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October 17, 2017

Fender Champ 5F1 Guitar Amp DIY Build

If you are looking for a simple guitar amp circuit with great tone and you don't need a lot of power, the Champ 5F1 is a great choice. The Champ 5F1 was introduced by Fender in 1958 and were produced in tweed covered cabinets until 1964 when the "Blackface" circuit and cabinets were introduced. The 5F1 features 6 capacitors (+1 additional bypass if desired), 12 resistors, 3 tubes, and one potentiometer. Not only is a simple circuit harder to screw up, it's easy on the wallet too! The output is a modest 5 watts, which is great for practice and studio work. There are some chunkier transformers that let you bump up to 15 watts with a tube and resistor swap if desired.

The Champ 5F1 starts its life as a turret board. If you're not familiar, these were very common in the 50s and 60s, where axial capacitors and resistors were lined up on the board. Why I wasn't alive back then, I assume this made electronics easier to fix for the visiting repairman, who could simply look at the board and see where the problem component is and replace it easily. The use of these faded as electronics were more commonly replaced rather than fixed. You can easily find one pre-made for the 5F1 on Ebay, Watts Tube Audio or buy a black FR4 board, drill the holes and affix the turrets yourself (It's fun!). You can get the tools to do that at Watts Tube Audio as well... I encourage you to support them, they are a great small business and a source for myriad board designs. 

A classic turret board

Adding the caps and resistors is easy, just ensure the leads are long enough. Some carbon comp resistors from Mouser were too short I found. The parts used here are Illinois Capacitor electrolytics and Koa Speers / Kiwame resistors. Some people prefer Sprague for the axial caps, however I've heard from a trusted source that he's experienced failures first-hand with them, so I steer clear. F&T is the only other high voltage axial capacitor maker that I am aware of. It's a niche market, so we're lucky we have three options.





Next, you'll need a chassis. While I often drill my own, sometimes it's nice to take a little break and get a pre-fab one. This one is from Tube Audio Supply and is very high quality. They supply a number of colors in addition to the typical polished/chrome, great for a personalized look.  

Tube Audio Supply 5F1 chassis in Oxblood Red

After much reading regarding transformers, ClassicTone by Magnetic Components seemed to be the best bang for the buck. I chose the 10-18019 model, 5/15 watt version for power. As you can see below they aren't too easy on the eyes, there's quite a bit of errant varnish. 


ClassicTone 10-18019

It also may have been the end of the day on Friday when they put this one together. The nylon washer broke off inside so the builder put a few lock washers there instead.



A little bit of elbow grease, paint and new screws/nylon washers go a long way. 


Before

After
...too bad, as I liked their logo on the bell. Aside from the visual issues, the transformers seem very solid. 

Below is the unit with the mostly-populated turret board in place. The light is the typical Fender jewel style that I like to use on pretty much everything. 1/4" jacks are Switchcraft, and tube sockets are Belton. The pot is a high quality PEC unit from Canada, which I feel is worth the extra scratch over CTS / Alpha. 




Getting all the wiring correct is important, and a little tricky as there isn't a ton of room once everything is in place. I highly encourage you to visit Rob Robinette's fantastic page on the Champ 5F1. It lays out all the parts and their purpose, as well as optional parts. Rob is an awesome guy. I once messaged him to donate some funds for site maintenance as I was building one of his designs and he told me "just buy yourself a few beers, I do this because I love it". Also on the page are various guitar mods, headphone circuits, car tweaks, you name it. 

Next we need a cabinet to drop this puppy in. I had one custom made for me by a Jim, who goes by tubeampcabinets on Ebay. The work is phenomenal, with Spalted Maple and Purple Heart accents. I highly recommend you reach out to him via Ebay to get yourself a nice cab yourself.

Beautiful Cab from Jim, Ebay user TubeAmpCabinets

While it's not necessary, I had some spare damping material which I added to the box to prevent standing waves. 



The driver I chose is an 8" 4 ohm ceramic from Jupiter Condenser. Anyone who's followed my blog knows I love Jupiter's capacitors, they have a warm, natural tone that does music right, so I HAD to try a Jupiter driver. 

