• Installing Cullen Circuits modified gain cells. Each Gain Cell upgrade (there are 2) includes the following:
  • Replace 28 resistors with Dale Rn55d copper leaded parts. These are all matched to .1%.
  • Replace 3 semiconductor devices with ipgraded parts yielding an improved bandwidth and decreased harmonic distortion.
  • Replace two lectrolytic capacitors with audio -rade Muse caps.
    
    

There are a total of 66 new upgraded parts in the Gain Cells alone. Once modified, Rick perfectly matches them.

• Replace 12 resistors on the main board with Dale Rn55d copper leaded parts.
• Install 4ea WBT 0765 insulated output binding posts.
• Install 2ea WBT- 0210cu ms Next Gen Signature RCA jacks on the #1 input
• Wire the speaker outputs with Kimber TCX 15 AWG multi gage/strand OFC wire.
• Install ERS EMI/RFI suppression paper
• Six hours total labor.
  

The sonic improvements to an already fine stock amp are extraordinary. The modified amps are:

• More dynamic
• More liquid in the midrange
• More Transparent
• Have better low level resolution and detail.
• Better at focusing images
• Able to throw a wider and deeper soundstage
• Better in the critical midbass area.
  
  

These amps are now a good bit better than the $2795 GCC-100 for a fraction of its price. We offer the same 3-year warranty as the factory.


We are now selling new and fully modified PS Audio GCA amps and GCC control amps. These mods were designed by Rick Cullen who builds the amps for PS. These are totally unique offerings wherein Rick performs a major modification to the PS GainCells that operate as the input stage to the amps. This mod is performed exclusively by Rick while he builds up the GainCells and is a proprietary development of PS Audio. Head honcho Paul McGowan has blessed this modification and Rick adds other major modifications to the rest of the amp.

We are offering Level-2 and Level-3 modifications to customer amps already in the field as well as selling new amps with pre-installed modification packages. The stock GCC control amps (integrated amps) and GCA power amps are excellent values and have received wonderful press. The GCC-100 is Class A rated by Stereophile. The GCC-250 and GCC-500 are basically more powerful versions of the 100. The GCC versions act like integrated amps while the GCA versions of all 3 are power amps only and require a preamp to run them.

Prices
$900.00 to do a Level-2 mod your GCA or GCC amp
New L-2 modified GCA-100s are available for $2,490
New L-2 modified GCA-250s are available for $3,090
New L-2 modified GCA-500s are available for $3,990
New L-2 modified GCC-100s are available for $2,990
New L-2 modified GCC-250s are available for $3,790
New L-2 modified GCC-500s are available for $4,490

Add $300 to the above prices for the Level-3 mod.

Options:
1. RCA Jack upgrade from WBT Next Gen Copper to Next Gen Silver - $50
2) Next Gen 710ag silver speaker jacks are available for an additional $195

The modified amps are a major step up over the excellent stock versions.

The following details the Level-2 modifications:

• We replace the GainCells with Cullen Design custom versions. This replaces 14 resistors with .1% matched Dale RN55 resistors, adds Muse caps, changes 3 crucial semi conductors to reduce distortion and increase slew rate, and custom tweaks the cell for minimum distortion, typically .003%. These gain cells are full-on replacements and a good bit better than the stock version.
• We replace 8 x resistors associated with the XLR inputs and 4 x resistors for each selected RCA jacks with Rn55 Dale parts on the input board.
• 6 x Muse caps are added to the input board. Two additional caps are added for every 2 pair of RCA jacks that are replaced.
• We replace the input jacks with 1 x pair of premium WBT-0210-Cu Next Gen 'direct gold plated over copper body' RCA female jacks.
• The output speaker jacks are replaced with 4 x premium WBT-0763 single output binding posts.
• We upgrade the speaker output wire with Kimber TCX multi strand/gage OFC copper wired in parallel with silver wire.
• We install ERS cloth where required to lower EMI/RFI.
• 4 hours of labor in the Level-2 mod
  

The PS factory warranty is good on the Level-2 modified amps. In the Level-3 modification we also upgrade the ICE amp modules. We do the following:

• We replace 8 x resistors on the ICE modules with Dale Rn-55 copper leaded parts and add 2 x Muse audio grade caps.
• 5 hours of labor for the Level three modification
  

The modified amps are warmer in the midrange. They are faster across the board with better transparency. Bass extension and detail is much improved as is mid bass slam and accuracy. Soundstaging is greatly improved. It is both wider and deeper with better image placement and size. High frequencies are more extended with less grain.

The Level-2 is a dramatic upgrade over the stock amps. It is 85% as good as the Level-3 that also has the amp modules upgraded. The Level-3 carries our Underwood Hifi 3-year warranty, the same as the factory warranty.

