Electro-Voice 12TRXB or 15TRXB based on Cabinets?

[RSMRecording]

I have a pair of vintage well built speaker cabinets that were made to close specs of a similar Altec cabinet. Currently, the cabinets are loaded with a Full-range Coaxial 15" type Stromberg-Carlson speakers from the early 1960's (chrome frames, red cones). Unfortunately, I blew one of tweeters and decided I want to get a pair of Electro-Voice full-range vintage speakers for the cabinets. I want to choose between the model 12TRXB or 15TRXB, or similar designs by other manufactures.

Cabinets volume is about 4.3 Cu.Ft and it is a bass reflex design.

Pros and Cons

Electro-Voice 12TRXB ?

Electro-Voice 15TRXB ?

Thanks for the help and advise

 

[mhardy6647]

Really too small for either if you want any bass; 12TRXB might be OK.
See EV Tech Bulletin 10A (e.g.) https://www.electrovoice.com/binary/Bulletin10A.pdf
The relatively high Qts of those drivers' woofers might make it worth trying your enclosures with the backs taken off -- i.e., as open baffles.

PS The 12TRXB and 15TRXB are both coaxials, not full range. Their full range counterparts are the SP12B and SP15B.

 

[RSMRecording]

Really too small for either if you want any bass; 12TRXB might be OK.
See EV Tech Bulletin 10A (e.g.) https://www.electrovoice.com/binary/Bulletin10A.pdf
The relatively high Qts of those drivers' woofers might make it worth trying your enclosures with the backs taken off -- i.e., as open baffles.

PS The 12TRXB and 15TRXB are both coaxials, not full range. Their full range counterparts are the SP12B and SP15B.

Thank you for the the information,

I guess should be looking for SP12B or SP15B then, Would these work in my cabinets?

So High Qts = needing a very large cabinet? I used to have a pair of 12TRXB speakers in a 4 foot by 2 foot 2 foot cabinets, hugh / heavy but the bass was fantastic. Thats why I wanted to get them again, but ideal don't want to have no backs on the cabinets.

 

[mhardy6647]

The coaxes are better for truly 'full range' sound -- the T/S parameters (so to speak) for the woofer sections - AFAIK - will be pretty similar.

If you were happy with them before, you should be happy with them again!

 

[gdmoore28]

Hi RSM. Why would you not go with the Electro-Voice 15TRXB? As brother Hardy pointed out, the TRXBs are coaxial and will make the SP15Bs sound dull by comparison. (Calling speakers like the 15Bs "full range" is really a relic from the past. We would not consider them full range today. The TRXBs would come much closer, though.)

What are you currently using as a crossover with the Stromberg Carlsons? There might be a chance of using them with the EVs. Mr. Hardy will know what is required there.

One final question: have you checked into the possibility of repairing the Stromberg tweets? Even if you switch to the EVs, you should be able to sell the SCs for a decent price.

GeeDeeEmm

 

[RSMRecording]

Hi RSM. Why would you not go with the Electro-Voice 15TRXB? As brother Hardy pointed out, the TRXBs are coaxial and will make the SP15Bs sound dull by comparison. (Calling speakers like the 15Bs "full range" is really a relic from the past. We would not consider them full range today. The TRXBs would come much closer, though.)

What are you currently using as a crossover with the Stromberg Carlsons? There might be a chance of using them with the EVs. Mr. Hardy will know what is required there.

One final question: have you checked into the possibility of repairing the Stromberg tweets? Even if you switch to the EVs, you should be able to sell the SCs for a decent price.

GeeDeeEmm

Hi Gee,

-I was just not sure how the speaker / bass response would be if I choose the 15TRXB. When changing speakers and stuff I lack in the dept. of knowledge. As said before, I use to have a pair of 12TRXB's is very large 13.5 cuft cabs and they were amazing and I was stupid to sell them.

-There is no crossover in the Stromberg-Carlson cabinets just speaker and 2 leads from the speaker terminals to the outside posts. I assumed the crossover was built into the SC speakers?

