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How To Wire 3-10" to 8 Ohms

refin
August 31st, 2012, 08:58 PM
Hey everyone...........
just bought a Weber 3-10 Bandmaster cabinet from a friend on another forum for a really great price.I actually bought it for my '56 Pro Amp (5E5-A) chassis,because the cab is tanked.He builds amps and said it is a perfect fit.
My question (obviously)---the Pro is 8 ohms....how do I wire 3-10" for 8 ohms?
Thanks in advance!

David Barnett
August 31st, 2012, 09:08 PM
Well, if you need exactly 8 ohm, you'll have to get creative. If you get one 16-ohm 10" speaker and two 8-ohm ones, you could put the two 8s in series, and the 16 in parallel with that.

But you won't get equal power sharing between the three. Half the power will go to one speaker, and the other half will be divided between two.

If you just put three 16-ohm speakers in parallel, you'll get about 5.33 ohms, which is probably close enough for a Fender transformer.

Tony474
August 31st, 2012, 09:19 PM
Can't really be done while still dividing the signal equally between all three speakers. If you have three 16-ohm drivers in parallel the overall impedance will be 5.33 ohms. Three 4-ohm speakers in series will present a 12-ohm load. Your amp may or may not tolerate one mismatch or the other.

Best way, possibly, is to use just two 16-ohm speakers of appropriate power handling, wired in parallel for an 8-ohm load, and blank off the third cutout to avoid phase cancellation and consequent loss of bottom end.

Edit: David (above) posted while I was typing this. Everything he says is true.

refin
August 31st, 2012, 09:31 PM
Thanks guys.....that's pretty much what the seller said too.
I would love to have a 1-15,the Pro sounded so good with that.Might have to go 2-10s and suggested.

fezz parka
August 31st, 2012, 09:35 PM
Get a new baffle cut for a 15.

bunny 7
August 31st, 2012, 09:36 PM
Thinking out loud here, is there an extension speaker jack on your Pro?
In looking at the schematic it shows one as extra 8 ohm speaker.
What about 2 16 ohm speakers wired in parallel to the main speaker jack and the other speaker at 8 ohms plugged into the extension speaker jack.
It would place the amp at 4 ohms total then.
I'm not sure how the volume would vary between the 2 speaker arrays, I'm thinking one set or the single speaker may get more power or be louder unless they were same db efficiency.

Like I said, thinking out loud and sometimes that may be dangerous. :razz:

Maybe Wally or muchxs will chime in and help you out. :grin:

bunny 7
August 31st, 2012, 09:40 PM
Get a new baffle cut for a 15.

While I was writing my novel there, Fezz came up with the obvious solution.
I salute you my good man. :grin:

refin
August 31st, 2012, 09:57 PM
Get a new baffle cut for a 15.

I have SERIOUSLY entertained that...........

fezz parka
August 31st, 2012, 10:01 PM
It's what I'd do.:lol:

5e7, 5f4, 5e5a are all pretty much the same except for the OT and speaker compliment.

refin
August 31st, 2012, 10:05 PM
I have a '59 Bassman,have always loved 4-10s.....a friend had an original 310 Bandmaster that sounded great,so I got curious...........

David Barnett
September 1st, 2012, 12:50 PM
What output transformer did Fender use in the 5E7? Did they bother to match it to the 2.6 ohm load, or just get "close enough?

Dr. Bill
September 1st, 2012, 01:30 PM
According to Greg Gagliano the brownface 3x10 Bandmaster had an 8-ohm output transformer but with the 3 8-ohm speakers the actual load was 2.7 ohms!

It is interesting to note that the original 6G7 Bandmaster used three 8-ohm speakers for a total impedance of 2.7 ohms which is a 3-fold mismatch for the 8-ohm output transformer. Post-tweed era Fender transformers (mainly Schumacher units) were very tolerant of up to a 2-fold mismatch in output impedance. This is why most of the brown, blonde and blackface amps have and extension speaker jack. You can run your Deluxe Reverb with an 8-ohm extension cab (yielding a total impedance of 4-ohms) without a hitch. Perhaps the 3-fold mismatch on the 3x10 Bandmaster is part of the secret to its great sound.
http://www.ggjaguar.com/projbmaster.htm

I would probably go with a 4-ohm transformer and call it close enough.

muchxs
September 1st, 2012, 02:07 PM
Well, if you need exactly 8 ohm, you'll have to get creative. If you get one 16-ohm 10" speaker and two 8-ohm ones, you could put the two 8s in series, and the 16 in parallel with that.

