Acoustat Monitor 4 with Interfaces?

john65b · 02:20 AM

Hey all,

I have a friend with Monitor 4 that has given up on his servo amps (not willing to sell them tho) and wants to know if his Monitor 4's can be run with a MK-121-2 interface. From his pics, it looks like he has banana plugs (blue, red, yellow).

Looks like (from schematic) red is bias, blue is front stator, and yellow is back stator.

He wants to keep his wiring intact for the servoamps (if he ever gets them fixed)...so the interface inputs will need a mod. Just thinking of three banana receptacles marked blue, red, and white on a wooden cover over the opening on the interfaces...

Any issues? I figured I would ask the experts...

tyu · 15th January 2013, 10:20 AM

...Be sure the yello tap is used ....less he like more bass... then Orange taps on the 121s bass Xfourmer...Good luck

john65b · 15th January 2013, 05:08 PM

tyu,

Yes, I have that planned - as far as I know, the Acoustat panels in teh Model 1/2/3/4 and Monitor series are interchangeable from servos to interfaces (aside from the yellow/white connection) correct?

tyu · 15th January 2013, 05:41 PM

Frist pr of Acoustats i had in the 80s were the Xs..... i got a pr of 1+1 ....called Jim he was in fortladerdail fl still then... he said yes...the 6-8s used two ea. 121 interfaces pr speaker...

I run my 121 on the Yello tap....i use the full winding...an put a 3ohm 30watt in were the 1ohm 20watt is on the bass Xfourmers neg input....
have fun ...long live Acoustats...An all other ESLs

AcoustatAnswerMan · 15th January 2013, 05:54 PM

Quote:

Originally Posted by john65b

Hey all,

I have a friend with Monitor 4 that has given up on his servo amps (not willing to sell them tho) and wants to know if his Monitor 4's can be run with a MK-121-2 interface. From his pics, it looks like he has banana plugs (blue, red, yellow).

Looks like (from schematic) red is bias, blue is front stator, and yellow is back stator.

He wants to keep his wiring intact for the servoamps (if he ever gets them fixed)...so the interface inputs will need a mod. Just thinking of three banana receptacles marked blue, red, and white on a wooden cover over the opening on the interfaces...

Any issues? I figured I would ask the experts...

Yes, the Monitor 4's can be driven by the MK-121 transformer interface. The later Model 4 was sold that way. As previously mentioned, you should use the YELLOW transformer tap for a 4-panel system.

Please note the blue wire goes to the rear stator. However, if you follow the color code on the MK-121, hook-up should be a no-brainer: RED to RED, BLUE to BLUE, and YELLOW to WHITE. You can easily remove the banana plug on the speaker, and substutute hook or ring terminals for the white and blue groups, and a pin plug for the red group.

ehous · 16th January 2013, 01:50 AM

Tyu, what results were achieved by substituting the 1ohm for the 3 ohm? Thanks

tyu · 16th January 2013, 10:53 AM

There other Mods that i have done also......diff caps on the secdary side... .15 6k oil ...an no 50k res..... set up like the soundLab back plate...an my bias is outboarded...an can be set from 4-7k.... an other mods on the primary side...
This bias mod is the best thing any one can do to the 121..if anyone wonts a BIg upgread!...bias bias bias..has a Lot to do with the sound of any eSL...an is allways over looket..Nuts from a sound standpoint!
But useing all the winding an the 3ohm gives better bass...an more output...
I drive my M3 with a 60 watt tube amp...get full output..[.in my setup!]
Lot life left in thes old Acoustats....have fun

15th January 2013, 02:16 AM	#1
john65b diyAudio Member Join Date: Jan 2005 Location: Chicago	Acoustat Monitor 4 with Interfaces? Hey all, I have a friend with Monitor 4 that has given up on his servo amps (not willing to sell them tho) and wants to know if his Monitor 4's can be run with a MK-121-2 interface. From his pics, it looks like he has banana plugs (blue, red, yellow). Looks like (from schematic) red is bias, blue is front stator, and yellow is back stator. He wants to keep his wiring intact for the servoamps (if he ever gets them fixed)...so the interface inputs will need a mod. Just thinking of three banana receptacles marked blue, red, and white on a wooden cover over the opening on the interfaces... Any issues? I figured I would ask the experts... __________________ All right, but apart from the sanitation, medicine, education, wine, public order, irrigation, roads, the fresh water system and public health, what have the Romans ever done for us? Life of Brian Last edited by john65b; 15th January 2013 at 02:20 AM.

15th January 2013, 05:08 PM	#3
john65b diyAudio Member Join Date: Jan 2005 Location: Chicago	tyu, Yes, I have that planned - as far as I know, the Acoustat panels in teh Model 1/2/3/4 and Monitor series are interchangeable from servos to interfaces (aside from the yellow/white connection) correct? __________________ All right, but apart from the sanitation, medicine, education, wine, public order, irrigation, roads, the fresh water system and public health, what have the Romans ever done for us? Life of Brian

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15th January 2013, 05:41 PM	#4
tyu diyAudio Member Join Date: Jul 2009	Frist pr of Acoustats i had in the 80s were the Xs..... i got a pr of 1+1 ....called Jim he was in fortladerdail fl still then... he said yes...the 6-8s used two ea. 121 interfaces pr speaker... I run my 121 on the Yello tap....i use the full winding...an put a 3ohm 30watt in were the 1ohm 20watt is on the bass Xfourmers neg input.... have fun ...long live Acoustats...An all other ESLs

16th January 2013, 01:50 AM	#6
ehous diyAudio Member Join Date: Jul 2006	Tyu, what results were achieved by substituting the 1ohm for the 3 ohm? Thanks

16th January 2013, 10:53 AM	#7
tyu diyAudio Member Join Date: Jul 2009	There other Mods that i have done also......diff caps on the secdary side... .15 6k oil ...an no 50k res..... set up like the soundLab back plate...an my bias is outboarded...an can be set from 4-7k.... an other mods on the primary side... This bias mod is the best thing any one can do to the 121..if anyone wonts a BIg upgread!...bias bias bias..has a Lot to do with the sound of any eSL...an is allways over looket..Nuts from a sound standpoint! But useing all the winding an the 3ohm gives better bass...an more output... I drive my M3 with a 60 watt tube amp...get full output..[.in my setup!] Lot life left in thes old Acoustats....have fun