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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. 

The Lessloss Power Conditioning Firewall Module

I've heard many positive impressions from fellow audio enthusiasts regarding LessLoss power conditioning products and have always been curious about how they stack up. The unique construction of the previous Firewall using exotic materials like Panzerholz, a plywood-like bulletproof material with high damping properties, and carbon fiber, had left me very curious. The new Firewall is a much more affordable endeavor, starting as low as $198 for the DIY version, $385 for the USB version and $410 for the power outlet version.

As nearly all of my gear is completely DIY, I took a special interest in the DIY version of the Firewall. I've come accustomed to the typical simple resistor/capacitor/inductor networks in discrete filtering circuits (those you commonly find in an audio power conditioner, the filtering IECs that are sometimes installed in DIY tube amps, and other DIY implementations), but have never seen an alternative to these.

The Firewall DIY module is relatively small, roughly 2" by 4" and has and input and output for L (line/hot) and an input and output for N (neutral). There are unique ripples/patterns in the surface of the solder mask which cover the copper underneath.

Click to enlarge the photo to see the solder mask

Five Firewall units lined up

Per the instructions, The Firewall units can handle up to 1000VDC and can be stacked and/or run in series to increase the level of the filtering. Kapton tape or discs is recommended to prevent the inputs and outputs from shorting.

Four LessLoss Firewall Modules stacked in series

There have been tests of up to four parallel stacks of eleven boards if you want to go super crazy ;) Do note that "LessLoss will not be held responsible for the fate of your equipment or health or other personal property should you choose to use our product in your own designs", so stick with the off-the-shelf units unless you know what you're doing.

More to come...

Burson Audio Opamp Review - Supreme Sound V5 / V5i

Op-amps, or operational amplifiers, are ubiquitous in solid state amplifiers. These little integrated chips are simple little building blocks designed to work in a wide range of electronics such as PCs and other devices. For those of you not familiar, op-amps are like vacuum tubes for the solid state world. Most manufacturers use sockets so the op-amps can be swapped, and each have a difference sound signature (e.g. warm, revealing, etc.). Some have voltage requirements that make them only compatible in certain designs, etc. Some are affordable (the LM4562 which runs less than $1), and some are expensive like the popular $25 Burr Brown OPA627.

Burson Audio is a company on a very short list of providers of discrete op-amps. Rather than having a bunch of teeny tiny components shoe-horned in a chip the size of a fingernail, Burson creates devices that plug into op-amp sockets that use a fully discrete set of diodes, resistors, etc. I remember my first purchase of several of their discrete op-amps  roughly six years ago, trying to breath some additional life into a Music Hall DAC. While their first iterations weren't super easy to install, they made a world of difference in the sound department. Everything was much more natural and effortless sounding than the stock op-amps which I believe were mid-grade models from Texas Instruments.

Fast forward to today and we have the Supreme Sound V5 and V5i Opamps. The V5 features fully discrete components including 0.5% tolerance metal film TKD resistors, hand-matched FET transistors, and a sleek looking red cover.

The Burson V5 (left) and V5i (right) in their packaging

Note the size difference between the two units

A fixed 8 pin DIP socket makes installation much easier

It's also a smaller form factor than the originals, which is crucial for installing in tight circuits / spaces. The V5i is a hybrid of sorts which includes both IC and discrete components, but is much smaller and should fit in virtually any build. Do note that these units can only replace op-amps as noted on the Burson site:

Dual Op-amps:
AD823, AD823AN, AD8066, AD8620, AD712, AD827, C4570, JRC4556AD, JRC4580, JRC5532, JRC5532D, JRC5534, LF353, LM4562, LME49860, LM833N, MUSES8920, NE5532, NEC4520, NEC4570, NJM2068D, NJM2114, NJM2214D, NJM4558, NJM4558D, NJM4560, NJM5532, NJM4558P, OP275, OPA1612, OPA2277PA, OPA2132, OPA2134, OPA2604, JRC4558, RC4558D, RC4558P, TL052, TL072, MUSES01, MUSES02, MUSES8820, MUSES8920, MUSES8832, BA15532

Single Op-amps:
NE5534, LT1122, TL071, OPA134, OPA627, AD811,AD829, AD844, OPA604, AD8610, AD711, AD797, LME49990, LME49710

Installing them in a unit that is not compatible could cause undue stress on the components / oscillation, etc.

