$vboptions[bbtitle]

Speaker cabinet for a Fender Twin Reverb Custom 15.

Tommasogezz
September 3rd, 2013, 06:21 AM
I own a Fender Twin Custom 15, essentially an 85 watt twin reissue 65 with an Eminence 15 speaker. I'm perfectly happy with the sound of this amp: extremely clean, fantastic low end and sparkling high end..
The only missing side, just to find one, is the middle range..
That's why I'm thinking about pairing a 2x12 cabinet to the 15 speaker.
I already divided the amp into head and cabinet so I'd like to know what kind of 12 speaker you suggest to combine with the 15 or just to use alone with the head.. Finally I want to have three one speaker cabinets: one with the original 15 and two with the 12 speakers.
I'm thinking about the EVM12L or the Eminence Swamp Thang.
The amp is a 4 ohm.
The 12s are both 8 ohm.
The in-built 15 is a 4 ohm.
How to combine them without blowing the transformer?
Any suggestion about the speakers?

Any help is welcome!

marshman
September 3rd, 2013, 08:04 AM
Well, the Twin Reverb comes with Jensen C12Ks as standard, so that might be a logical place to start. I've heard very few bad comments about Jensens' Neo 12" speakers, so that would save you a few pounds, and I'd like to think that the Jensen speakers would be easy to find as they are made in Italy.

Hopefully, someone with a better understanding of transformer/impedance interactions will help with the other part of your question.

waparker4
September 3rd, 2013, 08:19 AM
Might have to buy an 8 ohm 15 speaker, wire them all parallel for 2.67 ohms.

Tommasogezz
September 3rd, 2013, 08:30 AM
Well, the Twin Reverb comes with Jensen C12Ks as standard, so that might be a logical place to start. I've heard very few bad comments about Jensens' Neo 12" speakers, so that would save you a few pounds, and I'd like to think that the Jensen speakers would be easy to find as they are made in Italy.

Hopefully, someone with a better understanding of transformer/impedance interactions will help with the other part of your question.

I'll think about a couple of Jensen.. Thank you
Anyway you must know that in Italy we can find almost everything... 😏

Tommasogezz
September 3rd, 2013, 08:41 AM
Might have to buy an 8 ohm 15 speaker, wire them all parallel for 2.67 ohms.
Thanks a lot. If I plug just an 8 ohm speaker on a 4 ohm amp how will it work?

waparker4
September 3rd, 2013, 09:30 AM
Fender amps are suppose to be able to handle a mismatch up to a factor of 2. However I'd rather mismatch on the low side. Ymmv

eugenedunn
September 3rd, 2013, 10:54 AM
Tube amps behave better with a mismatch of higher impedance, due to the "blow back" voltage..... If you're gonna buy a couple new 12-inch speakers, make them each 16 ohms...then, when you wire them in parallel, the cabinet will be 8-ohm impedance total.

That means, you could conceivably run it daisychained simultaneously with the other 15-inch speaker for more sonic bliss (a total 4-ohm load to your amp).

waparker4
September 3rd, 2013, 11:06 AM
Tube amps behave better with a mismatch of higher impedance, due to the "blow back" voltage..... If you're gonna buy a couple new 12-inch speakers, make them each 16 ohms...then, when you wire them in parallel, the cabinet will be 8-ohm impedance total.

That means, you could conceivably run it daisychained simultaneously with the other 15-inch speaker for more sonic bliss (a total 4-ohm load to your amp).

I believe you have it reversed. Lower speaker load is safer.

http://www.geofex.com/tubeampfaq/taffram.htm

Go to Q: Why do I have to match speakers to the output impedance of the amp? and Extended A: It's almost never low impedance that kills an OT, it's too high an impedance.


Even so , you want to be careful what loads speakers you are mixing and matching, because their ohm rating determines how much of the amp's power they will dissipate. You (may not) don't want a situation where some of the speakers are doing all the work and the remaining speakers are relatively quiet.

eugenedunn
September 3rd, 2013, 11:27 AM
Sorry, you're right, fly back voltage is the phenomenon that's due to higher impedance mismatch..... I meant to refer to low impedances being hard on tubes because of over-dissappation. I believe tubes are the weaker link....so....

Tommasogezz
September 3rd, 2013, 12:31 PM
Even so , you want to be careful what loads speakers you are mixing and matching, because their ohm rating determines how much of the amp's power they will dissipate. You (may not) don't want a situation where some of the speakers are doing all the work and the remaining speakers are relatively quiet.

