Thanks Dave,
I have pretty much done as you have suggested except calculate the angles. I'm going to have friend do it up in cad and see what happens. I will post the results when I have them. As for the commercial rights... I have not been able to find anything on Chris Power, Alf or the club he belonged to.
I have pretty much done as you have suggested except calculate the angles. I'm going to have friend do it up in cad and see what happens. I will post the results when I have them. As for the commercial rights... I have not been able to find anything on Chris Power, Alf or the club he belonged to.
The initial build is almost done, next finishing
Here are a few more shots. Still have a couple of deflectors and chokes to add and then staining. Are there any horn builders out there with some experience with damping?
https://imageshack.com/i/0z15yxj
https://imageshack.com/i/f1dj19j
https://imageshack.com/i/0nuq4xj
Here are a few more shots. Still have a couple of deflectors and chokes to add and then staining. Are there any horn builders out there with some experience with damping?
https://imageshack.com/i/0z15yxj
https://imageshack.com/i/f1dj19j
https://imageshack.com/i/0nuq4xj
almost done with the sanding. Attached two links to the profiles of the horn. I have chosen to leave out the last deflector on the bottom of the mouth. My thanks to Bando for all the help in getting the angles right.
Any thought on finish or damping would be appreciated.
https://imageshack.com/i/0x79ulj
https://imageshack.com/i/b5d22qj
Any thought on finish or damping would be appreciated.
https://imageshack.com/i/0x79ulj
https://imageshack.com/i/b5d22qj
It is likely the horn was designed to use no damping except maybe in the initial chamber. I would at least line that with cottom or wool felt.
After that lining on the transitions (points at the folds) to help kill HF getting thru the horn -- the horn has smoothish transitions which will help pass HF you don't want gettingout the mouth.
Lastly experimenting with polyfill near the start of the horn to control the relative bass levels.
These last 2 really require being able to temporily attach the side so that it can be removed and yet be fully sealedup -- best to use draft exclusion tape (weather seal) and lots of screws.
dave
After that lining on the transitions (points at the folds) to help kill HF getting thru the horn -- the horn has smoothish transitions which will help pass HF you don't want gettingout the mouth.
Lastly experimenting with polyfill near the start of the horn to control the relative bass levels.
These last 2 really require being able to temporily attach the side so that it can be removed and yet be fully sealedup -- best to use draft exclusion tape (weather seal) and lots of screws.
dave
I'd agree with Dave that when it was designed, it was probably only the chamber that was envisioned to be damped. Which isn't to say, as is also mentioned, that it wouldn't benefit from some more. I'd probably be inclined to put a relatively thin layer around the 2nd 180 degree bend. As noted, that does made adjustments tricky, so a removable (but properly sealed) side panel is helpful until you're satisfied with the results.
I was able last night to get some measurements from this horn. It sounds amazing and I think it shows on the chart. The red line is the speaker measured in cabinet at 1/2" and the purple is the horn measured at 24 inches. The detail is amazing, both Sean (faithintruth) and I agree that the amp, a decware Zen kit #1 is running out of steam for the low end.
free upload image
An externally hosted image should be here but it was not working when we last tested it.
free upload image
Well, this is still a work in progress. The horns have been listened to and are finally getting numerous coats of tung oil, some cork, spikes....
The horn mouth will be black as will the back of the speaker whereas the sides and top will be a gorgeous cherry-like tung oil finish on the birch ply.
If there are any followers out there, stay tuned for some new pictures soon
The horn mouth will be black as will the back of the speaker whereas the sides and top will be a gorgeous cherry-like tung oil finish on the birch ply.
If there are any followers out there, stay tuned for some new pictures soon
Hallo everyone.
Several years ago I found the Alf Lepp plans and decided to build them.
I was very happy with this design and the only modifications was to change the material around the speaker: medium compressed rochwool.
With the component used, this solution was the betterchoice for me (a Ciare full range component).
I'm planning to substitute that speaker with a much better Ciare HX160.
I haven't made mesurement yet. Pheraps in the future.
I'm very sorry to know that Mr.Lepp passed away but his opera is still living on the other side of the planet...RIP
The ampli is actually a pcl86 single ended and is enough to sound a medium sized room with several bookshelf, a sofà, chairs a table ecc. (ahem, a wife...).
Curiously, this project has a high "WAF" (others, smaller, not!). My wife said me that the front tractrix horn is somewhat interesting. Also for my children that have pressed the central dust cover almost immediatly!
