RA Labs Mini-Reference speakers

[JKent]

Anybody know anything about these? I found a review here:

http://www.soundstage.com/entry01.htm

and a review of the “black gold” version here:

http://www.stereophile.com/standloudspeakers/494ra/

I need a tweeter. Now I’m making a couple of assumptions. According to Stereophile, the “black gold mini reference” has a

1" copolymer (ie, plastic) tweeter (footnote 3) is "sourced offshore" and may come from various sources, depending on the production run. I questioned whether or not this might result in a change of sound, but I was assured that Roy Allison personally selects and approves the tweeters, and they all closely match. The tweeters in my pair were made in Italy.

Footnote 3: Bob Barr told me that the tweeter is more or less a copy of an old Audax tweeter found in such neat, cheap speakers as the original Boston Acoustics A40. If this is the case, the tweeter sounds much more civilized, less strident, than the original Audax—at least to my recollection

I’m pretty sure the “black gold” is just the plain ol’ mini reference, based on the price quoted in the article. On the pair I just bought, one tweeter was replaced with a JBL tweeter. I don’t actually HAVE these yet, but once I get them, I’d like to have matching tweeters.

Any suggestions? Should I:

• Look for some Boston A40s? (now I wish I hadn’t sold mine).
  
• Find out what the Audax model was and see if I can get that?
  
• I happen to have a spare pair of Audax TW025A2 4 ohm tweeter, 1" textile dome--these are the tweets used in the Spica T50. I bought them to use in an Allison: Four but later obtained original Allison tweets. Use those?
  
• Just keep the JBL tweet?
  

Or……?

Thanks for any suggestions

Kent

[Pete B]

Hi Kent,

I do remember the glowing reviews of these when they first came out,

and I did hear a pair in a showroom back in the day. But I seem to remember

the 10mm Audax tweeter not a 1" do you know if there was a production

change or was it always a 1".

Do you have at least one good original tweeter? Can you read the model

number off of it, and measure the DC resistance? Year of manufacture?

I have early and later Audax data books and I can try to look it up.

I could measure Fs, Qts and Rvc if you want to bring one on Saturday, in

order to try to do a better job matching it up.

[Pete B]

Those TC-50 tweeters are valuable becasue they're hard to find and so many TC-50 owners need them.

It seems better for them to find a good home in a TC-50 or Snell.

I don't think those are an exact match for the Mini References since they're textile domes.

I'm considering these as a low cost replacement for the TC-50. They're not a perfect fit being 102 mm

in diameter as compared to 100 for the originals:

http://www.madisound.com/catalog/product_i...roducts_id=8312

Good that you have one working system since it provides an original as a reference.

[JKent]

Hi Pete

I'll check those numbers on the working tweeter, maybe bring BOTH tweets on Sat. Unfortunately, I discovered another problem: Looks like the previous owner decided to paint the entire woofer with shiny black goo to hide deteriorating foam surrounds. The black stuff never dried completely and is a bit tacky (maybe that's how it's supposed to be to remain pliable?) but I'm afraid this probably screws up the cone, even if I should decide to refoam them (any thoughts?)

You may want to check these out for your Spicas:

http://www.madisound.com/catalog/product_i...products_id=374

They're the ones I bought for the Allisons.and on the page it says:

"Used in the Spica TC50 speaker"

In fact, if you want to make me an offer on them. They've never been used. I could bring those on Sat also.

Kent

[l24e]

Hi Kent,

I was wondering if you won those speakers on the Canadian e-bay? As I , after reading your post decided to Google

RA Labs .

One of the links showed a pair of speakers matching your description ( JBL tweeter ) .

This might not be of any use to you, but on the English e-bay someone is selling a pair of Audax HD 100 D25 tweeters .

Item number: 260237828422

Good luck with the restoration!!! If they are the same speakers, it looked like they needed some serious TLC.

Ken

[JKent]

Hi Kent,

I was wondering if you won those speakers on the Canadian e-bay? As I , after reading your post decided to Google

RA Labs .

One of the links showed a pair of speakers matching your description ( JBL tweeter ) .

This might not be of any use to you, but on the English e-bay someone is selling a pair of Audax HD 100 D25 tweeters .

Item number: 260237828422

Good luck with the restoration!!! If they are the same speakers, it looked like they needed some serious TLC.

Ken

They're probably the ones you saw, but they were from Pennsylvania (Item number: 350054769786). Thought I had a bargain for $10 + s/h. Oh well.....

I looked at those tweets, but I don't think they're the right ones. Besides, he quoted 50GBP to ship to Toronto. Assuming it would be about the same to the US, that's $100 USD!!!!!!!!!!!!!!!!!!!!!

Thanks!

