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solid state comp/eq/pre amp in the range of avalon 737sp??

Discussion in 'Pro Audio Equipment' started by trock, Oct 16, 2004.

  1. trock

    trock Active Member

    Aug 20, 2004

    i was posting here that i was looking at an avalon M5, well a friend of mine told me to look at the avalon 737sp to use with SX 3 and an RME 800, however i have a friend who is a Ph. D in Physic's from MIT and CMU and i was asking him about these "military tubes" that avalon brags about. here is his reply, if this is true does anyone here know of a really good solid state pre amp/comp/eq??

    see i should never talk to these people cause it KILLS ME''thanks for any help

    Tubes do go bad, and they are very expensive to replace at this point. The real problem with vacuum tube stuff is that tubes by their nature are high impedance devices, whereas the loudspeakers are all (to the best of my knowledge), are low impedance devices. You probably know this, as speakers are generally 8 ohms. I think I have seen some sixteen ohm speakers in my day, but they are few and far between. Tubes are essentially voltage driven devices, and their internal impedances generally are in the thousands of ohms. Tubes don’t like high currents. Transistors, on the other hand, hate voltage and love current; they are low impedance devices.

    In order to transfer power from one device to another, say an amplifier to a loudspeaker, in order to have good efficiency you have to “match” the impedances. For optimum efficiency the output of the amplifier should be 8 ohms to match an 8 ohm speaker. If it is higher than that, not only will you not transfer power efficiently, you will also reach distortion levels sooner, because the possible voltage excursion of the tubes (limited by the power supply if nothing else) isn’t great enough. To get around that problem, a high quality audio amplifier will have a huge matching transformer. This works, and does a good job, but the iron in the transformer must be of high quality and there has to be a lot of it to achieve reasonable power output. So the high quality amplifers of the 60s generally had a huge output transformer that cost a lot, weighed a lot, and took up a lot of real estate on the hardware. You couldn’t even mount one on a circuit board. A good transformer for a 50 watt amplifier, not that big by today’s standards, would weigh fifteen or twenty pounds.

    Admittedly, there are ways to avoid the output transformer, but why bother when transistors do the job with great ease.

    I have heard audiophiles say that they can tell a difference between solid state and vacuum tube equipment, and I don’t doubt that that is true in some extreme cases. However, what they may be hearing is distortion introduced by the vacuum tube stuff, and they have grown so accustomed to it that they feel lonely when it is not there.

    The thing to look at is the harmonic distortion at rated power output. The one with lower harmonic distortion wins.

    Probably more than you wanted to hear. Save your money.
  2. Kurt Foster

    Kurt Foster Distinguished Member

    Jul 2, 2002
    77 Sunset Lane.
    Your friend is an idiot ... he may know about the physics involved but he doesn't have a clue about what makes audio sound good ...

    All you need to do is to get an old Fender tube guitar amp and a modern solid state Peavey guitar amp and plug into one and then the other and listen to what you hear ...

    The tube amp will have a big round sound with dimension to it ... front to back depth ... and when you push it into overdrive the distortion will be warm and full sounding while the solid state amp will be flat and demensionless and when distorted will be harsh and sterile sounding.

    Even the best solid state mic pres and compressors use transformers on the input and outputs because they sound better than electronic balanceing ..

    To boot, mic pres don't run 50 watts or even 10 watts ... they run at much lower line levels ... so the transformers employed do not weigh that much.

    Perhaps it's a bit harsh for me to say your friend is an idiot ... but it is no more harsh than his remarks about mic pres... He really doesn't know what he is taliking about in this particular instance.
  3. trock

    trock Active Member

    Aug 20, 2004
    well that is one way to put it??

    i mean, all i was aksing about was tubes in general and got that, so can you tell me what part was wrong??

    not trying to turn tis into a scinetific discussion but in what parts is he "wrong"??

    he has 72 patents for westinghouse and is also leading 2 projects for the Dept of Defense right now (not making this up)

    i only posted it cause for me i just wans't sure and thought it would spark a good conversation with you guys here who i consider very knowledgable

    calling my friend an idiot doesn't serve much purpost Kurt

    but i guess if thats your answer i will just live with it
  4. Kurt Foster

    Kurt Foster Distinguished Member

    Jul 2, 2002
    77 Sunset Lane.
    I was adding comments to my first post as you posted your last .. the explanations are in my first post ..
  5. trock

    trock Active Member

    Aug 20, 2004

    thats cool

    i can get my head around your answer, i was surprised when i first read "your friend is an idiot" cause i really wanted to knwo more about the "science" which he always tells me AND the "real world" scenario's you guys knwo about.

    i guess my big question is this

    if i get an avalon

    1) are they as good as what i have read?
    2) will a tube go bad quickly? or does it take years of regular use??
    3) are they expensive to replace and is something I could do or would the unit have to go back to the factory??

    I liked your reply and tend to agree he is not thinking of this in a "musical" sense.

    also he is a good guy, he is not a show off or ego driven, he just sometimes tried to hard

    I used to ask him for help with math homework, can you even imagine how confused i was in school??

