Bush AU51 : stereo AMP input

[jives11]

Hi,

I just got a Bush AU51 for a fiver. Works fine, and I have to say sounds very good.

I'd like to use it from an MP3 player dock which should provide a stereo line level output.

I have a DIN adapter, but of course the unit only has a single signal pin connected on the din socket as it expects to get a single mono signal. I was thinking of soldering a link between the two DIN socket pins on the AU51 to combine the two channels into a single mono "down mix". can anyone see any problems i.e overload, with doing this ?

[AndiiT]

Hi,
It shouldn't be a problem linking the two DIN socket pins as you suggest, you may even find that the TAPE socket already has them linked which will allow you to use the Amplifier to accept a "monoed" Stereo signal.

It might be prudent to fit a couple of buffer resistors in series with the DIN socket pins (usually 3 and 5 for Left and right channel respectively) and connect the lead that was originally attached to the DIN socket to the junction of these two resistors; you may have to experiment a little with the values of these resistors but something between 1k and 5k should be alright.

Regards
Andrew

[jives11]

Thanks Andrew,

I took a look inside and both the AMP and TAPE DIN sockets are wired mono. The TAPE also has one channel wired out i.e enabling you to record presumably, though only one channel !? Either that or my understanding of DIN numbering is wrong (adjacent pins for L & R, adjacent sides for INPUT & OUTPUT).

I dismantled it as my unit has a small hole in the grille in front of the speaker driver. I wanted to check that the driver was fine, which it was. I'll ponder how best to repair the hole. These things were very well made. Everything held together with wingnuts and small brass nuts.

It does have some mains hum which appears to be constant with all but full volume . Of course in this digital switched mode age, a bit of "analogue dither" adds to the charm, so I don't think I'll swap the main cap, which looks very clean

[AndiiT]

Hi,
The TAPE DIN socket does indeed have an output connection as well as an input route.

These units were originally intended to be used with "Stereo convertible" record player which would be cosmetically similar, the player being wired to provide a Mono signal when used on its own and switching activated by the insertion of a plug in to the "STEREO" socket allowing the Player to produce the Right hand channel and the additional amplifier to produce the Left hand channel of the stereo pair.
Bush thought it wise to provide a tape output on both the player and the amplifier so that a true stereo signal could be recorded on a stereo recorder (with quite a lot of wiring to achieve this IMHO)

The TAPE output on these units is tapped from the output stages so the Volume, Treble and Bass controls will affect any recording made on a machine connected to this output.

Regarding the hum another forum member has modified his BUSH SRP51 power supply to reduce this, the AU51 uses an identical power supply so it may be worth doing a search and checking out that thread.


Regards
Andrew


Regards
Andrew

[ben]

you could also try getting a 3.5mm to 3.5mm male lead, then plug that into a 3.5mm female stereo to mono male adaptor plug (which you'd connect presumably via another adaptor to your mono din plug. might save some soldering if you didnt want to modify anything....Ben