Netx days I hope to give you an update with the new Ciare.
And some pics.
Ciao.
Several years ago I found the Alf Lepp plans and decided to build them.
I was very happy with this design and the only modifications was to change the material around the speaker: medium compressed rochwool.
With the component used, this solution was the betterchoice for me (a Ciare full range component).
I'm planning to substitute that speaker with a much better Ciare HX160.
I haven't made mesurement yet. Pheraps in the future.
I'm very sorry to know that Mr.Lepp passed away but his opera is still living on the other side of the planet...RIP
The ampli is actually a pcl86 single ended and is enough to sound a medium sized room with several bookshelf, a sofà, chairs a table ecc. (ahem, a wife...).
Curiously, this project has a high "WAF" (others, smaller, not!). My wife said me that the front tractrix horn is somewhat interesting. Also for my children that have pressed the central dust cover almost immediatly!
Netx days I hope to give you an update with the new Ciare.
And some pics.
Ciao.
Here is the Alfredo Horn at my factory. The listening room is 6m x 5.5m (19.6ft x 18ft). This is the second and the last cabinet hand made and veneered by Alf Lepp who is sadly no longer with us.
Dave's Photo (Post 13) is the very first build of the Alfredo Horn. This photograph was taken by Alf in his garage which had tinted glass windows.
Alf brought the cabinets to my factory and together we experimented over a period of 3-4 months with diiferent chamber volumes and throat areas. The plans that Dave (Post 13) included in his post is the final version of the design. It is my handwriting "September, 1999" at the top right hand side of the plan. I had posted this on Bert's Forum.
Alf told me that the brains behind the design was Chris Powers, a brilliant and very clever engineer who has an interest in horns. Alf had obtained permission from Chris to use and develop this design. I tried to contact Chris who was busy downing Sasimi and Sushi.
Finally, I received a rather lengthy e-mail from Chris in July, 2010. Excerpt from this e-mail is noted below to understand the man and his thinking.
"Hi Mohan,
in much earlier times I sent many of my earlier tractix /other horn designs through Ian McPhail to Lewis (Muratori) who built and auditioned / measured some -against the Mauhorn I recall. All designs were highly calculated to the best knowledge of that time and not just artistic whims.
He was quite favorable to them and we corresponded.(I still have his lengthy letter and graphs somewhere) Summary of outcomes was, horn expansion was good/preferred to exponential , sound was natural, all designs benefited in the bass from using a smaller than optimum (calculated) back chamber volume, imaging was better in wider rather than narrower designs (hence 'good' TP1 /Dynavector, Coral Beta 10?)
Truncating the rapidly flaring mouth somewhat, did not change the sound much -or at all (notwithstanding the required "the mouth must subtend a 90 deg. included angle at the mouth” regime) etc etc.
He /I tried have many drivers including Lowther (PM7C silver for me, various Fostex' sigma’s /others , some vintage Goodmans and others - Most of these changed the balance /sound quite a bit more than the horn profile….
I then moved overseas (Hong Kong /China /Singapore ) around 1995 for more than a decade and continued to develop these designs further (plus open baffle etc.)
So to these earlier edicts I have now added plenty more :- based on experience as well as measurements / calculations -
You might be amused by some -or question your own experiences with others
-In my view Horns are generally preferred for their immediate bass rather than efficiency –and are often derided for their lack of balance .
Otherwise Full range drivers can work very/ better on open Baffle OB solutions
This is true notwithstanding that all the literature tells us quite different Thiele small TS parameters are required for OB’s (Evidence? Lowther PM2a II, Fostex FE168 sigma , some Phy, Fertin etc.?)
Of course you still have to deal with a bass integration with OB speakers and this is not so easy (try dipole /ripole) but you probably need multiple amps -not such a big deal today? Linkwitz and Martin King currently rule in these areas
-Whilst horn efficiency is ‘nice’ there are relatively few users who still use flea powered (71a, 417a ) amps and even moderately efficient speakers (92dB - 1W/1M) still easily provide strong volumes / peaks in most domestic situation with only 5-7 watts of tube power
-Similarly the better sounding horns (my arbitrary judgement) often also have the "wrong" T-S parameters .Evidence (many Tannoy horn drivers , Goodmans Axiom 80 , RCA lc1a, and various mission drivers I have used etc....) And if you measure (sound and dimensions) many Tannoy horns their claims for a usable hyperbolic/exponential expansion are often pretty laughable (particularly the flagship Westminster Royal)– yet the sound is very good in viable rooms. Bottom line is that is very easy to get too carried away with the maths and forget the ultimate objective –accurate facsimile of a real performance (albeit that the latter in many cases is subject to the many microphone boost/cut/limiting/room resonances adjustments before it hits the ear in a ‘live’ performance ?
