# MONITOR 1 AMP MODS (pics)



## drumcrusher (May 4, 2008)

hey there guys. for anyone interested, i thought i'd post some shots of some of the amps i've been working on. i've gotten into a bad habit of working on a half dozen at the same time. i think that i'm about finished with these two 
Monitor 1 mk 2.70's. i tried to keep them matching physically.


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## drumcrusher (May 4, 2008)

i think ive settled on a pair of burr brown opa0132 opamps soldered into a brown dog adapter. this adapter turns a pair of single opamps into a dual configuration that fits into a socket that i have mounted to the board. at present time i havent used any caps on it, but ill probably use a .001 silver mica to negate any oscilations that may be going on (unheard). im using mostly Muse caps in everything but power supply, where i am using FC Panasonics. there are also some silmics thrown in here and there too. as far as film caps, i probably overdid them, but i dont think it will hurt the sound. i used a combination of Wima polyprops, as well as ero mkt1837's, and obviously, the big orange drop caps that are mounted parallel to the 2200uf's in the power supply.


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## drumcrusher (May 4, 2008)

one amp is brand new, minus a small dent that it recieved because of poor packing during shipment, the other is in really good shape.
these things have a more bass heavy sound compared to the zapco's ive been working on too. remind me a lot of a couple of older fosgate amps that i have sound wise. the zapcos do vocals a lot better, but these will probably do really good on some midbass. they are still really smooth in the midrange, but not like the zapco studios. at least on my power supply, in my house, the burr browns do smooth things out a bit. not sure how that will translate into the car environment. they are definately more powerful than their ratings will lead you to believe.


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## underdog (Jul 5, 2011)

I like the way you think 
And your work looks good also.


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## Jagged Corn Flakes (Sep 10, 2013)

What was your main goal? These amps use Elna and Wima caps exclusively to begin with. They are outstanding sounding as is.


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## drumcrusher (May 4, 2008)

Like i said, compairing them to the zapcos for mids ( at least on the 2 sets i tried them out on) they were a little muddled sounding in the vocals. Theyre really warm, which i like. I was looking to get better vocals, and to satisfy curiosity as well. The wima and elna caps used are neither of the companies nicer lines as far as supposed sound quality. They are great sounding amps, just not exactly what i was looking for, for what i need them for. Im already good in the midbass department. Im sure with a tiny bit of eq i could have made the vocals sound just fine.


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## drumcrusher (May 4, 2008)

Thanks underdog.


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## knever3 (Mar 9, 2009)

Looks like a fun project, kudos to you. I don't have the knowlege to work on something so complex.


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## drumcrusher (May 4, 2008)

im definately not an electrical engineer. a lot was self taught, but i have a friend who is a guitar amp tech and he builds custom tube stuff. hes helped me out here and there. still need to get these amps to his house to use his osciliscope (to test for any oscilations caused by the opamps). i think they sound real good and punchy now. i think these amps must have a bass boost built into them at the factory. comparing them a/b with my other amps, they have a lot more punch in the midbass. kindof odd


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## Jagged Corn Flakes (Sep 10, 2013)

I have always felt the opposite. The Monitor 1 amps in stock form are very accurate, especially in the bottom end. They don't produce low end if it isn't there.


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## drumcrusher (May 4, 2008)

Hmmm thats curious. I had one of mine and a zapco studio 100 running dual mono. One running to its own fr89 mid, so i was able to listen to them both side by side, and balance them back and forth. They really sounded way different to me. Ill definately need to redo my tests. And maybe i need to put a stock opamp back in and see how it sounds. I do remember playing it before it was modded at all and noticing it being more punchy than my other amps. But regardless, "sound quality" is such a subjective thing...


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## drumcrusher (May 4, 2008)

And they look real cool to boot.


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## Jagged Corn Flakes (Sep 10, 2013)

drumcrusher said:


> Hmmm thats curious. I had one of mine and a zapco studio 100 running dual mono. One running to its own fr89 mid, so i was able to listen to them both side by side, and balance them back and forth. They really sounded way different to me. Ill definately need to redo my tests. And maybe i need to put a stock opamp back in and see how it sounds. I do remember playing it before it was modded at all and noticing it being more punchy than my other amps. But regardless, "sound quality" is such a subjective thing...


Meh. I was surprised when you compared their sound to older fosgate amps. They really don't sound anything like them. Now if you stated the Fosgate amps are internally EQ'ed and sound heavy and bloated on the bottom end; that would be an accurate statement. Monitor 1's; no way.


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## drumcrusher (May 4, 2008)

Just my opinion man. Like i said, to my ears they are bass heavy, and the vocals dont hold a candle to the zapcos. Thats why im going to use the zapcos instead. I cant chalk it up to one channel in my alpine being bass heavy and the other not. Maybe there is a reason that the monitor 1's are going for 70 bucks new now.


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## Jagged Corn Flakes (Sep 10, 2013)

drumcrusher said:


> Maybe there is a reason that the monitor 1's are going for 70 bucks new now.



There is a reason. They weren't on the market long enough to develop a following. Most people haven't even heard of them. 

I could also state that their current price tag is influencing your opinion of them. If they were selling at $300 a piece maybe you would have a different opinion of them.

Maybe you have a faulty/tweaked amp to begin with. All I know is they are accurate. Put one unmodded in your vehicle properly tuned and then come back and talk. Your less than ideal bench testing doesn't hold much water. Nonetheless, enjoy your Zapco. They sound nice.


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## drumcrusher (May 4, 2008)

Yea thats cool.


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## drumcrusher (May 4, 2008)

The chances of me getting two that sound exactly the same is pretty slim. All i buy is older, cheaper amps for the most part. Price doesn't matter to me one way or the other. But brands like esx or blade never were had a huge following back in the day, ( although blade definately put some money into advertising) and they command top dollar today. Especially if theyre brand new. Regardless, im sticking by my guns as far as the bass. I actually just compared it to my old fosgate transana, and it definately sounded more dynamic and less flat than the fosgate, it still had punchier midbass. Ha. I dont know when fosgate began putting in the bass boost but maybe it was after 1996 when this amp was made.


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## chithead (Mar 19, 2008)

Any updates?


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## legend94 (Mar 15, 2006)

chithead said:


> Any updates?


Don't let this make you second guess 

I disagree with everything the op has said on the sound of these.


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## drumcrusher (May 4, 2008)

hey man sorry about the delay. for some reason my iphone isnt getting any alerts from this email anymore. i sat these aside for a minute because ive been working on some Audio System Twister Amps for a guy from these forums. ill be posting some pics from that project soon. they are pretty sweet.
as far as monitor 1's, i dont think they sound bad. you can disagree with what you want obviously, but these two i have dont sound as good as the zapcos. one of the monitor 1's are brand new. maybe i got 2 bad copies?
i wanna do some more listening though. maybe those orange drops i bypassed to the PS affected the lower mids. i definately would like for them to sound awesome... no brand preferences here.


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