I made my own preamp...

[kiira]

cool!

I made my own tube pre.

http://www.2tough.com/~kiira/rec/preamp.html

 

[musical5]

Bob,

That clip sounds great. Good work. Sounds like that preamp is working for ya.

 

[Bob's Mods]

kiira,

Your project looks interesting. It takes some courage to dig into those kinds of circuits with limited training. I'm a little less keen on decent low cost tube mic pres because they are a very different animal. Its tough to make a good one that works right and keep the cost reasonable. My view is that decent software can simulate the effects of tubes. The simulation may not be anal dead on but it should be close enough to fool most of the people most of the time.

Bob

 

[turnitdown]

In reply to turnitdown, I'm guessing the unit would sell in the 200 to 300 range. It's hard to know for sure. This unit is not a toy, it is for someone who has a serious level of interest in the recording arts but on the lower end of the cost curve.

Fair enough.... Pending the sample audio clips, I see a new "RNP on the market!!

 

[Bob's Mods]

I'm hoping to hear what the newsgroupies think of the posted demo. Let me have it! Beat me up --- but be gentle.

 

[crazydoc]

I've sent my demo to NL5 so he'll point you to it.

This was just a quick put together short one track at a time demo. It was recorded and mastered by me using Voxengo plugins, a Behringer DEQ2496 that was modified by me and a CAD M177 that was also modded by me.

Bob

What parts were recorded through the preamp?

 

[kiira]

kiira,

Your project looks interesting. It takes some courage to dig into those kinds of circuits with limited training. I'm a little less keen on decent low cost tube mic pres because they are a very different animal. Its tough to make a good one that works right and keep the cost reasonable. My view is that decent software can simulate the effects of tubes. The simulation may not be anal dead on but it should be close enough to fool most of the people most of the time.

Bob

yeah I mostly do stuff to learn. I think it works pretty well because now I have some good pres to compare it to, my Langevin DVC. Tubes actually seem easier to design and build to me, there's tons of data and circuits around already. i've only built solid state things from kits, I don't know how to do simple designing like I can do with tubes. I've also built an LA-2a clone and put the Royer tube mod in an MXL 1006 and built an entire guitar amp from scratch. I do things to learn and have fun.

 

[NL5]

Kiira,

Do you have any pointers on where to learn how to build your own stuff - especially tube preamps?

Thanks,

NL5

 

[turnitdown]

Anyone here ever modded the PIAIA stuff??? (the preamps??)

 

[Bob's Mods]

The vocal, acoustic guitar, electric rythum and electric lead were recorded using the preamp. The bass was recorded direct. The drums an were an audio loop.

 

[kiira]

Kiira,

Do you have any pointers on where to learn how to build your own stuff - especially tube preamps?

Thanks,

NL5

Hiya,

well there are a some links on the page I wrote. I would download all of the Jensen schematics. There are schmatics for tube stages and aux circuits in there. Another link has info on power supplies and such and then there have been several articles on tube pres in tapeops and audioxpress. you could choose one and build it. What I did was look at several designs and then step through the circuits using info from a book called the ultimate tone and another book called tube amp design (?), I think. It was by a hifi guy named bruce rozenblit. Anyway I wanted to understand the theory and design my own thing. The schematic is on my web page and it just needs a phantom ps and a main ps to give 300/350 volts. I used 6072s on the input circuit for their very low noise and 5751s on the output but 12ax7s could be tried. I'd like to try designing another that uses octal tubes like 6sn7 and 6sl7 or maybe 12sn7 to save money (same tube but cheaper). I have a pile of those around. Oh and people would help me with advice too, Scott Dorsey and Dan Kennedy and EveAnna Manley and folks like that.

another thing...I learned things in stages. first I refurbed my guitar amps and learned how to bias them and then I rebuilt some old hifi amps, an Eico hf87 and an Eico hf81. Then I learned how to make things from schematics like my little 5 watt guitar amp. That's still hard I have to stare at the schematic and use a pencil to try and figure out the circuit. I use the "sliding line trick" ... you can slide connections along a line to rearrange things, etc.

i like tubes because the parts are big and you can sorta see what is going on. It's fun and can give you some good sound stuff. I had a guy a REAL AUDIOPHILE listen to my stereo with my old rebuilt 40 watt Eico hf87 and his jaw dropped he couldn't believe how they rocked. He was using like these huge audiophile amps, krell or something that cost thousands and thousands.

