DIY, Mods, Preamps & Mics

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Bob's Mods

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I've noticed that there is a lot of interest in modifying your own gear to improve it's performance. Is it worth the time and effort and risk to modify gear? Yes.
The subject of mods is a way huge one however. I could write the book on it. I've been modding my gear for at least year now as I have largely been dissatisfied with it's performance. Let's face facts, most, but not all us here are in the "audiophile" catagory. We are in that limbo above the Creative Labs users but below the high end studio level where the best gear can cost in the range of just below one grand and goes up from there. What we all really want is to sound like a decent high end studio on modest budget!
Software has come along way since the mid and late 90's when it was "crash city". Software these days seems to be relatively stable and there is such a huge selection available. The problem with getting a respectable studio sound from your DAW rig in no longer held back by software, in conjunction with hardware, as it once was, these days it's a strictly a hardware issue. And, although there a large selection of hardware out there at lower prices than in the past, it is the quality of this hardware that will determine (in addition to your own knowledge and experience of the recording arts and sciences) whether your final mix can compete with tracks and mixes done with more professional hardware. It is important to understand that no software, no matter how good, can make tracks recorded with lower grade gear, sound as good a those recorded with higher end gear. Let's assume a very experienced and knowledgable recording engineer here recording the same tracks using both an audiophile DAW rig - and - using a dedicated higher end studio rig, what ever that might be. The higher end gear will produce better sounding tracks.
As a home audio recordist we want the best sounding tracks on a modest budget. If you are like me, you have discovered that recording great sounding tracks with audiophile gear is a challenge. Lower cost mics and preamps just don't deliver the sonic results high end gear delivers. And there is nothing in software that you can do to magically make these "OK" sounding tracks and mixes sound like the high end stuff of your favorite commercial artist. I've ripped my hair out trying. It really wasn't until I actually started studying my gear by going in and reverse engineering it (studying it's guts)and making modifications to it. I need to make you all aware that I've studied electronics and have worked in this field for some thirty years so I know what I am doing. Plus I have a huge selection of parts and rework tools available to me in my work area at my job.
Once I began opening my gear and studying it's construction I soon realized just how much junk there is out there. A great many of these products can't deliver an even exceptable level of performance by virtue of the lousy components they are constructed with. I think some of these companies spend more on the multicolored product box than on the components that go inside the piece of gear you just bought. And they all do the same thing. That is why you'll buy a number of different mics for instance for $150 (give or take) and they are all only "OK". Each is just a different flavor of "OK". I'm guessing here, but somewhere around the $500 range (give or take) better parts and quality control begin to become a factor. There are some standout products in the under $500 range but most are just "OK". Many products are designed to look sexy with eye catching designs and mushy knobs and what not but it's the guts that count and because you, the consumer, doesn't understand a TL072 from a ceramic cap, they get away with it. What I'm implying here is that low cost doesn't have to mean cheap guts. But this is a marketing thing. They put the money into boxes and frames and knobs when they could the money into the guts and make less fancy visable stuff. You and I are just a "market" and "price point". They call it a "preamp" or "microphone" but using the components they use to construct these things, these devices really can't perform as well as they should be able to. They are not trying very hard at giving us, the consumer, a better product in the area where we must trust them to do the right thing. Instead they make gear that catches our attention but just doesn't perform as well as it could. And they all do this. They all use low end components. It's important to understand this because the better parts cost more and drive the cost up - some. The key word here is - some. There is a noticable improvement in performance using better parts - and better parts are not outrageous cost wise.
What about those low cost tube preamps for instance? These products in no way resemble a true tube preamp. What is the sense in buying one when a better simulation of a tube preamp can be emulated in software these days? A properly designed tube preamp is expensive. These lower cost knockoffs utilize a "tickle" plate voltage of only +48v dc. The minimum plate voltage should be at least +175 volts. These crippled products sell because we the consumer buy them, not because they offer true tube performance. Why do we buy them? Because we want that tube factor in our tracks and a real tube pre is out of reach. Anyway I have diverged a bit.
The main point I wish to make is that although we in the audiophile camp are only spending in the range of a few hundred dollars give or take on each piece of our gear, we don't have to settle for the so - so performance it resides at out of the box. There are modifications that can be made to some, but not all gear that can improve it's performance for a reasonable price.
For instance I upgraded my Oktave Mk-319. It's certainly better than what it was. It's no Neumann for sure but it's performance has been improved to the point where I can now live with it.
I will be hovering over this thread for a number of days. I will answer questions regarding modifications to your gear and hopefully everyone will learn something by it. Please be patient if I don't answer right away as I am not glued to my computer terminal!
I would like to make a final point, your modified gear will not necessarily be as good are better than the best audio gear a millionaire's budget could buy, but it will provide for a nice noticable boost to your quality! To the uninitiated, your mixes could stand side by side in the rotation of your commercial heros. Maybe not the best of the best but no slouch either!

