| Search | Login/Register
   Home » Horn-Loaded Speakers» Electro-Voice T350, T35, + Fostex tweeters. (35 posts, 2 pages)
  Print Thread | 1st Post |  
Page 2 of 2 (35 items) Select Pages:  « 1 2
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Tweeters: the most misused elements...  Tweeters: the most misused elements....  Audio For Dummies ™  Forum     0  14295  01-03-2005
  »  New  The realty of UHF and LF relation..  About the LF and HF relation by Jim Lesurf....  Audio For Dummies ™  Forum     1  18048  10-17-2005
  »  New  Tweeter for Vitavox S2. High-sensitively ribbons?..  Correction: Townshend Ribbon and sensitivity....  Horn-Loaded Speakers Forum     64  612613  10-19-2006
  »  New  Metal domes..  Try the one Lansche is using...  Audio Discussions  Forum     6  52953  11-08-2007
06-14-2007 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 26
Post ID: 4606
Reply to: 2789
Fostex T 500A MK 2 Horn Super Tweeter

Fostex T 500A MK 2 Horn Super Tweeter
Article By Bill Gaw at www.enjoythemusic.com


As most of you know by now, I'm a horny type of guy. While my wife may dispute this, my audio system (actually my second partner) would have to agree as all seven speakers are of that persuasion. While the subs, woofers and mid range horns and drivers have been acceptable and stable, using Electrovoice 12 and 15 L drivers for the woofer horns, and TAD 2002 and 4002 drivers for the mid Edgar Tractrix horns, the tweeters have been a problem, for two reasons.

First, to get the best possible sound from these expensive drivers one needs to match the woofers to the mids and the mids to the tweeters in as many specifications as possible to minimize parts needed to run them. Especially with horns and single-ended or low wattage amps, passive crossovers and parts significantly detract from their sound, especially higher order crossovers. Thus, for the main speakers I use VacuumState RTP-5 preamps that were built with 24dB active crossovers as part of the preamp's regular circuitry and Behringer 24dB active crossovers as the preamps for the other speakers. Thus theoretically, no parts are in the circuit between the preamps and amp other than what would have to be there anyway. Only the tweeters have 1 capacitor on them for a 6dB crossover to the mid-horn.

Second, most horn tweeters tend to have frequency ranges that tail off just above 20kHz, such as the Fostex T-500 which this unit replaces, or they extend into the upper 30's but with a somewhat ragged response curve that adds some tizziness in the hearable high end such as the T 900. The lower end of their frequency range may go as low as 3kHz to match up well with the mid range drivers, but the drop-off has to be steep as they begin to have frequency anomalies not too far below that.

If one is using a single amplifier for both the mid and tweeter, one has to match the various driver's efficiencies as close as possible so one doesn't need a volume control in between to muck up their sound. Also, their impedances should be matched. Preferably both should be 16 Ohms, or if one is 16 and the other 8 Ohms impedance then have different efficiencies to match them up. Over the past several years I've gone through several different horn tweeters, and had settled on Fostex T-900A's as the best at about $380 each, but they didn't match up perfectly with the mid-horns, having a lower efficiency requiring the mid horn to be padded down. Also, while they were flat out to 38kHz they had a peak at 5kHz to 8kHz, which is right at the crossover point with the TAD drivers that had to be compensated for.

About three months ago, Fostex came out with the T 500A Mk II driver that seemed to fit perfectly in specs with the TAD driver. While they are 8-Ohm impedance compared to the TAD's 16 ohms, they are slightly less efficient, thus should be a close to perfect match. Its frequency response is flatter than the T-900A, reaching out to 30kHz with useable response out to 50kHz. I know what you're going to say; "Only your dog can hear out to that range." That may be true, especially with my 60 year old ears, but with SACD and DVD-A and even Dolby and DTS digital with 88 to 96 kHz sampling frequency, that information is there and can intermodulate with lower frequencies allowing us to hear its effects on the lower overtones. I think it's that intermodulation that gives, for instance, the shimmer and sheen of violins that is missing in CD.

Anyway, on an online discussion board I came across John Kalinowski, another horny guy who was purchasing several of these tweeters for himself. He graciously offered to get me two at a group rate and also suggested using Mundorf silver-gold caps and the Fostex R100TX transformers for any necessary padding. So the extra pair of T-900's was removed to my rear two speakers with the T-500's placed on the main left and right ones. Using the WinAudio MLS program from Dr. Jordan design ( more to follow possibly next month) the tweeters were found to match almost perfectly with the TAD drivers using just a 2.2 mic. Mundorf cap without the transformer. Thus the transformers were transferred to the side and center speakers and the rheostats previously used on the main speakers were transferred to the rear horns to pad down the tweeters, and with the MLS program, all speakers were matched as well as possible.