HTH,

Kiira

 

[crazydoc]

Kiira,

Do you have any pointers on where to learn how to build your own stuff - especially tube preamps?

Thanks,

NL5

The Lab

 

[NL5]

Thanks Kiira and C.D.,

Looks like I have a lot of reading to do....

 

[kiira]

The Lab

cool cool... I didn't know about this place.

Oh yeah that reminds me the DIY forum on recording.org is also another good place to learn and ask questions... lots of really cool projects going on there!

 

[crazydoc]

cool cool... I didn't know about this place.

Oh yeah that reminds me the DIY forum on recording.org is also another good place to learn and ask questions... lots of really cool projects going on there!

This was the diy forum on recording.org until a couple of month ago. There was a big shitfest between the owner and Tech Talk regulars, and it rose anew at this site. Much of the archived material was lost, but much of it saved also.

 

[kiira]

This was the diy forum on recording.org until a couple of month ago. There was a big shitfest between the owner and Tech Talk regulars, and it rose anew at this site. Much of the archived material was lost, but much of it saved also.

wow so it's not there anymore? WTF could cause that on like a tech talk forum? oops never mind. ha ha I used to read it and look at the all the great project links but never posted there.

tra!

Kiira

 

[Afficianado]

Bob Wrote:
>>The vocal, acoustic guitar, electric rythum and electric lead were recorded
>>using the preamp. The bass was recorded direct. The drums an were an audio
>>loop.

What mic/mics were you using? I'm not an electrical engineer, so correct me if I'm wrong, but this pre you built is for dynamic mics only, yes? Have you thought about providing phantom power to facilitate condensors?

-Afficianado

 

[Bob's Mods]

Yes, it has a built in phantom power supply. It can be used for both types of mics.

 

[crazydoc]

Bob Wrote:
>>The vocal, acoustic guitar, electric rythum and electric lead were recorded
>>using the preamp. The bass was recorded direct. The drums an were an audio
>>loop.

What mic/mics were you using? I'm not an electrical engineer, so correct me if I'm wrong, but this pre you built is for dynamic mics only, yes? Have you thought about providing phantom power to facilitate condensors?

-Afficianado

The schematic does show phantom power capability. He said he used a CAD M177 (modded) - I wonder if he used this on all the mic'ed tracks?


BTW, Bob, from my limited viewpoint the electric guits sound really nice. The accoustic is pretty much buried, and the voice has lots of reverb so hard to make a judgment there.

What mods did you do to the 177? I have the cheapie version, the M37, which I wouldn't mind tearing into.

 

[Bob's Mods]

I think I added too much widener which caused the mixing to go out of balance when listened to on some different playback systems. It doesn't sound bad on my own system. I'll be reducing the reverb and widener next go round. I hope the MP3 didn't confuse alot of people thinkin, "Like hey, what's this guy talking about?"

In the M177 they use a TL072 op amp which is a middle of the road general purpose type. This is the best one I have found to date in any of the gear I've pulled apart. Everyone else is using the New Japan Radio (JRC) junk. It is an 8 pin dip which is easy to replace with a Burr-Brown audio specific OPA2134PA which is sold by Digi-key and others. If you get the brochure for the mic, it actually includes the schematic! Very rare to see this. There are two .047 coupling caps that I replaced with foil type capacitors which are some of the best. They used tantalum caps in this location which are total crap. They are the worst audio performers in the world. I also ripped out the inner screen which was a major pain as it is molded into the screen case. After these changes I compared it to a Shure KSM27 and it sounded slightly better than the Shure. Modding can be a dangerous past time and can turn your gear into junk fast if you are heavy handed and or careless. You certainly can void the warranty. I've been in the electronics biz for 30 years so I kind of have a leg up.