classicapi.com*VP2x Assembly Guide for 500 Series

[jsteiger]

Hey everyone,

As some of you may know, I offer a couple affordable 500 series, all discrete mic preamp kits over at my store, classicapi.com. I do offer them in fully assembled, tested versions also but the kits seem to be the most popular thing these days. I guess when you look at the “bang for buck” ratio, I don’t think they can be beat. They have been available now for almost a full year with an excellent proven track record.

The kits started off over at Prodigy and have been migrating this way to gs over the last few months. I could tell by some of the inquiries that customers were very much newb’s to DIY work. After noticing this progression, I started on a very detailed and complete, step-by-step Assembly Guide. This guide will take any and all guess work out of populating the PCB and the little quirks of physical assembly. I wanted to make sure that if a person has decent tools and can build a clean guitar cable, that this mic preamp kit would be a logical “first DIY project”.

I am also making this guide a free download for any and everyone. This way, if you are not sure about the kit, download the docs, read them over and get a feel for it before investing any hard earned money.

Click to download the VP2x Assembly Guide

VP2x Features:

• All discrete, vintage style circuitry with 60 db of overall gain
• Continuously variable control of Preamp Gain over a 34 db range
• Mute switch for quite & safe switching of microphones
• Polarity reversal
• 20 db Pad for input attenuation
• 48V switchable phantom power
• Fully variable, custom made output attenuator
• Custom made, Ed Anderson EA2622 1:7 input transformer
• Custom made, Ed Anderson EA2623-1 or EA2503 output transformer
• Standard 2520 DOA footprint mounts in Mill-Max sockets
• Standard 500 series compatible
• GroupDIY 51x compatible
• Multiple pre-built or kit form 2520's are available

More details can be found at the beginning of the Assembly Guide along with suggested and required tools and some important tips/pointers.

For some quick background, this preamp is directly based on the console preamp out of mid ‘70’s, vintage API™ console. It is not a 312 preamp. They sound distinctly different but still from the same great family of mid aggressiveness. I think they also prove that they don't have to be old to sound vintage!

My goal for this Assembly Guide was to have an interested but inexperienced person read it and come away with the "I can do it!" attitude. I hope I have done my job.

Link to pre-assembled VP26

Link to complete VP26 Kit

Link to complete VP25 Kit

Cheers, Jeff Steiger

[SWAN808]

Interesting - what are the cheapest cases?

edit - API Lunchbox is $375 at Mercenary - not bad for 6 slots - any 19" rack equivalent?

[bkbirge]

Anyone doing a DIY rack? 10-11 spacers from the usual suspects are on the pricey side.

[drBill]

Originally Posted by vin-gear

My goal for this Assembly Guide was to have an interested but inexperienced person read it and come away with the "I can do it!" attitude. I hope I have done my job.

Thanks Jeff. One thing - can you adress the differences (sonically and application-wise) between the 25 and 26. Why one might choose one over the other, etc..

At this point I'm still a bit unsure which I would prefer. At some point this year I hope to pick up several kits and break out the soldering iron!

Thanks for keeping these reasonably priced.

cheers,

bp

[hautacam]

awesome!

[ddageek]

Jeff Glad you took my idea to heart ! Looks great! Now if I could only get more manufactures to start taking my advice (and paying for it like in the old days)!

And Jeff and the Gang at Group DIY Have an 11 space DIY Rack coming I think most of the 1st run is spoken for but check out the thread at prodigy-pro!

[Coyoteous]

"GroupDIY 51X racks are due mid September!!"

[bkbirge]

Originally Posted by Coyoteous

"GroupDIY 51X racks are due mid September!!"

Cool, I went to the prodigy site and put my name in the bucket.

[jsteiger]

Originally Posted by SWAN808

...any 19" rack equivalent?

Not yet, but I have been considering it. I would want to allow for 4 channels in a 1u rack enclosure. I originally thought about a dual purpose card but wasn't thrilled with how it impacted the mounting bracket and so on for the 500 series. That being said, I would do a longer more narrow card for the 1u version and keep the PSU outboard. Daisy chain power connectors would be a simple must.

