Here-I-Come 10+ year member
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For sale is an ultra modified Clarion DRX9255 modified by the master Matt Roberts. This is unit 1 or 2 on the planet. This H/U has been transformed into a purists type of audio circuit.
So some to understand what has been done to this unit it is like; David Banner (stock DRX9255) getting mad and turning into the Incredible Hulk (This Matt Roberts Modified DRX9255) It is an unstoppable force. You have no idea what unrestrained sonic reproduction sounds like until you listen to this deck.
From Matt Roberts here is what has been done:
Here is a description of the oiginal vs. modified circuit.
In stock form the audio signal goes from the dac to an I/V converter (an opamp) out to two coupling caps then to two relays that switch from am/fm/cd. The coupling caps were removed and the relays were bypassed (no more am/fm). Then the signal goes to the l/r balance circuit (opamp, coupling caps and pot) to the bass treble circuit (opamp, coupling caps and pot) to the fader circuit (opamp, coupling caps and pot) then to the volume circuit (opamp,coupling caps and pot). All of this was replaced with one of the best audio attenuator/volume pots available, the Alps Blue Velvet. This pot has tracking accuracy within less than .4db and actually measured better than that. From the volume control the signal goes to the output stage which consists of two more opamps and more coupling caps. These op amps were replaced with very good units that have low dc offset, high output current, lower noise. That allowed me to remove the coupling caps at the output.
What all this means is the new circuit is very simple and has a very short signal path. It esentially goes through the dac to the voltage converter to the volume pot then to the output buffer. All coupling caps were removed so it's dc coupled with less than 3mv (3/100's of a volt) of dc offset. All the feedback caps were changed out to silver mica units. Power supply decoupling caps were added to better supply and isolate the dac, voltage converter, and output stage.
One of the voltage regulators and power supply caps had to be moved to make room for the volume pot. The side case of the H/U and the output circuit board were both cut to make room for the volume pot as well. This unit does 8.22 volts out at max volume with a zero db sine wave.
The face of the unit was redone to remove the bass treble knob and to relocate the hole for the new volume pot. Acrylic repair was used to fill the holes. A large (7/8") volume knob was installed for better looks and feel. This H/U is a true purists piece and is the real deal.
Bring on all comers, Z1, MX5000/MX4000, Sound Monitor 400, Pana tube head, will meet or beat any of them. $850 shipped in the US. $915 shipped international.
This is a pic of the dac, I/V converter, bypassing of the relays and the new volume pot.
On this unit the rear outputs has coupling caps and the front does not where add. Listen to and and choose your taste.
This pic is of the output buffer which uses Linear Technology IC's, Elna P/S caps, silver mica feedback caps and NO coupling caps.
So some to understand what has been done to this unit it is like; David Banner (stock DRX9255) getting mad and turning into the Incredible Hulk (This Matt Roberts Modified DRX9255) It is an unstoppable force. You have no idea what unrestrained sonic reproduction sounds like until you listen to this deck.
From Matt Roberts here is what has been done:
Here is a description of the oiginal vs. modified circuit.
In stock form the audio signal goes from the dac to an I/V converter (an opamp) out to two coupling caps then to two relays that switch from am/fm/cd. The coupling caps were removed and the relays were bypassed (no more am/fm). Then the signal goes to the l/r balance circuit (opamp, coupling caps and pot) to the bass treble circuit (opamp, coupling caps and pot) to the fader circuit (opamp, coupling caps and pot) then to the volume circuit (opamp,coupling caps and pot). All of this was replaced with one of the best audio attenuator/volume pots available, the Alps Blue Velvet. This pot has tracking accuracy within less than .4db and actually measured better than that. From the volume control the signal goes to the output stage which consists of two more opamps and more coupling caps. These op amps were replaced with very good units that have low dc offset, high output current, lower noise. That allowed me to remove the coupling caps at the output.
What all this means is the new circuit is very simple and has a very short signal path. It esentially goes through the dac to the voltage converter to the volume pot then to the output buffer. All coupling caps were removed so it's dc coupled with less than 3mv (3/100's of a volt) of dc offset. All the feedback caps were changed out to silver mica units. Power supply decoupling caps were added to better supply and isolate the dac, voltage converter, and output stage.
One of the voltage regulators and power supply caps had to be moved to make room for the volume pot. The side case of the H/U and the output circuit board were both cut to make room for the volume pot as well. This unit does 8.22 volts out at max volume with a zero db sine wave.
The face of the unit was redone to remove the bass treble knob and to relocate the hole for the new volume pot. Acrylic repair was used to fill the holes. A large (7/8") volume knob was installed for better looks and feel. This H/U is a true purists piece and is the real deal.
Bring on all comers, Z1, MX5000/MX4000, Sound Monitor 400, Pana tube head, will meet or beat any of them. $850 shipped in the US. $915 shipped international.
This is a pic of the dac, I/V converter, bypassing of the relays and the new volume pot.
On this unit the rear outputs has coupling caps and the front does not where add. Listen to and and choose your taste.
This pic is of the output buffer which uses Linear Technology IC's, Elna P/S caps, silver mica feedback caps and NO coupling caps.
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