Ahem
So...
Good friend of mine has a pair of vintage Bang and Olufsen Beovox 57OO speakers. Tweets are shot (old Celestion HF-2000 tweeters), mids are okay (he might sell), woofers are okay with no surround rot (good thing they used rubber surrounds instead of foam which was very popular in the early 1970's) or dust cap glue erosion. Oh, the funny looking woofer is a passive 10".
http://www.diyaudio.com/forums/atta...-66-needs-mid-range-beovox-5700-crossover.jpg
Here's a review of this speaker: Beovox 5700 / 5702 | BeoPhile.com
So my friend, instead of building an entirely new pair of speakers, wants to rebuild/upgrade/modify these classics. We will be removing the mid and tweet from the monkey coffin, placing them in their own sealed and dedicated cabinet atop the monkey coffin (away from all of that awful woofer traffic!) which will in effect be acting as an extended range subwoofer. Also, we will be replacing all of the electrolytic (leakylytic) capacitors in the crossover section and replacing one of the iron core chokes with an air core choke of the same value. We have not interest at this point in messing with the crossover points which are 600 and 6,000. I believe LR2 all the way across. 8 ohms of impedance total for each speaker.
We will be replacing the tweeter AND the mid-dome. The tweeter will be replaced with the highly touted and very affordable Vifa D19TD-05 which matches the impedance and sensitivity (withing 1db) of the HF-2000 tweets. For the mid-dome, our original idea was to replace it with the incredible Dayton Reference Dayton RS52AN-8 2" Dome Midrange, which also matches the impedance and sensitivity of the OE mid dome which is also a Celestion speaker (MD500, same as used in the Ditton 66 speaker). HOWEVER...I got to thinking, many seem to be of the opinion that mid domes are hard to tame, at least they used to be. I'd like to think this 2" dome made by Dayton does amazing things when used correctly. But as I was saying...I got to thinking..."which would sound better, the Dayton RS52AN-8 2" Dome? Or the very well reviewed and widely used Tang Band W4-1337SD 4" Titanium Driver?"
Very interested your input. And yes, I know, many restoration purists will scream "leave that poor speaker alone." At least we won't be cutting into the beautiful cabinets (real rosewood veneer, 60 lbs. each).
Thanks again in advance.
So...
Good friend of mine has a pair of vintage Bang and Olufsen Beovox 57OO speakers. Tweets are shot (old Celestion HF-2000 tweeters), mids are okay (he might sell), woofers are okay with no surround rot (good thing they used rubber surrounds instead of foam which was very popular in the early 1970's) or dust cap glue erosion. Oh, the funny looking woofer is a passive 10".
http://www.diyaudio.com/forums/atta...-66-needs-mid-range-beovox-5700-crossover.jpg
Here's a review of this speaker: Beovox 5700 / 5702 | BeoPhile.com
So my friend, instead of building an entirely new pair of speakers, wants to rebuild/upgrade/modify these classics. We will be removing the mid and tweet from the monkey coffin, placing them in their own sealed and dedicated cabinet atop the monkey coffin (away from all of that awful woofer traffic!) which will in effect be acting as an extended range subwoofer. Also, we will be replacing all of the electrolytic (leakylytic) capacitors in the crossover section and replacing one of the iron core chokes with an air core choke of the same value. We have not interest at this point in messing with the crossover points which are 600 and 6,000. I believe LR2 all the way across. 8 ohms of impedance total for each speaker.
We will be replacing the tweeter AND the mid-dome. The tweeter will be replaced with the highly touted and very affordable Vifa D19TD-05 which matches the impedance and sensitivity (withing 1db) of the HF-2000 tweets. For the mid-dome, our original idea was to replace it with the incredible Dayton Reference Dayton RS52AN-8 2" Dome Midrange, which also matches the impedance and sensitivity of the OE mid dome which is also a Celestion speaker (MD500, same as used in the Ditton 66 speaker). HOWEVER...I got to thinking, many seem to be of the opinion that mid domes are hard to tame, at least they used to be. I'd like to think this 2" dome made by Dayton does amazing things when used correctly. But as I was saying...I got to thinking..."which would sound better, the Dayton RS52AN-8 2" Dome? Or the very well reviewed and widely used Tang Band W4-1337SD 4" Titanium Driver?"