Kent

[Pete B]

Hi Pete

I'll check those numbers on the working tweeter, maybe bring BOTH tweets on Sat. Unfortunately, I discovered another problem: Looks like the previous owner decided to paint the entire woofer with shiny black goo to hide deteriorating foam surrounds. The black stuff never dried completely and is a bit tacky (maybe that's how it's supposed to be to remain pliable?) but I'm afraid this probably screws up the cone, even if I should decide to refoam them (any thoughts?)

You may want to check these out for your Spicas:

http://www.madisound.com/catalog/product_i...products_id=374

They're the ones I bought for the Allisons.and on the page it says:

"Used in the Spica TC50 speaker"

In fact, if you want to make me an offer on them. They've never been used. I could bring those on Sat also.

Kent

Hi Kent, sorry I spoke too quickly. Rethinking and as best as I can determine,

the Audax TW025A2 was never actually used in the TC-50s, the later TC-50s used a very

similar tweeter, the previous version in the evolution without the catenary dome. Those are

suggested as the closest replacement, but are not as valuable as I mis-stated previously.

My own TC-50s are the later type, the tweeter domes are a bit off center because the thick

felt pad sags in time and hits the dome. I see many on ebay like this, eventually permanently

displacing it. These now have a voice coil scrape that causes a large notch in the frequency

response and probably some serious distortion.

I'm hoping to recenter them since they are unavailable at this time, and I've

already purchased the replacement domes for the TW025A2 which are supposed to fit this

earlier tweeter. So, thanks for the offer but I believe I have those tweeters once I replace

the domes. I liked the Vifa because it is a non-catenary shape and looks very similar to the

earlier version, good price also. They might work well in your RAs.

I remember that the woofer was a treated paper cone, low cost Vifa driver. Don't recall if

RA treated the cone or Vifa. Vifa was good with cone treatments and I do think that it was a

black sticky coating, could it be original?

Sure bring the tweeters and I'll do a quick measurement, then send them back to you.

[Pete B]

Hi Kent,

These are the 10mm tweeter that I was thinking of, don't know why RA calls it a 1" tweeter.

This should be it, but with a round face plate, and in 8 ohms, not sure if the RA was 8 or 4:

http://www.madisound.com/catalog/product_i...;products_id=96

Here it is with a Neo magnet and in 4 ohms, with no face plate:

http://www.madisound.com/catalog/product_i...;products_id=92

I'll measure this one when I can get to it.

[teknofossil]

They're probably the ones you saw, but they were from Pennsylvania (Item number: 350054769786). Thought I had a bargain for $10 + s/h. Oh well.....

I looked at those tweets, but I don't think they're the right ones. Besides, he quoted 50GBP to ship to Toronto. Assuming it would be about the same to the US, that's $100 USD!!!!!!!!!!!!!!!!!!!!!

Thanks!

Kent

JKent,

I am not sure but I think the tweeters that were used in the RA Mini's were those inexpensive tiny Audax ones that used to be available everywhere. *IF* this is the case, Parts Express is selling a Chinese made version of the unit. There may be/probably is differences, but they are dirt cheap to give a try. I vaguely recall reading in Stereophile a review of the RA Labs Mini's....I think it was titled something like "Allisons Black Gold". If you haven't found it you might want to consider poking about the Stereophile archives.

http://www.partsexpress.com/pe/showdetl.cf...tnumber=264-840

-T

[Pete B]

Hi Kent,

These are the 10mm tweeter that I was thinking of, don't know why RA calls it a 1" tweeter.

This should be it, but with a round face plate, and in 8 ohms, not sure if the RA was 8 or 4:

http://www.madisound.com/catalog/product_i...;products_id=96

Here it is with a Neo magnet and in 4 ohms, with no face plate:

http://www.madisound.com/catalog/product_i...;products_id=92

I'll measure this one when I can get to it.

Quick Rvc measurement:

Original RA Labs Tweeter (looks like an Audax 19 mm dome - 10mmVC) is 6.24 ohms

Similar looking JBL tweeter is 4.94 ohms so I would not recommend using it.

DC resistance for the old Audax TW54A and TW74A is listed as 5.7 ohms and this

is the one I'd use as a replacement after comparing to the original RA Labs tweeter:

http://www.madisound.com/catalog/product_i...;products_id=96

[JKent]

Quick Rvc measurement:

Original RA Labs Tweeter (looks like an Audax 19 mm dome - 10mmVC) is 6.24 ohms

Similar looking JBL tweeter is 4.94 ohms so I would not recommend using it.

DC resistance for the old Audax TW54A and TW74A is listed as 5.7 ohms and this

is the one I'd use as a replacement after comparing to the original RA Labs tweeter:

http://www.madisound.com/catalog/product_i...;products_id=96

Thanks Pete & Techno. Pete, I'll probably use the tweets you recommend. Do you think they will fit the original mounting plate or will I need to fabricate something?