  6. Kurt Foster

    Kurt Foster Distinguished Member

    Jul 2, 2002
    77 Sunset Lane.
    A lot of these "NASA techie types" are genius's regarding communications type devices ... and they need to concern themselves about weight and longevity .. but in the musical applications, nothing is more important than the sound.

    Transistors when driven into clipping produce what is called square waves ... the top of the wave form is clipped off (hence the term "clipping") Tubes go into distortion more smoothly with less square wave effects .. if you view the wave form on a scope you will see that the wave form is more rounded out at the top of the wave.. also different harmonics are generated in clipping with transistors producing odd order harmonics (third, fifth, seventh) while tubes produce a more musical even order harmonic overtone content.. this translates into better "sound".

    Tubes can last for years, even decades but occasionally there will be problems either in the tube itself or in the device it is placed in that will cause early failures. I have a friend that has an old tabletop am fm radio in a bakelite case that must be 50 years old with the original tubes, that still sounds great. Tubes can be a bit pricey, especially if you opt for the better NOS types.. but you really shouldn't need to worry about this for at least a couple of years, if ever. Tubes are very easy to replace.. A five year old could do it in most devices.

    Avalon makes good stuff. I am sure you will be happy with it .. The 737 is not as well regarded as some others but is still a considerable step up from what I would call "rack crap". The Avalons are most popular it seems with hip hop and R&B producers..
  7. RandomGuest

    RandomGuest Guest

    Feb 10, 2001
    Kurt, I thought I was supposed to play the role of "asshole of the internet"... you tryin' to nail my gig?

    You are kinda correct... but... there are differences within audio from camp to camp. Look at that Millennia HV-3D you seem to like so much... IC chip to keep the cost down and the specs up, transformerless output to keep the cost down and the specs up... it's our rocket scientist's wet dream. Now I think the thing sounds boring as sin, but there are a whole bunch of audio professionals who do not share that opinion.

    Comparatively, tubes are expensive when you look at them vs. discreet transistors or especially next to IC chips... tubes also go south... you can only expect around 10,000 hours of service from the tube set in a 737 [which with 40 hours of use per week would be about 5 years... or around 10 years with 20 hours of use per week]... in other words, I wouldn't consider it a serious factor... but the PHD is indeed correct as transitors and chips will have a longer life. The electrolytic capacitors in the signal path won't have as long a life... but we're only talking about "drive elements" in this discussion... right?

    Transfomers... another topic of debate... their general application I find to net a more euphonic result... however, there is some very shitty iron out there so the coupling of a particular transformer to a particular design is of the utmost importance.

    Trock, if I may be so bold... use your ears and leave the "specification" crap to the people without ears.

  8. trock

    trock Active Member

    Aug 20, 2004
    kurt and fletcher

    thanks, after a rocky start i enjoyed reading both your posts. i am interested in the stuf under the hood too which is another reason i talk to him sometimes about this stuff. He doesn't do anything with music in terms of recording but he plays the banjo :)

    it amazes me, the people who "invent" and build this stuff for us to use. Anyway, still learning as much as i can.

    One thing Kurt, you said the 737 is not as well regarded as someothers? did you mean other avalon's or just in general??

    i really want a good preamp more than anything t9o go into the RME i am getting, an M5 was also recommended, how does that one rank?? that is the .imit of my avaible cost too, 1500K

    thanks guys
  9. sdevino

    sdevino Active Member

    Mar 31, 2002
    Holy $*^t, I have to spend more time here.

    Your friend is not an idiot and everything he said is true. Some of what Kurt said is true and most of what Fletcher said is true.

    Kurt you need to separate your opinion from fact. Comparing tubes vs transistors by using a guitar amp has nothing to do with mic preamps. While I greatly prefer the sound of tubes in my guitar amps, I am almost always going for moderate to heavy distortion. The Roland Chorus w/2 12" inch speakers is probably one of the all time favorite Jazz guitar amps and it is all transistors. (Peavey's all suck so why even bring them up).

    In Mic pre amps its all about variety. Its good to have some clean, some aggressive, some chocolate and some vanilla. Its up to you what flavor is appropriate for each. Neve pre-amps are not exactly crap and they are all transistor. In fact I would venture a guess that there are very few tubes in the signal chains of anything great records made in the last 20 years, with most tube apps being for the bass in the form of an LA-2A.

    The only current tube preamp I like the sound of is the Sebatron stuff (but that's just my opinion).

    Fletcher is very correct in that the tube life should be good for 5 to 10 years. In fact if you buy a spare set of tubes now you should be set for a long time. The bigger problem with tube circuits these days are twofold:

    1. power supplies needed to keep up the voltage demand for these beasts are critical and require large filtering caps which go bad over time.

    2. some current manufacturers use tubes as a marketing gimmick. They give you the tube circuit but they short change the power supply. I had a UA2-610 for 2 years, while Bill Putnam may have recorded lots of hits with his 610 based console, he sure as $*^t did not have the crappy little power supply that washes out anytime someone tries to drive the UA610 with any kind of input level. That pre-amp sounds great when it is not pushed but it just dissappears and turns to $*^t when pushed.