But you won't get equal power sharing between the three. Half the power will go to one speaker, and the other half will be divided between two.

That's perfect.

Go for a 16 ohm Eminence 10516 which handles 75 watts all by itself. Then throw a couple funky old 8 ohm alnicos in series.

The Emi will see around 20 watts cranked while your two alinicos will see the other 20.

You'll get definition and punch from the ceramic and a vintage feel (less definition and punch but the ceramic takes care of that) You'll get a vintage feel from the alnicos.

BiggerJohn
September 2nd, 2012, 12:51 AM
Hey everyone...........
just bought a Weber 3-10 Bandmaster cabinet from a friend on another forum for a really great price.I actually bought it for my '56 Pro Amp (5E5-A) chassis,because the cab is tanked.He builds amps and said it is a perfect fit.
My question (obviously)---the Pro is 8 ohms....how do I wire 3-10" for 8 ohms?
Thanks in advance!

You don't.

Tony474
September 2nd, 2012, 02:29 AM
You don't.

Unless of course you can get hold of three 24-ohm speakers...

refin
September 2nd, 2012, 12:07 PM
Unless of course you can get hold of three 24-ohm speakers...

:lol:

Paul in Colorado
September 2nd, 2012, 01:30 PM
What were the original speakers in a Tweed Bandmaster?

fezz parka
September 2nd, 2012, 04:07 PM
5e7's used a Triad 1848. 4 ohm OT, just like the Super.

Dr. Bill
September 2nd, 2012, 05:13 PM
5e7's used a Triad 1848. 4 ohm OT, just like the Super.

Yup. That's the way to go. Just like Leo done it.

tjalla
September 2nd, 2012, 07:27 PM
You could always try a weber z-matcher

http://taweber.powweb.com/store/zmatch.htm

BiggerJohn
September 2nd, 2012, 09:26 PM
What were the original speakers in a Tweed Bandmaster?

Three 8 ohm alnico Jensens in parallel.

Paul in Colorado
September 3rd, 2012, 12:50 PM
Three 8 ohm alnico Jensens in parallel.

I should have been more specific. What model Jensens?

David Barnett
September 3rd, 2012, 01:36 PM
I should have been more specific. What model Jensens?

"Jensen P10R, Jensen P10Q, or Oxford 12K5R-1" according to the Fender Amp Field Guide.

http://www.thevintagesound.com/ffg/

BiggerJohn
September 3rd, 2012, 05:55 PM
"Jensen P10R, Jensen P10Q, or Oxford 12K5R-1" according to the Fender Amp Field Guide.

http://www.thevintagesound.com/ffg/

Only ones I've ever seen in there are P10Rs.

fezz parka
September 3rd, 2012, 10:48 PM
Ditto.

Paul in Colorado
September 3rd, 2012, 11:47 PM
Thanks, guys!

timbo_93631
September 4th, 2012, 01:01 AM
You don't come across em too often but you could also hunt down three 3.2 ohm speakers, or have Weber make them for you, that way you'd get 9.6, pretty close to 8!

Tony474
September 4th, 2012, 04:56 AM
Maybe it's worth recalling that speaker impedance is nominal anyway and varies with the component frequencies of the signal. If the original OT can handle a 33% downward mismatch, which seems to be the case, there doesn't appear to be much of a problem with using three sixteens in parallel.

trev333
September 4th, 2012, 05:17 AM
I've got an old 3x12 bin rated at 4 ohms.... (12 ohms each?)

I disconnected one speaker to give me nearer 6 ohms which I use in my 8 ohm outlet on my 210...

close enough for the bush.... :wink:

Cliff Rogers
September 4th, 2012, 05:25 AM
Oooo... a Vase Cab, I have the head that goes with that.

http://i1075.photobucket.com/albums/w423/cliffrogersau/Guitar%20Stuff/VaseTrendsetter60Delux.jpg

BiggerJohn
September 4th, 2012, 11:49 AM
Vase?

