Mesa/Boogie Stiletto Traditional 4x12" cabinet modified with X-pattern speakers combination

Since I have a Diezel Herbert, I have been searching a great 4x12" cabinet to match with my Herbert.
None of my cabinets can handle the massive bass response from Diezel Herbert very well.

I know Diezel amp is better suit with Diezel cabinets and I believe a Diezel front-loaded 4x12" cabinet will match perfectly with my Herbert. Anyway, that's not easy to get a Diezel 4x12" cabinet here.
Besides I have another four 4x12" cabinets in my house, so I'm going to modify one of those cabinets
that I already have to match Diezel Herbert.

Therefore, I decided to take two Celestion G12K-100 speakers out from Orange PPC412 HP8 and swapped them with two Vintage30 speakers in my Mesa/Boogie Stiletto cabinet.

I chose Stiletto cabinet to be modified because its size is closer with Diezel cabinet.
Diezel cabinet dimension : H745 x W745 x D365mm
Mesa Stiletto cabinet dimension : H768 x W758 x D362mm

Left side is the Orange PPC412HP8 cabinet with Celestion G12K-100 (China made) speakers.
Right side is the Mesa/Boogie Stiletto cabinet with Celestion Vintage30 (UK/British made) speakers.


Four Celestion G12K-100 speakers in a cabinet sound too bassy and total 400w is too much headroom for me,
I feel more like plugged into a bass cabinet instead of guitar cabinet. G12K-100 speaker sounds mid-scooped,
just like a G12T-75 but with extended bass response and sparkling not harsh high frequency.
If you like G12T-75, I bet you'll like G12K-100 speakers too.

G12K-100 frequency response chart :
from http://professional.celestion.com/guitar/


G12T-75 frequency response chart :
from http://professional.celestion.com/guitar/


Vintage30 frequency response chart :
from http://professional.celestion.com/guitar/




I've blended Vintage30 speakers in my Stiletto cabinet with G12K-100 speakers. They are in the X-pattern,
just like what I have been done in my Marshall 1960B cabinet with G12T-75/Vintage30 speakers.


I like the result of this modification. Blended Vintage30 with G12K-100 speakers in Mesa/Boogie cabinet
really solve my problem. My Herbert sounds much tigher, no more flabby bass response. G12K-100 speakers can handle the massive bass response very well.
Anyway, I still want a Diezel front-loaded 4x12" cabinet with G12K-100/V30 speakers to match with my Herbert !
Too bad that my other ENGL and Mark V amps DON'T like the G12K-100/V30 speakers combination.


=Stay tuned. Video clip will be uploaded soon=

First Part - Marshall 1960B 4x12" cabinet modified with X-pattern speakers combination

Among all the extension cabinets of famous amplifications, Marshall 1960 Lead cabinet is the standard of this industry.
This cabinet is equipped four Celestion classic G12T-75 speakers (16 ohm, 75w).

My modification followed Bogner famous Uberschall 4x12" cabinet (a.k.a "Uberkab").
Bogner Uberschall 4x12" cabinet is loaded with each pair of Celestion G12-T75 speakers (8 ohm, 75w)
and Vintage 30 speakers (8 ohm, 60w) in diagonal way (X-pattern combination).
The purpose is to combine the different tones of these classic speakers into one cabinet.

G12T-75 speakers have more bass and piercing treble, mid-scooped sound.
Vintage 30 speakers have more midrange, smooth highs and lows are balanced.
Also, the Vintage 30 is much easier to breakup which gives it a more raw distorted sound.
Somebody like G12T-75 speakers very much, somebody hate them and love Vintage 30 speakers instead.

Vintage 30 frequency response chart :
http://professional.celestion.com/guitar/products/classic/index.asp


G12T-75 frequency response chart :
http://professional.celestion.com/guitar/products/classic/index.asp



Marshall 1960 Lead cabinet is a "stereo mode" cabinet,
but Bogner Uberschall cabinet has only mono input jack.

Tools :
Long Philips screwdriver or automatic screwdriver.
You need to unscrew total 17 long screws for removing the back panel of the cabinet,
so the automatic screwdriver will definitely help you a lot.


Pull out the jack plate, remember to label accordingly of that four speaker cables - two reds and two blacks.
Each pair of speaker cables (one red, positive and one black, negative) is connected with one pair of speakers
(2x12" speakers) from each left of right side in the cabinet.

Be careful ! Don't get confused with them because you need to connect them back again.