-My grandfather just found a pair of 12" versions of the 15" I have and said that one of tweeter's is blown on his pair, but I could probably switch out the blown tweeter on mine. But I am still very interested in changing speakers and trying to get the most out of these cabinets.

 

[gdmoore28]

Grandpa to the rescue!

I'm from the old school that says, all things being equal, bigger is better. That's why I would go with the 15" EVs if you stumble on some. I'm a fan of solid bass response, so 15s have always been dear to my heart - and ears!

And you and mhardy are right about the cabinet size issue. The 15s really need a larger one. Fortunately, if you have any woodworking skills, the cabinets are easy (and fun) to build, so whipping up a couple with the correct volume should not be an issue. I haven't seen your cabs (some pics would be nice, hint, hint), but there is also the possibility that you could increase their volume by adding an integral "riser" to the bottom to add another 1-2 cubic feet. I did this in a recent build (see my avatar) to add about 1.5 cubic feet to the volume. Feasibility would depend on the design of your current cabs.

GeeDeeEmm

 

[twiiii]

If the 12inch or 15 inch EV's have been reconed with more modern cones and you port the enclosure you can easily reach the 40 HZ, with the 12 and just above 30 HZ with the 15. Same goes for the later 604 Altecs and JBL 604 replacement they designed for Urei 800series speakers. The tweeter section of the EV coax speakers are the week link. With the crossover attenuated to match the woofer about 6 to 8 db the tweeters still can only handle about 20 watts under ideal conditions. Altec 605 and 604 are a much better choice, but cost a ton more.

 

[Retrovert]

The paper-cone tweeters on the coaxial Stromberg-Carlson drivers suffer from all of the drawbacks and liabilities of a paper-cone tweeter, particularly one that is sixty years old, and replacing with a modern soft-dome is likely the answer. The Bozak B-200X tweeter had the same issues, and even impedance compensation can't cure the lack of high-end response above about 10 kHz or the spikey nature as it nears that point.

I have one of the Stromberg-Carlson 15" coaxials and when I find its mate plan to replace both of the tweeters with soft-domes. (I'll stash the originals in the cabinet in case someone has a fetish for original sound.)

I agree with the above comments about the benefits of a coaxial over the purported "full-range". Even though the drivers are not perfectly time aligned, the sound is generally magickal.

 

[Goggle1824]

Retrovert, I have a single EV-12 RTXB that came out of a very beat-up Karlson style cabinet. The EV received quite a few cone repairs via a coffee filter...

Would a coiaxial be a good candidate for soft done tweeter replacement, I could try it back in the original cabinet or maybe in an open baffle mock-up.

 

[Drugolf]

So how do you replace the old original tweeter on these coaxials with a dome?
And where would a 3-way Wolverine driver fit into this?
Sorry for the diversion.

 

[Retrovert]

Would a coiaxial be a good candidate for soft done tweeter replacement, I could try it back in the original cabinet or maybe in an open baffle mock-up.

So how do you replace the old original tweeter on these coaxials with a dome? And where would a 3-way Wolverine driver fit into this?

Some confusion here.

A full-range driver, such as the Wolverine, with an integrated whizzer or similar cone cannot have a tweeter dropped in front. Well, it could, of course, if one built a bracket for it, but that's going to muffle the original tweeter and midrange, and load the cone, much like a slot-loaded woofer. YMMV.

The response I made was to the OP's original comment, see posting No. 1, about owning a Stromberg-Carlson full-range 15" driver with a damaged tweeter. See:

Currently, the cabinets are loaded with a Full-range Coaxial 15" type Stromberg-Carlson speakers from the early 1960's (chrome frames, red cones). Unfortunately, I blew one of tweeters and decided I want to get a pair of Electro-Voice full-range vintage speakers for the cabinets.

