Full Range Drivers

Hello Mohan.









I also am new here, still seeking the turntable/vinyl section :)







Are there any really 'Full Range' drivers larger than 8" diameter that do not need cross-overs.












yes, there are some. Supravox has atleast two different drivers and different motor choices, permanent magnet (ferrite or alnico) and recently, field coil motors. They have the reputation to have random manufacturing quality so I did not consider them.





Some Lowther clones exist, I have the German AER in mind and the fancy Reps driver.


LothX also has a fullrange driver but they do not give it to DIY people.





And then there is the Fertin FLB 20EX. This driver has a field coils and works extremely well in an open baffle. I am currently awaiting my Fertins and trying to get my Lowthers sold.





Greets,
 
Mohan,
I plan to run them an a 90cm wide open baffle with a Linkwitz-style open baffle subwoofer.

The Fertins are made for this if you look at the parameters.
They have a funny centering suspension with very high Q: a piece of 0.5mm thick epoxy PCB cut to a circular leaf spring.

As the leafsping is not airtight, you will experience noise from that if using the driver in a horn, I am convinced.

Having had a Lowther Acousta for years now and having done a long-term experimant with a good midrange driver operated in an open baffle, I doubt I will ever go back to enclosures of any kind. The experiment was meant to take an hour, it took six weeks and i could not convince me to end it.

At the dealer/distributor, I had a 5-hour long listening session to try out if there is any listening fatigue with the Fertin and the own equipment I brought. Not a tiny trace and I ordered them. Not cheap but worth it.
 
Yes, subwo1,



... infinite baffle ...




but then there is this thing called soundstaging.

I like the soundstage produced by a properly placed dipole speaker very much.

Hmmh, I do not listen to resonances, frequncy response and the like, I listen to music; AFA music is concerned, the Fertin in open baffle mode is extraordinary; µdynamics are just incredibly natural.

This is partially due to open baffle operation. Try it out yourself , take an old door, saw a hole in it for a, say 5 to 8" paper cone speaker in it, hook it to your amp, sit down, enjoy.

The Fertin field coil speaker gives a maximum of course as field coil speakers have their own beauty and as Qts optimum can be adjusted by supply voltage, but any given speaker with a Qts in the range of 0.4 to 0.5 run in open baffle mode brings you quite far on this road and produces sensations unobtainable with an enclosure speaker.
 
Bernhard,

Thank you for educating me on Fertins. Is the transient response of Fertin similar to that of Lowther or is it more like a Tannoy or PHY?

My experience and feelings about open baffle are the same as yours. When I was the Lowther distributor, I used to test all drivers that passed through my hands. I also used to set them, facing up towards the ceiling and play music. The sound is always so open with very low colouration …like my electrostatics at home. I used to say to myself and to others that it was a crime to mount these drivers in any enclosure.

But then… purists like Lowther fans (myself included to some degree) would not entertain the suggestion of multiple drivers and crossovers etc…etc..

Why do you need 90cm baffle boards when you have open baffle subwoofers? Why not say 40cm? Does this have more to do with your crossover frequency than with the Fertin driver? Just curious and for my knowledge only please.

Musical instruments are made to exploit resonances in their body structure. Their radiation is not confined to frontal modes only. It is the recording engineers who doctor the natural sound of these instruments to exploit our binaural senses and the mainstream market. Most recording engineers that I deal with agree with me on this. However, they have to produce material that is acceptable to the producer. Compression and rarefaction of air should not be obstructed both at the recording and reproduction stages. What I am saying is that there is no need to confine ourselves to frontal radiation only.

By the way, I noticed that you keep in touch with Allen Wright. He is a brilliant engineer. I used to talk to him many years ago while he was in Sydney developing his Vacuumstate amps. Allen made an AM tuner which most of us here in Australia regard as one of the very best tuners ever made.

Mohan
 
Hello Mohan,



Originally posted by Mohan Varkey

Thank you for educating me on Fertins. Is the transient response of Fertin similar to that of Lowther or is it more like a Tannoy or PHY?




Pleasure, I want to advertise for this exceptional driver. The driver's manufacturing quality is like seen from Altec or JBL in their best days (if not better).



Transient response is breathtakingly natural and I would guess, considerably better than a Lowther PM6A, vastly better than any Tannoy I heard. Vastly better than the Westminster Royal my brother-in-law owns. As I experineced it, the Fertin is seduuuucing without using sweet colorations for this.



