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Author Topic: DIY external preamp mod: Community project!  (Read 16773 times)

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Offline mmmatt

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DIY external preamp mod: Community project!
« on: September 01, 2006, 11:13:21 AM »
Hey all,
I've been dying to try a preamp mod for a long time.  I don't have full understanding of these things but I have been reading up on it some.  It doesn't seem like rocket science, but I certainly want community input.  I would like to go step by step with the community, talk things out as they come up, maybe try a few different things, and do testing and comps.  I will do my best to keep a good flow of pics going so every step is discussed and archived.  I'm a little surprised that this hasn't been done here before! 
     At this point I just want to say that the people who are doing this for others,.  Busman, Church, or any one else who is using their knowlege of these things to make a buck should not feel in anyway obligated to post here.  I will not be offended if you don't say boo, but your input is certainly welcome.  I know there is a lot of knowlege here and most likely a lot of people here like myself who would love the challange and the economy of doing their own mods, but just haven't ever known where to start. As diverse as this group of people here is it would not surprise me if the input of the masses can provide additional ideas to the pro's here and I'm completely down with that.  If somehow this project can allow you guys to produce a different or better product, then just send me my roylaty check  ;D Well... OK, just use it and remain a part of this communty, because you guys often provide the reality checks for the rest of us!  the information discussed here is to be free for the taking for anyone.  If it helps anyone make a buck... go for it!  That all being said...

My first step is going to be to deceide which unit I want to purchase for the mod.  For my purposes, I am not looking for something portable although I want something in a small-ish box.  I'm specifically looking for something that will match size-wise to my Motu Ultralight.  I have this dream of a little 1/2 rack rig with killer pre's and about 32 chan of analog input... starting point will be a single pre and a single Ultralight.   I will be using this in conjunction with my motu for multitrack applications and not in situations where I have to worry about power.  110 power will always be available to me when I need this unit.   Something that has minimum of 4 pre's in a maximum 1/2 rack footprint.  Other considerations are going to be cost and availablility.  I want to do this on the cheap and I want to be able to repeat the build so a new/current product will be my preference.
    The one unit I have found that has peaked my interest is the smpro audio pr4v http://www.smproaudio.com/PR4v.htm  .  These can be had for about $80 new.  The form factor is about right and the cost is inline with about what I'm willing to throw away if this ends up being a bust.  Any other suggestions would be great.

Step 1:  Picking the unit to mod,
from the stand point of modding a unit, I understand that a bit of space on the inside of the case is a good thing.  I have also read that a higher internal voltage level is a bennefit for many op amps.  What other things should I consider before I purchase? I'm sure that in a low end unit, everything is going to be low end such as gain pots and power supplies etc.  I may want to play with thoes things also but I really want to keep it cheap while making a less than above average pre sound above average.  I plan on buying new from a retailer that allow's returns so that if I open the thing up and find it is a mess, or otherwise unsuited, I can simply box it back up and return for refund.

Discuss!

Matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

Offline poorlyconditioned

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Re: DIY external preamp mod: Community project!
« Reply #1 on: September 01, 2006, 11:51:40 AM »
Hey all,
I've been dying to try a preamp mod for a long time.  I don't have full understanding of these things but I have been reading up on it some.  It doesn't seem like rocket science, but I certainly want community input.  I would like to go step by step with the community, talk things out as they come up, maybe try a few different things, and do testing and comps.  I will do my best to keep a good flow of pics going so every step is discussed and archived.  I'm a little surprised that this hasn't been done here before! 
     At this point I just want to say that the people who are doing this for others,.  Busman, Church, or any one else who is using their knowlege of these things to make a buck should not feel in anyway obligated to post here.  I will not be offended if you don't say boo, but your input is certainly welcome.  I know there is a lot of knowlege here and most likely a lot of people here like myself who would love the challange and the economy of doing their own mods, but just haven't ever known where to start. As diverse as this group of people here is it would not surprise me if the input of the masses can provide additional ideas to the pro's here and I'm completely down with that.  If somehow this project can allow you guys to produce a different or better product, then just send me my roylaty check  ;D Well... OK, just use it and remain a part of this communty, because you guys often provide the reality checks for the rest of us!  the information discussed here is to be free for the taking for anyone.  If it helps anyone make a buck... go for it!  That all being said...