Cheers, Jeff

[jsteiger]

Originally Posted by Coyoteous

"GroupDIY 51X racks are due mid September!!"

Ha, the elbow to the ribs smarts a little but notice I did not put a year on it.

I hate to say it but it is par for the course. Sometimes the initial run always takes a little time. The actual metal is coming from my colleague in Glasgow so I will pass the jilted ribs onto him.

But, on a high note, we have not excepted one cent yet from anyone.

Cheers, Jeff

[matta]

Well done Jeff! It looks great, very throughout and the great picture will really come in handy for the first time builder!

Cheers

Matt

[foldback]

I've bought some kits and transformers from Jeff.

Very fast shipping, ordered on Monday received on Thursday. Everything exactly as it was supposed to be.

I hope he keeps the prices reasonable after he finds fame.

Good job Jeff, keep up the good work.

[mva801]

Originally Posted by drBill

Thanks Jeff. One thing - can you adress the differences (sonically and application-wise) between the 25 and 26. Why one might choose one over the other, etc..

This! I'm very curious...

[jsteiger]

Originally Posted by drBill

Thanks Jeff. One thing - can you adress the differences (sonically and application-wise) between the 25 and 26. Why one might choose one over the other, etc..

Hey Bill,

I will do my best to describe the sonic differences but please keep in mind...it is only my opinion. I will throw in a little VP2x vs 312 too and cover all bases.

I have chosen to replicate the vintage console preamp over a straight up 312 clone for a few reasons. Mostly, I really love they way the old consoles sound! They for sure have a more distinct "tonal" footprint to them. The 312 is a bit more open and almost cleaner sounding compared to a VP26. That may be hard to believe with all the "mid-forward", "mid-aggressive" adjectives used to describe the coveted 312 sound. "Clean" is usually not one of them. Well, the VP26 has just a little more of that "it" sound, if you will. Even though they are not as open, they for sure do not sound dark when comparing the top. Similar, just not quite as "open". The bottom end on the VP26 is a bit tighter...maybe more round than a 312. It is subtle though. They are the most different in the mids though I think. The VP26 is very tight and focused while being even more forward and aggressive sounding but only in the bestest of ways. They have a unique and special character there that is not present in other preamps that I have heard. The VP26 output transformer can be driven hard with a nice, pleasing, gentle saturation. That will happen with a 2623-1 before it will with a 2503. Again, it's my opinion but I think there are other ears out there that can verify some of these same findings.

Contrary to some of the popular talk, the discrete opamps make quite a noticeable difference in these preamps. My favorites are the gar2520 and a Liebers' SL2520 red dot. Scott's red dots have a great, amazing detail thingy happening in the upper mid area while the gar2520 is a little smoother and more "creamy" sounding. Both of course retain the great mid-forward sound you would expect.

OK that being said, if a VP26 is 9:00 and a 312 is 3:00, I would put the VP25 in the 11:00 area. It has many of the same tonal signatures as a VP26 but a little more open sounding.

Those were some sonics. What other advantages does a VP26 have over a VP25? Well, a lower price for one thing which is very important these days. The 2623-1 has 2 secondary windings while the 2503 has 3. How many of these secondary windings are used in any 312 style preamp? Always only 2. They are wired in series for 6db of transformer step-up gain. The 3rd winding is used for nothing. Kinda like paying for something that will never be used. The eq's do use all 3 windings in series, BTW. Why not save a little money? How's that for an "up-sale"?

Thanks for keeping these reasonably priced.

The price is very key Bill and I have no plans of changing it in the near future. I do not have the same types of overhead as some of the big boys. That is a plus to my customers. I suppose you could say it is still the age of the boutique manufacturer? I do want to make sure that everybody knows, there is not a cheap, "cut the corners" part in these things.

I hope this all helps in some way.

Cheers, Jeff

[elmolemon]

This is great!

