Friday, 31 May 2013

The Tannoy Autograph I – A first Impression

Hello to everybody. Some month ago I had the rare chance to own a pair of Tannoy Autograph Speakers. These were located near Vienna in Austria, a good 1000 km away from here. So not a decision which will be made between the first and second coffee in the morning. For the first consideration each speaker is 152cm high, 110 cm wide and 80 cm deep, in a triangled shape to be ideally placed into the corners of a room. The Tannoy Autograph is one of really famous horn speakers of the 20th century, it is not only mentioned to be in a virtual top ten list, it is more one of the top five candidates. In this list other speakers like the JBL Paragon, or the Western Elelectric WE -type horns, diverse Klangfilm Horn constuctions or the Lowther Corner Horn will do the competion. To make it short, for a Tannoy addict the Autograph is the one of three full range horn cabinets available. Beside the Westminster the GRF Professional is the largest originally by Tannoy made cabinet for recording studios (180cmx120cmx80cm, with two dual concentric drivers in parallel), almost impossible to be used in home systems. The Westminster is a rectangular shaped box of similiar size as the Autograph (as well with rear and front loaded horn development from the mid 1980ties). These have a very "tasty" cabinet design for the "conservative hifi enthusiast wanting the very best" of the late "Prestige Series" as dedicated customer. Available in two different cabinets made from different wooden materials and equipped with modern ferrite magnet chassis or for a reasonable additional charge sold with "limited editions alcomax speakers". The West Norwood history of Tannoy with its founder Guy R. Fountain (GRF) and its engineer Ronnie H. Rackham will be topic of an own article soon.

"Luxurious Listening" (tannoy sales brochure of the 1960ties)
The Autograph has been initially designed in 1954 by Ronnie H. Rackham using the well known Paul Voigt (Lowther) as a experienced horn expert and consultant. It is a classic corner horn design and is dedicated to be used with both walls as extension of its side openings of the folded rear lf-horn. In theory this construction is superior to the Westminster and the different types of GRF's. This design will give the less limited low frequency response due to its wider openings. With a rear horn development of effectively 20 Hz to 250 Hz and a front horn development of effective 250 Hz to 12500 Hz the Autograph is one of the very rare horn type speakers which is capable to transmit the full audio frequencies with this design. 

With all this theory in mind I had to decide, if I am going to be adventurous and get these two monster sized speakers. "Who has the corners in place, where the speakers need to be placed to work properly?", "Do I really need to get two wardrobes in my livingroom?", "If you don't get these, you never will have a chance to get these again, so you never will know how good they really are?", lots of questions went through my brain. I could not decide between being serious or being adventurous. The memory was instantly awake to my GRF Rectangular in 1994. At that time I was also initially euphoric about the project, but then later very unhappy to get rid of the rather large enclosures. If you really want to have these big speakers you need to have the space, the money, you should be in the social situation to decide about. I decided I am not. So I left the rare opportunity to my friend Klaus, knowing that he would be very interested to get a pair Autographs as well. He has lots of other room taking hobbies like cars and planes, so another set of speakers for his hifi collection will not matter.
The adventure started already to find a car where these will fit in. With a ordinary estate car no way to come by, the minimum size of car would be a bus or a real transporter. A packed size front to front is 1.10x 1.10x1.50m and needs something with bigger space inside, packed side to side is 1.50mx0.80mx1.60m and might fit better?

The two enclosures taped together, so that there is no overwidth to the car, just 180 kg of weight.
Will the car survive to carry that overweight for 1000 km?

Luckily the weather was good through out the alps.
Klaus who has build up his own sport planes from plywood (Falcos) after they have been cut in handy pieces before shipped from the US over here, did not fear the transport. He just spanned the two speakers together with belts and fastened them on the roof of the car of his partner. Knowing that a overload of 120kg above the allowed 80kg at this car roof will not do any damage within 1000 km of survey?! Ok, he did it without getting any real trouble. The final problem was to get these monsters (90 kg each without speaker) into the first floor of his house, were his hifi room is located. With a little help of his friends he managed it.

First of all one of his Monitor Gold speakers needed a complete new adjustment of the hf-diaphragm with an oscillator. They did not have a smooth hf-response. Here shown wrongly mounted to the back board of the funnel. Since this mounting will amplify all the resonances initiated by the speaker.