As this is not a full review of the product I won't use any fancy high-end gobblydegook to describe my findings. First, listening only to the two main speakers, the difference was subtle but important. Gone was peakiness in the mid-high frequency range. With DVD-Audio and SACD recordings, there was a beautiful sheen to the violins not heard previously on my system and only on those systems heard in the past that used the newer super-tweeters with response extending out beyond 50kHz. You have to hear one of these speakers to understand what I'm talking about. I'm sure my ears cannot pick out sound in that range, but there is a distinct difference.

At the same time, there was an increase in the ability to hear those sounds that allow us to determine the hall space. No matter how quiet the room, except for an anechoic isolation chamber, there is always some movement of air and sound that allows us to determine space, and part of that is in the upper frequency ranges, which most speakers fail to reproduce properly. It is there with these drivers. After the addition of the T 500's and placement on the other speakers with the T-900's and MLS evaluation, the system is definitely more balanced with much better soundstage and a more believable movement of sounds through it. Are the T-500A Mk II's worth the added cost over the T-900 drivers ($756 vs. $380) plus the Mundorf caps at $70 each? To me, yes. But then I'm an audiolic.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-15-2008 Post does not mapped to Knowledge Tree
IslandPink
Posts 18
Joined on 02-08-2005

Post #: 27
Post ID: 9167
Reply to: 4606
T90A
fiogf49gjkf0d

Romy.
Have been reading various threads to glean information on tweeter options.
I read with enthusiasm your experiences with the RAAL teardrop tweeter until I saw the price, then had to change my plans.

Your brief comments on the T90A ( affordable in the near-term ) were interesting as they would be assisting a GPA 288-H driver on 425 Hz horn ( Azura ) . Do you think with care, in the context of this driver the T90A could add anything useful to the HF ?
Where do you think the problems of eg. the T90A are located - upper MF or HF above 10kHz ?

Thanks for any info you can offer
Mark

12-15-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 28
Post ID: 9168
Reply to: 9167
The T90A with Altec 288
fiogf49gjkf0d

Mark,

It is hard to say. I owned T90A sometimes in 2001-2002. At that time I was going through the drivers like crazy and T90A was just one of them. Looking from now I do not think that I gave to many drivers a chance as I did not “work” them trying to get best out of them. I do not remember that T90A gave me any problems, in fact I had the most expensive Fostex tweeter (T5000 or 7000) they had available at that time but I preferred T90A (it was the least expensive Fostex tweeter then).

You see, all those conversations about what I liked or do not likes make scene only in context of the MF drivers that I used at that time. A tweeter is not a self-contained element. A tweeter is a complimentary component for MF channel and they must work together. In the very beginning of 2002 I switched from many other MF drivers that I used before to Vitavox S2, and my first year with S2 driver I was “fighting” with it, learning how to make it to sound right. The Fostex T90A came to me right before or in the middle of the “S2 fight”, so I might be clueless what I was getting then.  In addition I do not know the GPA drivers. I experimented with Altec’s 288 and 290 but never had the GPA drivers. They shell be similar but you never know. JBL and Tannoy nowadays and 40 years back are kind of “similar” drivers, although they are very much not be the same…

The RAAL TearDrop tweeter was an interesting push up. It was an opportunely for me to see what 109dB sensitive ribbon is all about. In addition I was looking for a very narrow vertical window to let the tweeter in its time-aligned position to shoot between the horns. From what I see ribbons have advantages over compression driver in HF region. With each single hertz the frequency goes down the ribbons loosing their advantages and compression drivers take over…

Anyhow, I do not think that I might be a good source for you to learn about T90A. In past Madidound was offering to send drivers to try, they might still do it. If so, then grting from them the T90A for a week or two shell answer all your questions. Make sure that the T90A is scrupulously time-aligned and it’s axis is meticulously paralleled to the 288’s axis. 90% of the problems with tweeters out there are about the people do not align them properly….

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-15-2008 Post does not mapped to Knowledge Tree
IslandPink
Posts 18
Joined on 02-08-2005

Post #: 29
Post ID: 9169
Reply to: 9168
T90a
fiogf49gjkf0d
Ok Thanks Romy.
It might be worth a try then . In worst case I can afford to buy these, with luck I may be able to borrow a pair .
I will report back eventually , but at this stage the project is just forming, as the horns are only just ordered from Martin .