Very interested your input. And yes, I know, many restoration purists will scream "leave that poor speaker alone." At least we won't be cutting into the beautiful cabinets (real rosewood veneer, 60 lbs. each).
Thanks again in advance.
Last edited:
If you are going to look at the TB that opens up a whole new world of possibilities.
Given that they will be relieved of any bass duty, looking to a small "FR" for mid-tweeter duty has some significant advantages. My pick would be FF85.
This thread (and the others it generated) might give you some ideas.
http://www.diyaudio.com/forums/full-range/144099-thread-tysen-variations-fast.html?highlight=Tysen
dave
Given that they will be relieved of any bass duty, looking to a small "FR" for mid-tweeter duty has some significant advantages. My pick would be FF85.
This thread (and the others it generated) might give you some ideas.
http://www.diyaudio.com/forums/full-range/144099-thread-tysen-variations-fast.html?highlight=Tysen
dave
VERY NICE!!!
I had not considered this gem of a FF driver. Always heard so many good things about Fostex in the FF world. Many feel the mid-dome is superior when it comes to dispersion. Do you agree or disagree that the Dome would do a better job in this area? Also, what distinct advantages will the FF85K have over dome besides dispersion? What will it have over the the TB 4"?
I had not considered this gem of a FF driver. Always heard so many good things about Fostex in the FF world. Many feel the mid-dome is superior when it comes to dispersion. Do you agree or disagree that the Dome would do a better job in this area? Also, what distinct advantages will the FF85K have over dome besides dispersion? What will it have over the the TB 4"?
The FF85 can be XOed lower. And as to dispersion i wouldn't be surprised if the FF85 (at least the treated ones i use) have better dispersion. I think of the FF85 as a 3/4" dome with a really big surround.
The TB you pointed to has a pretty nasty metal cone resonance (which would needtaming before anyconsideration of use IMHO), and i've yet to see anything really positive on it. It will not have the high end extension of the FF85, but will produce better bass (a no care in your situation).
There are a lot of choices for the role of mid-tweeter, FF85KeN is just my personal favorite.
dave
PS did you get my email?
The TB you pointed to has a pretty nasty metal cone resonance (which would needtaming before anyconsideration of use IMHO), and i've yet to see anything really positive on it. It will not have the high end extension of the FF85, but will produce better bass (a no care in your situation).
There are a lot of choices for the role of mid-tweeter, FF85KeN is just my personal favorite.
dave
PS did you get my email?
I have not heard this dayton dome mid, but i guess the only reason to go for a dome mid would be to keep the overall LOOK of the speakers at least vaguely similar to the original, and im not sure that this is what you are planning. However, i know visaton also makes dome-midranges, whether these are up to the job, better or worse than the dayton i couldnt say with certainty, but i can say i havent had an issue with any of the drivers ive used from visaton, and i would recommend them very highly. Heres the link for you to check out at your leisure:
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories
(Ti dome)
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories
(soft dome)
dispersion wise both look fairly excellent, with the soft dome being the least directional by a small margin. Both drivers look to have a smooth FR within about 2dB max. personally, i wouldnt believe that a FR drivers dispersion would be a good as a dome mid, as the HF response is produced by beaming in a cone, however, with the band pass of the mid being up to 6k the increased beaming of a FR driver may not be very noticeable. At least until above 4k. How bad this is, you would have to decide. The domes however, have much less of an issue with beaming in the range 600-6000hz. the dome MAY sound better, it may sound more diffuse. Or it may sound worse. either way itll be less directional than a cone, full-stop.