Tech: Tang Band speakers have a good rep for bang-for-the-buck, so that is probably a good recommendation tooo.

Kent

[Pete B]

Thanks Pete & Techno. Pete, I'll probably use the tweets you recommend. Do you think they will fit the original mounting plate or will I need to fabricate something?

Tech: Tang Band speakers have a good rep for bang-for-the-buck, so that is probably a good recommendation tooo.

Kent

Hi Kent,

I'd say that the Audax is the closest, since it has the same polymer dome

and probably the same 10mm voice coil. I'd suggest you buy these and

first A/B one against the original to see if you hear any difference.

The TB's have a larger voice coil, ferro fluid, and a fabric dome; all are nice

improvements on paper, however it is different and there's no way to

know if they'll sound as good or better without a comparision. You could

buy these first since they're somewhat better on paper, compare to the

original then get the Audax's if they're not a good match. I'd probably

want to have a pair of Audaxs as backups.

I'm planning to order a pair of those TBs with my next PE order, for another

project that I'm working on, I could add them to my list of things to measure

and let you know, if you don't mind waiting a bit.

The face plate is different, I wouldn't hesitate to cut the Audax if necessary.

Depends on how big the cutout is if you'll need a plate.

I liked this simple design, would appreciate it if you'd tell us how the

crossover is wired, the cap value(s), and if there are any numbers

on the woofers.

[JKent]

Thanks Pete

I'll order the Audax's.

The RAL woofer has a sticker on the magnet, marked "4 OHMS D-92265".

The xo consists of a 6.9uF NPE, 1.8 ohm 6 watt resistor, and an inductor (value?). I'll post a photo.

Thanks for all the help

Kent

 

[Pete B]

Thanks Pete

I'll order the Audax's.

The RAL woofer has a sticker on the magnet, marked "4 OHMS D-92265".

The xo consists of a 6.9uF NPE, 1.8 ohm 6 watt resistor, and an inductor (value?). I'll post a photo.

Thanks for all the help

Kent

Thanks for the info Kent,

I don't recognize that number on the woofer, this was going to be my guess, but in 4 ohms:

http://www.madisound.com/catalog/product_i...roducts_id=1072

[JKent]

Hey Pete,

On your recommendation I bought a pair of the Audax TW010F1. Perfect drop-in installation--I'll just have to drill 3 new screw holes and fill the 4 originals. I also ordered 2 mylar film caps. Will post photos as soon as these are back together.

Kent

[Pete B]

Hey Pete,

On your recommendation I bought a pair of the Audax TW010F1. Perfect drop-in installation--I'll just have to drill 3 new screw holes and fill the 4 originals. I also ordered 2 mylar film caps. Will post photos as soon as these are back together.

Kent

Hi Kent,

I got your off list email where you say that the RA's are brighter than

your AR-2ax's, this might be completely normal. I tend to think of the RA's

as low cost mini-monitors, in that they should have a smooth midrange.

You could hook up an L-pad on the tweeter and see if a few dB attenuation

provides a correction that you prefer. You could then measure the L-pad

values and put in permanent resistors. Might be better to wait until I send

the original back to you.

Another experiment that you might want to try is to sit the RA's on top of

your AR-2ax's and use them as subwoofers (disconnect the jumper on back).

I'd expect this to be an impressive setup and I can offer more if you're interested.

[JKent]

Hi Pete (and others who may be interested)

Yes--I'll wait to compare the new tweet with the original, but I also need to spend some more time listening.

Compared to the AR2ax, these do seem to have that "pinpoint accuracy" typical of mini monitors, and on some recordings they really sound very impressive (Passion, Grace & Fire by DiMeola, DeLucia & McLaughlin sounded pretty awesome). I may try some female vocals next to see how that is.

And you're right--I did try the RAs and the ARs together and they they sounded pretty great! I did not disconnect any jumpers--just ran the ARs off "speaker A" and the RAs off "speaker B".

Kent

[JKent]

Here they are. New caps, repaired grille frame, new grille cloth, and--oh yeah, new Audax tweeters. They sound good, but after Pete tests the original tweeter I'll reinstall it and compare side-by-side. In the meantime, these excel on recordings like acoustic guitar, giving crytaline sound and pinpoint imaging. They're completely different from my AR2ax's of course, but I was horrified when I asked my wife to listen to Carly Simon (one of her favorites) thru the RALs, then thru the ARs. She thought the RAs sounded good, but when I swtched in the ARs (which I would have called "fuller" or "richer"), she called the ARs "muffled" compared to the RAs

Kent

Before & after:

[Pete B]

Hi Kent,

Looks good with the new tweeters!