So what's or what are the right combinations between
One 15 speaker 4 ohm
One 12 speaker 8 ohm
One 12 speaker 8 ohm

I already know the 15 works(...)
The two 12 together in parallel will be 4 ohm total (8x8)/(8+8)
The 15 with just one 12 in parallel will be (8x4)/(8+4)=2,66...7
Is there a way to plug just one 12 cabinet??

Any other suggestion about speakers type and brand?
What do you think about the EVM and the Eminence Swamp Thang?
Thanks a lot!!!

eugenedunn
September 3rd, 2013, 04:10 PM
One of the coolest "Swiss Army Knives of Connectivity" is the Weber Z-Matcher. It's an impedance matching transformer that allows you to dial in the desired impedance of the speaker loads you're connecting to almost any conventional amplifier..... check it out at Weber VST.

It also comes with a line out jack for extra connectivity options. I have enjoyed using mine for years.

waparker4
September 3rd, 2013, 04:12 PM
So what's or what are the right combinations between
One 15 speaker 4 ohm
One 12 speaker 8 ohm
One 12 speaker 8 ohm


I don't know, that's why I suggested an 8 ohm 15" driver..

One 15 4 ohm in series with
Two parallel 12 speakers 8/2 = 4 ohms

makes a total load of 8 ohms. Parallel would make 2 ohms.

The pair of speakers will get half the power (1/4 for each) and the 15 will get the other half of the power. By my calculations (which I think are correct :rolleyes: ... _)

Tommasogezz
September 5th, 2013, 07:33 PM
Is there anyone experienced with extra cabinet on a Fender Twin?
How to increase the mid response on a 15" jbl copy speaker?
Can a 1x 12 cabinet solve the "problem"??
Any advice will be appreciated!!

eugenedunn
September 6th, 2013, 01:14 AM
I've played through a couple rigs that are similar to what you're talking about and never found a particular lack of midrange.....

A silverface Fender Vibrasonic (essentially a 100-watt Fender Twin with 15-inch JBL D130F in combo format....my buddy dropped the chassis into a head cabinet and put the JBL in a ported sealed back extension cabinet.

A Fender Showman (essentially 85 watt Fender Twin in head format). This was paired with either a 15-inch sealed back tone-ring cabinet or my front ported sealed back cabinet loaded with an Altec 421A.

All of these cabinets were sealed back cabinets with different types of porting..... All are fantastic sounding.....plenty of bass and full range tone. So my point is that a fuller tone is gonna come from a ported sealed back cabinet. A sealed cabinet does tend to damp the speaker and give punchier bass...you can EQ appropriately without farting out and that also means your midrange is gonna sound stronger, without causing boominess.

Tommasogezz
September 6th, 2013, 01:51 AM
All of these cabinets were sealed back cabinets with different types of porting..... All are fantastic sounding.....plenty of bass and full range tone. So my point is that a fuller tone is gonna come from a ported sealed back cabinet. A sealed cabinet does tend to damp the speaker and give punchier bass...you can EQ appropriately without farting out and that also means your midrange is gonna sound stronger, without causing boominess.

Wow Eugenedunn!
That is what I call a real player suggestion!
Thank you very much!
I think I'm gonna bring the cabinet to my tech and ask him to seal the back by a removable piece of wood! This way I can easily remove it when I rec

Tommasogezz
September 6th, 2013, 02:00 AM
All of these cabinets were sealed back cabinets with different types of porting..... All are fantastic sounding.....plenty of bass and full range tone. So my point is that a fuller tone is gonna come from a ported sealed back cabinet. A sealed cabinet does tend to damp the speaker and give punchier bass...you can EQ appropriately without farting out and that also means your midrange is gonna sound stronger, without causing boominess.

Wow Eugenedunn!
That is what I call a real player suggestion!
Thank you very much!
I think I'm gonna bring the cabinet to my tech and ask him to seal the back by a removable piece of wood! This way I can easily remove it when I record as I also mic it from the back..
Last two questions:
What does it mean "ported"?... I tried to find it on the web but couldn't really understand the meaning in the sentence "ported sealed back etc.."
A closed back instead of the opened stock cabinet will not reduce the three-dimensional sound I really love in this amp?

JDC
September 6th, 2013, 02:55 AM
Here is some information on porting, what it is and what it is meant to accomplish.

Someone with more audio background than I will have to comment further, though.

http://thespeakerguys.blogspot.com/2008/03/how-port-on-speaker-works.html

marshman
September 6th, 2013, 07:53 AM
I'm not sure you'll be able to seal that amplifier...I presume the tubes will need fresh air circulation to prevent excessive heat buildup. If you only play the amp for 20-30 minutes at a time, it might not matter.