If you WANT to go for a FR driver in place of the midrange, then id dump the idea of a fostex, and go for a modern FR driver like the Mark Audio drivers. I havent heard them but the specs and reviews lead me to believe that they out perform Fostex by a mile, (and they cheaper) and having heard some fostex drivers a couple of years back, i wouldnt choose them. But each to their own.. fostex have a 'sound' all of their own, unfortunately, i prefer my speakers to have NO SOUND of their own
worth a try IMHO
Last edited:
Until you have actually heard them yourself, you are only reguritating your interpretation of what others have said.
I'm a big fan of the of the Mark Audio drivers (in fact i talk to Mark a lot). The Fostex too (at least the smaller ones). Which one did you hear (what box & amps).
Neither one is better than the other, they are just different. The amplifier (& other kit) you are using can sometimes push your choice in one direction or the other. The context of what you are trying to do also plays a role.
For mid-tweeter application FF85KeN is still my personal favorite (Scott, Mark & I all have FF85KeN uFonken to use as common reference). FE103, FE127, FE126, MA A7/CHR-70, CSS EL70 are a sampling of candidates for mid-tweeters.
Note that i don't bother with either brand until i've treated them (they get better, no question in my mind)
dave
Thanks to the both of you, Planet and Mondo. Both of you have given me excellent information and some very important things to consider. My interest is peaked in using both drivers and looking into the Mark audio FF drivers as well on a different project ahead of me. At this point, it looks like we are going to go with the mid dome for the 600-6k duty, even though an FF driver would probably do a great job, perhaps even a slightly better job? at communicating that band of of the spectrum. In part due to the fact that this is what the original design called for and used, and the other part due to the fact neither of us have ever listened to a mid dome and our interest is peaked in getting our hands on one and implementing it correctly.
Having said that, this has now spawned in me a new desire to go back to experimenting with FF drivers, in particular, Fostex and Mark Audio as I have already played with some of the Tang Band offerings (at least the W3871S).
We did at one point discuss the prospect of putting a TB bullet tweeter atop the box and leaving the mid in the box but decided against it for two reasons in particular: 1. because the distance between the two would be increased, thus messing with the voicing. 2. because the mid dome would still be sitting right smack dab in the middle of the woofer traffic. Were we correct in this conclusion?
Another question now arises given the fact that I just now realized PE is not expecting any stock of the Vifa D19TD-05 until April. If we cannot source one in time (next week), can anyone think of a suitable replacement at about the same price range with the same resistance and sensitivity (or close enough)?
PS - Planet, I did not receive your email. I will check my account to make sure it is listed correctly (tverner@comcast.net). Thanks for your help.
Having said that, this has now spawned in me a new desire to go back to experimenting with FF drivers, in particular, Fostex and Mark Audio as I have already played with some of the Tang Band offerings (at least the W3871S).
We did at one point discuss the prospect of putting a TB bullet tweeter atop the box and leaving the mid in the box but decided against it for two reasons in particular: 1. because the distance between the two would be increased, thus messing with the voicing. 2. because the mid dome would still be sitting right smack dab in the middle of the woofer traffic. Were we correct in this conclusion?
Another question now arises given the fact that I just now realized PE is not expecting any stock of the Vifa D19TD-05 until April. If we cannot source one in time (next week), can anyone think of a suitable replacement at about the same price range with the same resistance and sensitivity (or close enough)?
PS - Planet, I did not receive your email. I will check my account to make sure it is listed correctly (tverner@comcast.net). Thanks for your help.
I sent it thru the forum (and using my mod powers checked to confirm it was the same as you have given).
Lack of D19s brings my request on topic
So here are the contents of that email.I have some (OEM) versions of the D19 made for Mission (SEAS also made this tweeter). You have a blown set of Celesion HF2000 and i am in need of the metal dome covers for a restoration of a good friends LS3/5A (what he bought used as LS3/5A turned out to only be LS3/5 boxes with junk mounted into it) -- these screens are the last bit i need for the restoration (i sourced T27 locally and XOs & proper B110s are coming from UK). Into a trade?
dave
It's too bad Tymphany has taken over and is discontinuing such fantastic drivers, including the D19 tweets. Shame on them!
Regarding your offer, I forwarded the message on to my friend that owns the BV5700 speakers to see if he still has the domes and would be willing to trade. I'm sure if he still has them he would be willing to.
