DIY Solo Ultra Linear Headphone Amplifier Upgrade

A DIY Headphone Amplifier Upgrade Project

DIY enthusiasts can now upgrade their Solo headphone amplifier to a Solo Ultra Linear headphone amplifier using this pre-populated board.

Your Solo headphone amplifier must be 2004 onwards and feature the same case as shown here.

Models that can be upgraded to Solo Ultra Linear are: 2004, 2006, 2007, Solo "Green", Solo SRGI and Solo SRGII headphone amplifiers - in fact all Solo headphone amplifiers from early 2004 that look like the pictures.

The DIY Solo Ultra Linear headphone amplifier upgrade board can be ordered on our online shop by clicking here, choosing your destination area and clicking "DIY Kits, Parts Packs and DIY Upgrades" from the "Go To:" menu

The Slide show below shows each step and serves as the instructions to convert your Solo to the Solo Ultra Linear headphone amplifier.

Tools required: small adjustable wrench; 2mm AF allen key (in new condition); small flat blade screwdriver; M4/7mm AF open ended spanner or nut spinner; No.1 phillips screwdriver; No.2 pozi-driver or cranked pozi-driver.

After ordering your DIY Solo Ultra Linear headphone amplifier upgrade board - a whole new fully tested Solo Ultra Linear headphone amplifier PCB - you should receive it within 1-3 weeks of your order. Unpack the "europack carton" carefully and only handle the board by its edges. Only sit it on a clean surface and do not drop anything metallic into it.

By removing the top two front panel screws and the top two rear panel screws the lid of your existing Solo can be lifted clear and put to one side. Please ensure you don't lose any parts during the upgrade.

Stage 1: loosen and remove the control knob and park the switch in its centre position

Stage 2: using a suitable wrench such as an adjustable, turn the nut anti-clockwise taking care not to slip and damage the front panel. Remove the nut fully.

Stage 3: remove the washer from the volume control bush

Stage 4: do not remove the lower front panel screws

Stage 5: remove the lower two rear panel screws and slide out the board and rear panel assembly

Stage 6: remove the black self tapping screw from the middle of the phono block

Stage 7: from the Solo SRGI the case ground became an auxiliary ground so that a separate earth wire could be run to a convenient earth point. Remove the long nut and washer

Stage 8: The case ground screw head on this model is on the inside and if the nut on the outside will not loosen without the whole assembly turning a cranked No.2 pozidrive screwdriver will be required

Stage 9: on older models the case ground nut is on the inside with the screw head on the outside. On the very first 2004 models a threaded pillar is fixed to the rear panel. An open-ended M4 (or M3 on some models) spanner will be required to loosen the nut

Stage 10: The Solo Ultra Linear board is equipped with a solder tag to terminate the PCB grounds to the rear panel. After offering up the rear panel to the back of the board and fastening the rear panel to the phono block using the black self tapping screw (use No.1 Phillips screwdriver and see stage 6) the case earth screw, serrated washer and nut is used to secure the solder tag to the rear panel. Take care not to turn the tag when tightening.

Stage 11: when the rear panel is properly assembled it should look as shown in this picture

Stage 12: slide the assembly back into the case lower half on the lower of the two location grooves. Ensure the switch is set to its mid position and the LED is lined up with the front panel hole, and push fully home.

Stage 13: Replace the two lower rear panel screws and nip them tight. Take care not to slip with the allen key.

Stage 14: replace the volume control washer, then the nut nipping it up without over tightening to prevent stripping the threads, then turn the volume control shaft fully anti-clockwise and replace the control knob (see stages 1 to 3 in reverse)

Stage 15: replace the lid and the upper two front and rear panel screws and nip tight. If a multi-meter is available test for continuity between any of the phono socket outer contacts and a front panel screw head. This should measure around 1 to 5 Ohms depending on the multi-meter battery condition (essentially it would be zero)

Your upgraded Solo Ultra Linear headphone amplifier is now ready for use.

The DIY Solo Ultra Linear headphone amplifier upgrade board can be ordered on our online shop by clicking here, choosing your destination area and clicking "DIY Kits, Parts Packs and DIY Upgrades" from the "Go To:" menu

The DIY Solo Ultra Linear upgrade is £175.00 plus shipping and VAT where it applies.

If DIY is too daunting for you we offer a factory upgrade on your returned 2004 onwards Solo headphone amplifier for £219.00 plus return shipping and VAT where it applies.

See our Solo Ultra Linear headphone amplifier main page for further details and specification and also visit the GSPForum to read what other owners say about the Solo Ultra Linear headphone amplifier

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