Modification/Restoration/Destruction? of a Vintage B&O classic -- mid-range query

[SoundQuest]

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/attac...-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.

[planet10]

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.

A thread for Tysen and variations on FAST

dave

[SoundQuest]

Originally Posted by planet10

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.

A thread for Tysen and variations on FAST

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"?

[planet10]

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?

[mondogenerator]

Originally Posted by SoundQuest

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..."[B]which would sound better, the Dayton RS52AN-8 2" Dome?

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 :P

worth a try IMHO

[planet10]

Originally Posted by mondogenerator

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

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

[SoundQuest]

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.

[planet10]

Originally Posted by SoundQuest

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.

PS - Planet, I did not receive your email.

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

[SoundQuest]

Originally Posted by planet10

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.

[mondogenerator]

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.