Regarding your offer, I forwarded the message on to my friend that owns the BV5700 speakers to see if he still has the domes and would be willing to trade. I'm sure if he still has them he would be willing to.
FE126(e?) not sure
i have only heard the fe126, and i have no recollection of the amp..... and which variant i am unsure, however, it was fairly obvious when listening to this driver that the response rose maybe 5 to 10dB from the low mids up to high MR and into the HF, with some movement up and down throughout this range. That is to my ears at least they didnt sound smooth in FR at all. They were built by a friend in a smallish BR design, and the bass was sufficient to be pleasing, however ther mids were just too shouty and a little to forward in their presentation. In the end, with a couple of nights tinkering, we both fashioned a wide, very low Q notch, and centred it about 3k to flatten the (apparent though not measured) rise in response.
In this way they were much more listenable. maybe other drivers are better, i dont know. All i know is that from that experience, i wouldnt use a FE126 IF i were to build a FR system, as i would HAVE to employ the contouring filter again, and crossovers go against the whole idea of FR in my opinion. So yes i am regurgitating some info about MA drivers, but from the FR graphs alone(smoothed or not) and the TS specs, i would buy them over a FE126 anyday. Maybe thats because i abhor the vintage revival nonsense, after all Valves really ARENT better at amplifying, only at colouring sound in a way that is more pleasant to our ears; valves for music production but not for reproduction. More than likely its due to the TS and graphs, rather than the 'modern' look/approach to overall design, of the drivers, though it definately has something to do with it!
How aplairs compete with other Fostex drivers i dont know, nor would pertain to, but from MY small experience with unENABLED FE126's i wouldnt touch them with a bargepole, frankly i wouldnt touch enabled ones either.
i have only heard the fe126, and i have no recollection of the amp.....
and which variant i am unsure, however, it was fairly obvious when listening to this driver that the response rose maybe 5 to 10dB from the low mids up to high MR and into the HF, with some movement up and down throughout this range. That is to my ears at least they didnt sound smooth in FR at all. They were built by a friend in a smallish BR design, and the bass was sufficient to be pleasing, however ther mids were just too shouty and a little to forward in their presentation. In the end, with a couple of nights tinkering, we both fashioned a wide, very low Q notch, and centred it about 3k to flatten the (apparent though not measured) rise in response.In this way they were much more listenable. maybe other drivers are better, i dont know. All i know is that from that experience, i wouldnt use a FE126 IF i were to build a FR system, as i would HAVE to employ the contouring filter again, and crossovers go against the whole idea of FR in my opinion. So yes i am regurgitating some info about MA drivers, but from the FR graphs alone(smoothed or not) and the TS specs, i would buy them over a FE126 anyday. Maybe thats because i abhor the vintage revival nonsense, after all Valves really ARENT better at amplifying, only at colouring sound in a way that is more pleasant to our ears; valves for music production but not for reproduction. More than likely its due to the TS and graphs, rather than the 'modern' look/approach to overall design, of the drivers, though it definately has something to do with it!
How aplairs compete with other Fostex drivers i dont know, nor would pertain to, but from MY small experience with unENABLED FE126's i wouldnt touch them with a bargepole, frankly i wouldnt touch enabled ones either.
Last edited:
The FE126 has a nasty peak at 7k (one of things i (mostly) fix when i treat them), and it requires a horn to lift up the bottom so that they don't have a rising response.
One can't judge much by the FR curves... i know MArk hasn't yet gotten off-axis measures, and one has to remember that Toole has shown that just an on-axis FR is not all that useful in predicting performance.
Tube amps are not all about vintage revival. There is a niche that tries to reproduce what vintage tube amps did (and in many cases badly), but where i hang out it is about taken the advantages of tubes and using current tech to build very good amplifiers.
You really need to get yourself to an Egg-Fest.
dave
One can't judge much by the FR curves... i know MArk hasn't yet gotten off-axis measures, and one has to remember that Toole has shown that just an on-axis FR is not all that useful in predicting performance.