More to come...

May 24, 2017

Four Pairs of Headphones for Any Studio Setup

This guest post is brought to you by my friends at Headphone Ninja. Anyone following the blog knows I love headphones, and Jo-Ann and company have culminated four tried-and true classics to discuss.

Studio headphones fill the market today. However, many of them are either far too expensive or far too inaccurate when it comes to meeting the referencing demands of producers and audio engineers. While everyone would love to own a pair of the sleek Sennheiser HD800s or the beautiful Japanese cherry birch wood Fostex TH 900s, we don’t all have a Hans Zimmer’s budget.

In this post we explore four of the more preferred headphones available in 2017 that are well suited to the modern day studio.

Closed-back headphones

Audio-Technica ATH-M50X

Comfort is key when it comes to long studio sessions. The generously padded earcups and adjustable headband of the ATH-MX50 provides comfort, and while the headphones do clamp down reasonably hard, they do not physically strangle the life out of your temples. They are slightly heavy at 10-ounces, but this should not be a deciding factor for those looking to use these in a studio environment.

The ATH-M50X is fitted with large 45mm proprietary drivers that deliver exceptional clarity. Some individuals who have used these thought that the bass is slightly high, but the mid frequencies are fairly well represented. The higher frequencies also appear to be slightly bright, but not to the point of fatiguing the ear. The 90-degree swivelling earcup is great for single ear monitoring and the frequency response ranges from 15 - 20,000Hz.

Sony MDR7506

Introduced back in 1991, the Sony MD7506 has remained a firm favorite amongst many looking for high quality and reliable headphones. Their durability is as decent as a pair of plastic headphones can get, with the only real issue of deterioration being the earpads on the cups, but these are replaceable. At around 8-ounces, they are light enough to not burden the wearer much.

The MDR7506’s frequency response ranges from 10 - 20,000Hz. It has revealed a solid bass response in tests, albeit slightly bumped up in the 60 -100Hz range. Mids remain fairly flat while the low treble to the high treble frequencies are quite inconsistent; the sibilance range is slightly boosted and can be slightly piercing to the more sensitive ears. The soundstage is decent for a closed-back pair of cans. They have an 63-ohm rated impedance and their low leakage is also suitable for recording purposes.
The coiled 9.8-inch cord is more than enough for studio environments and it does come with a ¼ inch adaptor. The Sony MDR7506 gives many mid-range referencing cans a run for their money.

Open-back headphones

Sennheiser HD 650

The Sennheiser HD 650 are slightly pricier, but it seems important to add these cans for those who enjoy the spacier sounds that open-back circumaural headphones offer. The suede-like fabric is a nice touch on the large, encompassing cups that house the efficient neodymium magnets.

The slightly under-emphasized low bass frequencies with the minor boost on the high bass gives the headphones a more natural sounding low end. The mid range responses are pretty much flat throughout and the treble frequencies are consistent. Their impressive frequency response coupled with the spacious sound created by the deep drivers and open-back design makes these excellent for critical listening.

Needless to say, their isolation is pretty much non-existent, making these more suited to quieter environments. They are also less suitable for recording purposes, because they do leak quite a bit of additional noise, which in turn will bleed into your microphone. 

The Sennheiser HD 650 is an excellent referencing headphone and offer an awesome frequency response, though they are less suitable for recording purposes however.

Editors Note: The 650s can sound a little dull in the treble with the stock cable in some setups. A replacement featuring silver-clad copper can bring out the highs. Check with Zynsonix for additional details.


