Head Phone Amplifier Upgrades

I'm pleased to offer upgrades for two very popular headphone amps, the Pro-Ject Head Box Mk II and the Rega EAR. Both amps use a high current, discrete output stage which makes them a very good, muscular platform for upgrades compared to the very popular and common IC based designs.

Why Upgrade?
Unfortunately, the reality of mass manufacturing, and sales, means that a manufacturer makes less than 30% of the sales price. This means that compromises in parts must be made in order to get the products to a price point that the target market can afford. Because of this, investing in modestly priced upgrades delivered without distributors and sales people in between can yield benefits that surpass purchasing new kilobuck hardware.

These upgrades are based on respecting the existing designs, and making them perform as well as they possibly can. Each manufacturers have made a different set of compromises. The Rega EAR screams for a quieter, more robust power supply but starts with a decent op amp. The Head Box starts with a quiet power supply, but has a really sub-par op-amp. Both amps share the need for better quality audio caps. We leave the basic design alone, but enhance the areas where each is weak, giving you the best of all worlds.

Pro-Ject Head Box Mk II
Basic upgrade:

• Replace all electrolytic capacitors with very high quality, low impedance versions
• Improve reliability with upgraded specs on critical power supply caps
  
• Socket Op-amp with gold dipped machined low profile socket
  
• Replace Op-amp with same type as used in the stock Rega EAR

Cost: $90 + Shipping

Results:

• Much better midrange and treble
• Bass opens up completely
• Low impedance headphones no longer have severely restricted bass
  
• Performance exceeds stock Rega EAR in many ways, including lower noise, sweeter midrange through clear effortless treble, and an open easy breathing bass.
  

Rega EAR
Basic Upgrade:

• Replace most electrolytic caps with very high quality, low impedance versions (Black Gates by request, for an additional fee)
• Modify power supply for lowest possible noise, and gutsier performance. This includes a mod to the circuit design as well as adding parts.
  
• Add by-pass caps on outputs (subject to space limitations)

Results:

• Noise greatly reduced, especially hum
  
• Greatly increased clarity
  
• Better midrange through treble, more natural, less restrained.
  
• Slightly gutsier bass
  

Cost: $90 + Shipping

Advanced Mod (for both):

• Socket op-amp with machined, gold dipped low-profile socket.
  
• Replace op-amp with Burr Brown OPA 627s, considered by many to be among the finest available. At $50 per pair, they are certainly among the most expensive!
  
• Replace critical power supply resistors with ultra-quiet, Vishay MIL-SPEC metal film versions
  
• For Head Box only, replace ceramic disk caps to fit adapter

Results:

• Unbelievably natural and smooth transients and decay. This applies especially to listening to instruments as well as cues about the room space.
  
• Treble and midrange appear to be effortless, and unrestrained. You loose the sense of listening to headphones.
  

Cost:

• Basic + Advanced Upgrade: $150 if done at once.
  
• Advanced Upgrade: $95 if done after basic
  

FAQs:

Q: Why is the cost for the basic upgrade so similar for both?
A: Time vs. parts. The Head Box has more parts to replace. The EAR needs a board change to fit the necessary power supply changes, so it takes more time.

Q: Can I get Black Gate caps in the Head Box?
A: Sorry, unfortunately Black Gate caps tend to be physically large, there's only about 19mm of height available in the Head Box. The values that are needed for critical caps like the power supply and coupling caps that are needed are just too tall.

Q: What does the Black Gate upgrade do?
A: Honestly I've never listened to BG's in either of these devices, but there's always some one who wants them in, so yes, it can be done. This would be especially important in the coupling caps. One reasons why I don't usually like to use BG's is that they like to charged for days before sounding good, and I hate wasting electricity. However, the power draw of these amps is so small at idle, this is not an issue.

Q: Is the upgraded Head Box really better than the stock Rega EAR?
A: Clearly. The Head Box starts off weak in the bass, especially with low impedance headphones like the newest Grados. The basic upgrade makes the bass as good as the EAR while surpassing it on the midrange dynamics.

Q: What's the end result of both modified the same way?
A: Honestly, I'm afraid to say that the end result is very similar. Once the basic level is reached, they are very similar in performance. Unfortunately this also means that, in my opinion, if you are starting from scratch your best value is a modified Head Box. On the other hand, if you already bought an EAR and like it, you will be missing out on just how good this amp can be if you don't upgrade it.

Q: Is the Advanced Upgrade really worth it?
A: Yes, completely. When I do the advanced upgrade I socket the op-amps. If you want you can go back and forth between the upgrades I provide and the originals. Request this in advance please so I don't throw the originals out. (Head box op-amps are super cheap, and hard to pull out in one piece though, you may end up with an NE5532 instead of the original, but I promise, it's better than what you had).

Q: Can I get just the Advanced Upgrade?
A: Yes, but...why would you? The stock Head Box won't give you enough bass to drive your high output cans, and the stock Rega EAR won't be quiet enough. Upgrading the op-amp will just make it easier for you to hear how noisy the stock supply is.

Q: Will this void the factory warranty?
A: Yes. However, fixing a future problem with either of them should be a piece of cake. Chances are if anything goes wrong it will be the with the op-amps. The advanced upgrade sockets all of them, so replacing them is a matter of minutes.

Q: Do you offer a warranty?
A: Yes, 90 days parts and labor on parts I actually replace. If both op-amps go however, I'll charge for their replacement, as this tends to only happen after an electrical surge. Also, the Head Box is a very tight tight squeeze for the upgrade parts. If you decide to open it up to look and break off a capacitor, I will charge you for parts and labor. If you are the kind of person who is like that, let me know and I'll ship it to you out of the case, or send you pictures of the upgrade first. :)

Q: Do you have a sample I can listen to?
A: Yes. I have an upgraded Head Box you can listen to if you are in the Boston area.

Q: Do you sell "new upgraded" Head Boxes?
A: Yes, I can source them new. For these I offer 90 Days parts and labor on all parts. Saves you the cost of shipping one to me, but if you can buy one used or at a discount, you can get a better deal.

Q: Can I listen to the upgrade and return it if I don't like it?
A: Honestly I don't like doing this as a lot of people like to reverse engineer a great set of upgrades. If you don't believe the advanced upgrade is worth it, I'll exchange the op-amps and parts for $30.