Jupiter Condenser 8" ceramic cone woofer



It's a beauty in what looks like a hammertone green powdercoat. For $50 it's a straight-up bargain, considering the caps can cost many times that. The AlNiCo versions are notably more expensive, but there isn't an 8 inch version of those yet. It will likely give me an excuse to build something a little bigger ;)

Below you'll see the unit with everything fitted, including the Red Astron Jupiter tone caps and a burgundy hospital grade power cord that I purchased from a surplus electronics store. As the PEC pot did not include a switch, I added one, a surplus Carling SPST, thus the 2 Amp fuse had to be mounted inside the chassis vs. a panel mount. 

One of the greatest things about the Champ is that there are many NOS tubes out there for dirt cheap. I got a handful of 5Y3 rectifiers and 6V6 power tubes for a song online. You'll find plenty for around $10 each. The 12AX7 is going to be a little more pricey , but still much more reasonable than say a 6922. I had a spare Yugoslavian Ei from the 80s that I dropped in, nice and smooth sounding. If NOS is too expensive, there are many good new production 12AX7s out there. I personally like the long-plate Sovtek 12AX7-LPS, which are about $15 a pop.  

Cool looking red power cord sourced from an electronics surplus shop

The knob I chose was one I had in-hand. It needed to be milled a bit to fit, but I liked it a little better than the red chicken head knob I had selected for the amp initially. 

Milled aluminum knob for a custom look

What a beauty!

The result, beautiful tone from an amp that's very easy on the eyes. 

Please remember that building/modifying circuits can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. 






October 4, 2017

Low Cost DIY Personal Guitar Amp

Anyone who does DIY knows it can be expensive at times. As the dollar weakens and metal commodity prices rise, so do capacitors, resistors, transformers... you name it. There is a great way to get around that though, with surplus and buyout parts. There are many companies out there that procure these parts from discontinued products, company closures, old military stock and other sources and flip them at a discount. While you may need to modify your specs to accommodate some of these parts, they generally work perfectly well. Apex Jr. is one I frequent, and Partsexpress is also a great source for some unusual finds.

Partsexpress recently procured a buyout of Footnote electric guitar 5 watt amp assemblies and are passing them along for $15 a pop, a great deal given the complexity and quality of the unit. For $50-100, you can put together your own miniature guitar amp for practicing or small gigs. I decided to put one together as a gift for someone I knew would appreciate it, so I ordered the unit along with an A/C adapter, full range driver, grill and a few other items. Below is a list of parts with some embellishments that can be included as desired.

Inventory List
 Footnote 5 watt amp assembly
 $15 from PartsExpress
 9V 1000mA A/C Adapter (center pin negative)
 $5 from PartsExpress
 GRS 3FR-4 3" full range driver
 $5 from PartsExpress
 4" wire mesh grill with gold accent 
 $1.50 from PartsExpress
 Speaker Caulk
 $1-2 from PartsExpress
 $5 from PartsExpress
 Weather stripping
 $4-6 at your local hardware store
 Metal corner accents
 $3-5 shipped on eBay
 LED accent bulb
 $2-3
 Automotive damping sheets
 $10 on eBay
 $17 on Amazon
 $4 on PartsExpress
 Equipment feet
 $2-3 on PartsExpress

As you can see, nearly everything can be sourced from PartsExpress. Some other things that I had on hand that were needed were some 24 gauge wire, screws, solder, wood stain and seal, 2.5" hole saw, drill, etc.

The only modifications needed for the wine box were drilling the hole for the speaker, cutting the hole for the amp unit, and removing the little wood piece that would separate the two bottles of wine. I had a spare piece of mahogany that I used to reinforce the baffle area for the speaker. Drilling the parts in place like the handle and feet only takes a few minutes. There is a small amount of speaker caulk to seal the driver and amp within the box, the interior is covered with the automotive damping sheets, and the weather stripping helps seal the box around the perimeter.

The wiring to the driver connects directly to board via an adapter, but to add the LED pilot light I needed to solder some leads to the on/off switch so it would only turn on when the amp is on. The unit can also run on battery power, so I soldered another couple of leads to the board and ran them down to a 9V battery clip. As the amp creates a modest 5 watts, the battery should last a while. There was room in the box for the A/C adapter, but care was taken to ensure it would not short out or damage the board. After the photo below I added some additional wood to secure it in place.