The AKG K712 PRO are another great choice for mixing and mastering purposes. The design is slightly bulky, but they are purposefully built for studios, so that is completely understandable. The memory foam earcups captures the shape of your head, but they are rather large. Sound wise, they deliver a spacious and accurate audio reproduction, but the sound is a bit warmer in the upper bass. Still, it is well controlled overall. The mids are represented accurately.

Sensitive ears may find the slightly boosted (and somewhat inconsistent) higher frequencies a tad overwhelming, as they can sound harsh. The frequency response ranges from 10 - 39,800Hz in its entirety and it has a low harmonic distortion.

As a whole, the AKG K712 PRO have a natural sound and are well suited to intensive referencing sessions. The open-back design means they are more suited for mixing and mastering in studios.

Wrap up

This is by no means a comprehensive guide to selecting studio headphones, but a look at some of the more popular headphones around at the moment for any type of studio. While they may mostly be mid-range headphones, they perform well within their specific categories and are well suited for studio use.

May 22, 2017

Millett NuHybrid Headphone Amp Using Korg NuTube

In Mid-March, the prolific DIYer Pete Millett introduced a new hybrid headphone amp called the NuHybrid using the Korg Nutube 6P1. The design is similar to the original Millett Hybrid, which spawned both the exceedingly popular Millett MAX and stripped-down Starving Student builds. The Starving Student was super-popular as it could be built for as little as $35, which is unheard of for an amp with two tubes.

To shake things up (Millett designs are rarely status quo), the old car radio tubes were eschewed for the new Korg Nutube. The Nutube is a low-power, directly-heated dual triode tube built using a process originally used for Vacuum Fluorescent Displays (VFDs) and emits a bluish-white glow when the tube is powered up. The Nutube has been popular with DIYers in Japan since it was released at the tail-end of 2016, but hasn't really caught on with DIYers elsewhere, at least yet. The cost of a Nutube is around $50, which may seem a little steep, but two noval signal tubes will set you back at least $30-35 these days, along with another $5 for sockets and the potential to have to replace them in a few years, which makes $50 not seem all that bad.

The Korg NuTube

One of the nice things about the design is you don't have to feed it plenty of amps. The whole thing runs off of a 24V power supply, so it is much safer than a typical tube-based build. A pair of OPA551 op-amps to drive the headphones, but others can be rolled in for a different sound signature. Pete has made the design so it can be built cheaply (~$120) and placed in a Serpac plastic case. Much like Pete I don't like status quo, so I'll be building a case from scratch for my NuHybrid amp. I wanted to make the amp look like an old tabletop radio, so a wood frame would be needed.

A quick trip to Home Depot yielded a 6ft long by 3.5" wide piece of maple.

A little bit of routing and a few 45 degree cuts on a miter saw and we have a frame. Note the inside of the frame is rabbeted so the front and rear plate can sit flush. The 5/8" pieces in the middle are for screws to hold the plates in place. This is a photo after an initial coat of Minwax Pecan colored stain and seal combo. Yes I know it's sacrilege for anyone who works with wood regularly, but it's quite and easy.

Frame to hold PCB inside

As wood doesn't protect from errant EMI/RFI, I've added some copper shielding tape which will be electrically connected to the front and rear aluminum plates to get 100% coverage.

Copper EMI/RFI Tape for shielding

The board is quick and easy to populate and should take even the most OCD solder slinger less than 3 hours. Below is an image of the PCB. The checkered areas indicate where double-sided tape is applied to the board to hold the NuTube in place.

NuHybrid unpopulated PCB

Below you'll see my PCB about 90% populated. I changed a couple of the parts in the BOM. The BOM calls for Wima polyester, but you can switch them out with Polypropylene for about $2.50 more and they fit without issue. I also went with Elna Silmics in the power supply. The Silmics sport a 7.5mm lead spacing versus 5 on the Nichicons, so they have to be pressed into place otherwise they'd stand crooked. They also encroach a bit on other areas of the PCB, so the Wimas needed to be mounted on the bottom. I also went with Takman carbon film resistors in most areas. The 1/4 watt variety are only 36 or so cents a pop at Sonic Craft, so it won't break the bank to use them.