Happy trackin'
Bob
 
You will find an eager audience here for musings on gear mods.
 
Preamp mod question.

Bob,

I currently own an Avalon M5 and a UA M610. These 2 preamps cover most of my needs.

I recently bought a Behringer Tube 1953 pre on Ebay very inexpensively. This was purchased just to experiment with.

I've switched out the AX7's (generic) with NOS Mullard AU7's. The sound is improved although I did lose the expected output gain.

What other, if any, things I could try with this unit?

Thanks,

Earl
 
Bob

Thanks for the interesting post. There is certainly a wealth of information and misinformation extant on the www these days regarding equipment mods, and it's hard for non EE's like myself to wade through it and separate the food from the turds.

One area of interest that seems to have a lot of mystique associated is the replacement of passive components. I for one would appreciate your take on this, particularly regarding capacitors (and resistors and inductors of course.)

Here are a few links that delve into the subject for starters:
http://www.capacitors.com/picking_capacitors/pickcap.htm
http://www.aikenamps.com/ResistorNoise.htm
http://www.geofex.com/Article_Folders/carbon_comp/carboncomp.htm

I am currently on a road trip through the USA's Pacific Northwest, and only have sporadic access to a computer, so don't take my absence from participation in this thread as disinterest.

BTW, it's hard for old farts like myself to read long posts on a monitor (keep losing my place) without a line break every so often - if your posts are lengthy (and I hope they are) please break them up a little. Thanks.:)
 
Another interesting link for those who are interested in building your own effects.

www.diystompboxes.com

Aron's got some great stuff, and the folks over on his forum have helped me on several projects.
 
This is in response to pdlstl's question. I'm trying to figure out how to work out this newsgroup format so bare with me. It seems you've already got some high end gear in your arsenal.

As far as the Behringer is concerned the easiest thing to do with it is record the output directly into your audio workstation and then "normalize" the track. This way you would not have to make any changes to the Behringer. This is also a proving ground as well as increasing the gain to compensate for the gain loss would raise the noise floor. If the noise on the normalized track is exceptable, then increasing the gain on the Behringer shouldn't be too problematic. If the noise IS objectionable than that will be more of a problem to reduce it as the noise would need to be reduced in the tube circuit by a hardware mod. This would be a trial and error process of looking at feedback gain and/or bias voltage change and/or cathode resister change (and the high voltage power supply) to make the 12AX7 tube config more compatible with the Mullard tube requirements. This can be can of worms kind of project. My personal bias is away from lower cost tube gear as the designs are on the bare margin just to make them work to stay within price point targets.

In this case, if noise is not a problem and you want a hardware fix, the gain of the output opamps can be increased to compensate for the loss. Behringer, as most mass produced gear is these days relies on surface mount components. Surface mount makes for more of a pain in the butt mod experience. The feedback resisters on the final output stage would need to be located, their value determined and a new value calculated and installed.

You could also use the noise reduction feature of Cool Edit Pro to drop the noise down in quite sections as well.

As long as noise is not a problem and the parts are locatetable, this shouldn't be to much of pain to figure out and make happen.

Bob
 
crazydoc, THE single most important component change in a semiconductor based (non tube) design is upgrading capacitors in the signal path. This will yield the biggest improvement in performance than any other change you could make.

As far as resistors are concerned, I leave them alone. If the design used carbon comp thru hole types I leave them rather than swap them for metal film types. It's too much work for something you probably won't hear anyway. If the device is surface mount based then you get what you get. Most manufacturer's don't release schematics and layout diagrams anyway so these kinds of mods have to be reversed engineered. Depending how anal you are and how complex the design is, this could be one big pain in the arse or impossible altogether.

I just do not fuss with resistor type. There may be a small difference in sonic performance that is audible using high end gear but I tend to think using the audiophile level gear most home recordist use, investing the time, trouble and risk in resistor swapping would most likely not result in any meaningful change in performance. After all, we are talking noise floor here. How much would it go down? One or two dB maybe? It's not worth the trouble. Even noise added to the primary signal should not be that meaningful. Worst case would be if you used carbon comp resistors in a hot room. Non tube gear just shouldn't get hot enough where increased noise from heat would be a factor. If heat is a factor, just cooling it down should drop the noise.

Now what is said about capacitors is true. If you find your tracks are dark sounding and you need more EQ than what you think you should, capacitor's can cause that problem. ALL audiophile gear manufacturer's these days use electrolytic capacitors to couple internal stages together and as external device intraconnect gateways. Electrolytics are the worst offender of audio signal integrety than most any single other component. For those not inclined to perform electronic surgery by changing these offenders, minimize the signal chain by going directly to the input of your A/D as much as practical. If your mixer has a channel output then use it. If you track one or two tracks at a time this is best. If you record multiple tracks through a mixer into a two channel soundcard, that's more of a problem. I was simply amazed at how many electrolytic caps are in a Mackie board. And this is one of the better ones.

As far as inductor go, this is a "don't care". Inductors are mostly located in better power supplies anyway. They may be found in some preamps in the signal path to block rf noise. Their effect on sonic performance should be negligible.

You may wish go to this link -----

http://www.prosoundweb.com/recording/tapeop/hardy/hardy_15_1.shtml

----and read this interview with John Hardy, one of the top high end preamp guys out there. He clearly details the problem with capacitors.

enjoy,
Bob
 
Bob's Mods said:
This is in response to pdlstl's question.

As far as the Behringer is concerned the easiest thing to do with it is record the output directly into your audio workstation and then "normalize" the track. This way you would not have to make any changes to the Behringer.

Bob

Thanks for the information! I obviously need to try the process you described above then make a determination as to the next step. I've got a sneaking suspicion that the noise floor is going to end up being an issue.

As I stated, this was simply purchased, I guess, as a way for me to experiment. I have almost as much in the Mulllards as I do in the pre! :eek: So, if it ends up being a non-do-able deal, I'll yank the tubes and sell the Behringer.

Once again, thanks.

Earl
 
...

I'd like to see some cheap mods of say... a cheap radioshack mic. Are any worthwhile? I have expensive mics ranging from $100 to $500 dollars, but I also have cheap radioshack mics for demos or practices. Is there really anything you can do there to make it as good as say... a shure sm57?
 
I know this Question is not directed at me, but here goes:
In regards to grn's question about cheap mics, no, a radioshack mic probably cannot be made to sound like an SM57.

An SM57 sounds the way it does mainly because of 2 things: the Capsule, and the transformer. that's really all there is to a dynamic mic. To mod or change out these parts you will have to spend as much or more than the price of a 57, you might as well just buy a 57 from the beginning.
 
Mic mod

I did the royer tube mod to a useless, harsh MXL 2001 (that I was using, literally, as a paperwieght) and the mod made it into something VERY useful and interesting.

Ray
 
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