The SKB Footnote unit was actually made as a practice unit for guitarists that wanted to plug in a bunch of effects pedals, as it offers 8 separate power outputs for them. Per my research, the unit came with a 6" Eminence speaker, real-estate for all the pedals and cost around $300, so $15 is a bargain for the amp unit. 

The original SKB FootNote unit - neat idea


The FootNote Amp module installed

Even if you're just using the Footnote as a power supply it's worth the price of admission. The only trick is you'd have to build power cables to work with it as the kind it uses are hard to come by (9v center negative on both sides). PartsExpress does show you how to make one though. 



Here's the unit in its finished glory. I used a woodburning pen to decorate the surface of the unit and personalize it. I applied the stain selectively to allow some of the objects to stand out a little bit. Should make a great gift!





Please remember that building/modifying circuits can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. 








July 18, 2017

AMB σ11 Sigma 11 Regulated Power Supply

Version 2 of AMB's σ11 (Sigma 11) regulated power supply has been out since June of 2015, but I'm finally getting around to building my own. AMB (Ti Kan) is mostly known for his headphone amp and DAC designs, but his site offers several power supply options as well.  

The σ11 is a top notch DIY single-rail linear regulated power supply known for low-noise, high-current, excellent line/load regulation, wide-bandwidth, and stability. The circuit features all discrete components and high-current MOSFETs for the output. Per AMB, the σ11 is a great choice for DIY headphone amplifiers, pre-amps, DACs, network media players, and other devices needing a single-rail regulated power supply.

AMB o11 Power Supply PCB

This power supply is a pretty quick build with ~40-50 total parts. A typical builder can populate the PCB in an hour or two. AMB offers the PCBs for sale on his site, along with some of the necessary parts. The rest you'll need to get from Mouser / Digikey or your favorite parts supplier. I went with all stock parts aside from an Antek 50VA toroid instead of the Amveco TE62062 25VA as it was much more reasonably priced, albeit a little larger. Because of this, the Hammond 1455N2201 was the best chassis size for the job. 

Antek 50VA toroid

Rather than leave the Hammond case plain, I wanted to give it a little more character. I sourced a piece of wood online which didn't have a species listed, it simply was called Asian burlwood. I cut a front plate with about a 1/2" overhang in each dimension and drilled holes for the screws to line up with the existing screw holes in the Hammond case. Two coats of satin lacquer gave it a nice sheen. 

Asian burlwood front cover

Two holes were cut into the top of the Hammond case and it was sanded down with 180 grit sandpaper to reveal a grain-like anodization pattern. Powercoated aluminum grating was secured with adhesive underneath the holes... then a permanent furniture market was used to give the bare aluminum a bronze-like color. 

In the rear, I've installed a pair of outputs. The board offers up to four outputs if desired, but an appropriately sized toroid should also be used. If you're not sure about the rating needed, the forum on the AMB website can be very helpful as other people have likely already asked the questions you are wondering. 


AMB σ11 Sigma power supply rear

A Fender-style pilot light was installed up front with an Amber jewel and LED. 

AMB σ11 Sigma power supply front with pilot light

All done! Now I have a nice regulated 24v power supply now with a pair of outputs. 

Please remember that building/modifying circuits can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. 

July 11, 2017

Modifying the MHDT Atlantis DAC

MHDT has a cult following in the DAC world, and for good reason. They may not all be featuring the latest chip designs and 768kHz inputs, but new technology doesn't always have a direct correlation with better sound. Case-in-point, the prices of 1960s equipment made by H.H. Scott, Harmon Kardon, Marantz and McIntosh all continue to increase from more and more audio enthusiasts desiring the musical qualities inherent from the Golden-era of audio. Granted if you are a purist and want a straight line response curve, these won't scratch that itch, but if you crave a warm musicality MHDT has few peers that can rival.