Note the large-and-in-charge Silmics in the power supply section  

I picked up two aluminum plates 1/8" thick for the front and back. I usually get them pre-cut from eBay but will also use a miter saw with a metal blade if the size I need isn't available. The back of the unit needs holes for four RCAs and 24v DC. Although I doubt the unit gets very hot due to the low power requirements, I drilled a hole pattern at the top for heat to escape, as with wood it will trap it in otherwise. The aluminum is spritzed with Hammertone paint in a copper finish.

1/8" thick aluminum plate with holes for RCA, DC

Attaching the unit to the front panel are the 1/4" inlet nut and the TKD potentiometer nut. I went with the nicer TKD potentiometer as suggested by Pete. $40 is a bit painful but I'm tired of using Alps Blue Velvets for every build. The front LED, switch and coupling capacitors (Russian Silver Mica) are connected with fly leads (22ga. silver clad teflon solid core wire I had left over from a Bottlehead build). The wiring to the RCAs is Cardas 24ga. stranded in teflon. Note the space between the two mica caps in order to reach the adjustment pots. The RCAs are Switchcraft units I had on hand. The switch is much higher rated than it needs to be, but I have tons of surplus switches and like the big old school ones. If you're looking for low cost and high quality, check out Apex Jr.

Attaching the panels gives the nearly finished product...

Vent holes probably not needed, but look nice

More to come...

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. 

May 19, 2017

Help out Dave from Planet 10 HiFi

Dave over at Planet 10 HiFi has been instrumental in pushing the envelope for single driver speaker designs, including the much lauded Fonken and MiniOnken designs and the amazing Frugal horn which can be built with Mark Audio or Fostex drivers.

He also developed and patented the EnABL process which dampens and improves drivers (an interesting read if you have time). He's also developed many speaker cabinet designs, hosted a number of group buys, and has been a cornerstone of the DIY community.

Dave currently needs our help. Last year Dave's wife, Ruth, found him laying on the bathroom floor, ghostly pale and staring wide-eyed. Ruth immediately called an ambulance and Dave was taken to Vic General where an emergency CT Scan and speedy blood work prompted another ambulance to rush him to Royal Jubilee for emergency surgery less than an hour after leaving their home. It turned out that an abdominal aortic aneurysm had burst (one of multiple previously undetected aneurysms), his chest was full of blood and infection was raging through his upper body. Two gifted surgeons spent over 10 hours working valiantly to save his life. Dave survived the surgery to replace his entire aorta, top to bottom, and was kept in an induced-coma for almost a week to allow the body to begin to heal. The surgeon said Dave had incredible tenacity to make it through the surgery. 

Fortunately, Dave just got back at home last month and has been slowly recovering, but as you can imagine there are many expenses associated with medical difficulties of this magnitude and being out of work for so long. 

I encourage you to join in the GoFundMe to help out Dave and Ruth as they traverse this challenging time in their lives, especially if you value the great things Dave has done for the DIY community. You can also see the latest updates at DIYAudio

February 20, 2017

TRU-LIFT Automatic Tonearm Lift Review

With the resurgence of vinyl over the last decade manufacturers have taken notice and there are more offerings than ever for new vinylphiles. Not only do we have a great selection of turntables from VPI, Clearaudio, Music Hall, Marantz, Pro-Ject, etc. but there are lots of great new accessories as well to enhance your vinyl listening experience.

As we all know, listening to records can be a little inconvenient compared to firing up a Spotify playlist, however there are a few new items to the market that can help you out. If you're like me and can't always immediately get up at the end of a record side, you can now get a device that lifts your tonearm so your stylus isn't sitting there grinding on the end loop for several minutes. If you are using a $25 cartridges, this might not be a big deal, but there are some people out there using fancy pants carts that would be very interested in these.

