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  • Restoration of vintage studio/recording gear

    I work on a variety of vintage audio gear, and I've developed different approaches for different types of gear. For HiFi reproduction, for example, I'll often go further with modern parts replacement than I might in a guitar amp.

    I've been getting more requests over the last year to work on vintage studio/recording gear, and I'm trying to figure out what my approach should be. Some of this stuff was built with parts that were high-quality at the time, parts that are still technically "good."

    For example, I'm looking at a 1965 Collins 26U-1 Limiter that came in blowing fuses. I've done the basic repairs, and it's working fine. It has Sprague 160P paper/Mylar caps in it in the signal path that aren't leaking, and they run conservatively for their voltage rating. If it were mine, my impulse would be to replace them with polypropylene film for better transparency.

    To what degree do people using this gear want the sound of vintage parts (as, say, you wouldn't necessarily remove some blue caps from a vintage Fender amp), or do they tend to be happier with the sound of a vintage circuit with modern parts that I'd call more neutral and transparent?

    In a way, I hate to ask this question because it brings up all the various disagreements about parts replacement philosophies. What I'm more interested in is hearing from people who've worked with the end users of this kind of equipment and who know what makes them happy -- or unhappy. For example, if it would upset the owner, I don't want to replace functional Spragues even if I think they probably mask detail and color the signal.

  • #2
    Originally posted by Rhodesplyr View Post
    For example, if it would upset the owner, I don't want to replace functional Spragues even if I think they probably mask detail and color the signal.
    I think that you have answered the question yourself right there. You need to discuss with and advise the owner the pros and cons of keeping and/or changing the parts.

    Obviously you need to change the parts that keep the unit from functioning, but you need to find out from the owner what his feelings are regarding the rest of the parts.

    I really don't do much audiophile stuff, because I don't really enjoy it. But I've seen owners that are very particular about the sound, about the originality and about the cost. No different that Vintage guitar amp collectors, really.

    Some will want all of the old caps pulled and replaced with their favorite brand/type of cap before they even hear the amp with the original parts. Others want originality at all costs including replacement parts. Others want to spend as little money as possible, "Just make it work."

    Comment


    • #3
      I used to fix basic stereo receiver stuff, but it was more a courtesy than an interest. When someone complains ther is a little too much graininess in the upper midrange, what the fuck an I supposed to do with that?


      The thing to do is ask the customer what he wants and expects. Ask him how it sounded before it failed, and if it was slowly degrading, did it sound good in its better years. You may feel some caps improve transparency, but if the guy was happy before, why change things on him. restore it to the point HE wants.

      Bill brings up a good point, ask if the customer sees this as a collectible piece of history or is it a tool he wants to use all the time. A guy trying to get good mixes and recorded tracks is maybe less concerned over the historic content than he is the sound output.

      Just like an old Fender, there are some brands of film caps that are still just fine after 40 years or more, and there are some that just sucked.
      Education is what you're left with after you have forgotten what you have learned.

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      • #4
        There are probably a couple basic "vintage" gear users. One is the guy that bought it to get that vintage sound. They are probably going to demand looking for original type parts.
        The other guy is the one that bought it new and doesn't realize it's vintage yet. He's like me with cars, "whaddya mean it's old, that's our new one!"
        This guy would probably have no issue with using modern replacement parts.
        Just so long as no one tells him that this was some valuable piece and the mojo has now left the building.
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


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        • #5
          Thanks, Bill & Enzo.

          The people I'm dealing with are actively using this equipment for recording, so it's part of their signature. They have collections of vintage mics, but they use them in their work.

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          • #6
            Originally posted by g1 View Post
            There are probably a couple basic "vintage" gear users.
            One of the problems I'm running into is that some of these users themselves aren't sure what they want.

            At some level, they've heard that some of these vintage mic preamps, etc... are "the thing to have," so they buy them, but they don't know whether that "golden tone" they're looking for comes from vintage parts or a rebuilt circuit.

            But like guitar amps guys, they do worry about ruining the vintage mojo.

            Comment


            • #7
              Originally posted by Rhodesplyr View Post
              One of the problems I'm running into is that some of these users themselves aren't sure what they want.

              At some level, they've heard that some of these vintage mic preamps, etc... are "the thing to have," so they buy them, but they don't know whether that "golden tone" they're looking for comes from vintage parts or a rebuilt circuit.

              But like guitar amps guys, they do worry about ruining the vintage mojo.
              Having done some repairs on "legacy" gear, I generally do what I'd do with an old amp. Working interstage or audio filter - equalization - caps, leave 'em be. Failing ones, I generally use Mallory 150 polyester/mylar film. Resistors, they're generally carbon comp. Noisy or burnt? Replace with new carbon comps. Much of the rest is inductors in EQ gear, never seen one fail, same for output or interstage transformers.

              For one Pultec EQ the studio owner did the usual stupid stupid thing, sling in a bigger fuse when all it needed was a $5 rectifier tube. By the time he called me the power transformer was smoking and all he could do is whinge about how it made is studio smell awful. Found the nearest-fit Hammond PT and it's good as new.

              First time I had a peek inside an LA-2A, horrors it was loaded with carbon comp and disc caps in all circuits. All of which contribute to its sought-after sound: leave alone! Don't monkey with the monkey.
              This isn't the future I signed up for.

              Comment


              • #8
                Originally posted by Rhodesplyr View Post
                One of the problems I'm running into is that some of these users themselves aren't sure what they want.

                At some level, they've heard that some of these vintage mic preamps, etc... are "the thing to have," so they buy them, but they don't know whether that "golden tone" they're looking for comes from vintage parts or a rebuilt circuit.

                But like guitar amps guys, they do worry about ruining the vintage mojo.
                Funny thing is that most do not realize that when the famous song whose magic they are trying to copy, said equipment was NEW, properly manintained if not, and that high ESR or leaky caps, worn tubes , poor grounding due to corrosion after 50/60 years , etc. which are coloring the sound TODAY were not present wqy back then.

                WAY more important anyway is that those recordings became Classics is because the SONG and the PERFORMANCE were killer.
                And they are not matching that, no Sir !!
                Recording skill and ideas?
                Yes, that too.
                ^^^^^^^ nothing of this can be bought, of course, at any price.

                Recording equipment? ...... a very far behind third place (if that much) in the race.
                Juan Manuel Fahey

                Comment


                • #9
                  Originally posted by J M Fahey View Post
                  WAY more important anyway is that those recordings became Classics is because the SONG and the PERFORMANCE were killer.
                  And they are not matching that, no Sir !!
                  Recording skill and ideas?
                  Yes, that too.
                  I thought I was reading on of Stan's posts for a second

                  Originally posted by Rhodesplyr View Post
                  One of the problems I'm running into is that some of these users themselves aren't sure what they want.
                  Tell the customer that you do technical work, and that you need a detailed technical specification to meet in order to ensure the quality of the equipment is maintained to their satisfaction. If they can't offer more than vague desires, maybe waving one of Enzo's business cards over the equipment will make it sound better But seriously, you need to agree with the customer on what maintenance means for these units.
                  If it still won't get loud enough, it's probably broken. - Steve Conner
                  If the thing works, stop fixing it. - Enzo
                  We need more chaos in music, in art... I'm here to make it. - Justin Thomas
                  MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

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                  • #10
                    I try to do as little as possible in terms of component changes and only replace something if it is faulty or likely to give problems. There are some things that I will do to make the equipment more useable in a modern context, but only in agreement with the customer. A recent 60s Ampex preamp I did got phantom power, XLRs wired to modern spec, meter disable so the preamp could be overdriven without damage, captive mains cable (instead of octal), ground lift/death cap fixed. This was in addition to some component replacement, power supply work and general clean-up.

                    This all makes this a practical every-day preamp.

                    Customers comment was

                    "Hi Mick, so..... The Pre amp sounds amazing!!!!! We tried it on vocals, which to be honest I didn't think would work that well but it sounds awesome and we normally use a £3000 tube tech, so it was up against it! It seemed to transfer to protools really well although I haven't tried it with my setup yet. I'm sure it will be fine.

                    As it stands, it's a winner."

                    Comment


                    • #11
                      As a repair or restoration tech, don't get involved with "sound signatures". You will be forever praised or bashed based solely on inarticulate imaginary traits the user wishes to hear. Tell him if there is a particular sound you can reproduce it if he specifies what electronic elements of the transfer function of the unit determines the character he wants. Anything else and you are working in cross purposes and with no common language to communicate with.
                      You can return a unit to original spec in terms of published performance and if very very familiar with the operation and sound of a unit(most "units" have much less sound signature than most users assume, so are willing to invest large sums on magic units when the real sound they are chasing came from a total system approach).
                      Compare long experience plus published specs for distortion, phase, CMRR, responsive, sensitivity etc, to the unit in from of you. The most ethical approach is to bring to the same specs as published.
                      But it STILL not going to sound like the old records. Studios were system, not a collection of gear. There was a design standard for all the wiring, matching etc since there was so little else to work with. I know on hobbyists forums like this anyone who claims, like Juan or I am accused of, that it was the song, performance, production skills and experience in the context of the time that made the great songs great and VERY little to do with equipment. When trying to recreate a vintage "sound", a lot is working against the user. One item that is almost always ignored is that the old systems were power systems, meaning terminated balanced matching source and load Z. System signal level was often high, (+8 or +12) and terminated 600 ohm lines, no mults, no mixing voltage networks with power networks. If a mult was needed a bridging transformer was used to get two 600 ohm or 150 ohm balanced lines out. Dynamic Mics are still optimized for power networks but are used on voltage networks so newcomers think their mics are not as good as the "better" mics. Plugging in a dynamic mic into a transformerless balanced line input of mid or hi z like all modern effects and consoles puts the mic at a disadvantage. Not the mic's fault but few new recordists understand why they want to ditch the SM57 and replace it with a $1000 condenser. For most things the '57 would have been better if terminated as it was designed for.
                      So stay out of the sound realm, unless you have the chops in the studio and design then entire system to create the sounds contracted for. Any mods will be entirely at your risk alone. The customer says "I want more upper mid clarity and better imaging" and whatever you do, you are likely not to be able to satisfy such a nonsense request. The only way such mods work is if you approach it as in fashion or art, charge outrageous sums so the buyer assumes you are the arbiter of magical traits in the end result and will learn that your way was the best possible. Guitar amp and hi-fi gurus work that way by creating mythology that transcends technology and sound so convince buyers that they are more hip and cultured to even have their equipment in their rack.
                      Mixing and matching generations of technology never gives predictable results. The craze of using old vintage broadcast or studio gear from the 50s in home studios hit a frenze in the 90s when everyone one a RCA Ba-6a limiting amp as a compressor for their Mackie ADAT "studio", or a V-76(although most could only afford the V-72 with the feedback loop broken so it was used as a pre-amp) and immediately found their dynamic mics worked better, or old condensers were better so assumed they were brilliant for adding vintage gear. Actually they wasted their money unless they bought early before they were bid up to thousands of dollars for gear sold off from radio stations for scrap a few years before. By simply matching a power device to a voltage device with a matching transformer would have made the mics improve just as much or more since the noise level was lower.....running a Ba-6a that was intended for +12 in a system level of +0, or -10dbv, the mismatch in levels killed signal to noise ratio. A well designed SYSTEM where equipment was run optimized in conjunction with other items in the chain need not be expensive or have magic to run circles around many of the typical studios which used equipment interchangeably of various eras of technology. But still, the gear never sold one more record or generate one more fan, only amateurs assume they do because it is the most accepted excuse why they do not have hits or fans. Few people believe me about the song, performance and studio chops outweighing gear 10 to 1. because very few people have ever been on the inside to see it in action.

                      So repair what needs to be repaired, don't change anything that you can't demonstrate needs to be replaced, document it with before and after spec measurements and photos of spectrum analyzer to cover your ass if the user thinks some of the magic escaped. Leave it to his system integrator to worry about satisfying his "sound" requirements.
                      As a tech, all you can do is return it to design intent without becoming liable for unrealistic expectations. Be just as wary about customers who claim you worked wonders and it is the best sounding unit ever after a repair, just as you would be wary of a customer who makes you the goat by losing his magic sound because your replace the line cord. Both are unreliable judges of your work. Good engineers who understand the processes of making good recordings will be much more realistic than amateurs or second tier studios, who are still locked out of "inside".

                      Comment


                      • #12
                        Originally posted by km6xz View Post
                        As a repair or restoration tech, don't get involved with "sound signatures". You will be forever praised or bashed based solely on inarticulate imaginary traits the user wishes to hear.
                        This is absolute +1, never get drawn into a pointless "IT sounds Like" debarcles.

                        Originally posted by km6xz View Post
                        Good engineers who understand the processes of making good recordings will be much more realistic than amateurs or second tier studios, who are still locked out of "inside".
                        Being involved in tech repair and a recording engineer,Wise words, never deal with both at once ! ,
                        In fact never deal with the audiofools at all.

                        Comment


                        • #13
                          I've done a bit of work with vintage studio gear - I tend to avoid it now if I can, though I rarely need to nowadays. Customers wanted my advice - not on transparency, grain, soundstaging or such, these were not unreasonable people - but some kind of guidance as to how best to get it where they felt they wanted it. So discussing what they wanted would generally end up at this same place, with them asking me what was the best thing to do. I'm supposed to be the expert after all... I've developed a general approach which works with guitar amp mojo quests too, I say in the nicest possible way I am a repairman not a guru, all I can really do for you is fix what's broke. And you know what we do if it ain't broke . Because in truth, unlike Stan, I do not have much recording studio experience with any kind of kit.

                          If they then say 'make it as reliable as possible' then all out of date electros come out too. Leaky coupling caps and failing resistors and noisy transistors etc have already been replaced under the previously-explained rule, as they are clearly broke. But actually the small studios I've dealt with often don't mind a bit of brokenness - there will be channels not working on their vintage analogue desk, keyboards with dead keys, etc, because I guess they're not touring and have a set of alternatives, don't know but in general I find small studios have lower standards for reliability than do road managers.

                          Maybe the analogue boom is over, or maybe I put them off, but I haven't seen any studio gear for a while now. Reading this over, maybe I can see the reason

                          Comment


                          • #14
                            I don't see much point in buying vintage gear just for the sake of it, but some people appreciate the particular characteristics of a certain piece of equipment mainly due to inherent flaws present in the original design. In the case of the Ampex preamps, the level control is placed after the first gain stage, so part of the character is the way it distorts with a high input signal - especially if run from a DI box. This makes these a nice unit for guitar or bass, though they're not particularly quiet compared to modern SS preamps. Additionally, the unit is capable of driving any subsequent stage (or even a guitar amp) into distortion due to the high-level PP output amplifier.

                            So, the shortcomings become features. It would be easy to 'improve' the design, but that would defeat the intended use. I agree though that taking a single piece of gear out of its original context can be a lottery-draw and a disappointment - even if it's bought back to 100% original spec. Noise, impedance, frequency-response and levels are not generally what people expect in a plug-and-play world. There's also the risk of customers making really bad decisions over vintage gear and expecting you to sort it out; I had one guy who'd bought a load of expensive pulls from a vintage desk. He never realized it was a backplane design and the incomplete modules weren't much use on their own without a lot of work. He though they just 'worked' because they came from a working desk that was being broken up. So all he had was unpowered channel strips he wanted to drop on me to sort out for next to nothing.

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