Tube amps are not all about vintage revival. There is a niche that tries to reproduce what vintage tube amps did (and in many cases badly), but where i hang out it is about taken the advantages of tubes and using current tech to build very good amplifiers.
You really need to get yourself to an Egg-Fest.
dave
I can understand the use of valves for preamp duty, but not really for power amp stages, i think this is mainly as i like a low output impedance. The subject of valves interests me a lot, and im sure in the correct app, then they perform equally to transistors, however they are outdated in some ways, and on paper they just dont cut it anymore.
LOL whats an 'Egg-Fest'?
Low output impedance is not a panecea. Many applications prefer a higher output impedance. And one always has to ask how the low output impedance is achieved.
better in my experience. I'm still working to find a SS amp that equals the valves. F2 is up next. And now we hear about F2J.
dave
lol
ok.
provided the rest of the path from amp to speaker is also low impedance, high df or low power amp output impedance, is better for the damping of spurious cone motions, THAT is FACT.
obviously, high output impedance can be a great benefit in preamp stages and also buffer stages, but definately NOT power output. high o/p impedance plus cable capacitances/inductances lead to one BIG aerial for EMI reception, and a much greater likelihood of ultrasonic oscillation and amp instabilty. Although this is a factor to consider for ALL amps ss or valve, the higher output impedance increases the total output reactance of amp and cabling to an unacceptably high level IMHO. add to that the distortions created by a o/p matching t/former, no matter HOW high end it is, and youll have at least 1% THD from 0-whatever watts. even if the valve circuit was perfect and did not distort harmonics at all, the tranny would still introduce measureable distortion that would compromise the otherwise 'perfect' design. So unless you can suggest a reasonable method for direct coupling valve power amp stages to L/s without the use of a o/p tranny i wouldnt try it. it would be simply starting with a flawed ideal.
ok.
provided the rest of the path from amp to speaker is also low impedance, high df or low power amp output impedance, is better for the damping of spurious cone motions, THAT is FACT.
obviously, high output impedance can be a great benefit in preamp stages and also buffer stages, but definately NOT power output. high o/p impedance plus cable capacitances/inductances lead to one BIG aerial for EMI reception, and a much greater likelihood of ultrasonic oscillation and amp instabilty. Although this is a factor to consider for ALL amps ss or valve, the higher output impedance increases the total output reactance of amp and cabling to an unacceptably high level IMHO. add to that the distortions created by a o/p matching t/former, no matter HOW high end it is, and youll have at least 1% THD from 0-whatever watts. even if the valve circuit was perfect and did not distort harmonics at all, the tranny would still introduce measureable distortion that would compromise the otherwise 'perfect' design. So unless you can suggest a reasonable method for direct coupling valve power amp stages to L/s without the use of a o/p tranny i wouldnt try it. it would be simply starting with a flawed ideal.
Last edited:
It may be a fact that a low output impedance will damp a speaker more, but it is possible to damp a speaker too much in which case it is not good (ie too much damping can be a bad thing)
We have a variable transimpedance amp where the output impedance can be varied from (close to) 0 to infinity. Every loudspeaker works best with a different impedance.
dave
too much amplifier current/voltage damping on a driver? no such thing as over damped. Here damping = 'horsepower' and the amps ability to accelerate/decelerate the cone through its required waveshape with accuracy, due to the 'stiffer' source, much in the way a 'stiff' psu benefits a good amplifier....
too much acoustic damping due to over large box or over damped design, CAN be bad thing
a high damping factor is a great benefit to ALL loudspeakers as the control of the cone is greater. Be that in controlling the cone to conform as near as possible to the AC input voltage, or be it to control the production of spurious sounds being NOT present in the original signal.
This is fact, i dont see how anyone can even argue against it.
