I was asked by a friend to upgrade his Havana DAC with some better capacitors and non magnetic resistors in key locations which he supplied. This is the result and these are Val's ideas for upgrades. Output coupling is now by Clarity caps with Glass based Russian silver mica and BlackGate caps used elsewhere except the power supply which keep the original Gold Muse caps. This DAC uses a classic Bur Brown PCM56P chip with a simple form of conversion using matched resistors in a ladder configuration. This results in less signal manipulation during the conversion process. Those clarity caps are huge and only just fit in the case and I had to fit them rotated 90 degrees compared to the originals. These would not be my choice for practical reasons of fitting as the unit is very compact. Other upgrades include Silver WBT RCA sockets and flat sliver wire on the output plus a gel tube damper socket, although a Teflon socket could be used here instead. Build quality as standard is good with Nichicon Muse Gold electrolytic capacitors along with regular film foil caps used else-where.
Non polar capacitors are best used in key dac chip locations and regular polar caps are fine for the psu and tube output stage. Silver Mica caps have been used to replace some of the more important 0.01uF caps. Silver mica caps are very stable and superior to film caps. However large silver mica are difficult to make without problems and it is rare to find anything above a few 10nF, although I have a pair of 0.1uF 500V specially made by DiyHS.
Other possible upgrades include film caps on the PSU, maybe choke loaded, dual power supply or a battery supply for the lower voltages. However all these require an external supply case with a connecting cord, either fixed or detachable. I am sure this would make further improvements but you need to decide if it is worth the extra cost and time or just buy a better DAC with a dual power supply to begin with.
On testing, the sound is good and with these mods resolves more detailed than standard. This DAC arks back to the traditional non up-sampling, non oversampling (NOS), 16 bit days. This is a compact little DAC and good value if you can find one 2nd hand on eBay or in the classifieds if a bit expensive brand new imported to the UK for what it is. The Havana is natural sounding and free from the digital signature and hash that some DAC's and CD Players chuck out.
This Havana has been compared to an heavily upgraded Sony DAS-R1 DAC. The DAS-R1 was sony's reference DAC back in the day (1987 - 1990) which uses 2 x TDA1541A Crown chips with a complex dual power supply. The Sony had a bigger sound-stage and more fleshed out sound, making the Havana sound small in comparison. However this is a little unfair as it was comparing an 800 USD DAC with a Sony that cost 2.5K GBP in 1990 with over 1.5K GBP worth of expensive upgrades and mods.
The Havana was more etched and detailed esp in the mid and upper bands compared to the reference Sony. The Sony paints a large scale picture with broad brush strokes were-as the Havana is a smaller finer picture. The speakers used in this test were Tannoy Gold's, with heavily uprated cross-overs, and some rather expensive amplification. I think in a more modest system were the Havana is likely to be used, the difference between the Sony and Havana would not be quite so obvious. It really depends on the level of your HiFi and how revealing it is. I have heard the Havana in 4 systems including my own modest system; and in only the most expensive was the Havana clearly out ranked.
Therefore, if you are in the market for a DAC under 1000 USD it is worth considering the Havana, along with something like the TDA1541A Satch DAC for example, if you cannot go down the DIY route and make your own. Also bare in mind the Havana can be modified with better parts, de-coupling caps, output caps and resistors like here. Also the Havana has a USB port were some DAC's do not so this makes it suitable for direct connection to your computer eliminating the transport mechanism.
Tube and DAC Rolling
The Havana has no digital filters after the DAC chip and no Op-amps at all. It is a Single Ended tube buffered output using a 5670. Other tubes can be used such as 5670, 2C51, 396A, 6385, 6CC42, 6854, 6N3, 6854, CV2575, CV4013, CV5894, CV8247 and CV2381 so much room for tube rolling without circuit mods. The DAC chip can also be substituted for an Analog Devices 1856 as they are pin compatible.
MHDT Labs make a few other NOS style DAC's so they might be worth investigating such as the TDA1541 version although I have no experience of the others and what they sound like.