Wally
September 4th, 2012, 01:00 PM
I also have a 45216 OT number listed in the trannie charts for the Super. Both that number and the 1848 are penciled in because that OT spot in that chart was blank. INterestingly, that chart does indicates a 2.6 ohm impedance. I am sure that is optimal....and we know that Leo understood that that 'match' is not written in stone, correct?
Personal experience.....I have an older transformer chrt that I copied out of a Vitnage Gutiar issue from 1994 in which I made a note about two '59 5E7 BAndmasters that I owned. I made this note because that chart had no info for the 5E7 Bandmaster. the '59 5E7's that I had carried original equpment 45217 OT's...which were indeed 8 ohm Trannies used in 5E11 adn 6G11 Vibrolux amps, the 6G9 Tremolux amps,and the 6G7 signle sepaker Bandmaster amps.

So, that would make 3 different OT's that mgiht be found in the 3 x 10 BAndmasters???

trev333
September 4th, 2012, 07:01 PM
Vase was the brand on most band gear/bins in OZ when I was a teen....

I once thought they were OS gear like Fender Marshall etc....
turns out they were made in Brisbane, my home town then...

a pommy guy Tony Troughton came over here in the 50's and started making Vase here....http://www.vase.com.au/detail.php?id=67

in a weird twist of fate he sold the company late 70's... and went on a fishing holiday to the barrier reef soon after......
story I heard was ..on his first morning he went for a swim and was stung by an irrikanji or box jellyfish and died.... sad eh?...:cry:

I got that 3x12 Cab for free , it was tossed in with another auction lot of keyboard stuff I bought on ebay.... the guy says.. I've got an old broken amp and speaker box here, you want me to throw them in?...

sure I says why not..... :roll:

the amp was a rare Oz made Goldentone Reverbmaster from the 60's .. for free..:shock:.. a cap job and some tubes and it's a goer...:grin:

big-daddy-59
September 4th, 2012, 07:09 PM
Get a new baffle cut for a 15.

+1

Cliff Rogers
September 4th, 2012, 07:12 PM
The head is a Vase Trendsetter 60 Deluxe.

I scored it for $153 in an auction & the only thing I have had to do is clean the pots & change the electro caps. I love it.

Vase has reformed & is making them again.
A brand new Trendsetter 60 Deluxe with that same cab & transit cases is $4K AUD.

David Barnett
September 5th, 2012, 07:07 PM
For the Bandmaster, I think that three 16-ohm speakers in parallel, with the 8-ohm output transformer secondary, will get you as close as possible to the performance of an original 5E7 without changing transformers.

Drak
November 15th, 2012, 10:10 AM
I have a 3-10 baffle I made years ago that I have picked back up and want to finish now.
The amp is an old 1950 tweed era amp much in the spirit of an old tweed Fender, 8 ohm output tranny.

After pondering the possibilities of what I have on hand, this has been what I keep going back to.
Looking for comments on how it may sound.

Top 10 - Weber P10N or P10B 16 ohm
Bottom 10's - CTS alnico 10's 8 ohm wired in series
Wired series/parallel, it gives me the 8 ohm requirement.
But I'm more concerned with the power division and what it will sound like.
Will the 1-10 be totally dominant over the CTS?


I ALSO have a Weber 15" alnico speaker as well, and was wondering why a lot of people seem to prefer the 1-15 as opposed to the 3-10, I personally really dig 3-10 and 4-10 setups, but am open to people who've used both who'd like to comment.

What you think? :idea:

Wally
November 15th, 2012, 12:36 PM
I am thinking...could be wrong...that the single 16 ohm will be working twice as hard as the two in the series arrangement....not 'dominant' but overworked, maybe?. I prefer balnced circuits. I also prefer parallel arrangements in case of speaker failure. YMMV...
I would run the 15" at the 8 ohm match. IF I had 3 x 16 ohms, I would not balk at running those in parallel against that OT. Again..others might disagree. Ime, this amplifier circuit sounds good with any arrangement...and FEnder built in 3 different arrangements...Super 2 X 10, BAndmaster 3X10 and the Pro 1X15. AS to what the WEber will sound like in it, that depends on the WEber.

