Beggining - Historical 2005: My previous Tannoy Westmister Royal HE based speakers

Hello!

Here you have my text written in 2005 about my speakers at that time based on 15" Tannoy Westmister Royal HE drivers.

Here you can find a bunch of information regarding my experiences with Tannoy Dual Concentric 15” speakers.

My first contact with Tannoy DC drivers was in my audio friend – DANEK- house.

He used Westminster Royal HE 15” DC drivers (bought, when Tannoy was more open to sell its drivers without cabinet) to build the R-GRF speaker clone. Nice made, with shiny black piano lacquer, opened my mind to the previously unknown musical experiences. Dynamics, scale, drive, presence etc. destroyed my peace of mind.

For at least 5 years I was living with Audio Note E speakers, a perfect tube amplifiers partner, but finally I moved to a much bigger room (about 35 sq. m) and AN speakers simply couldn’t make a proper scale of sound.

Desperately browsing the internet I managed to find in Czech Republic a pair of Lockwood Major speakers built around Tannoy HPD 15” DC drivers. After extensive crossover modifications, replacing the old connector, wires, resistors and capacitors I got a very nice sound. Tone was almost perfect, but was missing some dynamic heard in Danek’s house.

After short negotiations with Danek I decided to buy his speakers. This was a win-win deal. He can finance his new PHY speaker passion and is now strongly motivated to work on an open baffle/cabinet for them, and I have a nice pair of unobtainable Westminster HE drivers with original crossovers in a handsome cabinets and a strong base for further cabinet researches.

15” 3806 speakers are very nice, huge and didn’t change much during the last 50 years. They even have the famous ALNICO magnet in the modern version called ALCOMAX 3.

Here you can find some pictures of a driver:

Back view

 back cone,

 front cone,

 front cone close up

, Alcomax 3 magnet

 and HE surround cone holder.

The original crossover is also almost the same as for old Silver, Gold, HPD and the other vintage DC drivers. At the input of HF crossover there is an auto transformer allowing the adjusting of treble energy, later the signal is attenuated by resistors and for highest frequencies bypassed by capacitor. This is to achieve the relatively flat frequency response. The HF driver has the resonance at about 3kHz, so in older drivers there was a special notch filter in parallel to the HF coil, consists of 3.3uF capacitor, 0.775-0.82mH coil and a resistor (up to 15ohm). This filter was to equalize the frequency curve in 3kHz region. In the latest Westminster crossover, there is still a resonance, but it is not attenuated. It has the strong influence on speaker tone, but can be accepted. Adding the notch kills some of an excitement in sound.

The Tannoy Westminster Royal HE schematics

At the link below, you can see the difference in frequency response when using a notch.

Notch influence on DC speakers response

There is one thing I can’t understand – crossover capacitors quality.

Comparing the older crossovers I can notice, that LF crossover iron core coil was changed to air core coil, which is good, by why Tannoy uses in its flag ship speakers the 50 cents capacitors?

If you don’t believe, look at the below pictures. Both capacitors are IN SERIES with sound, so have a huge influence on sound quality.

2.2uF metalized polyester capacitor passing the highest frequencies

6.8uF capacitor at the HF crossover input

, passing ALL frequencies above 1kHz, so the majority of sound information.

You can see here the difference between new and an old 2.2uF cap.

Changing the above capacitors to Mundorf silver in oil or Audio Note or Jensen copper foil capacitors, brings tremendous sound improvement, removing the harsh from sound and giving the brilliant HF. Next step is changing resistors to MILLS MRA-12 type.

After changing 5 standard resistors to MILLS sound has changed. Making tube amplifiers, I noticed the big resistor influence on sound. I suspected that similar changes can be heard in crossovers. Sound became rounded, warmer, civilized but I heard some HF roll off.

After a few hours or playing music, sound started opening. I expect another at least 50 hours of playing for final breaking-in, but for sure the previously heard unpleasant tension in sound will not come back.

Danek’s R-GRF speaker can be seen here

….and both speakers in my room

The Westminster Royal HE HF crossover picture is here

, and LF crossover is here.

24. March.2005: Finally I have finished upgrading the crossover with better caps and resistors.

As I told before, the sound improvement is obvious and for sure worth trying. This is less expensive than adding the supertweeter, but the result is probably better, because you keep the sound homogeneity.

14.04.2005 I have also changed the capacitors in LF part of the crossover

, using Mundorf Supreme 22uF capacitor. A small increase in capacity is insignificant. Sound is better now, but change is rather subtle.

I had a problem with determining the proper polarity of each speaker. There is no clear + or – sign.

There is a nice method to find out the polarity.

For Low Frequency driver, you need a simple 1.5V battery. You have to attach the “+” of the battery to one terminal and “–“ to the other terminal. If, for such a connection, the cone will move forward, the polarity is the same as for battery.

For high frequency (HF) speaker I used a generator, microphone and a spectrum analyzer (can be a computer program). The crossover point is at 1kHz, so this is a point, where there is a highest overlap of the signals from LF and HF speaker. 1kHz tone from generator will go through the amplifier and to both HF and LF speakers. If both speakers are in phase, you will get the higher level of 1kHz tone detected by microphone and spectrum analyzer. When the speakers have the opposite phase, the signal will be lower. I think that it can be also done by ear. For my speakers, the difference was about 3dB, so the lower level signal had about 2x lower volume.

My previous Lockwood Major speakers had the Tannoy HPD 15” drivers.

As you see, the speaker is very similar to current 3806 version. 30-50 years ago, when cost cutting wasn’t so common, products were more solid. If you think, that modern speaker technology is better and more advanced, you have to verify your point of view here. New driver doesn’t offer better sound, even the crossover is the same. Good old ALNICO magnet is still the best solution in terms of sound quality. You can buy old 15” drivers on e-bay. Prices at about 1000EURO/pair will tell you everything about the driver quality. If a cone is damaged, you can still buy a new cone with coil and other parts from Lockwood Audio in UK