My first step is going to be to deceide which unit I want to purchase for the mod.  For my purposes, I am not looking for something portable although I want something in a small-ish box.  I'm specifically looking for something that will match size-wise to my Motu Ultralight.  I have this dream of a little 1/2 rack rig with killer pre's and about 32 chan of analog input... starting point will be a single pre and a single Ultralight.   I will be using this in conjunction with my motu for multitrack applications and not in situations where I have to worry about power.  110 power will always be available to me when I need this unit.   Something that has minimum of 4 pre's in a maximum 1/2 rack footprint.  Other considerations are going to be cost and availablility.  I want to do this on the cheap and I want to be able to repeat the build so a new/current product will be my preference.
    The one unit I have found that has peaked my interest is the smpro audio pr4v http://www.smproaudio.com/PR4v.htm  .  These can be had for about $80 new.  The form factor is about right and the cost is inline with about what I'm willing to throw away if this ends up being a bust.  Any other suggestions would be great.

Step 1:  Picking the unit to mod,
from the stand point of modding a unit, I understand that a bit of space on the inside of the case is a good thing.  I have also read that a higher internal voltage level is a bennefit for many op amps.  What other things should I consider before I purchase? I'm sure that in a low end unit, everything is going to be low end such as gain pots and power supplies etc.  I may want to play with thoes things also but I really want to keep it cheap while making a less than above average pre sound above average.  I plan on buying new from a retailer that allow's returns so that if I open the thing up and find it is a mess, or otherwise unsuited, I can simply box it back up and return for refund.

Discuss!

Matt

Hey, if you do buy that thing, pleae post some pictures of the innards.  I'm guessing it is something like the Rolls line, 4580 opamps or the like.  But it would be fun to see, and certainly fun to mod.  You can't go wrong for $80...

  Richard

PS: As far as sellers (Church, Busman, etc) posting, I think that would be great.   Retailers probably realise this already, but sharing of information will help everyone in the end.  It will help retailers to develop new products/markets, and it will help DIY types to get better.  That is (mostly) working on this forum!
Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
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Offline mmmatt

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Re: DIY external preamp mod: Community project!
« Reply #2 on: September 01, 2006, 12:01:15 PM »
Great guys.  so far the usual suspects jumping on this thread  ;D.  The opamps are njm4558d's and from what I understand they are absolute ass.  From my reading I'm thinking I want to go with AD825's.  Ithink that is the opamp that is in the v2/3 and for most of us that is the holy grail of pre's!
     As for pictures, Yes... I will post every step and I will ask the most basic questions as to the how to's and why's, and post everything I learn and every step I make.  I really want to make this into a "anyone can do it" kind of project.  I have a friend in town who is an electronics engineer who knows nothing about audio but who can help me with soldiering/desoldiering techniques and things like that.  He's kind of excited about this also.

Matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

Offline baustin

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Re: DIY external preamp mod: Community project!
« Reply #3 on: September 01, 2006, 12:30:01 PM »
    The one unit I have found that has peaked my interest is the smpro audio pr4v http://www.smproaudio.com/PR4v.htm  .  These can be had for about $80 new.  The form factor is about right and the cost is inline with about what I'm willing to throw away if this ends up being a bust.  Any other suggestions would be great.


Hey!

I'd definitely be interested in a 4 channel unit like the one above to go with my 744t. I'd consider buying a few so modders could toy around with them.

I'll stay tuned!

-ba

Offline mmmatt

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Re: DIY external preamp mod: Community project!
« Reply #4 on: September 01, 2006, 12:41:02 PM »
you know, if we have a few people playing with these at the same time it would make things go even more quickly.  we could all do it together!!!

Matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

Offline poorlyconditioned

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Re: DIY external preamp mod: Community project!
« Reply #5 on: September 01, 2006, 12:51:44 PM »
you know, if we have a few people playing with these at the same time it would make things go even more quickly.  we could all do it together!!!

Matt

Probably not.  Just buy the damn thing, then you've got some motivation (financial and personal investment) to move forward!

That is what I'm doing with my projects (AKG CK9x actives and now CK6x actives).

Less talk and more hacking!

Good luck whatever you do...
  Richard
Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
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Offline mmmatt

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Re: DIY external preamp mod: Community project!
« Reply #6 on: September 01, 2006, 01:34:42 PM »
you know, if we have a few people playing with these at the same time it would make things go even more quickly.  we could all do it together!!!

Matt

Probably not.  Just buy the damn thing, then you've got some motivation (financial and personal investment) to move forward!

That is what I'm doing with my projects (AKG CK9x actives and now CK6x actives).