Remove the speaker cable connectors.


After the jack plate is removed, put your hand in and pull out the back panel of the cabinet.


You can see the stock Celestion G12T-75 speakers.


Marshall wires the four speakers in "series-parallel wiring" (16 ohm) or "parallel-parallel wiring" (4 ohm).
=Stereo and Mono Mode=
In "Stereo mode", each left or right side of the 16 ohm speakers are wired vertically in "parallel" wiring,
total impedance is 8 ohm for each side.

In "Mono mode", PCB circuit of the jack plate connects each left and right side of "parallel-wiring" speakers into either "series-wiring" (Total: 16 ohm) or "paralle-wiring" (Total: 4 ohm) again.

Marshall factory wiring diagram like below :

Second Part - Marshall 1960B 4x12" cabinet modified with X-pattern speakers combination

Disconnect all the cables which are connected between four G12T-75 speakers.


Remove two speakers of them. Bear in mind to keep these screws and washers carefuly. You need to use them later.


Finally became like this.


Stock Celestion G12T-75 and Vintage 30 speakers.
Which one is the Vintage 30 ? Ans : Left one.


Here is the picture of Bogner Uberschall 4x12" cabinet(from Bogner Amp Forum)


Even though this modification which is using the same speakers combination from Bogner Uberschall cabinet,
but you won't get the exactly Bogner cabinet tone from Marshall cabinet.
It is because the cabinet structure, size and material are also the major parts which affect cabinet sound character.

Two types of "X-pattern" wiring -
Series-Parallel "X pattern" wiring diagram


Parallel-Series "X pattern" wiring diagram


I followed the Series-Parallel "X pattern" wiring diagram.
Attention !
Reconnect all the speaker cables. Red speaker cable connects to "+" terminal of the speaker and
Black speaker cable connects to "-" terminal of the speaker.


Put back the back panel of the cabinet.
Reconnect the speaker cables onto the jack plate.


Congratulation ! Mission completed !
Marshall 1960 Lead cabinet - X pattern speakers combination modification

=Mono Mode=
Left input jack (Total impedance : 4 ohm) became "Parallel-Parallel X-pattern wiring"
Right input jack (Tota impedance : 16 ohm) became "Series-Parallel X-pattern wiring"

=Stereo Mode=
Left side input jack (Total impedance : 8 ohm) became TWO Vintage 30 speakers wired together in "Diagonal" position.
Right side input jack (Total impedance : 8 ohm) became TWO stock G12T-75 speakers wired together in "Diagonal" position.


You will need to break-in the new speakers.
Suggestion from Celestion website : http://professional.celestion.com/gu...l/faq.asp?ID=3
Or using "Variac" to break-in. http://www.unclespot.com/speakerbreakin.html

Last Part - Marshall 1960B 4x12" cabinet modified with X-pattern speakers combination

Here is the video clip of my Marshall 1960B with X-pattern speakers combination.


From the video clip above, you can hear the tone differences between stereo and mono mode
under different kind of speakers combination.

On 1:07 and 1:31 from the video clip, there are only either each pair of G12T-75 speakers or
Vintage 30 speakers connected. You can compare these two classic speakers easily.

The sensitivity of Vintage 30 is 100dB, but G12T-75 speaker is 97dB.
When you connected these two kind of speakers together,
you can hear the Vintage 30 more than G12T-75.

What you need to take note are these :
1) Speakers total impedance.
2) Speakers total pwer handling.
3) Positives and Negatives of the speakers.

No matter you have either 2x12" or 4x12" speakers cabinet,
you can use any kind of different speakers combination.

Besides this Bogner Uberschall cabinet type of diagonal X-pattern speakers combination,
you can also follow the design of Mesa/Boogie Roadking 4x12" cabinet(parallel and vertical combination).
- Black Shadow C90 and Vintage 30 speakers (picture from Harmony Central Forum)


I want to emphasize that using same kind of speakers combination will NOT let you to get
the exactly tone of either Bogner or Mesa/Boogie cabinets.
Your Marshall 1960B cabinet definitely will NOT become Bogner Uberschall cabinet.

This modification is just to let you know more about that final sound of different kind of speakers
in the same cabinet that you have. Please be remember different cabinet design in different size,
structure and material will also affect the tone.

=Final=
This modification brings my Marshall 1960B cabinet to life.
My Marshall 1960B cabinet became much tighter and smoother highs by using Vintage 30 speakers in.