There are a couple solutions I'm aware of: The Pahmer Enterprizes Q Up, which appears to be a great choice for value oriented listeners, and the Integrity HiFi Tru-Lift, which, in my opinion, seems a little more elegant and "at home" on a nicer turntable. The job of these devices is relatively simple, as the tonearm reaches the end of the record, it presses against a lever or switch and the tonearm is lifted to prevent the stylus from remaining on the record.

This post is going to be a brief review of the Tru-Lift. I say brief as it does exactly what its supposed to do without any notable flaw. Below is the no-frills packaging, which I actually appreciate. It drives me nuts when I purchase something I already knew I wanted and it seems like the manufacturer spent more on the package than the product itself... but I digress.

The Tru Lift is available in Brass and Stainless Steel, both relatively heavy metals. For the science savvy, the density of brass is between 8440-8730 kg/m³ and the density of stainless steel is between 7480-8000 kg/m³, so the brass units of the same size will weigh slightly more.

I like the look of the brass (and the added weight) but the stainless matches my setup better. I purchased the Deluxe package that included four different heights, should I ever change my turntable down the line. The units can be purchased individually for $199 (as of this writing) and are available/adjustable from 1 1/4" to 2 3/4", and the Deluxe package is available for $259.

The Deluxe set comes with 4 different sized bases

The units have a nice heft to them, which is good as you don't want them to fall over. Unscrewing the unit gives easy access to the internal mechanism.

The height is easily adjustable via set screw. 

Setup took me a couple of tries, but once it's in the right spot you're good to go. I had to adjust a bit after these photos were taken, the little lever needs to be facing toward you to work as intended. There's a video that explains the setup. Once the lever is slowly pushed into by the tone-arm, the spring loaded piece slowly and carefully lifts up the tonearm. The unit remained stationary when the mechanism was struck, which is great as you don't have to move it back into place. To reset the mechanism, you simply push the spring loaded piece back down and you're good to go.

Overall I'm fond of the Tru-lift. It's a simple, elegant solution that does exactly what it is supposed to do and is easy to use. Pricing seems on par with other audio accessories, but may be a little high for those with modest systems. I'm actually surprised there are not more products like the Tru-Lift available, but it definitely satisfies a need for avid vinyl listeners. Highly recommended. 

The Fine Print: Zynsonix Audio LLC and DIYAudioBlog have no affiliation with Integrity HiFi and/or the Tru Lift product. The author of this review was offered dealer pricing for the Tru Lift system as consideration upon request, however was not a factor in the evaluation of the product. 

February 1, 2017

Tube Kits, Solid State Kits, PCBs, Transformers, and Where to Buy

I've been quite busy over the last couple of years and haven't been able to build as much as I would have liked, but now that I'm getting back into the swing of things, there are a number of DIY providers who have left the space, so I wanted to put together a list of all the great companies who still offer DIY kits, boards, transformers, etc. I hope it's of use to you, and please try to support the DIY community in any way you can. There's not much money in selling just boards, it's more of a community service in many cases. This is a growing list and I'll be adding more as time goes on. If you have one you'd like to see here, please add in the comments section.


AMB Labs (Solid State board and part provider): Ti Kan has lots of great solid state options including headphone amps (desktop and portable), power amps, DACs, power supplies and more. The famous β22 (Beta 22) balanced headphone amplifier is here, as well as the portable Mini³ headphone amp which shouldn't be too hard for beginners. Tons of boards and parts available and a good forum.

Antek (Transformers): My favorite provider of toroidal transformers, Antek has fantastic pricing and a large variety of values, most of which are typically in stock. You'll find tube-friendly 6.3V and 12.6V heater secondaries here as well.

Audio Note Kits (Tube amplifiers, Preamplifiers, DACs, etc.): A little higher end than the typical DIY kit, ANK has quite a few nice offerings, most of which are based around universal chassis that work with several different configurations. Also one of the very few kit providers that offer a DAC, perhaps the only tube-based one I am aware of.  Prices range from $1,300 - $6,850 per kit, so these may be out of reach for the budding audiophile, but I still consider them a good value for the parts that are being provided. One thing to note is that the tubes are hidden within the chassis on some models (many of us like the tubes out in the open because they not only look nice but it's easier to roll them).