I will also phone CV this evening to see if he has any experience .

I will follow your advice to become thoroughly acquainted with the MF driver's sound without tweeters first before I try to assess the effect of T90As .

More eventually...
Mark 
12-15-2008 Post does not mapped to Knowledge Tree
mats
Chicago
Posts 76
Joined on 09-18-2005

Post #: 30
Post ID: 9171
Reply to: 9169
T90A with JBL 2435
fiogf49gjkf0d
I have found the T90A to be reasonably in-offensive with JBL 2435 Neo/Be compression drivers.
I use them with relatively small caps, currently 0,3uF.
The effect is a welcoming of a higher frequency palette that to my ears does
not seem incongruous with the JBL's.
I notice in the article above that Bill Gaw used his 500's with a 2,2uF cap.
That is a very different implementation.

Mats
12-16-2008 Post does not mapped to Knowledge Tree
IslandPink
Posts 18
Joined on 02-08-2005

Post #: 31
Post ID: 9179
Reply to: 9171
Thanks
fiogf49gjkf0d
Thanks Mats
Also very helpful comments . Will file for future use.
MJ
12-16-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 32
Post ID: 9184
Reply to: 9171
The use of the T90A diver...
fiogf49gjkf0d
 mats wrote:
I have found the T90A to be reasonably in-offensive with JBL 2435 Neo/Be compression drivers. I use them with relatively small caps, currently 0,3uF. The effect is a welcoming of a higher frequency palette that to my ears does not seem incongruous with the JBL's. I notice in the article above that Bill Gaw used his 500's with a 2,2uF cap. That is a very different implementation.
With .3uF you are very far in the transition slope. This is around 60kHz filter and you roll off near 9dB of the tweeter output. There is nothing wrong with it if it is what you need to do. The Bill’s 2.2uF is 9kHz filter but he looks like used 24dB active digital crossovers. It is only God know what garbage active digital outputs and what kind amplification he used to have after it. Interesting the in my time of use Fostex drivers I also found them to be “in-offensive” but it is does not mean that continue playing with the driver it would not be possible to found a setting where it would do just fine.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-17-2008 Post does not mapped to Knowledge Tree
IslandPink
Posts 18
Joined on 02-08-2005

Post #: 33
Post ID: 9191
Reply to: 9184
500 II
fiogf49gjkf0d
Speaking to Mr CV the other evening he admits to having ordered a pair of the T500 mkII with magnesium diaphragm . With luck we may have a report from him on their performance within 5 years .

MJ
12-17-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 34
Post ID: 9192
Reply to: 9191
It is not just about a tweeter
fiogf49gjkf0d
I would rather to hear from the people who use tweeters over 10K to comment not about the “quality of the tweeters” but about the quality of amplification and the quality of electricity that they use to drive those tweeters. The better tweeter it is the more sensitive it will be to ugly phase distortions coming with amplification and to the noise coming from power lines.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-17-2008 Post does not mapped to Knowledge Tree
Wojtek
Pinckney (MI), United States
Posts 158
Joined on 09-01-2005

Post #: 35
Post ID: 9193
Reply to: 9192
TAD ET-703
fiogf49gjkf0d
You could source used TAD tweeters for ~$1K pair .They sound exceptionally smooth and extended .More so than infamous T-350 and with better "tone" which may be relevant since your 288 are tonaly "dead" according to the Cat. Who knows, he may be right in this regard Wink
Page 2 of 2 (35 items) Select Pages:  « 1 2
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Tweeters: the most misused elements...  Tweeters: the most misused elements....  Audio For Dummies ™  Forum     0  14295  01-03-2005
  »  New  The realty of UHF and LF relation..  About the LF and HF relation by Jim Lesurf....  Audio For Dummies ™  Forum     1  18048  10-17-2005
  »  New  Tweeter for Vitavox S2. High-sensitively ribbons?..  Correction: Townshend Ribbon and sensitivity....  Horn-Loaded Speakers Forum     64  612613  10-19-2006
  »  New  Metal domes..  Try the one Lansche is using...  Audio Discussions  Forum     6  52953  11-08-2007
Home Page  |  Last 24Hours  | Search  |  SiteMap  | Questions or Problems | Copyright Note
The content of all messages within the Forums Copyright © by authors of the posts