In part I think this explains the interest in DIY horns –thinking your way through them problem , even laterally (compound damped/reflex horn cabinets) and component matching can sometimes produce better results than just blind calculations
-and in my experience it is usually better to put a larger than recommended driver in a horn cabinet -almost always smoother. Aficionados will say this is just defacto reducing the rear chamber size and lowering the horn throat size with no detriment to the bass = mouth size . Maybe so but it works and technically allows and improved WAF as well
-So for me the challenge is more a well integrated horn bass –much more than bass extension. Many back horns sound too chesty as the mouth frequencies impinge on the horns forward output -in some cases worse than 'horn /Lowther shout' or baffle step diffraction issues.
Early designs of Dinsdale 1940-50's also always attempted to match the phase of mouth and forward waves in horn length -you never see this acknowledged in modern designs?
- The location and number of horn folds is more important than the expansion profile -I have built many 'identical' horn profiles with different folding cabinets and the results are always quite different audibly.
There is a good demonstration of this on the acoustichorns.com site (a great site but difficult to navigate all the data held within) where he build a common horn in both straight and single fold form – the latter (unaccountably? ) has a much better bass performance?
I think this is why Ontomo Mooks designs often sound quite good despite appearing quite radical –and not matching many design criteria . He seems to try to optimize the expansion of the pressure wave (a bit like pro horns ) - which can have the effect oft breaking up / eliminating standing waves which are often more prevalent in smooth horn profiles.
-It is much easier to build successful horns with small drivers than large .
I have built many minihorns, recently with Fostex fe107e’s (shouldn’t work) which have great flat bass performance circa 40Hz (much lower than their notional Fs) –obviously also exciting some room characteristics but audibly very well.
Similarly I have built Jordan JX92x (Fs circa 55 Hz) small transmission lines with long haired wool stuffing which have convincing output at 30Hz (see Jordanusa.com or similar for even better designs). These are excellent everyday speakers and I can really see why some listeners say “ why would I ever want anything more (in a domestic environment)
Horn mouth sizes of 300-400sq cm still provide very convincing bass, even well away from walls (although all the calculations will tell you otherwise) and 16ch FR drivers can provide all the bass most listeners require.
Have you ever tried turning off the satellite speakers of a well balanced system having a subwoofer and hearing just how little recorded sound occurs below 50Hz??
Also, the BBC LS3/5A and Ted Jordan (when designing the Goodmans speakers) both enunciated a preference for more limited bass when dealing with restricted HF response (and vica versa ) or the speakers would be ‘unbalanced’ .
The off-axis response of most HF drivers is pretty woeful –and often does not extend much beyond 12 KHz anyway-so there is a good case to go for good quality in preference to muddier depth.
In my view there is a strong case for not attempting to go too low with most back loaded horns anyway … Even the so-impressive Vitavox corner horns and RCA LC1a in Jensen imperial cabinets – have superficially great , immediate bass –but do not measure with much output below 45Hz…… and that’s without even discussing the rooms requirements to deliver such lower note convincingly
Anyway most of my interests lies in expanding the knowledge /experience bass; then amend / build something new /hopefully better, each time .
To this end I will soon be selling my various Horn speakers and drivers on Ebay and starting anew. We expect to return to live in Hong Kong again in the next couple of years .
As with Japan, Hong Kong real estate prices and astronomical and apartments modest , including our own
So this probably proscribes different /new paths and this (saw a nice OB setup on thick polyglass baffle /unimpeded harbour views? , recently…..
And despite frequent disparagement of Chinese audio on mostly US fora , the Chinese audio industry is energetic and developing very quickly in southern china. I have many contacts there and never ceased to be amazed by the speed of turnaround of advice to them in electronics and speakers..
The future looks interesting.
Thanks for your details .When next in Melbourne I will try and get together with you.
I recall my good friend Trevor Cooke (of T&M Cooke Motor Repairs ) was also located in Michellan court when I departed Melbourne - so your location could be convenient for me .
