Speaker wadding advice - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

stuart_morgan_64 · 16th Aug 2019, 2:04 pm

Just found some info
https://hifiwigwam.com/forum/topic/1...-labeled-mdkt/

stuart_morgan_64 · 16th Aug 2019, 2:05 pm

These looking at the bottom grill have loft insulation in them

Radio Wrangler · 16th Aug 2019, 2:21 pm

Some info on just what you have in this thread:

https://www.lencoheaven.net/forum/in...7&topic=5605.0

Makes interesting reading and seems to say that Fried himself had no technical input, just sales in the beginning.

David

gramophone1 · 16th Aug 2019, 9:25 pm

You could try this from Russ Andrews.

Acousti-Wool | Resonance control | Russ Andrews Accessories Ltd. I am considering trying it with my own speakers.

Russ Andrews can be expensive, so check prices first, and decide whether it is worth the expense.

Radio Wrangler · 17th Aug 2019, 4:44 am

The usual stuff (bad pun!) for transmission lines is long-fibre wool as championed by Dr Bailey himself.

You want the transmission line path to be low loss but slowed wave velocity... IE some suspended mass in the air, but little damping. Recycled wool fibres tend to be short and you can't get them stable at the low density needed. OK if you want total damping in a simple sealed or ported box.

Use anti-reflection material to line the walls of the transmission lines, but have the path of the line filled with low density fluffed-up long fibre wool.

I think Bailey had an article in Wireless World on it.
Chris Rogers explains transmission line stuffing in the notes for his PRO9TL design. Worth reading

Wilmslow or Falcon ought to supply the right stuff.

David

simpsons · 17th Aug 2019, 9:53 am

I wonder if the extra wadding was used to tame the bass response when the loudspeakers were placed directly on the floor.

I have placed my Celestion Ditton 44's on metal stands for that very reason and this is in a room 20'X13'. Given that transmission line speakers will probably reproduce at even a lower frequency, used in a small room and placed on the floor, it could be an issue.

Too late now, but always use gloves when handling loft insulation. It is not accoustic wadding.

16th Aug 2019, 2:04 pm	#21
stuart_morgan_64 Heptode Join Date: Aug 2004 Location: Woodbridge, Suffolk, UK. Posts: 501	Re: Speaker wadding advice Just found some info https://hifiwigwam.com/forum/topic/1...-labeled-mdkt/

16th Aug 2019, 2:05 pm	#22
stuart_morgan_64 Heptode Join Date: Aug 2004 Location: Woodbridge, Suffolk, UK. Posts: 501	Re: Speaker wadding advice These looking at the bottom grill have loft insulation in them

16th Aug 2019, 2:21 pm	#23
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,877	Re: Speaker wadding advice Some info on just what you have in this thread: https://www.lencoheaven.net/forum/in...7&topic=5605.0 Makes interesting reading and seems to say that Fried himself had no technical input, just sales in the beginning. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

16th Aug 2019, 9:25 pm	#24
gramophone1 Pentode Join Date: Apr 2018 Location: Tyne and Wear, UK. Posts: 168	Re: Speaker wadding advice You could try this from Russ Andrews. Acousti-Wool \| Resonance control \| Russ Andrews Accessories Ltd. I am considering trying it with my own speakers. Russ Andrews can be expensive, so check prices first, and decide whether it is worth the expense.

17th Aug 2019, 4:44 am	#25
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,877	Re: Speaker wadding advice The usual stuff (bad pun!) for transmission lines is long-fibre wool as championed by Dr Bailey himself. You want the transmission line path to be low loss but slowed wave velocity... IE some suspended mass in the air, but little damping. Recycled wool fibres tend to be short and you can't get them stable at the low density needed. OK if you want total damping in a simple sealed or ported box. Use anti-reflection material to line the walls of the transmission lines, but have the path of the line filled with low density fluffed-up long fibre wool. I think Bailey had an article in Wireless World on it. Chris Rogers explains transmission line stuffing in the notes for his PRO9TL design. Worth reading Wilmslow or Falcon ought to supply the right stuff. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

17th Aug 2019, 9:53 am	#26
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Speaker wadding advice I wonder if the extra wadding was used to tame the bass response when the loudspeakers were placed directly on the floor. I have placed my Celestion Ditton 44's on metal stands for that very reason and this is in a room 20'X13'. Given that transmission line speakers will probably reproduce at even a lower frequency, used in a small room and placed on the floor, it could be an issue. Too late now, but always use gloves when handling loft insulation. It is not accoustic wadding.