I cannot comment on the PHY, never heard it. My friend Hartmut's remarks about the PHY's colorations extincted any interest in the PHY on my side; I know Hartmut's preferences to be very close to my own ones.



My experience and feelings about open baffle are the same as yours. When I was the Lowther distributor, I used to test all drivers that passed through my hands. I also used to set them, facing up towards the ceiling and play music. The sound is always so open with very low colouration …like my electrostatics at home. I used to say to myself and to others that it was a crime to mount these drivers in any enclosure.




Tried exactly this it out with 5 different midranges. It could be said about other speakers too. Particuarly the Lowther PM 6C was better than when mounted in an enclosure, but not as much as the other drivers (did not try it out with my own PM6A; intend to sell the Acousta and do not want to damage it's custom-made frontshield)



By its parameters the Lowther is meant to run in a horn; open baffle is a less than optimum solution allthe more as the lowther has an airtight inner suspension.



But then… purists like Lowther fans (myself included to some degree) would not entertain the suggestion of multiple drivers and crossovers etc…etc..




Yes, right, so do I. But the Fertin is so terrific over the whole range that the missing range cannot be overseen. For 100% satisfaction a worldcalss sub is needed. An open baffle sub I presume.




Why do you need 90cm baffle boards when you have open baffle subwoofers? Why not say 40cm? Does this have more to do with your crossover frequency than with the Fertin driver? Just curious and for my knowledge only please.




1st,

the sub is intended to used two 18inchers, 90 cm is the least width I can realize.

2nd

I want the option to switch off the sub, neighbor comaptibility for listening after 22:00, yanno :) and then the speaker should still have enough LF

3rd

I am afraid of the baffle step and do not intedn to have to correct it.

4th

I have atleast 3 valid reasons :)



Musical instruments are made to exploit resonances in their body structure. Their radiation is not confined to frontal modes only. It is the recording engineers who doctor the natural sound of these instruments to exploit our binaural senses and the mainstream market. Most recording engineers that I deal with agree with me on this. However, they have to produce material that is acceptable to the producer. Compression and rarefaction of air should not be obstructed both at the recording and reproduction stages. What I am saying is that there is no need to confine ourselves to frontal radiation only.




Interesting. Agreed.




By the way, I noticed that you keep in touch with Allen Wright. He is a brilliant engineer. I used to talk to him many years ago while he was in Sydney developing his Vacuumstate amps. Allen made an AM tuner which most of us here in Australia regard as one of the very best tuners ever made.




Agreed, he is a brilliant engineer.

Allen's and my preferences are not as well aligned as I thought for a long while. And we do not agree on some philosophical issues including design philosophy (probably a normal thing).

However, his RTP5 is a DIY kit preamp challenging the most expensive preamps on the market. It may not appear cheap, but it is riidiculously cheap compared to the current ARC, CAT, Spectral, Rowland Research or other fancy brands. his SE preamp (guess it meanwhile is called SVP, six valve preamp) is a killer for the money. And his cables also are gorgeous and very price-competitive. Look at www.vacuumstate.com .
 
Bernhard,

Thanks. I shall consider Fertin for my next project.

I am developing a tube amplifier for electrostatic loudspeakers. I need high stability Carbon Film Resistors(50-100pcs each). 5W rating in various values 50-100 pcs. Do you know where in Germany I may be able to purchase Beyschlag Carbon Films. Local Beyschlag distributor is not interested in small quantities.

Mohan
 
Originally posted by Mohan Varkey
Thanks. I shall consider Fertin for my next project.
fine, I would love to have this gorgeous speaker to have more success,
But ... be aware a pair of the field coil speakers ai at about US$1500.


I am developing a tube amplifier for electrostatic loudspeakers. I need high stability Carbon Film Resistors(50-100pcs each). 5W rating in various values 50-100 pcs. Do you know where in Germany I may be able to purchase Beyschlag Carbon Films. Local Beyschlag distributor is not interested in small quantities.

I help if I can; I am interested in a source for Beyschlag myself.
But, why are you after Carbon films? I always thought them to be inferior from my tests, and as one of my electronic wizards tell, they are not that stable.