The Atlantis is one of the latest offerings from MHDT, and much like last generation's Havana, along with the current generation's Stockholm, features a R/2R Multibit DAC. The Stockholm, Atlantis and Pagoda are unique as they have discrete transistors in the I/V stage, no opamps at all. Opamps are often looked down upon as they can be a "one-size-fits-all" type of solution, and the tasks they perform can generally be done better with discrete components. The Atlantis features a AD1862-J DAC chip, and uses a tube-buffered output stage (GE5670).

MHDT Atlantis with stock internals


Luckbad, a member at headphone enthusiast forum HeadFi, created an AWESOME table that compares the more recent MHDT DACs:

Mhdt Labs DAC Families ​
                      Models​
Havana​
Havana 2​
Stockholm 2​
Atlantis​
Pagoda​
Steeplechase​
      Spec
Input Capacity USB (Max)​
16bits/48kHz​
24bits/192kHz​
24bits/192kHz​
24bits/192kHz​
24bits/192kHz​
24bits/192kHz​
Input Capacity SPDIF (Max)​
24bits/96kHz​
24bits/192kHz​
24bits/192kHz​
24bits/192kHz​
24bits/192kHz​
24bits/192kHz​
Output  Format​
16bits​
16bits​
16bits​
20bits​
24bits​
24bits​
Digital Receiver Chip​
CS8414​
CS8416​
CS8416​
CS8416​
CS8416​
CS8416​
USB Chip​
CM102AS+​
CM6631A​
CM6631A​
CM6631A​
CM6631A​
CM6631A​
DAC Chip​
PCM56P-J​
PCM56P-J​
PCM56P-J​
AD1862-J​
PCM1704​
AK4396​
DAC Chip Construction​
R/2R Multi Bits​
R/2R Multi Bits​
R/2R Multi Bits​
R/2R Multi Bits​
R/2R Multi Bits​
Delta-Sigma 1 Bit​
I/V Stage​
Voltage out
 DAC's Internal OPAMP ​
Current Out
Discrete Transistors I/V,  No OPAMP, No feedback​
Current Out
 AD847AQ as I/V​
Tube Buffer​
Tube Buffer with 5670/2C51 ​
Output level​
2.6V​
2.6V​
3.0V​
3.0V​
3.0V​
2.8V​
Output impedance​
32 ohms​
32 ohms​
32 ohms​
32 ohms​
32 ohms​
32 ohms​
Inputs Available​
3 Inputs -- USB/ RCA/Optic​
4 Inputs -- USB/RCA/BNC/Optic​
USB Input Topology​
USB1.0​
USB2.0​
USB Driver for Win XP/W7/W8​
No Needed​
Yes, Needed​
USB Driver for Linux/Mac​
No Needed​
Dimensions clear (WxDXH) ​
260X150X60​
276 x 150 x 60 mm​
Dimensions w/ socket ​
280X170X60​
295 x 170 x 60 mm​
Weight​
1.8Kg​
2Kg​
Box Color Avialable​
Black Only​
Black/Silver Selectable​
Silver Only
It's been fun to see the progression of MHDT DACs over the years. The chassis used to be made completely out of acrylic. Now only the front cover is acrylic (a nice thick acrylic) and the rest of the body is make of aluminum panels that screw together. In addition, the op-amps are going away and there is more utilization of surface mount components on the PCB. The circuit boards have also become more robust, which is nice when exchanging components. Other components generally stay about the same, from Nichicon Fine Gold electrolytic caps in the power supply, Nichicon Muse caps and Sanyo/Panasonic OS-CON caps elsewhere, as well as MHDT brand film caps which I imagine are sourced in Taiwan.

I generally like to replace the Muse caps with Elna Silmic II for a little more warmth, as well as Soniccraft 600v 0.1uf and 0.22uf Sonicaps for the smaller film caps, as Sonicaps are a great value and are small in form factor compared to most other audio capacitors. For the output caps, replacing with the best quality that fits that you can afford is generally the best strategy, as they are directly in the signal path.

MHDT includes a larger toroid in the Stockholm, so I wanted to upgrade the power supply in the Atlantis. I checked Mouser and Digikey for a larger toroid and no one seems to make a unit with the two secondaries needed, so you'd either have to have two toroids (which wouldn't fit in the case) or snag one from MHDT directly. The larger unit from the Stockholm fits perfectly well in the Atlantis, you don't even have to drill a new hole to mount it. While they look similar in size, the larger one is twice the volt-ampere rating.