AudioSector (Chip Amps): Nice simple circuit PCBs designed around Texas Instruments LM3875 and LM4780 chips.

Beezar (Tube Amp Kits): Tom (Tomb on HeadFi) runs Beezar and offers great, proven designs from ECP Audio (The Torpedo I and II headphone amps) as well as other DACs and headphone amps. Tom puts together a great kit and the documentation is unbelievably good. Every step is illustrated similarly to the Bottlehead kits. Highly recommended and beginner friendly.

Bottlehead (Tube and Solid State Kit Provider): Bottlehead provides mostly tube builds, from headphone amplifiers, to low-wattage speaker amplifiers, to pre-amps, etc. This is a good company for the budding DIYer as the directions are very explicit with color photographs and the support is quite good. Most of the builds are point to point with a few small circuit boards here and there for constant current upgrades usually. I'm certain they've sold a truckload of Cracks, a very affordable headphone amp offering. Below is Tyll Hertsens of InnerFidelity (great site) building a Crack.

Cinemag (Transformers): Very nicely made signal conversion and moving coil step up transformers.

DigiKey (General Supplier): Carries all the various passive and active components you'll need to fill a circuit board (resistors, capacitors, op-amps, sockets, etc.). If they are out of a product, try Mouser.

DIYAudio Store (Solid State PCBs, Kits, Chassis): Never to be overlooked, DIYAudio.com has its own store with some great little accessory PCBs like the soft start board, a universal power supply, as well as some legendary Nelson Pass designs and big hulking chassis you'll need to house them in. Pricing is very reasonable.

DynakitParts (Tube Kits, PCBs, Transformers): Kevin at Dynakit parts is an incredible guy. You can build Dynakits just like you used to back in the 1950s thanks to his incredible efforts. Dynaco, if you aren't familiar, is likely the most legendary audio kit manufacturer of all time. The ST70, their 35 watt-per-channel amplifier is a ubiquitous favorite, and their other models, including the ST35, MKIII, MKIV, and PAS pre-amp all have a very strong following. Dynakitpart's uses the original circuits, which are excellent, but perspective buyers may also use alternative boards from a variety of producers (and will need to in the case of the PAS pre-amp and SCA35 integrated). The newly designed boards have some nice attributes in some cases, but are becoming harder to obtain lately. The Quad-caps are very cool and vintage looking, but some people prefer cap boards on the inside instead. The beautiful thing is that this is DIY, and you can do whatever you like.

Edcor (Transformers): Affordable custom-made "E I" transformers with iconic blue bells. Everything is made to order at Edcor and takes 6 weeks to get produced. If you need something immediately, Hammond may be a better bet.

ElectraPrint (Transformers): Well-made custom "E I" and moving coil transformers at reasonable prices and excellent customer service. Check out the ebay page for ready made units.

Glass Jar Audio (Solid State Kit Provider): Jeff is kind enough to assemble kits with designs from AMB, Cavelli, Toole and others. It's much easier to order through him than sourcing all the parts all over the place and the pricing is very reasonable.

Glassware Audio Design (Tube PCBs and Kits): Glassware has an impressive collection of designs, mostly around the Aikido circuit. You'll find pre-amps, phono pre-amps, headphone amps, volume attenuators, and power rectifier boards. Nice really thick PCBs that are well laid out and some offer the ability to fit bypass capacitors and large coupling capacitors (for DIYers who have strong opinions ;) ). Manuals and schematics are included with purchases. Not as friendly for beginners, start with Bottlehead unless you have some experience under your belt.

Hammond (Transformers and Chassis): Hammond offers a great array of transformers, inductors and chassis which are perfect for small to large DIY projects. Hammond is carried by a number of suppliers such as Angela, Digikey, Mouser, Allied, and others.

