its very hard to filter out. That disrecommendation doesn't apply though when both the DAC and amp are within the same box as in our example below, in that case the CM noise isn't a worry. We have a suitable LM317-based board which takes in an AC feed from a mains transformer at 18V and down-regulates with a buck converter prior to the linear regulator. The use of the buck means it runs cool as the linear regulator is operated with just enough voltage drop to ensure good line rejection.
Second - you may need a digital interface card. I say 'may' because some digital sources produce I2S directly (like Raspberry Pi, dedicated SDcard players) but most sources will either output USB (like a PC or laptop) or S/PDIF coax (a CD or DVD player) or Toslink. We can supply a card for interfacing one (or more) of those sources to Abbado's I2S input. A CM6631A-based card for USB input is the premium choice as it operates under 'async USB' and offers up to 192k sample rates. However in stock form it isn't suitable because at 44.1kHz it outputs a 128fs BCK - when we supply such cards we upgrade the firmware for you to support a standard 64fs BCK. Async USB has the lowest jitter however given it operates under high-speed USB it needs a fairly expensive isolator to protect your DAC and amp from common-mode noise. A TE7022-based interface has the advantage of only needing a $5 full-speed USB isolator while still offering up to 96k sample rates and is normally cheaper than a CM6631A board. For S/PDIF inputs, the board we recommend handles both coax (two inputs) and Toslink. Further, it has a switched I2S input - this can accept I2S from the USB source. A single pole switch acts as source selector, cycling through the inputs. An OLED screen is an option to indicate the selected input. This board needs a 5-12V supply, so it is fine being run direct from the DAC's 9V rail.
Third you'll be wanting some output sockets, typically RCAs so you can connect your finished DAC to your amp or preamp. We can supply these and we also have a PCB to mount them to make outputting Abbado to your system easier. XLRs would be the recommended way to output in balanced mode.
Lastly, and this is obviously optional for a DIYer, is a case. We haven't supplied cases in the past because they're so heavy (i.e. expensive to ship).
USB CM6631A card examples : https://www.aliexpress.com/item/32874113831.html www.aliexpress.com/item/1005004083748180.html
TE7022 interface example : https://www.aliexpress.com/item/1005005388553366.html
USB isolator, full speed : https://www.aliexpress.com/item/1005001369085297.html
USB isolator, high speed : https://www.aliexpress.com/item/1005001379930133.html
Multi-input S/PDIF card : https://www.aliexpress.com/item/1005002923079600.html
Coax/Toslink S/PDIF card : https://www.aliexpress.com/item/1005002772984954.html
What's supplied with the DAC?
The inputs and outputs of Abbado use Molex type 2510 4pin connectors which mate with a shell containing crimp-terminated wires. We supply those wires pre-crimped with shells along with the DAC. If you buy an input board through us we'll also provide the I2S cable ready-made to suit that board. If you buy our PCB mounted RCAs we'll include the 4 wire cable to interface to that.
What, if anything, is unique about Abbado's design?
Commercial NOS DACs typically have minimal filtering after the DAC chip itself whereas Abbado has a steep (9th or 11th order) low-pass passive filter afterwards. By strongly attenuating the NOS image frequencies this LC filter improves dynamics and makes the aural picture more clearly delineated with acoustic instruments having a well defined position in space. Passive filters like this are extremely difficult to implement using off-the-shelf inductors as no commercially available ones have sufficiently close tolerance. So Abbado's inductors are custom, hand-wound using gapped ferrite P14 cores. Having a passive filter prior to any active analog stage means the downstream discrete buffer stage no longer 'sees' a step waveform out of the DAC chip, rather a continuous signal. The volume control option uses the lowest resistance ALPS pot available (5k) so as to add the least extra noise, its driven directly from the I/V resistor which is only possible because of the substantial output current from the array of TDA1545s. Abbado's DAC chips are 'multibit' but they're not strictly speaking 'R2R' as internally they use no resistors. Instead, capacitors are used as elements in the DAC which have their charge constantly refreshed (similar to the DRAM in your computer) to compensate for any drift. By paralleling 24 of these devices and running them at higher current levels than typically used, the noise floor is considerably lower than with a single chip - this translates in practice to a 'warmer' sound where the acoustic ambience captured on a recording is more easily perceived. In order to achieve retrieval of these low-level ambience cues, the DACs' power rails need to be extremely clean and this is achieved through use of a pair of discrete series regulators fed from an IR LED derived reference voltage.
The development of Abbado III has taken place over several years and it builds on and improves prior designs, most particularly it draws its heritage from Celibidache. While Celibidache used an array of 20 TDA1387s, Abbado swapped the DAC chips to TDA1545 because each chip has a 3dB improvement in SNR compared to TDA1387. Thus Celi's already black background has been darkened further. Celi used a pair of current sources to 'steer' the current into the I/V resistor whereas on Abbado I've been able to delete one of those CCSs with the aim of further lowering the noise. The last improvement over Celibidache has been made in the output stage - its now fully discrete whereas Celi used a very low noise opamp. The discrete nature of the output stage seems to contribute a more relaxed sound, particularly in the higher frequencies.
Abbado III is well-suited to the creation of a convenient 'all-in-one' box - aka a 'DAC-AMP' using its volume control option. Here's a picture of an Abbado (green PCB bottom right), minus filter to reveal the DAC array, in such a configuration. There are two power supplies - a 24V SMPSU top left for the amps (our own monoAMPs) and a hybrid linear-buck for the Abbado DAC. The input board (yellow colour bottom left) supports USB, Bluetooth and S/PDIF - switching of sources is done with a push-button on the front panel with LEDs for indication.
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Interesting- Any more details / pictures / walkthrough on the boards and their development?
Thanks for the comment - I've now added some more eye candy and a further paragraph on the heritage of Abbado's design. Would a block diagram help?