Best Regards
Chris P"
The cabinet is made from 22mm thick soft plywood. I need to search for the plan showing the varying thicknesses and dimensions of the internal reflectors (numbered parts).
Regards,
Mohan
19th April, 2015
Dave's Photo (Post 13) is the very first build of the Alfredo Horn. This photograph was taken by Alf in his garage which had tinted glass windows.
Alf brought the cabinets to my factory and together we experimented over a period of 3-4 months with diiferent chamber volumes and throat areas. The plans that Dave (Post 13) included in his post is the final version of the design. It is my handwriting "September, 1999" at the top right hand side of the plan. I had posted this on Bert's Forum.
Alf told me that the brains behind the design was Chris Powers, a brilliant and very clever engineer who has an interest in horns. Alf had obtained permission from Chris to use and develop this design. I tried to contact Chris who was busy downing Sasimi and Sushi.
Finally, I received a rather lengthy e-mail from Chris in July, 2010. Excerpt from this e-mail is noted below to understand the man and his thinking.
"Hi Mohan,
in much earlier times I sent many of my earlier tractix /other horn designs through Ian McPhail to Lewis (Muratori) who built and auditioned / measured some -against the Mauhorn I recall. All designs were highly calculated to the best knowledge of that time and not just artistic whims.
He was quite favorable to them and we corresponded.(I still have his lengthy letter and graphs somewhere) Summary of outcomes was, horn expansion was good/preferred to exponential , sound was natural, all designs benefited in the bass from using a smaller than optimum (calculated) back chamber volume, imaging was better in wider rather than narrower designs (hence 'good' TP1 /Dynavector, Coral Beta 10?)
Truncating the rapidly flaring mouth somewhat, did not change the sound much -or at all (notwithstanding the required "the mouth must subtend a 90 deg. included angle at the mouth” regime) etc etc.
He /I tried have many drivers including Lowther (PM7C silver for me, various Fostex' sigma’s /others , some vintage Goodmans and others - Most of these changed the balance /sound quite a bit more than the horn profile….
I then moved overseas (Hong Kong /China /Singapore ) around 1995 for more than a decade and continued to develop these designs further (plus open baffle etc.)
So to these earlier edicts I have now added plenty more :- based on experience as well as measurements / calculations -
You might be amused by some -or question your own experiences with others
-In my view Horns are generally preferred for their immediate bass rather than efficiency –and are often derided for their lack of balance .
Otherwise Full range drivers can work very/ better on open Baffle OB solutions
This is true notwithstanding that all the literature tells us quite different Thiele small TS parameters are required for OB’s (Evidence? Lowther PM2a II, Fostex FE168 sigma , some Phy, Fertin etc.?)
Of course you still have to deal with a bass integration with OB speakers and this is not so easy (try dipole /ripole) but you probably need multiple amps -not such a big deal today? Linkwitz and Martin King currently rule in these areas
-Whilst horn efficiency is ‘nice’ there are relatively few users who still use flea powered (71a, 417a ) amps and even moderately efficient speakers (92dB - 1W/1M) still easily provide strong volumes / peaks in most domestic situation with only 5-7 watts of tube power
-Similarly the better sounding horns (my arbitrary judgement) often also have the "wrong" T-S parameters .Evidence (many Tannoy horn drivers , Goodmans Axiom 80 , RCA lc1a, and various mission drivers I have used etc....) And if you measure (sound and dimensions) many Tannoy horns their claims for a usable hyperbolic/exponential expansion are often pretty laughable (particularly the flagship Westminster Royal)– yet the sound is very good in viable rooms. Bottom line is that is very easy to get too carried away with the maths and forget the ultimate objective –accurate facsimile of a real performance (albeit that the latter in many cases is subject to the many microphone boost/cut/limiting/room resonances adjustments before it hits the ear in a ‘live’ performance ?
In part I think this explains the interest in DIY horns –thinking your way through them problem , even laterally (compound damped/reflex horn cabinets) and component matching can sometimes produce better results than just blind calculations
-and in my experience it is usually better to put a larger than recommended driver in a horn cabinet -almost always smoother. Aficionados will say this is just defacto reducing the rear chamber size and lowering the horn throat size with no detriment to the bass = mouth size . Maybe so but it works and technically allows and improved WAF as well
-So for me the challenge is more a well integrated horn bass –much more than bass extension. Many back horns sound too chesty as the mouth frequencies impinge on the horns forward output -in some cases worse than 'horn /Lowther shout' or baffle step diffraction issues.
