Philips Pancake Speaker, Model 2003 - UK Vintage Radio Repair and Restoration Discussion Forum

YoungManGW · 22nd Apr 2014, 2:19 pm

Dear All, I have just acquired the above. I believe it has an impedance of 3,000 to 4,000 ohms. I'd like to try playing my modern(ish) amp, a NAD 3020, through it. What do I need to know, consider, and get/do before I accidentally damage anything? Many thanks.

Herald1360 · 22nd Apr 2014, 10:56 pm

You'll need to drive via a "backwards" output transformer and I would suggest loading the amp with a power resistor rated for its full output followed by a suitable attenuator to limit the maximum power available to the old speaker to maybe one watt!

Come to think of it, if you just connect the speaker in parallel with the load resistor, you should get 50mW or so into 3-4K. Enough to hear what it sounds like for starters.

It would be a shame to cook the old unit.

YoungManGW · 23rd Apr 2014, 7:55 am

Thank-you Chris. So could I simply connect the amp to an audio transformer, and the transformer to the pancake? If so, can anyone recommend a suitable audio transformer please? Many thanks.

Peter.N. · 23rd Apr 2014, 12:15 pm

Pretty well any standard output transformer should be OK but the low impedance end, thick wires, goes to the amp and the normally 'input ' end to the speaker. The low impedance end may be labelled 3 or 8 ohms or similar.

Peter

Herald1360 · 23rd Apr 2014, 12:49 pm

In principle, yes, but be very careful about how high you set the volume on the amp. A 20W amp at full chat matched to 4K will put something like 280V rms on the speaker

if the transformer can take 20W or else the transformer will saturate and do nasty things to the amp or a bit of both!

I would be inclined to put a potential divider on the amp side of the transformer. Something like a 10R 20W and 3.3R 5W in series across the amp output with the TX connected across the 3.3R will limit power at the speaker to around 1W (still around 70V).

YoungManGW · 23rd Apr 2014, 6:28 pm

Thank-you Peter and Chris - I will acquire the requisite components. May come back on this when I start putting them together, as am very much a novice at this game.

unclemanly · 5th Feb 2016, 5:49 pm

You could try running the speaker from the headphone socket. Headphones generally have a higher impedence than speakers and require a lower output. I used to run one of these Philips pancake speakers from an amp's headphone socket with reasonable success.

dominicbeesley · 5th Feb 2016, 7:56 pm

I'd be tempted to try it from the headphone socket with a 1k resistor in series and work up from there. It should be quite sensitive and you wouldn't want to break it!

AC/HL · 6th Feb 2016, 2:06 am

Might be too late, the thread is the best part of two years old.

22nd Apr 2014, 2:19 pm	#1
YoungManGW Hexode Join Date: Dec 2011 Location: Oswestry, Shropshire, UK. Posts: 408	Philips Pancake Speaker, Model 2003 Dear All, I have just acquired the above. I believe it has an impedance of 3,000 to 4,000 ohms. I'd like to try playing my modern(ish) amp, a NAD 3020, through it. What do I need to know, consider, and get/do before I accidentally damage anything? Many thanks.

22nd Apr 2014, 10:56 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Philips Pancake Speaker, Model 2003 You'll need to drive via a "backwards" output transformer and I would suggest loading the amp with a power resistor rated for its full output followed by a suitable attenuator to limit the maximum power available to the old speaker to maybe one watt! Come to think of it, if you just connect the speaker in parallel with the load resistor, you should get 50mW or so into 3-4K. Enough to hear what it sounds like for starters. It would be a shame to cook the old unit. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

23rd Apr 2014, 7:55 am	#3
YoungManGW Hexode Join Date: Dec 2011 Location: Oswestry, Shropshire, UK. Posts: 408	Re: Philips Pancake Speaker, Model 2003 Thank-you Chris. So could I simply connect the amp to an audio transformer, and the transformer to the pancake? If so, can anyone recommend a suitable audio transformer please? Many thanks.

23rd Apr 2014, 12:15 pm	#4
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Philips Pancake Speaker, Model 2003 Pretty well any standard output transformer should be OK but the low impedance end, thick wires, goes to the amp and the normally 'input ' end to the speaker. The low impedance end may be labelled 3 or 8 ohms or similar. Peter

23rd Apr 2014, 12:49 pm	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Philips Pancake Speaker, Model 2003 In principle, yes, but be very careful about how high you set the volume on the amp. A 20W amp at full chat matched to 4K will put something like 280V rms on the speaker if the transformer can take 20W or else the transformer will saturate and do nasty things to the amp or a bit of both! I would be inclined to put a potential divider on the amp side of the transformer. Something like a 10R 20W and 3.3R 5W in series across the amp output with the TX connected across the 3.3R will limit power at the speaker to around 1W (still around 70V). __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

23rd Apr 2014, 6:28 pm	#6
YoungManGW Hexode Join Date: Dec 2011 Location: Oswestry, Shropshire, UK. Posts: 408	Re: Philips Pancake Speaker, Model 2003 Thank-you Peter and Chris - I will acquire the requisite components. May come back on this when I start putting them together, as am very much a novice at this game.

5th Feb 2016, 5:49 pm	#7
unclemanly Triode Join Date: May 2008 Location: Sheffield, South Yorkshire, UK. Posts: 36	Re: Philips Pancake Speaker, Model 2003 You could try running the speaker from the headphone socket. Headphones generally have a higher impedence than speakers and require a lower output. I used to run one of these Philips pancake speakers from an amp's headphone socket with reasonable success.

5th Feb 2016, 7:56 pm	#8
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Philips Pancake Speaker, Model 2003 I'd be tempted to try it from the headphone socket with a 1k resistor in series and work up from there. It should be quite sensitive and you wouldn't want to break it!

6th Feb 2016, 2:06 am	#9
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Philips Pancake Speaker, Model 2003 Might be too late, the thread is the best part of two years old.