• We replace 28 resistors in the audio signal path with Dale Rn55d copper-leaded parts.
• We replace 7 electrolytic capacitors around the DAC with audio-grade Muse caps.
• We add 4 audio-grade Muse caps to the output stage.
• We replace 8 FETs in the DAC's output stage.
• We install ERS cloth to damp EMI/RFI.
• Three hours total labor
  

Sonic Improvements of the Level-1 mod
It is warmer with a more liquid midrange. The little glare of the stock unit is now gone with a warmer presentation. Bass extension is improved with fuller weight and authority. The unit is quieter. Blacks are darker, thus resolving more low level detail. Transparency is improved and you can now look farther into the soundstage as stage width and depth are both improved. The modified DAC is a nice step up over the stock unit at a very reasonable price.


The following details the Cullen Level-3 modification for the PS Audio Link DAC III [$1,590 for new modified machines + freight; $690 + freight retrofit]:

• Install custom clock modification board that replaces the 2 stock clocks with new Cullen-designed clocks with ultra low jitter. This is done to both the clock and CODEC.
• Replace 28 resistors in the audio signal path with Dale Rn55d copper leaded parts.
• Replace 11 electrolytic capacitors with audio grade Muse caps.
• Replace 8 FETs in the DAC's output stage with hand-matched low noise parts.
• Install ERS EMI/RFI Suppression cloth.
• Install WBT NexGen 210cu RCA jacks.
  

Performance enhancements of the Level-3 are as follows:

• The unit is warmer with a more liquid midrange. The little glare of the stock unit is now gone with a more liquid presentation.
• The unit is quieter. Backgrounds are bloacker, thus resolving even more low leveldDetail with better ambiance retrieval.
• Bass slam and extension are dramatically improved with fuller weight and authority. The DAC now sounds more like big buck units that sell an the $3000 - $5000 range
• Transparency is improved and you can now look farther into the soundstage as Stage width and depth are both improved.

The modified DAC is superb as well as being an exceptional value and covered by the PS factory warranty. We also have a new Level-4 version for users running the coaxial inputs. In the L-4 we add an isolation stage to the coaxial input. This makes it perform like the balanced AES/EBU input. Add $150.00 for the L-4 mod. Info can be found on the stock DAC on PS website here.


The stock PS Audio GCPH phono stage is Stereophile Class B rated and very good. We turn it into a Class A performer that will compete with much more expensive phono stages.

The following details the Level 1 modification for the PS Audio GCPH [$700 retrofit, $1,495 + freight new]:

• 4 x Japanese Riken ½ and 1 watt signal-path carbon resistors (gold-plated leads)
• 4 x International Rectifier Hexfred ultra-fast soft-recovery rectifying diodes
• 4 x BlackGate ultra-premium FK-Series electrolytic capacitors
• 1 sheet of SoundCoat chassis damping material cut & applied where applicable
• 2 pair of premium WBT-0210-Cu direct gold plated over copper body RCA female jacks
• 1 sheet of ERS EMI/RFI suppression paper applied in critical locations
• 4 feet of DH Labs 18 awg Revelation Series pure 99.999% silver solid core input signal wire,with Teflon tape-wrap dielectric
• 4 EAR small Sorbothane isolation feet to suppress vibration and airborne feedback
• TRT WonderSolder used throughout
• 4.5 hours labor
  

Sonic changes of the Level 1 mod
We make a major improvement to the midrange. It is more liquid and tube-like. It sounds warmer and more like a tube stage. This was the major design goal of the mod and we think that we have accomplished the task. The unit is quieter, the silences are blacker for more dimensional retrieval of ambient information. Bass response is improved. Both bass depth and mid-bass slam are much improved. Imaging is more focused while the entire soundstage is both deeper and wider. Transparency is improved. You get a much cleaner look into the musical soundstage. Dynamics are improved. The stock unit is good here. Once modified, it is as though we added a few more dB of headroom. We add killer dynamics and the unit has better pace. It seems to play much louder on peaks. There is a more excitement in the music. It now plays with the competition that sells for thousands of dollars more. Treble detail, both micro and macro, are improved and now keep up with anything that we have heard under $3k

Optional Upgrade: We can change the female RCA Jjcks to the new ultra-premium WBT 0210-Ag platinum over silver type. This adds $125 to the base Level-1 mod.

• 1sheet of SoundCoat chassis damping material cut & applied where applicable
• 1 sheet of ERS EMI/RFI suppression paper applied in critical locations
• 1 foot of Neotech 20 AWG UP-OCC solid-core copper hook-up wire added
• 1 pr of Vampire “direct gold plated over copper body” RCA female input jacks replace the bronze jacks of the stock amp
• 4 premium WBT-0763 direct gold over copper single output binding posts
• 4 EAR small Sorbothane isolation feet
• 5 feet TRT WonderSolder used throughout
• 3 hours labor
  

The Level-1 modified player adds better bass definition, extension and low level resolution. At the same time it is more detailed across the entire frequency range. It now is more dynamic with a wider and deeper 3D soundstage. Images are better defined.

Options: Add WBT 710 binding posts and Next Gen inputs for $200