Acoustics > Building and Room Acoustics

Planning a production of special speakers - anyone interested? Lowther TP1A PM3

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David Pinnegar:
Hi!

As other threads in this topic include speakers and speakers are often used for improving room acoustics as well as for hi-fi I hope that I might not have to apologise too heavily for posting this thread here.

For many right the way through from the 1950s the holy grail of loudspeakers has been the Lowther TP1 in its TP1A TP1B or TP1C incarnations:

fitted with a Lowther PM3 or PM3/5 unit mounted in what looks like a saucepan:


The design might look like a dalek but in a domestic environment does not scream "ostentatious hifi" and can achieve remarkable WAF as a result. The sound doesn't scream ostentatious hifi either, and is natural. It's so natural that someone in another room can imagine a physical presence of a person on the radio. The sound is so spacious that one does not need stereo . . .

Finally I have managed to obtain the plans of this speaker - so complex as to require 91 pages even if the sectional diagram appears simple:

and in the Autumn I'm planning a production run of 10 to 20 units.

Obviously with such complexity, the units won't be cheap, but in long experience of speakers, few others compare.

Best wishes

David P

JBR:
This is interesting.  Presumably, the 'saucepan' must have an opening at the back somewhere in order for sound to enter the extended bass cone.

Also, it is noteworthy that many modern sub-woofers are downward firing and can utilise the room itself to provide increased bass.  On the other hand, many speaker manufacturers advise against siting speakers in corners as it produces excessive bass(!).

David Pinnegar:
Hi!

Yes - there is an opening about 2 inches by 3 inches in the suacepan which mates with the corresponding start of the bass horn.

The unit is a corner horn and is well balanced although best in rooms with low ceilings. With higher ceilings one has to turn up the bass a little with the bass control and if not corner placed one supplements it with a speaker in a box in addition.

Another interesting design is the Voigt corner horn and I have a friend who is a mono audio freak of the valve and vinyl variety who maintains the Voigt to give the most natural reproduction of all. I used to use a Voigt corner horn for the Tuba stop of my organ but the corner in which I used it was too damp, to the detriment of the speaker cone resulting in its demise . . . However, if anyone is interested I have a pair of a variety of these which can provide a model to be copied. A single one is currently in the barn and out of curiosity a friend put into it a 10 full range unit and attached it to a transistor radio, to good result. . . .

If used with a straight top horn rather than one with a reflection, or a bass horn with no more than a 1:2 compression ratio a unit such as http://www.ebay.com/itm/200778253597 can be effective.

In contrast however, the compression ratio of the TP1 horn requires a unit with a strong magnet to drive the air column efficiently but does so very naturally.

Most of the time normal listening levels require only less than a tenth of a watt, half a watt being loud and 5 watts being utterly deafening.

Best wishes

David P

revtonynewnham:
Interesting project David.  Hope it works out.

MusingMuso:
I don't know a lot about loudspeaker design, but I do know that some of the old vintage units are awfully good.

I personally cherish my old Celestion Studio 66 Monitors, which are still in daily use and sound terrific. Very big and bulky, (not to mention heavy), I've not come across many speakers that compare, and with the added advantage that they're just the right height for reading-lamps or vases of flowers; being about 3ft high.

I don't think I ever heard a Lowther Acoustics speaker in the old days, but I did used to admire the old KEF units, with their folded horn construction.

Sounds like an interesting revival of a good old design....good luck with it.

MM

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