The Stromberg-Carlson full-range drivers are constructed as coaxials with a woofer-midrange and separate tweeter driver mounted on a bracket and suspended in front of the woofer-midrange, creating a aligned speaker. The original tweeter was paper-cone which can be replaced with a soft-dome.

My comment was about replacing that separate tweeter, again, in the Stromberg-Carlson coaxial, with a modern unit. Which is why I wrote:

I have one of the Stromberg-Carlson 15" coaxials and when I find its mate plan to replace both of the tweeters with soft-domes.

Ok, that should explain the context.

 

[Goggle1824]

Ah, I see where I crossed my wires, or more specifically, my drivers, there. Apologies to the thread on that. Appreciate you clarifying for me Retrovert.

 

[bimasta]

I use to have a pair of 12TRXB's is very large 13.5 cuft cabs and they were amazing and I was stupid to sell them.

This question is not about cabinets, but the drivers. I have a pair of the 12-TRXB. They're in great condition, no problems I'm aware of. If I build cabinets, will I have great speakers? I don't have space for 13.5 cuft, as RSM mentions. I'm in an apartment, I can accommodate large speakers, but not that large. Also, building the cabinets will take a real effort as I'm not presently equipped with a workshop. I can do it — but will it be worth it?

They sound great in free-air, but of course they would given that they're 3-way. I'm dubious of the whizzer-cone — the only other speaker I've had with a whizzer was a pair of Lowthers, in Lowther cabinets, and I didn't like them. But the whizzers weren't the sole cause of that dislike. Also, I know a 12" woofer can produce prodigious bass, both deep and powerful — but can these 12" woofers? I could add another woofer, or PBR to supplement it; I could add another tweeter, another midrange, etc — but this is defeating the purpose.

In short, If they were Tannoy 12" Reds, I'd gladly proceed because I know their sound. But I've never heard the 12TRXBs, properly housed in good enclosures. They're a mystery to me, I have no idea what the final result will be. I like their efficency because I'll be using a 15-Watt 2A3 amp. I like the concentricity, I've heard some great ones — but haven't heard these. I don't need good speakers, I have other good speakers, and I don't need "unique" speakers whose shortcomings I have to make allowances for.

So my question is simple — but maybe unanswerable: will they be great speakers? Is the 12TRXB capable of greatness?

 

[Drugolf]

Yeah, I was asking two different questions. The Wolverine question was more about the original premise of the thread pertaining to mounting them in a new cabinet as compared to the TRXB's etc.

The tweeter thing was a general question as I didn't think about swapping the old mounted tweeters on drivers like the TRXB's before. (Retro- could this be done on a Bozak B-199 with the mounted B-200?)

 

[Drugolf]

This question is not about cabinets, but the drivers. I have a pair of the 12-TRXB. They're in great condition, no problems I'm aware of. If I build cabinets, will I have great speakers? I don't have space for 13.5 cuft, as RSM mentions. I'm in an apartment, I can accommodate large speakers, but not that large. Also, building the cabinets will take a real effort as I'm not presently equipped with a workshop. I can do it — but will it be worth it?

They sound great in free-air, but of course they would given that they're 3-way. I'm dubious of the whizzer-cone — the only other speaker I've had with a whizzer was a pair of Lowthers, in Lowther cabinets, and I didn't like them. But the whizzers weren't the sole cause of that dislike. Also, I know a 12" woofer can produce prodigious bass, both deep and powerful — but can these 12" woofers? I could add another woofer, or PBR to supplement it; I could add another tweeter, another midrange, etc — but this is defeating the purpose.

In short, If they were Tannoy 12" Reds, I'd gladly proceed because I know their sound. But I've never heard the 12TRXBs, properly housed in good enclosures. They're a mystery to me, I have no idea what the final result will be. I like their efficency because I'll be using a 15-Watt 2A3 amp. I like the concentricity, I've heard some great ones — but haven't heard these. I don't need good speakers, I have other good speakers, and I don't need "unique" speakers whose shortcomings I have to make allowances for.