The JBL tweeter is difficult to measure since it seems to have thick ferrofluid

so there is hardly any peak in the impedance curve. Fs seems to be 3200 Hz,

which does pass a sanity check.

The original Allison also seems to have ferrofluid but with a small peak that

allows for a better measurement. Fs is 2800 Hz, very close to the 2900 of

the Audax replacement, also:

Rvc = 6.24 ohms

Qt of .86

Qm = .92

Qe = 13.1

The Qt seems reasonable, not sure about the others. Voice coil inductance

measures 47 uH at 10 KHz.

Here's the impedance data:

1K 7.0

2K 7.3

2.8K 7.5

3K 7.4

6.3K 7.37 Min

8K 7.6

10K 7.9

These figures are all very close the the Audax.

[JKent]

Thanks Pete (for the compliment, but especially for the info!).

I see on the specs page at Madisound they do not give all the specs you measured on the RAL, so I guess it's hard to compare (unless you also measured an Audax yourself). Here is the info they provide:

Znom 8 ohm

Re 5.5 ohm

Le@1kHz .03 mH

fs 3000 Hz

Qms -

Qes -

Qts -

Mms .11 g

Cms - mm/N

Sd .03 cm2

BL 1.3 N/A

Vas - ltrs

Xmax 0.25 mm peak

VC Ø 10 mm

Sensitivity

1W / 1m 90 dB

Kent

[Pete B]

Hi Kent,

I've been saying 2900 Hz because that was the figure for the older version

from Audax that this new tweeter is a replacement for. Not a big issue.

We mainly care about Fs, Re (or Rvc), the shape of the impedance curve,

sensitivity, and the frequency response. This was a good small tweeter and

I don't think they changed it much, or that it is very different from the RAL.

I do have an old one around here somewhere, but they made many different

versions and mine had the titanium coating. I believe that they actually

measured worse than the uncoated ones, LOL. Marketing?

I might buy a pair of the latest next time I place an order.

[Pete B]

I have an old pair of Audax TW60As which look like the RA Labs and Audax drivers

but have the titanium coated dome. Some measured data, which shows that they

are very similar to the RA labs unit:

Audax TW60A Tweeter PLB#1

Fs = 3161 Hz

Rvc = 5.49 ohms

Qt of 1.09

Qm = 1.32

Qe = 6.23

Audax TW60A Tweeter PLB#2

Fs = 3173

Rvc = 5.43 ohms

Qt of 1.07

Qm = 1.30

Qe = 6.07

Zpeak = 6.86 ohms

Z1K = 5.77

Zmin = 6.20 at 5.38 kHz

Z10K = 6.83

Lvc10K = 46.3 uH

[Pete B]

Just purchased a pair of the current TW010F1 10mm Audax dome tweeters.

It is remarkable that they are so close to the TW60As which are over 15

years old!

Well, now that I have a pair of the current tweeters I'm able to put them side

by side with the original RAL tweeter. First, it is obvious that the RAL has a

little ceramic magnet, whereas all the others have the magnet enclosed in

a plastic cover. Looking at them from the front, what do you know, they

certainly look the same but it is as if the Audax was put in the copier machine

with about 1.2 magnification, LOL! The front plate hole is .95" on the RAL, and

.8" on the Audax. The center dome is about .5" on the RAL and 10 mm

with the Audax. There is a .5" dome copy available from PE that might

be worth looking into but it is a cloth dome rather than mylar:

http://www.partsexpress.com/pe/showdetl.cf...tnumber=264-840

Measured data for these TW010F1 10mm Audax dome tweeters:

Audax TW010F1 10mm Tweeter PLB#1

Fs = 3164 Hz

Rvc = 5.57 ohms

Qt of 1.17

Qm = 1.39

Qe = 7.10

Audax TW010F1 10mm Tweeter PLB#2

Fs = 3129

Rvc = 5.60 ohms

Qt of 1.24

Qm = 1.49

Qe = 7.34

Zpeak = 7.07 ohms

Z1K = 5.95

Zmin = 6.39 at 5.09 kHz

Z10K = 7.03

Lvc10K = 46.1 uH

[JKent]

So many speakers, so little room! Thanks for all the help, Pete. I have to do some "house cleaning", so these are going on *-***. Hope they find a good home after all this work!

Kent

[carsdealer]

Great speakers!

I bought these used speakers for 20euros and they sound great! In my second listening room they have replaced the Boston A60II , more extended bass and softly but detailed mids.

Very nice sounding!

Attached 1 pic of my Mini's.

ps .the woofer have a strange sticky paint, but the surrounds are really ok after 15years! Why not in others speakers?

Roberto/carsdealer