For a back loaded horn type cabinet the hard edge coned speaker types from the Tannoy Monitor range are a must. The paper surround with the light weight cone benefit a lot in this application. This cones have a better free air resonance and work with  reduced distorsions without the typical air suspension of a closed cabinet. Here the models Monitor-Black, -Silver, -Red and -Gold are rated a lot better than the later HPD type with its foam surround and weighty stiffed up cone design. Their design has been optimized for high power applications with transistor amplified systems.

These enclosures have been built carefully by some carpenter in Munich in the late 1980ties using the original diagrams published in these days by "la maison l'audiophile". Klaus did check materials and the construction before he took them back to Germany. Only little details had been changed from original, so these cabinets were quite well made from northern coniferous plywood of the right dimension (16mm). He did know from other speaker projects that here no compromise can be accepted for a expected perfect final result. In this days a lot of vintage speaker plans got changed for more rigid materials in order to reduce any resonant distorsions. In many cases the all around coherence, which is often a clear sign of a early process of experimental design gets lost for "improved measurements".

Klaus and me arranged a first auditioning for the end of April and I was very excited to have a first hand experience with this legends. I drove the long way to his house (100 km distance) with his speakers in my mind: "will they really be that good?" It is rumored that they will completely disappear in acoustic terms when perfectly matched into a room. As well they are known to behavor than with the fastest and most deep bass response of all Tannoy cabinets, lots of other superlative attributes are as well published in the web. I am always more than sceptical about such superlatives and in particular when the rumors is from the web. Who is able to proof it or has a real first hand experience with this rare legends, not to question who knows one person owning a stereo pair?

Klaus hifi-setup uses a lot of common components I do use. He has a Platine Verdier turntable with SME 3012 and SPU Gold pick up, but he uses additionally a EMT studio turntable with EMT arm and dedicated "EMT Tondose"-pickup. His amplifying chain is completely different in character to my equipment. Were I prefer DHT triodes as well in the preamplifying stages for their exeptional linearity and fine resolution, he prefers mainly vintage professional studio components from Telefunken and Maihak because he believes into their professional engineered qualities. With a Leak TL12.1 as power horses we find our way back together to drive our Tannoy speakers. So there are differences, but the corner stones are comparable enough to justify a new speaker in his room. This room with wooden floor and ceiling has a very good shape (similiar to mine with roughly 4x6 meters), but is much better damped than mine.

When opened, it could be seen that the last owner had changed the mounting of the speakers. The baffle board is made from different material and looks very customized, so it might be be introduced later on. Originally the speakers need to get mounted at this square baffle board. This board closes the pressure chamber of the horn against the back of the speaker with a seal. It is completely damped with acoustic foam here?.

The first listening test ended completely frustrating, the speakers sounded the absolute opposite way of what I did expect. They did sound very heavy and dark, almost like driven with defective hf-units. The sound is characterized by a big boost of the lower registers, mainly the frequencies transfered by the back loaded horn. The cabinets seem to push the frequency between 100 and 200 hz to an extreme (some +6db?), the other areas of the tonal spectrum are completely dominated by this effect. I really could not believe what I did hear, these legendary speakers were so far out of a balanced range, that I could not even remember that here Tannoy speakers were installed. We did sit for three hours in front of the them listening to different records without having a clear concept to follow for improvements?

Do the cabinets need their dedicated covers as dampers for a optimized lf-performance?

Pulling them out of the corners might get good effects, but for a legendary corner speaker not a good idea. Klaus insisted that we did hear them without the dedicated covers on their openings, he was convinced that these will do a good portion of damping. A perfectly working low frequency horn has not to be damped, or am I wrong?! I did remember the day when I had my newly built GRF rectangulars on start, which ended with a big pillow in each of the openings to make them listenable...?! Today it ended with the complete set of Klaus bedclothes of his sleeping room in both speakers, to shut down the horn effect in general. Al the way driving back home I was thinking: what might have been wrong? We had checked all details of construction, but could not find any substancial problem with them? They were made very precisely orientated to the original drawings. The next day Klaus rang me up and we discussed what to do as the next step? He decided to complete the covers as first step and later he wants to change the speaker mounting back to the baffle. May be a new damping material for the compression chamber is on demand as well? Are these systems extremely room dependend because of their corner construction for their position and its physical expanse?

Read on soon for part two, Volker

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