So my question is simple — but maybe unanswerable: will they be great speakers? Is the 12TRXB capable of greatness?

I had a similar wonder a couple weeks ago as some 12TRXB drivers came available here locally so I researched them. What I found in reading what I could find was that the final product would still be a limited and an extensive effort building nice cabinets may be better suited to better drivers than the TRXB's. My next curiosity though was could you build cabinets with good dimensions for a 12" or 15" driver like those, start with the TRXB's but swap in others later without having to change much other.

 

[bimasta]

the final product would still be a limited...you build cabinets with good dimensions for a 12" or 15" driver like those, start with the TRXB's but swap in others later without having to change much other.

Good advice, Drugolf — but I'm not really into building cabinets unless I have drivers and xovers to put into it, and know it will be great.

But you've saved me time, money, and frustration, so thanks. I think I'll just sell them... I only bought them because they came with a Fisher 800C tube receiver, so I'm still ahead in the game...

 

[Retrovert]

The tweeter thing was a general question as I didn't think about swapping the old mounted tweeters on drivers like the TRXB's before. (Retro- could this be done on a Bozak B-199 with the mounted B-200?)

Yes, of course. But that is not necessarily the best approach. Coaxial is different than three-way.

I've previously suggested, on numerous occasions, replacing the tweeters on the B-207 bracket that if one wanted to maintain the original configuration on the Bozaks. For those of you not familiar with the Bozak B-207, this nomenclature describes a 12" woofer (B-199) with two tweeters (B-200X or B-200Y) mounted on a bracket across the woofer. This loads the cone as in a slot-loaded woofer.

The B-207 was also sold as a two-way system upgradeable to a three-way by adding a B-209 midrange, and the B-207 may be an artifact of that upgrade path. I tend to think it was slot loading, but note that such loading was never done on the larger units (Concert Grand, Symphony) and, as above noted, two of the bookshelf units (one a full-range driver using the B-800) did not use the bracket, instead mounting the tweeters higher up.

For example see:

http://audiokarma.org/forums/index....ods-on-my-bozaks.732688/page-14#post-11232755
Yes, this is a huge issue. I've always said that if, like crickets and grasshoppers, we heard with our knees then we'd experience excellent imaging. Only the smaller Bozaks placed tweeters lower (B-313, B-302, and B-305, as I recall) but two of the small bookshelfs (B-503, B-801) did not. I suspect this was slot-loading the woofers to put weight on the cone and thereby extend the low-end response. The bookshelf cabinets are smaller and loading the B-199 was likely suboptimal in that size.​

But this is off-topic for the OP's question, best have it moved to its own thread.

 

[Retrovert]

Good advice, Drugolf — but I'm not really into building cabinets unless I have drivers and xovers to put into it, and know it will be great.

But you've saved me time, money, and frustration, so thanks. I think I'll just sell them... I only bought them because they came with a Fisher 800C tube receiver, so I'm still ahead in the game...

Ummm, before you do that, why not pick up a pair of empty Bozak B-302 cabinets and do an experiment? Many B-302 cabinets are readily available for little to no cost as the separated drivers are worth more than the complete speakers.

Then cover the midrange and tweeter holes using a plug cut from plywood using a router and epoxy the plug in place. You could even screw a rectangular piece over the hole for this experiment. Leave the cotton batting and maintain the cabinet as infinite baffle. That should deliver excellent sound from the Electro-Voice 12TRXB. Infinite baffle is superior to bass reflex and other ported designs.

A full-range driver should nicely work in the infinite baffle cabinet, and you'll have minimal work to do this experiment. If you don't like the result you are out very little money and time.

 

[HTHMAN]

Years ago I had a pair on 12TRXb's that I built a ported enclosure according to their plans. I typically prefer sealed cabinets, but those sounded great and were not overly large. This may help properly port your cabinets
https://www.dropbox.com/s/r8cothm5a8rto8m/EV 12TRXB plans.pdf?dl=0