Tuesday, 11 June 2013

The Tannoy Autograph II – Improvements on a legend

Hello again,
for some continuation of the story about Tannoys legendary vintage full range horn speaker cabinet.

Klaus and me met again three weeks later for a Sunday to work at the cabinets. Klaus had tested in the meanwhile different positions in his room for the cabinets instead the dedicated corner position. They were placed like ordinary speakers with distance to the rear and side walls and some 15° degree inverted angle to the listening position – with good success how he said?! A much better low frequency response with much reduced boost effect in the region around 100-200 hz was listenable. Of course this type of positioning must have this sort of influence to the sound performance. The cut horn openings (off the walls extension) will lift the cutoff frequency of the lf-horn up into the registers of 150-200 hz region. Together with a shortened opening it will decrease the efficiency for some decibels, so the horn will be a lot less present in the all around performance of the speakers.
The inverted angled position of the them make the front loaded horns to work better focused in the listening position. So the illusion of imaging in the projection seem to improve a lot. A by far more defined soundstage with much better width and depth was the result of the new position.
Klaus did finish the covers and ordered some 12mm woolen felt as new damping for the compression chambers. The felt was used to exchange the former acoustic foam in the compression chamber. This implies the same sort of damping, but with thinner and stiffer materials, taken less air space and therefore a better adjusted chamber volume?

The new damping of the compression chamber and a new seal for the speakers. These will be mounted now at the baffle board instead the wrong mounting behind the front horn.

When I arrived at Klaus house he needed my helping hand to get the speakers layed back on the floor. With a good 100 kg of total weight these speakers are not easy to handle, for every step you need a helping hand, better two. On the floor he could apply the felt in the compression chamber and mount the speakers in their original dedicated position.
We installed the new boards covered with grill cloth for both side openings of the cabinets. Klaus still did insist that the covers will reduce the effective openings to 50% of their former uncovered surface. This will have a noticeable influence in damping the back loaded horns.
The drivers got now screwed to the originally dedicated baffle boards of the compression chambers and were sealed it with new foam tape. Between front horn and driver now there is a 5mm air gap without physical connection, this helps to prevent the introduction of resonant energy, which will be boosted from the horn itself. This has a tremendous effect in reducing the resonances around 500 hz, which were more than present before. We placed the cabinets back in the corners and started the second audition after several hours of work.

Working at the second speaker in front of the finished speaker. The decoupling of the funnel can be seen by the disappearing of the four screws in the corners of the funnels base board.

 After six hours workwe started to drink some remarkable wine from Klaus vine cellar as a good alternative for
listening to good jazz music.

They did already look like originals from the 1950ties with the newly made covers and the perfect matching grille cloth. The sound improvements introduced by the changes were nothing else than tremendous, from the first moment the big bass boost and the whooly mids did disappear completely, the tonal range opened up to a much better audible richness of tonal color spectrum. As well the illusion of the projected space has got a much better dimension, even when it is not the perfect discipline of this angled construction. The corner design fixes the inverted angle of the hf-horns to a 45° degree position, which is mostly not a optimized angle seen from the listening position. The complete wrongness of the first audition did disappear and as a new dimension it was noticeable that we did listen to 15-inch Tannoy speakers with their typical sound stage and advantages, other duplex speaker constructions of that time don't have.

We did listen to several records and switched to digital programme material later on. After another three hours we closed the test and cooked a late night meal. Eating and drinking was a must to complete our discussion about further improvements in the coming future. Some french "soupe de poissons" closed the day at 1:00h o'clock late at night. We decided that it will need further improvement into the same direction and I needed desperatly to drive home to get some sleep.


Delicious "Soupe de Poissons a la Provencale" as a late night meal

On my way back home I made a summary of the today realized improvements. But I am still very sceptical about the process of damping to a given horn development and its "resulting improvements". – Yes the improvements were listenable, but from a technical point of view this change does not make sense to me.  My expectations of the "legendary horn design" and all the internet gossip did not match reality, the all around performance of this speakers still does not impress me. After 25 years of living with Tannoy sound I still did expect some more affection from incomparable qualities other speakers don't can deliver.

If there will be somebody out who has some personal experience with this or similiar type of speakers like the Westminster I would be interested to know about. Read on soon on further improvements on this legends, Volker