Less talk and more hacking!

Good luck whatever you do...
  Richard

I wasn't planning on waiting around!!!!  Already ordered it!  I'll have it next week.
$80 shipped, 30-day return policy

http://www.samedaymusic.com/productreview--STOPR4

Matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

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Re: DIY external preamp mod: Community project!
« Reply #7 on: September 01, 2006, 01:56:58 PM »
Excellen +++++++++++++++++T

you know, if we have a few people playing with these at the same time it would make things go even more quickly.  we could all do it together!!!

Matt

Probably not.  Just buy the damn thing, then you've got some motivation (financial and personal investment) to move forward!

That is what I'm doing with my projects (AKG CK9x actives and now CK6x actives).

Less talk and more hacking!

Good luck whatever you do...
  Richard

I wasn't planning on waiting around!!!!  Already ordered it!  I'll have it next week.
$80 shipped, 30-day return policy

http://www.samedaymusic.com/productreview--STOPR4

Matt
Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
** This individual has moved to user "illconditioned" **

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Re: DIY external preamp mod: Community project!
« Reply #8 on: September 01, 2006, 10:00:14 PM »
Emminently moddable, I'd bet.

BlackLionAudio has a mod for their 8 channel pre:
http://www.blacklionaudio.com/sm_pro_8_mki_mod.html
@rowj | Host of The Brokedown Podcast
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Offline mmmatt

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Re: DIY external preamp mod: Community project!
« Reply #9 on: September 02, 2006, 01:06:16 PM »
Step 1:  Picking the unit to mod

Based on initial posts, it seems that the smpro audio pr4v is a good candidate for modding.  Of course we don't know till I get it and open it up, but it seems like something that is usable for many tapers who dable in 4 track and or thoes who just want an external 110 powered pre.  I will be expecting mine late next week!  I purchased mine here http://www.samedaymusic.com/productreview--STOPR4 for $80 shipped.


Step2:  Initial testing and testing tools

Ok, so other than a visual inspection of the physical size limitations and visual  identification of componants.  What other testing should be done prior to ordering parts?  What tools do I need to do this?  Is a multimeter going to get me through this project or do I need other testing equiptment?

Matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

Offline Church-Audio

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Re: DIY external preamp mod: Community project!
« Reply #10 on: September 02, 2006, 02:17:29 PM »
Let me know if you need any advice for your mod project. I would be glad to help you out.

Chris Church


Step 1:  Picking the unit to mod

Based on initial posts, it seems that the smpro audio pr4v is a good candidate for modding.  Of course we don't know till I get it and open it up, but it seems like something that is usable for many tapers who dable in 4 track and or thoes who just want an external 110 powered pre.  I will be expecting mine late next week!  I purchased mine here http://www.samedaymusic.com/productreview--STOPR4 for $80 shipped.


Step2:  Initial testing and testing tools

Ok, so other than a visual inspection of the physical size limitations and visual  identification of componants.  What other testing should be done prior to ordering parts?  What tools do I need to do this?  Is a multimeter going to get me through this project or do I need other testing equiptment?

Matt
for warranty returns email me at
EMAIL Sales@church-audio.com

Offline mmmatt

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Re: DIY external preamp mod: Community project!
« Reply #11 on: September 02, 2006, 02:25:28 PM »
Let me know if you need any advice for your mod project. I would be glad to help you out.

Chris Church


Step 1:  Picking the unit to mod

Based on initial posts, it seems that the smpro audio pr4v is a good candidate for modding.  Of course we don't know till I get it and open it up, but it seems like something that is usable for many tapers who dable in 4 track and or thoes who just want an external 110 powered pre.  I will be expecting mine late next week!  I purchased mine here http://www.samedaymusic.com/productreview--STOPR4 for $80 shipped.


Step2:  Initial testing and testing tools

Ok, so other than a visual inspection of the physical size limitations and visual  identification of componants.  What other testing should be done prior to ordering parts?  What tools do I need to do this?  Is a multimeter going to get me through this project or do I need other testing equiptment?

Matt
I was bustin' your chops in that other Thread Chris.  Although, if you can tell me what tools I will need for this type of thing that will be nice (step 2) I would like to get whatever I need so I can start working on it as soon as I get it.  I'm very excited about this!  My words about pro's helping on this at the top of the thread are true.  I don't want thoes using their skills to make money to jeprodise their income by putting their tricks out for all to see.  As Richard stated though, that probably isn't going to be the case, but it is each's own decesion to make.

Matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

Offline Church-Audio

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Re: DIY external preamp mod: Community project!
« Reply #12 on: September 02, 2006, 03:00:33 PM »
Tools for moding preamps
In no particular order
1 DREMEL TOOL

2 WELLER SOLDERING STATION WS51

3 GOOD SOLDER WICK AND GOOD SOLDER SUCKER MADE BY SOLDAPULLT get a metal one if you can find it

4 Good solder very important I use silver solder but you don't have to have it. Regular will do in a pinch

5 Demineralized water for soldering station to clean tip with never use tap water.

6 Good set of hand tools good set of electronics cutters like Xcelite 170m needle noise pliers and good jewelers screwdriver set.

7 Good multi-meter with capacitance and db if possible (remember caps are something you will change with moding a preamp) so you have to have accurate capacitance measurements and voltage.

8 Good work lights I have 3 50w halogen work lights so I can see what’s what.

9 A plan, never do a mod with out a good plan. How are you going to fit the parts in and what the end result will be?

10 Patients every time I screw something up its because I was in a hurry to get it done doing mods and working on electronics especially when you did not design the circuit involves patents always take your time, Make sure caps are in the right way IC'S are in the right way and transistors are not backwards :)


I was working for this music shop as a summer job when I was 16 as an electronics tech, this customer brought in this compressor because one light in the vu stayed on he was a bass player and needed it for a gig that night. I found that it was the display driver IC chip for the vu that was shot so I got a new one at my local electronics shop and put it in BACKWARDS! Now his compressor is toast and I have allot more to fix then just a broken led driver. I learned my lesion I actually got fired because of it. So take your time :)

Last but not least a good way of checking your mods, and is what I do is use a computer program like WINAUDIOMLS to measure the preamp before and after using MLS or some form of spectral analysis to see the difference. BUT the most important tool is your ears at the end of the day. If you do not like the sound of your mod be able to put it back.

As far as testing goes send me a picture of the inside of the preamp I can give you a few ideas a schematic would also be good.


Good luck let me know if I can help you in any way I have access to all types of parts if I don’t have it I know where to get it.


Let me know if you need any advice for your mod project. I would be glad to help you out.

Chris Church


Step 1:  Picking the unit to mod

Based on initial posts, it seems that the smpro audio pr4v is a good candidate for modding.  Of course we don't know till I get it and open it up, but it seems like something that is usable for many tapers who dable in 4 track and or thoes who just want an external 110 powered pre.  I will be expecting mine late next week!  I purchased mine here http://www.samedaymusic.com/productreview--STOPR4 for $80 shipped.


Step2:  Initial testing and testing tools

Ok, so other than a visual inspection of the physical size limitations and visual  identification of componants.  What other testing should be done prior to ordering parts?  What tools do I need to do this?  Is a multimeter going to get me through this project or do I need other testing equiptment?

Matt
I was bustin' your chops in that other Thread Chris.  Although, if you can tell me what tools I will need for this type of thing that will be nice (step 2) I would like to get whatever I need so I can start working on it as soon as I get it.  I'm very excited about this!  My words about pro's helping on this at the top of the thread are true.  I don't want thoes using their skills to make money to jeprodise their income by putting their tricks out for all to see.  As Richard stated though, that probably isn't going to be the case, but it is each's own decesion to make.

Matt
for warranty returns email me at
EMAIL Sales@church-audio.com

Offline mmmatt

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Re: DIY external preamp mod: Community project!
« Reply #13 on: September 02, 2006, 03:21:30 PM »
Thanks Chris,
that is all VERY helpful information!!!

matt
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

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Re: DIY external preamp mod: Community project!
« Reply #14 on: September 03, 2006, 01:33:49 PM »
good news on the mod front is I found a thread where a bunch of people who actually know what they are doing modded out the 8 chan version of this pre.  Seems like, if the basic pre design is the same,  they have already done a lot of the legwork for us!!!

http://www.prodigy-pro.com/forum/viewtopic.php?t=344&postdays=0&postorder=asc&highlight=pr8&start=0&sid=e19afe0246d51954c877e62f523fb090
I do think taping is the reality of the business..it is also an impetus for artists to create studio CDs that are ART, not just another recording...    Fareed Haque  2-4-2005




Canon 24-70 f2.8L, Canon 135 f2L, Canon 70-200 f4L, Canon 50 f1.8, > Canon 5D or Canon xt (digi) and Canon 1N (film)

 

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