There should be much more assembly guides for the masses of broke tech-noobs out there!

[SWAN808]

yeah if a cheap rack comes out this will be hard to resist...

[Coyoteous]

Originally Posted by vin-gear

Ha, the elbow to the ribs smarts a little but notice I did not put a year on it.

I hate to say it but it is par for the course. Sometimes the initial run always takes a little time. The actual metal is coming from my colleague in Glasgow so I will pass the jilted ribs onto him.

But, on a high note, we have not excepted one cent yet from anyone.

Cheers, Jeff

More like a finger poke than an elbow, and I thought the same thing about the year.

BTW, the assembly guide is great... worth the read as general kit/DIY tutorial, too.

[jsteiger]

Originally Posted by Coyoteous

More like a finger poke than an elbow, and I thought the same thing about the year.

BTW, the assembly guide is great... worth the read as general kit/DIY tutorial, too.

It felt more like sledgehammer! Just kidding. We are working out the US Customs clearing thing now. What a PIA all the way around. I guess the racks can still be considered vapor-ware huh?!!

[pan60]

sweet Jeff!

[kiopo]

Originally Posted by vin-gear

Not yet, but I have been considering it. I would want to allow for 4 channels in a 1u rack enclosure. I originally thought about a dual purpose card but wasn't thrilled with how it impacted the mounting bracket and so on for the 500 series. That being said, I would do a longer more narrow card for the 1u version and keep the PSU outboard. Daisy chain power connectors would be a simple must.

Cheers, Jeff

Worth it I think. I'd love to build the preamp, the instructions are excellent, but the lunchbox rack is just too expensive. Is it possible to convert this build to a standalone unit, or is that too complicated for a novice?

[gar381]

Just a quick look at Jeff's VP26 Kit...



With Jeff's new manual this kit is a snap and fun to build !!

GARY

[kiopo]

I think it is too complicated to convert.. lol

[jsteiger]

Originally Posted by kiopo

I think it is too complicated to convert.. lol

Weird, I haven't been receiving notifications the last few days so, sorry for a slow response. With the current size boards, I have had customers install 2 pre's in a standard 1U rack. They have used either the JLM PSU kit or the Five Fish Studios PSU kit from Owel. Both have great companies and are great guys to deal with. Th guys have been buying a stock 1U enclosure from Parmetal or one of the other standard companies. Front panels they have done thru Front Panel Express.

So, it is doable now with only 2 preamps. I would not say it is a good first project though. There is a lot to handle on your own plus building the PSU portion of it.

4 preamps in a 1U is most desirable. It is in the back of my mind. The PCB only would be simple to do. The enclosure and front panel would also not be hard but expensive to initiate.

The best deal going is still the 500 series I think. With an 11 space rack, the cost per module is averaged down very nicely.

So, long answer short, I may do the PCB for a 4 pre in a 1U sometime soon but probably not a full kit with enclosure and front panel.

Cheers!
Jeff

[indie]

4 channel eh? will it have the output control on each channel????thumbsup

[drBill]

Originally Posted by vin-gear

Hey Bill,

I will do my best to describe the sonic differences but please keep in mind...it is only my opinion. I will throw in a little VP2x vs 312 too and cover all bases.

I have chosen to replicate the vintage console preamp over a straight up 312 clone for a few reasons. Mostly, I really love they way the old consoles sound! They for sure have a more distinct "tonal" footprint to them. The 312 is a bit more open and almost cleaner sounding compared to a VP26. That may be hard to believe with all the "mid-forward", "mid-aggressive" adjectives used to describe the coveted 312 sound. "Clean" is usually not one of them. Well, the VP26 has just a little more of that "it" sound, if you will. Even though they are not as open, they for sure do not sound dark when comparing the top. Similar, just not quite as "open". The bottom end on the VP26 is a bit tighter...maybe more round than a 312. It is subtle though. They are the most different in the mids though I think. The VP26 is very tight and focused while being even more forward and aggressive sounding but only in the bestest of ways. They have a unique and special character there that is not present in other preamps that I have heard. The VP26 output transformer can be driven hard with a nice, pleasing, gentle saturation. That will happen with a 2623-1 before it will with a 2503. Again, it's my opinion but I think there are other ears out there that can verify some of these same findings.

