Tannoy information page

Updated on: 7 March 2004

On this page, I will discuss my experiences with the Tannoy Cheviot and SGM-12X speakers.

The Tannoy Cheviot (HPD-315)
Regrettably, the quality of the photos is quite low; they have been made with a digital videocamera. The Cheviot is driven by a modest set, consisting of an Onkyo Integra A-8057 amp and a Rotel RCD-950 CD-player. The speakers have just been resurrounded. They need further repair; the difference in sound between the two speakers is too large. I will start by cleaning and aligning the tweeters, followed by bypassing the crossover switches and mounting new speaker connectors. This pair of speakers is located in my parents house in Friesland (the Netherlands).

Cheviot modding
The following text was sent by me to the Tannoy e-mail group:

This weekend I spent some time to repair the Cheviots of my father. Here is a summary of the modding process ;-)

I started by removing the drivers. I still wonder what the best procedure for this is. Once I tried it with the speaker laying down on the floor. In that case, it is hard to remove the drivers. On normal (vertical) position, the drivers tend to fall down. Luckily, I didn't damage anything. The best procedure is probably to remove the upper bolts first and then the lower ones. Internally, there was a small (wooden) board from the front side to the back side. Very funny, almost every part of the speakers had a quality control stamp on it. The stamp was dated 25 july 1978, so the speakers are 25 years old. I removed the back plate (with the awful connectors to be replaced). New (gold-plated) connectors were inserted. This is much better, the speaker cables did fall out of the previous connectors. The new connectors fitted perfectly in the place of the old connector after drilling a 7 mm hole and removing a small part with a sharp knive (to hold the connector in one position).

After this, I had a look at the tweeters. I cleaned the tweeters (very gently!) with alcohol and cotton buds. They looked ok. The mechanical tolerance was very small, so I didn't align the tweeters while closing (I couldn't change much anyway). Maybe I will do that later.

During the third part of the modding process, I removed the cross-overs. The switches are in a really bad condition. If I only moved the switches a tiny bit, the speakers made a cracking noise. The removal of the cross-over caused some problems. I removed the four screws on the front side of the speakers, but the cross-over was still mounted on the top side. After moving around for a while I noticed that the upper part of the cross-over was glued to the cabinet. With a bit more force, the cross-over could be removed. I drilled a part of the pcb tracks away that were connected to the main contacts of the switch (the two inner contacts of the switch). Then, I connected the remaining part of the pcb tracks to the neutral contacts of the switch (with small wires).

After reassembling the speakers, it was time to listen to the results. Wowie! I was quite surprised about the results! They sounded a bit muddy before. The sound was much more accurate after the modding. The bass was tighter, mids clearer and the top-end was also better. The stereo imaging was improved quite a lot too. They sound quite nice&crispy. The bass really kicks ass with some tracks, very deep! :-)

One problem remains. It seems that the right speaker is less loud in volume. I have to research this problem further, but for now I am quite happy about the results of this relatively easy (and cheap!) modification...

The Tannoy SGM-12X
The Tannoy SGM-12X is used in my current system. I drive it with my Chill-amp 'gainclone' amplifier. The digital source is the Nonoz III DAC combined with a modified Philips CD-960 transport. The CD-960 is equipped with a Guido Tent XO clock module and its power supply is improved with better caps.
My SGM-12X's have not been modificated yet. The only thing I did to the speakers was to get rid of the 4 pole connector of the driver; the contacts were heavily corroded!

Here you can find more information about the SGM-12X: original sales brochure.

The official Tannoy homepage
The Tannoy e-mail group
The Tannoy page of Hans Hilberink
The Tannoy page of Steve

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