ADA Depot - A Forum To Support Users of ADA Amplification Gear

ADA Preamps => Original MP-1 => Topic started by: gb on August 13, 2019, 11:30:08 PM

Title: MDRT vs Standard PS
Post by: gb on August 13, 2019, 11:30:08 PM

Ok so i have an MP1 with standard 220v transformer and another with MDRT.

Remind me will i hear a noticeable difference in sound between the 2 because they sound the same so im wondering what im doing wrong as i got the impression the MDRT makes a substancial difference but im not hearing it.

What should i be checking. I recall MJMP mentioned a while ago that a resistor needs to be changed or something like that? Can someone remind me what that is
So i can double check. Sorry its been a while since ive played with this.

Edit.. i found the manual to install. Looks like i did change the resistor.. but whats the go with this cap..looks likr its about to explode
(https://i.imgur.com/2lEspYF.jpg)

Title: Re: MDRT vs Standard PS
Post by: gb on August 14, 2019, 02:52:06 AM

Ok so looks like these caps are replaced in the noise mod kit anyway.. i didnt get the big noise mod kit so ill have to buy them. Can the aussie guys tell me if the jaycar variety of caps will be sufficient or is there a mouser brand or type that is superior?

My plan is to do the noise mod on this mp1 with mdrt to start with.

Title: Re: MDRT vs Standard PS
Post by: MarshallJMP on August 14, 2019, 02:26:27 PM

Replace that cap ASAP before you blow up the high voltage winding. That cap can be replaced by a 22µF/400V cap, (or 450V) lead spacing is 7.5mm. Panasonic are good caps.

Title: Re: MDRT vs Standard PS
Post by: gb on August 14, 2019, 02:36:47 PM

Will do!! Thanks!
I also just realised there is a big cap on main board thst3needs to be replaced for mdrt..different value to standard..so maybe thats why im not hearing a difference. So i figured if i did the noise mod it covers everything. 

Im good with soldering but not familiar with high voltages..if i left the mp1 unplugged over night will it be safe to work on next day or how do i discharge the voltages 

Title: Re: MDRT vs Standard PS
Post by: rnolan on August 15, 2019, 02:20:25 AM

Hey gb, discharge should be ok after a few minutes (say 10  :dunno: ) but MJMP will know better than me.  I think you need to leave it plugged in but turned off so it can discharge to earth, it has to go somewhere.You should hear a noticeable change with the MDRT.  From memory, when MikeB did his, the sound was much more dynamic and open but it looses some of the creaminess of the original.  But the difference, while subtle, was very apparent.Given the age of MP-1s, the noise mod is very sensible.

Title: Re: MDRT vs Standard PS
Post by: MarshallJMP on August 15, 2019, 10:06:51 AM

The caps will bleed out after a few minutes, but ALWAYS check with a multimeter.

Title: Re: MDRT vs Standard PS
Post by: gb on August 15, 2019, 01:35:29 PM

Thanks guys.. so check on both cap leads.. is that where you check for voltage? AC?