But this resistor comparison was not as scientifically performed as my cap test, so I maybe fooled myself.
What tried out , carbon composite can sound quite pleasant, with metal film is is unpredictable, they can sound fine or like crap.
Metal oxide resistors turned out to be surprisingly good, particularly tantalum oxide, although maybe not as good as tantalum nitride.
but I would stick with Beyschlag metal film, they are fine.
In any case I would avoid magneitc resistors. All world class sounding resistors I had in a small listening comparison were non-magnetic. As it was with capacitors.
I tend to avoid any magnetic piece in my stuff, except chokes and trannies. I even avoid magnetic material for the housing or it's screws.
 
Bernhard,

Fertins are expensive….for experimental purposes. Do they have a site in English?

I did consider and trial many types of resistors. Beyschlag metal films do not have voltage ratings to suit tube amps. I prefer carbon film to metal oxide and carbon composition resistors. This is sound wise. There are high stability carbon film resistors and I have not had any stability problems over the years with 1W and 2W types. I must admit that I have not tried Tantalum nitride units.

Mohan
 
Hello Mohan,
Originally posted by Mohan Varkey




Fertins are expensive….for experimental purposes. Do they have a site in English?





try: http://perso.wanadoo.fr/hpfertin/specif2.htm




the site is in French but the page i gave you is the specsheet.




Yes, they are expensive, but worth it.




If you want to know whether you can live with open baffle in your personl audio universe, take an old door or table plate or a piece of plywood, saw a hole for a speaker in it, mount the speaker and listen for a while.









So did i six weeks ago, just that I let the speaker run even w/o a baffle. Just wanted to try it out for an hour or so, then the Focal 7N303 I used was sitting for six weeks on the top of my Lowther Acoustas, making music. A little fabric dome tweeter was added in a rough manner to fill in some treble, worked fine.









So did i yesternight. I had sold my Acoustas the day before, the Fertins have not yet arrivend and i still am not happy with the baffle design so nothing has been built/prepared yet. I was longing for music and so i made a baffle from corrugated cardboard (32 cm x 32cm, assymetric placement), mounted the lil'tweeter also in the cardboard and put those units on a pair of moving boxes to have some stands and a bottom extension of the baffle.




And found myself still trapped in the music 3 hours later. In my audio universe, open baffle is magic. I repeated the experience that the Focal run open was outperforming (okok, no bass of course) the Lowther PM6A mounted in an enclosure.









So, the Fertin. I auditioned the Fertin in a 5-hour long listening session before i ordered a pair. A better speaker than the Focal, no question, everything more smooth and round and balanced, more detail resolution, more impact when needed, seduuuucing µdynamics. But, seducing µdynamics are a property of open baffle in general. Just, the Fertin seems to be developped for open baffle operation and does everything a bit better than just a given driver as the Focal is.









I should add here that if i hadn't exerienced a long-term listening fatigue with my Lowthers, i never would have started to experiment with other speakers. The Focal was not the 1st driver i tried, it was the one I decided to settle on for longer listening. My first test was done with an oval TV speaker bought at a surplus shop for one Euro per piece and even this speaker i preferred to the enclosured Lowther. I crawled through my attic and found other drivers, tried them out, liked them all. Sorry for giving the Lowthers such a hard time here :( , just reporting my experiences. I never tried the Lowther out in an open baffle, i had a buyer for it and did not want to scratch the veneer or to unmount the special unmountable front shield. I had read websites claiming the Lowther in open baffle mode outperforms any Lowther enclosure. From my experience i believe any single word. But from an engineering point of view, i would never do it except for a caaaareful try. Xmax is 1mm total, TMK, and i don't want to smash the delicate voice coil into the pole piece by an accidental pressing bubble pop on the record (or by forgetting the GC is open when i lower the tonearm :) ).










I did consider and trial many types of resistors. Beyschlag metal films do not have voltage ratings to suit tube amps. I prefer carbon film to metal oxide and carbon composition resistors. This is sound wise. There are high stability carbon film resistors and I have not had any stability problems over the years with 1W and 2W types. I must admit that I have not tried Tantalum nitride units.










Interesting. Beyschlag metal film is preferred by most for tube amps here. I suppose they are specified for 300V across the resistor. Few resistors have to bear full supply voltage though so this may work out.




If the carbon films sound fine to your ears, no reason to weed them out.




Carbon composite is noisy. Tantalum nitride resistors are hard to obtain, very expensive and not all values are at hand. I tried them out, sonic beauties. but then there are also Caddocks and Vishay metal band resistors and i believe the latter are the most accurate sounding ones.