The low distortion amplifier nonprofit DiY kits


Recently I sell a few low distortion amplifier (LDA) DiY kits without any profit and without any wage for work (I sell the kits at the price that I buy the components for, with no any additional fee for the cost of labor.) With this, I'd like to support the first people who will build this amplifier, and so make this amp more popular.

There are 4 somewhat different kits offered. All the kits consist of

- the specified number of "LDA amplifier board(s)" with the specified component set,

- the specified and specified number of "Power supply & relay board(s)" or "Power supply board" with pertaining components,

- the specified and specified number of "Protection circuit board(s)" or "Protection circuit board with relay" with pertaining components,

- the "Mains input board with auxiliary 12VDC supplies" with the specified component set, except for the LDA MIN kit.

The following are included with the kits: all the specified PCB's with all components that need to be soldered or fitted to the PCB's, except for the main rail filter caps for the power supply(s). I also send transistor thermal pads and the screws for fitting electronic components onto the heatsinks.

(A few examples of what is NOT in the kits: chassis, transformer(s), main heatsink(s), cables, on-chassis connectors and switches, main rail filter caps, glue, etc.)

The assembly instructions are being written. If you're interested, please send me an email.

So here we go, the following non-profit kits are available for those who'd like to be the first to build this amplifier.


LDA 53DM kit

Suitable for building a 2x200 watts per 4 ohms low distortion DUAL MONO power amplifier (protection is via ultra low distortion solid state relays).

Non-profit price: 148 EUR + postage.

- consists of the following kit components: 2x"A1" + 2x"SRo" + 2x"Po" + 1x"M1" (see the LDA kit component descriptions below)

- intended as home audio power amplifier for high power audiophile loudspeakers

- recommended unloaded power supply voltage: +/- 52...54V

- recommended transformers: two pieces of 300VA transformers with 2x38...2x40VAC secondary voltage

- please indicate in your order if you want to use a fan to cool an internal heatsink, then I will send kit component "P1" instead of "Po"

- a suitable chassis that includes side heatsinks: Dissipante 4U (e.g. with deluxe-style faceplate) or Deluxe 4U (see diyaudiostore.com) -- not supplied within this kit


LDA 43S kit

Suitable for building a 2x110 watts per 4 ohms low distortion STEREO power amplifier (protection is via individual mechanical relays).

Non-profit price: 92 EUR + postage.

- consists of the following kit components: 2x"A2" + 1x"SR1" + 2x"Po" + 1x"M3" (see the LDA kit component descriptions below)

- intended as home audio power amplifier for medium power audiophile loudspeakers

- recommended unloaded power supply voltage: +/- 42...44V

- recommended transformer: 350VA transformer with 2x31...2x33VAC secondary voltage

- please indicate in your order if you want to use a fan to cool an internal heatsink, then I will send kit component "P1" instead of "Po"

- a suitable chassis that includes side heatsinks: Dissipante 2U or 3U e.g. with deluxe-style faceplate  (see diyaudiostore.com) -- not supplied within this kit


LDA MIN kit

Suitable for building a 2x110 watts per 4 ohms low distortion STEREO power amplifier (with minimalist protection circuit via a mechanical relay).

Non-profit price: 62 EUR + postage.

- consists of the following kit components: 2x"A2" + 1x"S1" + "PR1" (see the LDA kit component descriptions below)

- intended as home audio power amplifier for medium power audiophile loudspeakers

- with only loudspeaker protection and turn-on thump muting via a DPDT mechanical relay

- recommended unloaded power supply voltage: +/- 42...44V

- recommended transformer: 350VA transformer with 2x31...2x33VAC secondary voltage

- a suitable chassis that includes side heatsinks: Dissipante 2U or 3U e.g. with deluxe-style faceplate  (see diyaudiostore.com) -- not supplied within this kit


LDA 53M kit

Suitable for building a 200 watts per 4 ohms low distortion MONO power amplifier (protection is via an ultra low distortion solid state relay).

Non-profit price: 77 EUR + postage.

- consists of the following kit components: 1x"A1" + 1x"SRo" + 1x"Po" + 1x"M2" (see the LDA kit component descriptions below)

- intended as home audio power amplifier for high power audiophile loudspeaker

- recommended unloaded power supply voltage: +/- 52...54V

- recommended transformer: 300VA transformer with 2x38...2x40VAC secondary voltage

- please indicate in your order if you want to use a fan to cool an internal heatsink, then I will send kit component "P1" instead of "Po"


The LDA Kit Component Descriptions

Note: Only the PCB's are shown -- you'll get all the electronic and mechanical parts pertaining to the PCB with your order.