Comparing the larger toroid from the Stockholm (black) to the stock Atlantis unit (white)

The RCAs on the unit are perfectly fine, but I was able to source some nice ones with teflon insulation, so I installed those. The unit on the left is the teflon insulated one, it looks a little bit different but fits perfectly. 

Teflon RCA left, stock RCA right

The RCA for the digital coax was replaced with a Vampire BNC (about $13-14). I chose Jupiter HT paper in wax caps for the output. They've served me well in other applications and have a nice natural presentation. I happened to have several Kiwame resistors that I ordered from Partsconnexion



The Jupiter 2.2uF 600V caps had to be shoehorned to fit. While they fit fine in the Havana (albeit tightly), the Atlantis opening was a little narrower despite the slightly larger chassis footprint. Reviewing my options, I decided to stand the caps off the board slightly to clear the small Oscons and sand down the heatsink to allow the capacitor to wedge up next to it. It doesn't get terribly hot, so we'll see how that goes.

While I don't go out of my way to get audio fuses (I'd be pretty grumpy if a $70 fuse broke, and I'm a little skeptical as the resistance in a fuse is minimal), PCX had a few on sale for $12 from HiFiTuning so I figured I'd give it a shot. $12 is a drop in the bucket for audio gear as you know. Swapping the 400ma stock fuse with the gold fuse seemed to increase the higher frequencies (by a small degree), so it may be counteractive when you're after a warm-sounding DAC. I'll be testing more, but that's my initial finding. I may try in some other equipment to see if that's consistent if they're still cheap for my next order ;).  

Click to zoom in

The DAC sounds excellent. More resolving and clear than my Paradisea and less forward than my Havana. It's my favorite sounding MHDT so far and very easy to listen to. I hear the Stockholm is even better (based on forum banter around the web), but this is a DAC for a few bucks less. 

UPDATE: I found some 30mm aluminum feet with a damping ring on Aliexpress that are a nice step up from the stock plastic feet. They're  quick and easy replacement and are less than $10 for a set of 4.




The Fine Print:
Please remember that modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a posted modification and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. 


July 7, 2017

Fred's Amplifiers Portable 12AU7 Tube Headphone Amp

I was browsing around the net looking for a quick and fun little project when I discovered Fred's Amplifiers. Fred has a small site with a number of PCBs and kits, most of which are portable headphone amplifiers, along with a portable guitar amp kit and a couple of crossfeed units.



I decided to order the 12AU7 Valve headphone amp PCB. It's a single sided PCB and was only $10, with the BoM (bill of materials) posted on the site. I went with the PCB versus the kit as I have tons of parts lying about, but the kit is only $45 if you want to go that route, just note you need to buy the chassis (Hammond 1593) and A/C adapter (12v 1A Regulated DC supply, center pin positive) on your own. The unit only requires around 25 parts to complete, so you'll be done in no time. The Op-amp in the kit is the venerable JRC 4556 used in most CMOYs / RA1 clones and similar portable low-power headphone amps.

I went with the translucent blue version of the Hammond case (1593KTBU). Trimming into the plastic Hammond case requires you to go slowly on the drill press or the plastic will crack. You may want to buy two cases (they're $4 each) just in case your holes don't line up perfectly.





My unit features Takman carbon film resistors, a diffused 5mm amber LED, a milled aluminum knob from Kilo, and 470uf 16v Elna Silmic II capacitors. Elna Silmic II are widely accepted as the best electrolytic available for the signal path. They are a tough fit, and will require you melt down the PCB standoffs on the bottom of the Hammond case to get everything to fit nicely. You could also drill holes at the top of the chassis for clearance, but that reduces the portability in my opinion. The AC adapter I went with was a $10 Meanwell unit - SGA12U12-P1J. I'm sure there are cheaper, I just plugged the specs into Mouser and bought the first one on the list. 

