Howard sent me a quick email and photo of the superb internal Duelund high-frequency crossover he developed for his Tannoy Westminster Royal SE loudspeakers.

Jeff,

I have been following your articles on the Duelund mods to your Westminster Royals over last 6 months. Really excellent work – congratulations.

I have carried out - maybe - the final mod to my Royals (I attached a photo of the mod). It shows the last section of the treble circuit – it is preceded by a 6.8 uF Duelund silver CAST. The photo shows the Duelund silver transformer and Path resistors. The 33 Ohm is bypassed with 0.047 uF V cap CuTf cap. Gives 1 dB lift at 20 kHz. The transformer sits on a silicon rubber pad and acrylic bar secures to the bottom of the loudspeaker frame to give minimum vibration. Audio Note binding posts in the acrylic bar and high content silver solder used through out.

Wire is Mundorf Silver Gold – several strands twisted as per litz construction. 

I ran in all the components with a test cd and a few Watts power for 2 weeks prior to installation.

The sound quality after 2 days is staggeringly better!

All you reported about the transformers is true!

Hope all is well.

Best Wishes,

Howard  

Many thanks for sharing your Duelund-WRSE Project with us, Howard, that's an awesome high-frequency crossover! I keep wanting to run in my crossovers' components on my Cable Cooker, but I haven't had a chance to do it yet. Hopefully one of these days I'll be able to fit it into the schedule!

Update:

As you can see below, Vlad has responded to Howard's post with the following request:

"Hi,

Howard, can you please post some more photos of the location in the WR where you placed your treble section with Duelund silver transformer? It’s not clear if it is upper or lower part of the cabinet. And what is it (brown) beneath the transformer sitting on a silicon white rubber pad?

Best wishes

Vlad"

Howard has responded with the following photo and email:

Jeff,

In answer to Vlad's query and response on your site I am attaching a further photo of the treble crossover showing that it is mounted inside the cabinet at the bottom and this is a view of the complete treble circuit seen through the space with the small panel removed.

Note the 6.8 uF silver cast cap on the right.

The “brown” colour is the material of the base of the loudspeaker.

Hope that this helps.

Best Wishes,

Howard

PS sound is sublime!!!

Many thanks to Howard and Vlad for the exchange. I really like what I see here in Howard's HF crossover, as it's both very well thought out and very compact, allowing it to be internal to the loudspeaker. Very nice Howard!