LDA amplifier board

LDA162: low distortion amplifier, PCB

    - suitable for 4-ohms load

    - very low distortion at all power levels (sub 0.0014% 1kHz THD with LDA162hc, sub 0.0022% with LDA162mc at all power levels)

    - low noise (S/N ratio: >115dB at 200 watts / 4 ohms or >113dB at 110 watts / 4 ohms)

    - can be ordered with high power or medium power component set as follows:

Order code "A1" LDA162hc: LDA162 PCB + high power component set (max. 200 watts per 4 ohms)

Order code "A2" LDA162mc: LDA162 PCB + medium power component set (max. 110 watts per 4 ohms)


Power supply & relay boards / Power supply board

PSSR350: high power mono power supply & a single ultra low distortion solid state relay with its control circuit, PCB

    - max. +/- 70V supply voltage

    - PSSR350 can serve a mono high power amplifier (or two PSSR350's can serve a dual mono high power amplifier)

    - two pairs of snap-in type electrolytic filter caps up to 35mm diameter can be fitted (not supplied with kit)

    - needs 12V 40mA regulated supply (MIB12 is a suitable 12V supply)

    - connects to an APBF (or an APBM) protection board for the relay control

Order code "SRo" PSSR350c: PSSR350 PCB + all components except main filter caps

 

PSMR101S: stereo power supply & two independent SPST mechanical relays with their control circuits, PCB

    - recommended for up to +/-50V supply voltage, but higher voltage might be used if needed

    - max. 10A output current per relay

    - independent fuses and relays for two (i.e. stereo) channels

    - one pair of snap-in type electrolytic filter caps up to 35mm diameter can be fitted (not supplied with kit)

    - needs 12V 100mA regulated supply (MIB12sc is a suitable 12V supply)

    - connects to two APBF's (or two APBM's)  protection boards for the relays' control

Order code "SR1" PSMR101Sc: PSMR101S PCB + all components except main filter caps


PS1S: stereo power supply, PCB

    - recommended for up to +/-50V supply voltage, but higher voltage might be used if needed

    - one pair of snap-in type electrolytic filter caps up to 35mm diameter can be fitted (not supplied with kit)

Order code "S1" PS1Sc: PS1S PCB + all components except main filter caps

Protection circuit boards / Protection circuit boards with relay

APBF: mono protection circuit board with fan control capability, PCB

    - loudspeaker protection

    - overcurrent protection

    - switch-on/ switch-off muting

    - thermal protection (heatsink overtemperature sensing)

    - 12V power supplied through PSSR or PSMR module

    - all analog, no need for special preprogrammed chips

    - tested with with LDA162 and PSSR702 / PSSR350 / PSMR101S, but may be suitable for other amplifiers and other relay circuits

    - if you wish to use a fan, then you must make a suitable power supply for the fan, APBF only switches a DC fan in or out of circuit

Order code "P1" APBFc: APBF PCB + all components


APBM: older version of APBF without fan control circuit, PCB

Order code "Po" APBM: APBM PCB + all components


SPRS: simple stereo protection circuit board with relay, PCB

    - loudspeaker protection

    - switch-on muting

    - needs 12...17VAC 50mA power supply

    - simple and all analog, no need for special preprogrammed chips

    - suitable for all amplifiers with dual (+-) power supply

Order code "PR1" SPRSc: SPRS PCB + all components

Mains input board with auxiliary 12VDC supplies

MIB12: mains input board with auxiliary 12VDC power supplies, PCB

    - includes mains input connector, fuses, line EMC filter cap and solder pads for on/off switch(es) and transformer primary side(s)

    - supplies 12VDC needed for the power supply & relay board(s) and protection board(s)

    - MIB12 can be configured and ordered with dual mono, stereo or mono component set as follows:

Order code "M1" MIB12dmc: 2x 12VDC 50mA with separate ground -- MIB12 PCB + dual mono component set, e.g. for two PSSR350's

Order code "M2" MIB12mc: 12VDC 50mA -- MIB12 PCB + mono component set, e.g. for a single PSSR350

Order code "M3" MIB12sc: 12VDC 100mA -- MIB12 PCB + stereo component set, e.g. for the PSMR101S

 

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