'Ported' refers to specifically engineered holes in the cabinet to reinforce certain aspects of the response, can be adjusted to enhance specific ranges of the output. I have no understanding of the science involved, though.

Tommasogezz
September 6th, 2013, 08:29 AM
I'm not sure you'll be able to seal that amplifier...I presume the tubes will need fresh air circulation to prevent excessive heat buildup. If you only play the amp for 20-30 minutes at a time

Hi Marshman,
I started the thread writing than the combo has already been divided into head and cabinet so I don't think is going to be a problem for the valves if I seal the back of the cabinet...
Anyway I'm a professional player and amp is on around 5 hours a day as I use it for practicing, teaching, recording and of course gigging.
That's why I want to improve the sound. I'm not that kind of gear collector with 10 guitars and 5 amps for playing in the bedroom..
I'd really love suggestion from people who owns the same amp I know and solved the problem before me: how to increase the mid response in a fender twin custom 15"??
Thanks a lot!!!

mabley123
September 6th, 2013, 09:34 AM
like eugenedunn says. the ev and jbl both are recomended to have a sealed ported cabinet.

the ev and jbl both do best in a ported and tuned cabinet and both are recommended to have ported cabinets by the manufacturer.
the thiele cabinet is 1 that is available from mesa that is made for the EV but is actually a bit small.

an ev requires a 1.3 cubic foot cabinet ( internal measurement ). same as for a JBL D130F.
the E series JBL requires a 1.5 cubic foot box and slightly over 4 inch ports. EV need some where around a 3 inch port.

Ive been looking for cabinet(s) for the E120's.

even though not ported.. hard truckers makes a nice semi open back cabinet they have told me works well with JBL's as they designed cabinets for grateful dead... and the dead used JBL speakers so the have a long experience with these speakers.

at the moment I run 4 x 12 jbl e120's in a sealed back and ported sound city cabinet and a 69 dual showman reverb

eugenedunn
September 6th, 2013, 10:58 AM
As some of the others have suggested, DO NOT seal up the back of your combo amp, because you will cut off air circulation to the amplifier electronics!!!
I was suggesting that you buy or create a separate head cabinet for your amp chassis, then put your 15-in speaker into a ported extension cabinet.

Not only do you gain the tight bass and mids you wanted, you'll also have two lighter units to carry to gigs, instead of one large "all-in-one" combo.

Years ago, I moved over to a couple amplifier heads, and use a variety of extension cabinets to mix or match, depending on situation.

eugenedunn
September 6th, 2013, 11:07 AM
Here's my examples: The Allen head with the silver grill is connected to a semi-open backed 4 ohm 2x10 cabinet.

The black amp head on the far right is connected to a WEBB sealed back, front-ported 8-ohm 1x15 cabinet.

I can mix or match for a lot of different tones & volume. There's also a groovy Leslie 18 cabinet in the middle for a measure of swirly goodness....that can be daisychained with either cabinet, if I use my Weber Z-matcher to ensure that amp and speaker load impedances are matched optimally.

It's a flexible and tuneful setup.

eugenedunn
September 6th, 2013, 11:16 AM
Here's a shot of the 2x10 cabinet... it's not completely sealed, and gets a huge amount of bass response I think. The 10-inch speakers are a couple of 50-watt reconed 1966 Jensen C10N's. There's a Weber beam blocker on only the top speaker.

This cabinet still retains some of the airy-ness of an openbacked cab....The ceramic 10-in drivers are punchy and smooth....no farting out.

I added parallel jacks so I can daisy chain with another cabinet....I also put a power strip inside to power my whole rig....very convenient, because you only need to find ONE outlet at your gig.

eugenedunn
September 6th, 2013, 11:25 AM
Here's a shot of what my buddy did with his silverface Fender Vibrosonic combo amp....he installed the chassis into a head cabinet......Awesome.

He paired that with a 1x15 cabinet that had several ports in the back of the cabinet (I've seen a few vintage cabs with those small ports in the back). He tried both a JBL D130F and a JBL D140......he preferred the D140.

Good thing....because the D140 has a much higher power handling capacity.

Tommasogezz
September 6th, 2013, 12:12 PM
Ok Eugenedunn, I understood!!
Before buying an extension cabinet I think I have to work on my 15 cabinet and try to get the best from it..
Anyway I have to repeat that the amp is not a combo anymore!! :)
I have an appointment on Monday with my tech(the one that already built the head and cabinet for my amp) and I'll speak with him about the different possibilities you suggested to me.
Thanks again!!