BiggerJohn
November 15th, 2012, 01:06 PM
Yeah, the Weber will be getting twice the power of each CTS.

Only way to know what it will sound like is to wire it up and try it.

I also like the idea of three 16 ohm speakers in parallel driven by the 8 ohm OT.

GearHund
November 15th, 2012, 06:43 PM
I've been running two 8's and a 16 in a 3 x 10 cab for over a year with a Lil' Dawg D-Lux head that has been built to run both 6V6 or 6L6 power tubes. I can understand the theory behind the power mismatch, but I don't hear any single speaker dominating over the others. I haven't had any problems with it handling what the head sends out. I have never cranked it wide open though for more than a few minutes.

Now, I'm wondering should I go with the mismatch or run with a lower ohmage by combining three 8 ohm speakers?

Wally
November 15th, 2012, 06:57 PM
gearhund, you don't say how those speakers are wired??? OR...what OT you have in that amp?
If you are in parallel against a Bandmaster type of OT, the load mismatch is not bad but the 8 ohm speakers are working harder than the 16 ohm. IF you are wired as the OP suggests and have a BAndmaster type OT,then you have a mismatch of loads.
As for hearing the difference, that might take a very careful listening. Some folks hear what others don't.... I adhere to the thought that matched loads yield the best sonics and safest situations.

Marshall Thinline
November 15th, 2012, 10:33 PM
If you just put three 16-ohm speakers in parallel, you'll get about 5.33 ohms, which is probably close enough for a Fender transformer.

+1.....I've been doing this with my 5E3 in a 3x10 Bandmaster cab for a few years...no problems!

John Thigpen
November 15th, 2012, 10:52 PM
I have a Genz Benz Black Pearl 3x10 and the load is 5.33 ohms, and you use the 8 ohm setting on the amp. I'm not sure how it is wired to get to 5.33, though.

Inventour
November 16th, 2012, 12:40 AM
My 1959 Pro has the triad 45217 OT, and it's the 8 ohm unit.

I just made a 2x10 baffle for my Pro and got two Celestion Gold/40 15 ohm speakers,
to run it as a Super. Then I can run an extension cab to run a 2nd cab with a single 8 ohm speaker off the Ext. Speaker Jack.

I noticed you can fit the 3-ten's in the Pro Baffle, you can wire it will with the 2 - 16 ohm speakers, then run the 8 ohm speaker in the ext jack, works good and is within the limits.

LeeInAustin
August 17th, 2013, 02:22 PM
Re. Emi 10516's (only about year late in responding, muchxs): I've got a pair in a 2x10 and love 'em for a nice, full balanced tone. BUT I just discovered today that their actual impedance is 11 ohms each, not 16. My impression is that actual impedances are often just under the nominal impedance, so an "8 ohm" speaker might be 7 ohms (for example, the Emi Legend 1028K). But these 10516's are way under their "16 ohms" at 11.2 ohms. In parallel, the 2x10 cab is at 5.6 ohms.

Having discovered that, I'm now thinking about grabbing a lightweight Bandmaster cab from Mojotone (16#) and popping a third 10516 in...now we have 3 x 12 ohms = 4 ohms in a 3x10. My Gries 35 (BFVR clone) has a 8/4 ohm switch. Sound tasty?

I like the 2x10 combo setup I've got in the Gries 35, but I'd like more headroom. Y'all think adding the surface area of a 3rd speaker would help? Alternately, could jump over to a lightweight 4x10 in parallel/series wiring for an 8 ohm cab. That'd be Emi 1058's and maybe 1028K's. Hmm.

BiggerJohn
August 17th, 2013, 02:37 PM
I have been interested I'm the 3x10 idea for some time, but was thinking of adding a twist Make one if the speakers a 12 instead of a 10. I talked to a tweed cabinet maker about that and he said it would fit in a DeVille size csb. So a pair of Emmi Cajuns paired with a CRex or something like that. Drive the thing with a Bassman head or possibly. jTM45/50 or some such. Should have a nice snappy high end with some low end thump.

homesick345
August 17th, 2013, 04:01 PM
The Techs may need to correct me, but a 12 ohms cab (3 4ohms speakers in serie) would work perfectly with an 8 ohms tap on your amp,

Nothing to worry about