A lower damping factor will only exacerbate these spurious motions and also allow the cone a margin more movement outside the input signal, and hence increase hangover and decrease the accuracy of reproduction. over excursion at some frequencies and increase resonance will be the product.
special amplifier designs with variable damping factor should and would show this to be the case, and as you have access to this equipment im sure you could prove it too. what a good amplifier has, regardless of DF is an inherent highly damped VHF oscillation characteristic which likley would improve transient response and spurious speaker noise rejection in a more audible way.
in a reasonable sense, a DF of more than 1000 probably serves no practical purpose, however one with a DF of more than 100 is almost certainly a minimum, imho.
Amp topology and design will always make more perceivable difference to the audible quality of reproduction, but ultimately, low DF being the ideal condition, with all others equal, is an inescapable fact.
too much acoustic damping due to over large box or over damped design, CAN be bad thing
a high damping factor is a great benefit to ALL loudspeakers as the control of the cone is greater. Be that in controlling the cone to conform as near as possible to the AC input voltage, or be it to control the production of spurious sounds being NOT present in the original signal.
This is fact, i dont see how anyone can even argue against it.
A lower damping factor will only exacerbate these spurious motions and also allow the cone a margin more movement outside the input signal, and hence increase hangover and decrease the accuracy of reproduction. over excursion at some frequencies and increase resonance will be the product.
special amplifier designs with variable damping factor should and would show this to be the case, and as you have access to this equipment im sure you could prove it too. what a good amplifier has, regardless of DF is an inherent highly damped VHF oscillation characteristic which likley would improve transient response and spurious speaker noise rejection in a more audible way.
in a reasonable sense, a DF of more than 1000 probably serves no practical purpose, however one with a DF of more than 100 is almost certainly a minimum, imho.
Amp topology and design will always make more perceivable difference to the audible quality of reproduction, but ultimately, low DF being the ideal condition, with all others equal, is an inescapable fact.
Last edited:
That is decidely false. If you start with an inherently well damped speaker, more damping just means no bass. Many of the speakers i design like high output impedance.
And what does your statement imply about amplifiers like the FirstWatt F1 & F2?
Once you add the speaker voice coil and the speaker cable there is no damping factor of even 100.
High damping factors also lead to problems with backEMF loading into the amplifier.
There are some real advantages to amplifiers with amplifiers with damping factor <1 in the right situation.
There is no 1 right solution. You need to do some more research.
Check this out: http://www.diyaudio.com/forums/vendors-bazaar/157787-secret-tube-amplifiers-revealed-much-more.html
dave
interesting link.
once made a current amp. FET current amp o/p transistors, driven by a voltage source(if i remember correctly) which together, modulated the bias current throungh the output FET. course it was push pull so inherently flawed too. class B was designed as i wasnt exactly sure it was possible, with ease at least, to cope the amp stage operation in class A. probably is, i just havent made enough amps to know for sure. This sounds similar to what your talking about, If i am with you correctly. Although this being said the output impedance was still very low, as many MOSFET designs are. My current amp has DF of about 150-200, and DOES sound warmer than the former amp which was cheap sony fet amp. might be interesting to make a current source amp, although with the majority of amps designed for voltage source and the speakers themsleves in the main designed for such, i am not sure of the benefits, UNLESS some major industry players decide this is the way to go. Since thats unlikely, ill stick with a BJT class A amp, unnless anyone has a cheap current drive amp circuit i can try for myself???
once made a current amp. FET current amp o/p transistors, driven by a voltage source(if i remember correctly) which together, modulated the bias current throungh the output FET. course it was push pull so inherently flawed too. class B was designed as i wasnt exactly sure it was possible, with ease at least, to cope the amp stage operation in class A. probably is, i just havent made enough amps to know for sure. This sounds similar to what your talking about, If i am with you correctly. Although this being said the output impedance was still very low, as many MOSFET designs are. My current amp has DF of about 150-200, and DOES sound warmer than the former amp which was cheap sony fet amp. might be interesting to make a current source amp, although with the majority of amps designed for voltage source and the speakers themsleves in the main designed for such, i am not sure of the benefits, UNLESS some major industry players decide this is the way to go. Since thats unlikely, ill stick with a BJT class A amp, unnless anyone has a cheap current drive amp circuit i can try for myself???
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.