Magnequest (Transformers): Some of the best custom wound "E I" transformers for audio. Magnequest transformers are used in designs by Wavelength Audio, Curcio Audio, Alessandro, and other well-known makes. Check out the site for Bottlehead upgrade transformers as well.

Mouser (General Supplier): Need to populate a PCB? Mouser likely has everything you need aside from tubes and traditional tube sockets. If they don't... try Digikey.

Neurochrome (Tube and Solid State PCBs): The Modulus86 seems to be a popular design based around the LM3886 chipamp with some performance enhancements. Very low total harmonic distortion, if you're into that ;) Also a very cool 300B SET (single ended triode) PCB set is available.

Oddwatt (Tube Kits): Oddwatt is a two person team (Bruce and Rodney) offering a number of tube amplifiers and a preamplifier with simple but effective circuitry. The kits include Edcor transformers and custom chassis and PCBs. I don't know too much about the company,  but there is a nice write up on DIYAudioProjects.

Pete Millett (Tube PCBs): Tons of great designs for tube amplifiers, pre-amplifiers, headphone amplifiers and the like. Some beginner friendly designs like the Butte and Jonokuchi headphone amps, as well as expensive, esoteric amplifiers designed around unusual tube compliments. Definitely worth checking out!

Transcendant Sound (Tube Kits): I havent purchased a kit from Transcendant Sound (yet), but have heard many good things. From what I see they look to be a tremendous value. The Grounded Grid pre-amp is quite popular, and the OTL (output transformerless) tube amp designs are said to offer treble clarity rivaling solid state.

Triode Electronics (Tube PCBs and Kits): Dynaco-based amp kits as well as some guitar amplifier kits. Very nice selection of parts and tubes as well if you are building a vintage amp. Directions not quite as perfect as Tubes4HiFi or Beezar, but still very good.

Tube Audio Lab (Tube Amp Kits and PCBs): Great and not overly complex tube-based point-to-point kits and PCBs using the classic 300Bs, 45s, 2A3, etc. Parts selection based on your preferences.

Tubes4HiFi / Bob Latino (Tube PCBs and Kits): Roy and Bob run a really great DIY amp and preamp site. There are models based on the Dynaco ST70 and MKIV, as well as some higher wattage versions if you have some pretty demanding speakers or a big room to fill with sound. Lots of great kits, excellent directions for most offerings (some of the pre-amps have more basic schematics, etc).
Great products at reasonable prices from my experience.


ChipAmp (Solid State PCBs and Kits): Allen at Chipamp has a fantastic array of chipamp / gainclone builds based on the LM1875, LM3886, and LM3875. He also has some great power supply, volume and switcher PCBs. Very simple and easy builds. Beginner friendly except the power amps use high amperage and would be dangerous if safety measures aren't followed carefully. UPDATE: per communications at DIYAudio.com and HeadFi.org, it seems there may be issues with order fulfillment in 2016-2017.

Classic Valve (Tube and Solid State PCBs): Geek at Classic Valve is getting out of the PCB business to shift his attention to building turn-key amplifiers. I encourage you to buy up what he has left. There are a number of very unique Dynaco boards for the PAS, ST70, MKIII and MKIV as well as power filters and other great stuff.
UPDATE: It looks like the supplier CK Magnetics is also clearing out their leftover PCBs, so grab em while you can: http://www.ebay.com/usr/ckmagnetics

DIYTube (Tube PCBs): Shannon at DIYTube is getting out of the PCB business to shift his attention to building turn-key amplifiers. You will still find excellent documentation on DIYTube.com and a semi-active forum, however the boards are no longer available.

Transcendar (Transformer Producer): Once an extremely high value "E I" transformer producer, this maker appears to no longer be producing new products.

The Fine Print: DIYAudioBlog and Zynsonix Audio, LLC does not represent or have any business affiliation with any of the above businesses or individuals. 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. Please keep this in mind.