    My advice when buying tube based technology: Give it a good thorough tryout. Turn the gain up to max and listen for excess hiss and occasional pops or clicks. Tap lightly on the case to see if the circuit is microphonic (sign of a bad tube or a bad circuit design).

    Then decide if you like the sound because it will have a very specific tone to it (which is good if its what you need).

    Just because something has tubes does not make it better. A well designed tube circuit is a wonderful thing and no solid-state desing can copy it, but then again no tube circuit can sound like solid state. It all depends on what you are after.

    My 2 cents.

  10. RandomGuest

    RandomGuest Guest

    Feb 10, 2001

    Dude... that should tell you all you ever need to know...

    There are many designers who also operate studios and are engineers. There are some who do some engineering work but only function as the "administrator" for their companies [these are generally the ones to watch out for... but that's a discussion for another day]. Finally, there are people who have been involved with distribution, hired a designer [stated that it was a "work for hire" up front... didn't ^#$% the designer by making him think he was a partner as at least two, and probably more, have done in this industry], farmed out the manufacturing and have product on the street... this doesn't lead to updates of the product as it becomes apparent they're necessesary, but it is better than [at least in my mind] than the 'engineer / administrator' paradigm, yet no where near as good as the designer/engineer/studio owner paradigm. [We won't even begin to discuss the "built to a price point paradigm that comes with most (not all, but most) "budget" equipment].

    What goes on under the hood of these things is facinating. There are soooooo many thing that have to be considered... down to the minutia of proximity of the traces to each other on the circuit boards [and which trace is carrying what, and how that affects the traces surrounding it!!!], where each component is on the board, and how that has an influence on the components surrounding it... trace width, hand wired, combination... pots vs. stepped attenators, power supply issues, linear? switching? if swithcing, at what frequency? [switching supplies were one thought to be evil... however, with modern components and facilities they are indeed viable for high end audio applications], current on demand capabilities of both the power supply as well as the ground drain and the circuit path, frequency response character, phase anomolies through the audio spectrum [both good and bad anomolies], how airborn radio freqency stuff will affect the linearity of the audio portion... yada, yada, yada, yada... hence why there is no "perfect" design, but merely a sequence of educated compromises that make the tool useful or not useful to a given user in a given application.

    For almost every decision there are a hundred variables. Building any product is all about having a design philosophy, knowing what you want to hear, understanding what elements of what you want to hear that will give you the net result you are trying to achieve... and then going through the rampant trial and error to excecute that philosophy with the desired elements [and features]... I've been through this a half dozen times now with a bunch of different designers... which is why it takes a good year or two of design time to get a "Mercenary Edition" product on the street. I'm not the designer, but in working with real designers [and I dare say/brag, some of the absolute finest this industry has to offer], I have learned about the things that must be taken into consideration.

    I could no more design any of this hardware than I could climb Mt. Everest in a pair of Chuck Taylor Converse's while wearin Levi's... but it has afforded me the opportunity to peek into the process and understand many of the struggles and trade offs [especially when I don't give a $*^t about their struggles... until the damn thing is 110% the way I want it, it ain't coming out... but for some reason, they still like me... go figure].
    Avdhesh Tondak likes this.
  11. jonyoung

    jonyoung Well-Known Member

    Dec 31, 2003
    Something else to consider... you won't be driving 8 ohm speakers with an Avalon 737sp. To turn your friend's power transfer argument back on him, a preamp needs to have at least 10x the impedance of the source signal plugged into it, whether mic or instrument. By the time the signal gets to the end of the chain, the impedances are where they need to be to make the power amp and speakers happy.
  12. trock

    trock Active Member

    Aug 20, 2004

    hey fletcher and Sdevino

    fletcher very funny post, yet very true! Well this is what i had kind of hoped for, with all the "normal" posts on recording, equipment or whatever else i thought this would be a nice change of pace and address a very important topic, namely tubes vs solid state??

    i think a good post or topic would be having people list there fav pre's etc and whether they are tube or solid state, and/or both and what people use them for and in what circumstance??

    i thought it would be a good guide for people who are newer since a pre amp can really make such a world of differnece

  13. Davedog

    Davedog Distinguished Member

    Dec 10, 2001
    Pacific NW
    Listing favorite pres and such is a good thing and becomes subjective at the first word...It is all about how one hears things and ones choices to achieve that noise in the head....fletcher hit it on the mark...the design of a device goes way way beyond simply putting parts together that happen to have the correct values to complete an audio circuit....his statement about the proximity of traces to others and the type of signal being exposed at these points is so so true and many an experienced and serious electronics guy has gone down in flames when not considering these aspects.Now Leo got it right in his simple tube amp circuitry from the get-go...and CBS screwed it right into the ground later on in trying to make it a more profitable endeavour in production...The take on the transformers and their windings and winding materials is right on....soft-annealed copper is not too prevalent in todays off-the-shelf 'formers, but is a big part of that old-timey tube sound...It goes on and on....As for an Avalon 737 being a 'good' buy it again becomes subjective to your ear and to your needs...it will do a job and do it fairly well....will it do the job for you???who knows? The best pre is the one you choose and the one that immediately gets a huge AW $*^t YEAH reaction at first hearing...for the job.

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