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Tannoy Cheviot...HPD 315A...what's the scoop...

lexi said:
I believe it is a slight difference in crossover.
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Thanks, anyone know the detail's please?

Also just noticed on mine, which have been re-foamed before I got them, that the phasing of the bass units seems to be reverse of normal, When a battery positive is connected to positive speaker terminal, bass cone moves in. This is on both speakers.

Can anyone confirm if this is correct or not?
 
LF and HF are out of phase on Tannoy Dual Concentrics. Your HF unit is 0 degrees with
respect to absolute polarity, LF driver at 180 degrees.

James.
 
sybil said:
LF and HF are out of phase on Tannoy Dual Concentrics. Your HF unit is 0 degrees with
respect to absolute polarity, LF driver at 180 degrees.

James.
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Thank you for the reply, I have confirmed (from the Yahoo Tannoy group) that the bass units are correct in moving inwards when the positive terminal of a battery is connected to the positive of the bass unit.

I tried reversing the phase of one bass unit, leaving the tweeter as is. It was
difficult to tell much difference on music. I thought that I detected less mid
colouration, but little else. I returned the bass unit to original phasing.

I next fed the speaker with a 1KHZ sine wave tone and disconnected the tweeter.

Re-connecting the tweeter produced an increase in the tone. I then disconnected the tweeter and connected the wires the other way round, a decrease of tone was noted.

This pretty well proved that the bass unit and tweeter were originally connected correctly and so were "in phase" around the crossover point.
 
RustyB said:
Very modern!

A cabinet vol of 150 L, tuned to 35 Hz, works a treat with the HPD 315.
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any idea on best cab size for the hpd 385.'am using them in york cabs which i think are 180l but tempted to go bigger next year.
 
pil said:
any idea on best cab size for the hpd 385.'am using them in york cabs which i think are 180l but tempted to go bigger next year.
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The York is probably the ideal cab for the HPD 385.
So long as it is well constructed. I think they are more like 210L btw.
 
It depends. The value is virtually all in the drivers so there shouldn't be a huge difference between the Devon and Cheviot unless the cabs are in really good condition and you are chasing originality. Pay for the state of the drivers.
 
Okay - how much are they worth then cable monkey? How much does it cost to fit new surrounds these days?
 
Value for a re-foamed pair of HPDs is between £500 and £600, and about £100 to £125 more with crossovers.

The Devon cabinet is FAR too small for 315 HPDs. They work best in a net volume of anything between 110 and 150 litres depending on tuning.

I have experimented a lot with these (as well as developing fixed inductor crossovers for them) and the optimum tuning achieved appears to be using a cabinet with a net volume of around 120 litres tuned to about 40Hz. They work great in larger cabinets but you start to lose a bit of bass impact and speed which is the trade off for extension to lower frequencies with these.

Cheviot cabinets can be made to work very well but require re-tuning and stiffening/damping.
 
I have a pair of monitor golds in about 70 ltr IB cabinets,as winter project I hope to build new, would 100 to 120 ltre IB's be suitable do you think? I like the sound as they are, but the cabinets are really tatty. when i first built them (many years ago) I had the notion that Tannoy's were designed to work in IB cabinets, but may be wrong - it was about 40 years. Were the surounds then Neoprene or something similar?
Not trying to hijack the thread just interested and noted the knowlegable replies
PS I think the question is does the transient repnse reduce with larger / ported cabs.
 
westsea said:
I have a pair of monitor golds in about 70 ltr IB cabinets,as winter project I hope to build new, would 100 to 120 ltre IB's be suitable do you think? I like the sound as they are, but the cabinets are really tatty. when i first built them (many years ago) I had the notion that Tannoy's were designed to work in IB cabinets, but may be wrong - it was about 40 years. Were the surounds then Neoprene or something similar?
Not trying to hijack the thread just interested and noted the knowlegable replies
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What size Monitor Golds? They tend not to be used in infinite baffle cabs very often, though 75L internal volume is apparently correct for the 15" driver. I'm not sure about the 12" or 10". I had my 15"s in very solid 75L corner cabs for a while and they sounded very good to me in a typical smallish UK living room. Very tight and controlled bass if lacking some of the scale and ease they have in much larger ported cabs.
 
50 to 70 litres is fine for 12 inch MGs in IB enclosures, and you can get away with larger for the 15 inch MGs, as Tony says, 70 litres is ok, and up to around 100 litres also fine. For HPDs you should aim for around 70 to 100 litre cabs for 12 inch HPDs and 100 litre cabs for 15 inch HPDs if looking to build closed cabinets. Interestingly, the 12 inch HPD gives similar acoustic response to the 15MG (ie bass response) in a 100 litre closed cabinet. Upper bass impact to around 100Hz is excellent but dont expect much below 50 or 60 Hz for Tannoys in IB enclosures. Their best bass response tends to be from vented/ported enclosures or very large back loaded horn designs such as Autograph or Westminster type cabinets. Even the humble 12 inch HPD will deliver deep bass in a modestly sized vented enclosure and is a match for the 15 inch MG in this respect.
 
I seem to remember the sound from my corner Chatsworth's fitted with 12" Silvers was very nice. They were infinite baffle, not sure of the volume of the cabinets. I still have the empty cabinets, thinking of putting HPD315's in there.
 
Thanks Tony L and Pac1 - the MG's are 12inch, at the time I thought that 2.4cuft was an optimum size for an IB (the freq response graph had a significant change in the slope at that point) also influenced by what her indoors would tolerate in the size of big boxes. Now they are in a largish attic and the new boxes are not limited by domestic needs, think I will try a medium size ported or back loaded horn, although the latter will be more difficult to build. Guess more research needed, however, maybe its just subjective, but the MG's give the impression of a sharper transient response than the ported ATC 100's in the living room Anyway thanks again, I'm a now clearer on the options.
 
westsea said:
Thanks Tony L and Pac1 - the MG's are 12inch, at the time I thought that 2.4cuft was an optimum size for an IB (the freq response graph had a significant change in the slope at that point) also influenced by what her indoors would tolerate in the size of big boxes. Now they are in a largish attic and the new boxes are not limited by domestic needs, think I will try a medium size ported or back loaded horn, although the latter will be more difficult to build. Guess more research needed, however, maybe its just subjective, but the MG's give the impression of a sharper transient response than the ported ATC 100's in the living room Anyway thanks again, I'm a now clearer on the options.
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Ported is your best bet if going DIY to keep things simple and economical. Aesthetically you may wish to use side vents rather than ports (a la the new Prestige range).

For the 12 inch MG I would recommend a cabinet of 110 to 120 litres tuned to 47 or 48Hz. Tune any lower and you'll lose lots of bass impact with the 12 inch MG. The HPD for reference delivers about 15Hz more extension in a similar sized cabinet in vented configuration for the same SPL.
 
I like the style of the Prestige Tannoy's and think the 110/120 ltrs quite feasible, and could at least do some construction drawings for that size. Not sure how to size the slots - length, width and depth to tune to the frequency you mentioned. Do you have any thoughts on how to develop some methodology, or do I just make an educated guess? I think you are right about the rear loaded horn, I have seen various designs and apart from the skill level the time to sort out the workshop set up is too much at my age!
 
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