Early designs of Dinsdale 1940-50's also always attempted to match the phase of mouth and forward waves in horn length -you never see this acknowledged in modern designs?
- The location and number of horn folds is more important than the expansion profile -I have built many 'identical' horn profiles with different folding cabinets and the results are always quite different audibly.
There is a good demonstration of this on the acoustichorns.com site (a great site but difficult to navigate all the data held within) where he build a common horn in both straight and single fold form – the latter (unaccountably? ) has a much better bass performance?
I think this is why Ontomo Mooks designs often sound quite good despite appearing quite radical –and not matching many design criteria . He seems to try to optimize the expansion of the pressure wave (a bit like pro horns ) - which can have the effect oft breaking up / eliminating standing waves which are often more prevalent in smooth horn profiles.
-It is much easier to build successful horns with small drivers than large .
I have built many minihorns, recently with Fostex fe107e’s (shouldn’t work) which have great flat bass performance circa 40Hz (much lower than their notional Fs) –obviously also exciting some room characteristics but audibly very well.
Similarly I have built Jordan JX92x (Fs circa 55 Hz) small transmission lines with long haired wool stuffing which have convincing output at 30Hz (see Jordanusa.com or similar for even better designs). These are excellent everyday speakers and I can really see why some listeners say “ why would I ever want anything more (in a domestic environment)
Horn mouth sizes of 300-400sq cm still provide very convincing bass, even well away from walls (although all the calculations will tell you otherwise) and 16ch FR drivers can provide all the bass most listeners require.
Have you ever tried turning off the satellite speakers of a well balanced system having a subwoofer and hearing just how little recorded sound occurs below 50Hz??
Also, the BBC LS3/5A and Ted Jordan (when designing the Goodmans speakers) both enunciated a preference for more limited bass when dealing with restricted HF response (and vica versa ) or the speakers would be ‘unbalanced’ .
The off-axis response of most HF drivers is pretty woeful –and often does not extend much beyond 12 KHz anyway-so there is a good case to go for good quality in preference to muddier depth.
In my view there is a strong case for not attempting to go too low with most back loaded horns anyway … Even the so-impressive Vitavox corner horns and RCA LC1a in Jensen imperial cabinets – have superficially great , immediate bass –but do not measure with much output below 45Hz…… and that’s without even discussing the rooms requirements to deliver such lower note convincingly
Anyway most of my interests lies in expanding the knowledge /experience bass; then amend / build something new /hopefully better, each time .
To this end I will soon be selling my various Horn speakers and drivers on Ebay and starting anew. We expect to return to live in Hong Kong again in the next couple of years .
As with Japan, Hong Kong real estate prices and astronomical and apartments modest , including our own
So this probably proscribes different /new paths and this (saw a nice OB setup on thick polyglass baffle /unimpeded harbour views? , recently…..
And despite frequent disparagement of Chinese audio on mostly US fora , the Chinese audio industry is energetic and developing very quickly in southern china. I have many contacts there and never ceased to be amazed by the speed of turnaround of advice to them in electronics and speakers..
The future looks interesting.
Thanks for your details .When next in Melbourne I will try and get together with you.
I recall my good friend Trevor Cooke (of T&M Cooke Motor Repairs ) was also located in Michellan court when I departed Melbourne - so your location could be convenient for me .
Best Regards
Chris P"
The cabinet is made from 22mm thick soft plywood. I need to search for the plan showing the varying thicknesses and dimensions of the internal reflectors (numbered parts).
Regards,
Mohan
19th April, 2015
Attachments
Here is my Alfredo.
I am really impressed with sound , bass specially. Who said that horn speakers don`t have enough bass. Speakers inside is Lowther EX3.
After many, many years of big close speakers and lots of big transistor amps I go in totally opposite direction first OB and now horn speakers and SET tube amps and I am more than happy for that change in my hi fi life.
We put them on test in my friends room and with his system also more people come to hear and see .
Here is the picture from that listening session.
I am really impressed with sound , bass specially. Who said that horn speakers don`t have enough bass. Speakers inside is Lowther EX3.
After many, many years of big close speakers and lots of big transistor amps I go in totally opposite direction first OB and now horn speakers and SET tube amps and I am more than happy for that change in my hi fi life.
We put them on test in my friends room and with his system also more people come to hear and see .
Here is the picture from that listening session.
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