Contrary to some of the popular talk, the discrete opamps make quite a noticeable difference in these preamps. My favorites are the gar2520 and a Liebers' SL2520 red dot. Scott's red dots have a great, amazing detail thingy happening in the upper mid area while the gar2520 is a little smoother and more "creamy" sounding. Both of course retain the great mid-forward sound you would expect.

OK that being said, if a VP26 is 9:00 and a 312 is 3:00, I would put the VP25 in the 11:00 area. It has many of the same tonal signatures as a VP25 but a little more open sounding.

Those were some sonics. What other advantages does a VP26 have over a VP25? Well, a lower price for one thing which is very important these days. The 2623-1 has 2 secondary windings while the 2503 has 3. How many of these secondary windings are used in any 312 style preamp? Always only 2. They are wired in series for 6db of transformer step-up gain. The 3rd winding is used for nothing. Kinda like paying for something that will never be used. The eq's do use all 3 windings in series, BTW. Why not save a little money? How's that for an "up-sale"?


The price is very key Bill and I have no plans of changing it in the near future. I do not have the same types of overhead as some of the big boys. That is a plus to my customers. I suppose you could say it is still the age of the boutique manufacturer? I do want to make sure that everybody knows, there is not a cheap, "cut the corners" part in these things.

I hope this all helps in some way.

Cheers, Jeff

Jeff, just saw this. Thanks for the explanation. That was very helpful. Looking forward to getting my soldering station dirty......

Cheers,

bp

[ResonantMind]

If you wanted to do something innovative... you could create a sort of vintage-modern-hybrid pre with both op-amps inside and allow people to switch between the two.... Would this be possible...?

[elmolemon]

Originally Posted by ResonantMind

If you wanted to do something innovative... you could create a sort of vintage-modern-hybrid pre with both op-amps inside and allow people to switch between the two.... Would this be possible...?

+1

[thenoiseflower]

you can swap out the opamps in seconds, and I don't think there is a switch known to man that could so that without tons of other supporting circuts...

I have two of the VP26's (swapping beetween GAR, Melcor, and Huntington, and even the modern 2520) and they are getting heavily favored over the 312's we have, which have the regular modern API opamps (PIA to swap out, obv).

These pre's just sounds better than a 312, in every single way.

[thenoiseflower]

Originally Posted by vin-gear

The 312 is a bit more open and almost cleaner sounding compared to a VP26. That may be hard to believe with all the "mid-forward", "mid-aggressive" adjectives used to describe the coveted 312 sound. "Clean" is usually not one of them. Well, the VP26 has just a little more of that "it" sound, if you will. Even though they are not as open, they for sure do not sound dark when comparing the top. Similar, just not quite as "open". The bottom end on the VP26 is a bit tighter...maybe more round than a 312. It is subtle though. They are the most different in the mids though I think. The VP26 is very tight and focused while being even more forward and aggressive sounding but only in the bestest of ways. They have a unique and special character there that is not present in other preamps that I have heard. The VP26 output transformer can be driven hard with a nice, pleasing, gentle saturation. That will happen with a 2623-1 before it will with a 2503. Again, it's my opinion but I think there are other ears out there that can verify some of these same findings.

Contrary to some of the popular talk, the discrete opamps make quite a noticeable difference in these preamps. My favorites are the gar2520 and a Liebers' SL2520 red dot. Scott's red dots have a great, amazing detail thingy happening in the upper mid area while the gar2520 is a little smoother and more "creamy" sounding. Both of course retain the great mid-forward sound you would expect.


Cheers, Jeff

thumbsup
agreed 100%

[pjleavitt]

Built my pre last week, too about an hour and a half and sounds amazing. By far the best deal on any 500 series pre!