Here are a few more photos of the amp:    










There's nothing challenging or unusual about this build, so if you'd like a fun and affordable little portable tube headphone amp, put this one on your short list. 


Please remember that building/modifying circuits can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. 

June 23, 2017

Modifying the MHDT Havana DAC

MHDT has a cult following in the DAC world, and for good reason. They may not be featuring all the latest chip designs and 24bit oversampling converters, but new technology doesn't have a direct correlation with better sound. The equipment designed in the 1960s from H.H. Scott, Dynaco, Harmon Kardon, Marantz and McIntosh is still well sought after today for it's excellent sound qualities. Granted if you are a purist and want a straight line response curve, these won't scratch that itch, but if you want to enjoy the music they'll fit the bill perfectly well.

The MHDT Havana comes after the venerable Paradisea 3, which is an excellent sounding example of a NOS (non over-sampling) DAC with a tube buffer. Both the Paradisea and the previous Constantine make use of a Philips TDA 1545A DAC chip and come in a handsome translucent dark acrylic. (See the posts covering the modification of the Constantine and the Paradisea.) Unlike the previous two, the Havana uses no op-amp for I/V conversion. Opamps are often looked down upon as the tasks performed can generally be done better with discrete components. The Havana features a 16 bit R-2R Burr Brown PCM56P DAC, and uses a tube-buffered output stage (GE5670).


A stock MHDT Havana DAC
It's interesting to see the progression of MHDT DACs over the years. Not only are the op-amps going away, there's more aluminum panels and less acrylic body panels, as well as the utilization of more surface mount components on the PCB. The circuit boards have also become more robust, which is nice when exchanging components. Other components generally stay about the same, from Nichicon Fine Gold electrolytic caps in the power supply, Nichicon Muse caps and Sanyo/Panasonic OS-CON caps elsewhere, as well as MHDT brand film caps which I imagine are sourced in Taiwan. 


The stock PCB removed from the chassis

I generally like to replace the Muse caps with Elna Silmic II for a little more warmth, as well as Soniccraft 600v 0.1uf and 0.22uf Sonicaps for the smaller film caps, as Sonicaps are a great value and are small in form factor compared to most other audio capacitors. For the output caps, replacing with the best quality that fits that you can afford is generally the best strategy, as they are directly in the signal path.

Below is a partially modified unit. Note the Nichicon FG power supply smoothing caps have been bumped up to 3,300uF (there's plenty of room), most film caps have been replaced, and I had just started installing the Elma Silmic II caps.


Partially modified PCB, note larger Nichicon FG filter caps, Sonicap film caps

The RCAs on the unit are perfectly fine, but I was able to source some nice ones with teflon insulation, so I installed those. The unit on the left is the teflon insulated one, it looks a little bit different but fits perfectly. 

Teflon RCA left, stock RCA right

The RCA for the digital coax was replaced with a Vampire BNC (about $13-14). I chose Jupiter HT paper in wax caps for the output. They've served me well in other applications and have a nice natural presentation. I happened to have several Kiwame resistors that I installed in the tube buffer. 

The completed mod

The Jupiter 2.2uF 600V caps just narrowly fit in the Havana chassis. I tombstoned one of the Sonicaps to ensure there was enough clearance. One thing I found odd was MHDT never grounds their DACs. I understood there wasn't much of a point with an acrylic chassis, but now that they're brushed aluminum, might as well use it as a shield. The electroplating is very thick on the chassis and needs to be sanded away to make contact. I used a Dremel on the metal under each screw and put everything back together, checking for continuity with a multimeter. I had to re-hit a few of the holes but eventually got there. I ran a wire from the ground on the IEC to circuit ground and connected to chassis ground, so now we have a safe and shielded DAC. 


Boxed back up

Everything is sounding very nice so far. The op-amp-less design is a little more forward than the Paradisea (which is very warm and syrupy), but still very natural sounding and makes for an enjoyable listen. When I say forward, I simply mean related to other MHDT DACs. It's still warm compared to 95% of DACs on the market. I still have to let the Jupiters burn-in, which in my experience just takes a couple of nights of audio running through them, but everything will open up once they do. 


The Fine Print:
Please remember that modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a posted modification and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard.