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Forssell Technologies SMP-500. Interview with Fred Forssell of Forssell Technologies. by  pan60 pan60      So let’s have some fun: )~  Tell me a bit about yourself, I always like starting with this... Any hobbies we can learn about? Fred Forssell       No, not really. I’m big into outdoors stuff and that’s why I’ve lived here in northern Idaho for almost 30 years.  I used to hunt alot, but, now I do my hunting with a camera and a field recorder.  I’ve been a birder since I was very young, but in the last 10 years I’ve gotten pretty heavily into neo-tropical songbirds.  Our property, here, in Idaho has 130 species of birds on it and many of them breed here.  With the help of some very well-qualified friends, I have learned how to identify most of the birds that we have by sound, rather than strictly using visual identification. It’s really fun and very good listening practice.    I find that spending hours walking quietly around in a forest or jungle and listening very intently provides me with a useful reference point for listening to my equipment designs. There is a softness to sounds in nature that is present, even when sounds are very loud.  Man-made sounds tend to be more harsh and offensive to my ears than those that occur naturally. I don’t know, maybe I’m just rationalizing the amount of time I spend in the forest, but I find that when I walk into my mastering room after a long walk in the woods and listen to music there, I tend to hear the subtle sonic qualities even more than I normally do.  It works for me anyway. pan60      Wow, very cool!  I have a modest plant collection, as well as a collection of Tarantulas.  Not spiders, mind you, Tarantulas: )~  We had an awesome chat the other-day, and you spoke about so many things, I felt we needed to do an interview with or without gear to review. In this case, the gear will be an added treat: )~  How did you get started in this industry? Fred Forssell       If you mean the music business, well that started before I was born. My mother is a classical music accompanist and played piano for hours everyday. My father was in radio and then television when it came into its own in the early 1950s. As a child I had the run of the radio and television stations and I use to sit for hours and watch everyone work. It was cool to see the racks of tube equipment and cabling that made up those studios. So, it was music and equipment that I was drawn to from a very early age. If you mean how did I start making equipment, that’s a slightly different answer. I was a touring tech, sound guy, stage manager, and production manager in the rock and roll world from the early 1970s until I quit touring in 1991. In the early days you really couldn’t just drop into some music store and buy all the complicated stuff that the tours were starting to need, we had to figure out how to build it ourselves. We were kind of making it up as we went along. I would figure out how to build a piece of equipment so it could be set up and torn down every night and still function without ground loops, RF problems, or reliability issues. Once I learned how to do that that I started really listening to it. Does everything sound the same as it did before I starting using the thing I just built, or did something change? Was the change sonically good or bad? What caused the change? Can it be improved? How did it effect the performers? That type of thing. When you take that form-follows-function/need-design approach, and then carefully evaluate the effects on the music and sound, in my opinion, you have a good basis for learning and evaluating design techniques and approaches. In the end, it is all about the music and musical performances. We tech people are only there to help the artist do what they do, and let others share that experience in a meaningful way. Everything else is secondary… to me anyway. Did that answer your question? pan60      Yes! I love piano music, you were fortunate to grow up with such a great tactile input. A couple of my uncles, and my grandfather played guitar, my grandfather also had a small home studio and recorder to the old cylinder. I used to love watching and listening as a child. So, tell us about the type of music you get to work with as an engineer and/or producer, or what do you prefer to work with? Fred Forssell       After seeing Jimmy Hendrix for the first time I decided I wanted to play guitar. That didn’t work out for me, but I spent the next 25 years working with rock and roll acts. My work was mostly as a tech, sound man, roadie, and/or stage/production manager.    I built a lot of studios for the people I worked with, and I built a lot of custom equipment for those studios and touring stage set-ups. But,  rock and roll was my music. I didn’t do a lot of engineering with those acts because they had REALLY good people doing that already. But I was watching and learning how they did their stuff. So, I was always thinking about how I could build equipment that helped them do what they do, or that sounded better than what they were using at the time. I did lots of modifications to existing equipment. To do that, I had to figure out how the stuff worked. As I gained more knowledge in the area of equipment design, I came to know a couple of really good designers who became my mentors in the area of circuit design. They also introduced me to the concept of REALLY listening in a controlled high-quality listening environment. That was the mid-1970s and I’ve been hooked on listening to good music played on good systems ever since. And for me, my sonic point of reference was actual live musical performances. Why didn’t these systems sound the way the live performance sounded? What caused the disconnect between actual musical performance and reproduced versions of the same thing? When I burned out on touring and doing large shows, I just started working on my design and listening chops. I hooked up with an old friend, who is a recording engineer, and he asked me to do some work for him. That got me back into the studio and we have spent years tweaking and working on his set-up. This continues even today. The equipment that I started making from that experience eventually came out into the marketplace and has been pretty successful. As a result of that success I got turned on to modern bluegrass music. I was quite stunned to discover the level of musicianship and quality of the acoustic instruments being played in the bluegrass world. It was something I was unaware of and I was totally hooked on it instantly. Hearing musicians like that, playing those instruments in close proximity, all hours of the day and night, simply blew me away! I starting working even harder on my designs, using those sounds, as my reference. That lead me to meeting, and later working, with a lot of really top-notch bluegrass players. I even went out on the road again for a couple of small tours working with two of the best mandolin players in the world. And (surprise!) I really had fun with them during this time. It was WAY different that rock and roll, and a lot more enjoyable, as well. So, that is the type of music I’ve been working with for about 10 years now… bluegrass, acoustic jazz, and acoustic music, in general. I still like classical music, but that is not as accessible to me as the other genres I just mentioned.  I did some recording work and some producing work, too, but, really, my place is in the lab and the listening room evaluating my design work so that others, who are more talented than myself, can use my gear to help them make better recordings. pan60      Wow, you have a very interesting background! I bet you have some very cool and amazing stories you could tell! Okay, more to the topic: )~ The SMP-500 Microphone Preamplifier Pasted Graphic.tiff ¨ Fred, tell me, is there a difference between the SMP-2 and the SMP-500, other than the format? I ask this because the question will be asked at some point, by someone. So let’s just begin with that. : )~  It seems, at times, companies get a bit of slag because their 500 format product is not exactly what their 19'' rack version is. Oddly, I find in many cases, they never intended it to be, so I wanted to touch on this topic. Fred Forssell       It is a logical question for anyone to ask: Does the SMP-500 sound the same as the SMP-2? My answer is: No, it does not sound identical. But, it sounds very close to the same. To be honest, I would have been bummed if the SMP-500 sounded the same as the SMP-2. I put a lot of work into power supply design and in selecting the support circuitry of the SMP- 2. Almost none of that could be included in the SMP-500. 500 series modules have a lower power supply voltage specification than I use in the SMP-2. Depending on which specific 500 compatible rack or lunch box enclosure is being used, there can be very different power supply designs. I learned a long time ago that power supply design can have a VERY big impact on how a circuit sounds.  Some other designers might not agree with me on this subject, but I find that power supply design is a very important aspect of equipment design. It is tempting to just build a simple regulated supply with the right voltage and current rating, and then call it good. I feel that one has to look at the specifics of the regulator design, filtering, and other critical aspects related to noise, grounding, and power supply source impedance as a function of frequency. pan60      Most of the guys I have spoken with seem to agree with you in regards to the power supply being a part of the sound. Fred Forssell       I did all of that and more with the SMP-2 design, but I could not address many of those factors with the SMP-500 design because the power supply specifics are outside of my design control. So, that is one factor that makes the two preamps sound somewhat different. Another change in the SMP-500 vs SMP-2 occurs because I do not use transformers (see below) in my designs. The bipolar 16 volt power supplies of a 500 series enclosure presented me with a problem. Many designs use a step-up transformer to get a higher maximum output level, but I did not like that approach because I don’t like transformers. I opted to use an active balanced- floating cross-coupled output stage in the SMP-500. This acts very much like a transformer, but without the sonic impact of a transformer. Just as you would with a transformer, you take your output signal between pins 2 and 3 of the XLR, not between pin #1 and one of those pins. This is true, even for unbalanced loads. The result of my approach is a 6 dB increase in output level. Also, my designs swing pretty close to the power supply rails. The SMP-500 will put out +27 dBu into 600 ohms in a 500 series rack without using output transformers. pan60      Why not utilize a bit more of the current draw and better regulate and filter the voltage? Could this be done without the use of a set-up transformer? I don’t want to sound like I'm too ignorant, but doesn't a power need some form of transformer anyway? Fred Forssell     I believe in keeping things as simple as possible. So, no DC-to-DC converters in the SMP-500. I am running as much current as I need to get good performance, and no more than that. I am filtering the DC rails pretty heavily on each SMP-500. pan60      As I understand, some of your earlier work incorporated transformers. Is that correct? Tell us why you chose to move away from the use of transformers. Fred Forssell       Yeah, some of my early work did use transformers.  Back in the mid-1970s,  when I started building preamps, I didn’t really know any approach other than using input transformers. I had already learned that with careful attention to grounding details, one could get rid of the output transformer in most existing designs without ground problems. Typically the result was an improvement, sonically. I started wondering what it would sound like if you got rid of the input transformers, too. So, I did mods on a lot of line-level equipment that did just that. Again, I had to be very careful with grounding. But, I was already pretty sure of myself in that department, so, I just removed the input transformers and we started evaluating the effects, sonically. It was a pretty big eye opener for all involved. I was still making mic preamps with input transformers. I had not yet gotten to the point of designing circuits with actively balanced inputs that had good common-mode performance but could also handle phantom power. About that time, Paul Buff came out with the Valley People TransAmp modules. I snatched up a bunch of them and started building preamps using them as the front-end. In some cases, the output stage was a JFET/MOSFET circuit that I was using at the time, and in some cases it was Deane Jensen’s 990 opamp design. Deane had given me a copy of his AES paper on that opamp and I liked his approach, so I used that design for awhile. But it didn’t really work for me,  sonically. So I started using different output circuit designs with the TransAmp front-end. pan60      I have been looking for some of the old Valley People gear, but for now, I am consumed with the 500 format: )~ Fred Forssell       I really don’t know much about VP stuff, at least, sonically. I know what they made, but, I didn’t use it much in the studio. I did like the concept of the TransAmp and that inspired me to pursue my own transformerless input stage designs back in the 1970’s. When I was designing with input transformers, I was using the UTC LS (Linear Standard) series transformers. These were hands-down the finest input transformers ever made, IMO. They were huge and really expensive,  but they were beautiful transformers. I also used Peerless and Freed transformers in some designs. The Ford truck of transformers, at the time, was the Triad HS series.  I used them on designs that needed smaller, less expensive transformers, as well. I also used the HS-58 and HS-56v frequently, and sometimes the HS-66, too. But, I never felt that the Triad transformers were as good sounding as the UTC LS series and they didn’t measure as well, either. The bottom line, for me, was simply this…. even with the UTC transformers, there was no transformer that sounded like no transformer. Every time I performed listening test switching a transformer in and out of the circuit, the sound was best with no transformer. As a result, my overall design philosophy switched to a transformerless approach. The only exceptions was, and still is, mic level splitters and DI boxes. After many years of taking the transformerless approach, I decided to design and build a mic preamp that used modern, good quality transformers for the input and output sections. I used that design approach with a vacuum tube opamp that I designed for a product for Anthony DeMaria Labs. That design became the Presonus ADL 600. But, that is the only transformer coupled mic preamp that I’ve done in the last 30 years. Recently, I also used a really good high turns ratio transformer for the new AEA A440 active ribbon mic, and the same circuitry for another mic for AEA, as well, which hasn’t come out, yet. pan60      You have designed a fair amount of gear in your time. Any other units you would be at liberty to mention? Fred Forssell       I probably shouldn’t talk about it too much. For some reason, some of the people that I’ve designed for get upset when I mention that I did the circuit design for some of their products. pan60      I have, it seems, been drawn to the way many dynamic mics perform with IC base preamps. So, I was very excited to try your new SMP-500 pre. But,  always there has to be a "but", the SMP-500, is, in fact, not an IC-based preamp. In fact, this is a Discreet J FET. Fred Forssell       Right! But, the SMP-500 does use an IC opamp configuration for the output stage. This is a cross-coupled, floating output topology, as I mentioned above. With this configuration, you can get over +26 dBu output with 16 VDC rails, instead of the usual +20 dBu. That means there is +6 dB additional headroom, which is great. The front-end JFETs and differential amplifiers they are connected to are all discrete, Class A, JFET designs, so only the output stage in the SMP-500 is IC based. pan60      Now, I am a very big fan of discrete gear. But, I also have IC-based gear, and feel I should make it clear, I have nothing against IC's. Fred Forssell       While I think modern IC opamps are getting better and better in terms of sonic quality, I do not think they can match a good discrete design. From an equipment manufacturing point-of-view, it is difficult to not be attracted to IC opamps. They are small and cheap compared to discrete Class A opamps. They also present a lighter load on the power supply and generate less heat than a discrete design. But, as is usually the case, there is a trade-off. Easy to use, yes. Best sounding circuit possible, no. I guess I make different choices than some others because I have a different set of priorities driving the process. pan60      Can you explain, for those who are just getting into collecting their studio gear, what a Discreet J FET preamp is? Fred Forssell       Well, discrete means - made of individual parts. JFET stands for Junction Field Effect Transistor. So “Discrete JFET” means - made up of individual JFET transistors. JFETs differ from bipolar transistors in fundamentally important ways that I will not go into here. As a vast generalization, JFETs operate more linearly than the bipolar transistors. They tend to look like capacitors on their inputs instead of diodes (which can cause RFI problems), and have distortion products that tend to be made of even-order harmonics of low order (number of harmonics). Low order even-order harmonic distortion is fairly well cancelled out in the circuit topologies that I tend to use. This happens without negative feedback. I won’t go into my thoughts on feedback here, except to say that while I am not afraid to use it in my designs, I think it is best to have a really good linear design that has good performance without feedback and then apply the feedback to that circuit. Someone really smart once said that negative feedback should be thought of as a coat of paint on a house. I’ll leave it there. JFETs also operate more like vacuum tubes than bipolar transistor in the way they are biased to reach their operating point. This is because they have a voltage-based input, as opposed to a current based input. While I won’t say they sound like vacuum tubes, I will say they sound MORE like vacuum tubes than bipolar transistors do. Also, you can get really good low- noise JFETs that are matched N and P channel devices. There are no P channel vacuum tubes, so when designing with JFETs you can use circuit topologies that make use of N and P devices, just like with bipolar transistors. With tubes, you simply cannot do that in any practical way. So for me, JFETs offer the best of both the vacuum tube and transistor worlds. pan60      Let’s chat a bit about your parts choices, if you don't mind. I see lots of surface mount components in this bad boy. Let me say first and foremost, surface mount has always give me a great deal of fear. I have never been a fan of surface mount components. It seems they just never delivered the sound. That is not the case with the SMP-500. This is most likely a fear, and a lack of understanding, not just on my part, but with many others. So, Fred, you’ve got to tell us why we should not fear the surface mount components. Help us understand the technology a bit better, educate us! : )~ Fred Forssell       Well, think about it for a minute... what would cause SMT parts to sound different than through-hole parts? To me the only answer can be because of what is inside the parts, not the method of mounting the part to a circuit board. Early in the SMT age, components such as resistors were made using thick film processes. Thick film resistors did not have sound the same a high-quality metal film that through-hole resistors made using thin-film technology. Today, however, thin-film SMT resistors are readily available. One can even get tantalum nitride resistors in SMT, which are thought by many, to be the best sounding resistors available. So, if one were to use the same type of resistor composition (thin-film) in through-hole or in SMT packages, why should they sound different? I contend that they won’t sound different. In fact, if there is a difference at all, it would favor the SMT part over a through-hole part of the same composition. Why? Because SMT parts are simpler in every way. There is no welded end-cap to lead connection. SMT parts tend to be smaller and can be packed into MUCH higher densities than through-hole parts. Higher density means shorter lead length. Some people don’t want to deal with assembly and repair issues for SMT-based equipment because they think SMT is difficult to work with. I found that once you ramp up to do SMT work, it is actually easier to work with and it is much easier to rework or repair than through-hole. pan60      So, surface mount components have evolved to a level of quality that is equal to the more traditional through-hole components so many of us are accustomed to seeing. The past concerns due to quality, and the bias due to ease-of-use and durability should be set aside, at this point, in your view. Fred Forssell       Well... yes! But, you still need to pay attention to the details of parts selection. That is the same with SMT or through-hole. pan60      Give me the specs on the SMP-500 Preamp. Fred Forssell       General Specifications:  Gain range = +8 to +64 dB  EIN (20 Hz to 22 KHz) = better than –128 dBu  CMRR = better than 60 dB  Input configuration = actively balanced AC coupled input  Input Impedance = 13k ohm  Max Output Level = +28 dBu into >= 10k load  +27 dBu into 600 ohm load  Minimum load impedance = 600 ohm  Output impedance = 4.5 ohm  Output configuration = actively balanced and floating (Signal between pin #2 and pin #3).  Current Draw = 60 ma per power supply leg  Circuit Topology = Discrete JFET input stage, Discrete JFET opamps (2), IC opamp balanced-floating  output stage  LED Level indicators = Green at 0 dBu output, Red at +24 dBu output (2 dB before clip)  Switch Functions = Polarity Rev (switch in), and P48 Phantom Power (switch in)  Gain control = 24 Position Elma rotary switch with thin-film SMT resistors Specifications: (Measurements taken with module in an API 6 space lunchbox.)  Gain Range = +8 to +64 dB in 24 steps  Frequency Response @ 45 dB gain from1 Hz to 200 KHz = +0, -0.5 dB  EIN at +65 dB gain (22 Hz to 22 KHz) better than –127 dBu unweighed  Input Impedance = 13k ohm Max Input Level at min gain = +18 dBu (output clipping)  Minimum output load = 600 ohm Max Output level +26 dBu/dBm pan60      I got to say, the SMP 500, is a very nice, clean, modern sexy kinda of looking pre, and I love the color.  : )~ On the inside, everything appears nice, clean, and SMALL! Oh.. so very, very SMALL, LOL. It boggles my mind, to see just how small these components are. And there is so much stuff in there, lots o’ stuff, LOL. Fred Forssell       Well, for some things in life, small is good. Hopefully, the SMP-500 circuitry is one of those things. pan60      I think the SMP-500 will be very, very well received! Now, My Thoughts. First, what about the man behind the company - Service? It has been a real pleasure chatting with Mr. Forssell. I could have spent much more time, but there are only so many hours to work with. : )~ I can say, based on my chats and many email correspondences with Mr. Forssell, I believe service is at the top of Fred's short list. So, I see no worries, there. Second - Quality? The SMP-500 looks amazing inside and out. There’s lots of stuff, I have to admit. I am more than just a little lost on the surface mount products, but if sound (or the lack of ''A'' sound), is any indicator, I say top shelf! Everything is clean and looks great. The gain is managed by a stepped detent switch, which I think has a great feel to it. And the fit to the format, is just as it should be.    Okay, what did I not like?  I must admit, I would like to see, a slightly smaller knob on the gain switch.                Third and lastly - What do I think?  So, do I like it? Well, do I? I’ve got to say, this is another big home run product, that fall into the 500 series format. 500 format slutz, in the world, will now have a very clean (virtually transparent), pre to add to the tool box. The SMP-500 pre is simple in appearance and function. It has the basics and it’s to the point by providing the polarity, phantom power, and gain. This is a fast, and I feel, very accurate pre which delivers plenty of gain  with clarity and definition. As previously mentioned, the gain switch and buttons feel great! The SMP-500 delivers flawlessly and accurately to the source. Rather than using large Capsule condensers, as well as small ribbons, and/or, a variety of other dynamic mics, from my humble collection, the SMP-500, excluding the mic vibe, is a ‘what you hear is just what you get’ unit. I must add that being the dynamic mic slut that I am, this is another pre that really trips my trigger when being used with dynamics. This has no bearing on how much I liked it with condensers. I just wanted to mention I loved it with dynamics! : )~ Description:         The Forssell Technologies SMP-500 is a version of our well- known SMP-2 microphone preamplifier that has been adapted to work with the API 500 series enclosures. The SMP-500 is an extremely high-quality, sonically neutral microphone preamplifier designed for the most demanding applications. The SMP-500 circuitry features an all Class A discrete JFET front-end with a gain range of +8 to +64 dB in 24 switched steps. The output of the SMP-500 is fully balanced and floating, and with a maximum output level of greater than +26 dBu. Front panel LED signal level indicators are provided to indicate 0 dBu output level (green) and output clipping (red). The clipping LED lights with at +24 dBu output, which is about 2 dB before actual clipping. Polarity invert and P48 Phantom power switches with LED status indicators are also located on the front panel. The SMP-500 is a to-the-point pre, unassumingly simplistic, yet delivers depth and clarity with such elegance. Yes, it is VPR Alliance approved. pan60      A big thumbs up Fred! Description:         The SMP-500 is priced at $795 plus shipping and is available directly from Forssell Technologies directly. pan60      Also, can you give us a quick run down of some of the other gear you offer? Fred Forssell       If anyone wants to see more, they can check out our website… www.forsselltech.com pan60      Check out the link, guys and gals. Fred is offering some very amazing gear! Contact Information:  Forssell Technologies Inc.  235 Wild Horse Trail  Sandpoint, ID 83864  208-263-0286  info@forsselltech.com  www.forsselltech.com


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