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Flatback vs. Roundback

Discussion in 'Basses [DB]' started by MikeCanada, Jan 27, 2014.

  1. MikeCanada


    Aug 30, 2011
    Toronto, ON
    So I did a search on this, and didn't find much. There is a post about it in the "Newbie Links" Sticky, but it doesn't say a whole lot. I deeply value and encourage people to share their personal experiences, and I am also hoping that some of our luthier friends here will chime in with some knowledge from the bench.

    What I do know about construction:
    Roundbacks are more expensive to make. You need significantly more wood to allow for the arching, and you need significantly more time to carve the wood to create that arch.
    Flatbacks come from the Viol family. In a lot of ways, the double bass is much more a member of the viol family than the violin family. Violin shaped outlines and corners are fairly common, but from what I know (very little) about bass construction, they are structurally closer to big viols than big violins.

    What I would like to know about construction:
    What are the pros and cons of both construction methods?
    Are flatbacks really more prone to cracks than roundbacks What do people do from a construction point of view to reduce that risk?
    Although the back is one of many choices you make when making a bass, other than customer requests, what makes you pick one construction method over another?
    Does one result in significantly different characteristics than the other?

    What I know as a player:
    Each individual bass is different. This comes up when anything related to construction is mentioned, and is extremely valid. How a bass feels and sounds is dependant on a lot of factors, the back just being one of them.
    Some players have preferences. Some love roundbacks, some love flatbacks. Some really don't have a particular allegiance and just look for "the best" bass when shopping. Some feel that flatbacks are more comfortable to play, etc.

    What I'd like to know:
    If everything else was the same, (let's say you took the back off of a flatback and put a roundback on it) what would the differences be?
    Why do you prefer one over the other?
    Do flatbacks really "project" more/further? Do roundbacks really have a "fuller/rounder" sound? What characteristics can (even partially) be attributed to the differences in back construction?

    I know there are a lot of questions here. There are probably a lot more I am forgetting to ask as well. Although I am not currently in the market for a new instrument, I am considering commissioning a modern instrument for my next instrument, and this is one of the many choices I will eventually have to make.

    PaperbackRyder likes this.
  2. Eric Hochberg

    Eric Hochberg

    Jul 7, 2004
    I can't offer any thing from the sound perspective, only that due to their reputation as prone to problems, I've avoided flatbacks as Chicago climate creates a lot of wood movement. All three basses I've owned as a pro have been rb's and I've never had a back problem.

    I've rarely, if ever, seen an old flatback without cracks. I do know Chicago players that own them, but I don't know what their maintenance experience has been. Would be good to know. One of my old rb's did have a repaired crack, but from years before I owned it.

    Check this http://iwk.mdw.ac.at/?page_id=100&sprache=2. Also this from Arnold Schnitzer http://www.aesbass.com/bassgear7.htm
  3. mjt0229


    Aug 8, 2007
    Bellingham, WA
    Perhaps we can get a real luthier to chime in here, but I'm under the impression that the belief that basses are "structurally more like viols than violins" probably is somewhat misleading. From conversations with luthiers and other bassists, I get the idea that by now, differences in bass construction/structure have more to do with the size of the instrument (or in the case of corners, aesthetics) than any sort of familial history.
  4. MikeCanada


    Aug 30, 2011
    Toronto, ON
    While I also am not a luthier, I got the opposite impression. Things like the ratio of rib depth to table size, the flatback and the bracing that comes with it, canted backs, the "traditional" tuning of 4ths instead of 5ths, gamba outlines, sloped shoulders all point towards viols. From what I have gathered, there is a lot of overlap and a lot of violin-like aspects to double bass construction, but there are still a lot of ties to viol roots.

    I am guessing that a lot of this has to do with size and playability. Sloped shoulders, canted backs or tapered ribs, and several of the other construction differences could just be "natural evolution" or "necessary evil". We demand a lot of things of double basses. We expect to be able to get to the end of the fingerboard and a lot of things that were not required on a viol family instrument, but are on a violin family instrument, so some crossover/hybrid construction methods to get the best of both worlds definitely makes sense. I am just speculating at this point as well, which is why I asked so many questions.
  5. Lee Moses

    Lee Moses

    Apr 2, 2013
  6. MikeCanada


    Aug 30, 2011
    Toronto, ON
    Thank you Eric and Lee. I just finished reading both articles. The "Institute of Music Acoustics" article is largely gibberish to me given it's a little too science intense and over my head, but the "take home" I got from it was that the back of flatbacks and roundbacks vibrate very differently. The bracing on flatbacks also comes into question, (as it does in Arnold's article) and it is interesting to hear that a lot of makers are now using different bracing patterns than the "traditional" ones, to positive effect.

    Arnold's article is great. He addresses the "stability" or "vulnerability" of flatbacks nicely, and it sounds like if a flatback is made with newer bracing methods, you consider a summer and winter sound post, and are extra careful with climate, they don't have to be a powder keg of potential problems. While I don't particularly travel that much, Southern Ontario's climate does wildly vary, so the possibility of a roundback being able to weather that storm better is appealing.

    The article mentioned cost, wood conservation, and climate as possible considerations when determining construction methods. I am also wondering if flat or round comes into discussion when (un)desirable tonal/playability characteristics are discussed with a potential buyer? If I go to a maker and say "I want to buy a bass" and I'm not particularly sold on flat or round from my personal experience, what factors would a maker have for either camp?

    This really interests me. If those basses are finished and Arnold has the permission of the maker to chime in, or the maker can share their two cents, that would be a great source of valuable information.

    Hopefully Arnold and a bunch of our other luthier friends can jump in here too. I am vaguely aware that there are some guidelines in place about what makers and shops can and cannot say about their own instruments, but I think a discussion about different construction methods should hypothetically be within the allowed boundaries?
  7. Lee Moses

    Lee Moses

    Apr 2, 2013
    One thing I found interesting in that article that I don't recall ever considering before was the difference between sitting or standing with a flatback vs. a roundback.

  8. Eric Hochberg

    Eric Hochberg

    Jul 7, 2004
    There are threads dealing with the issue of sitting damping sound, but I'm not sure about the fb vs rb distinction being addressed.
  9. MikeCanada


    Aug 30, 2011
    Toronto, ON
    I have heard that flatbacks suffer more from dampening, but it really depends on how you sit with the instrument. If you sit on a higher stool "beside" the instrument in what resembles a modified standing posture, with the right leg fairly straight, your left foot on a rung and your left leg behind the instrument, there is a potential for a lot of contact there. Typically the point of contact is around the middle of the back, which would be the worst/most (negatively) effective place for contact to occur. On a roundback bass, a lot of players have the side of their knee in contact with the top of the arch, and that is the only contact. On a flatback with a similar posture some players have the majority of their leg against the back of the bass. If that was your chosen posture, it could potentially have a significant dampening effect on the instrument on a flatback, and potentially less so on a roundback.

    People who sit lower and/or more behind the instrument, tend to have less contact with the instrument, and it tends to be towards the ribs. My left knee cap is against the back of the instrument just inside the bottom treble side corner, and my right leg slightly touches the bass side rib. My only other point of contact is up very close to the neck block on the canted back against my chest. I don't see that as much more contact than I would have if I was to stand with the instrument, so I don't see a flatback being particularly troublesome in that case.

    It definitely seems like an issue that would negatively effect the experience of a flatback for some players, but would be inconsequential to others. Not something to be disregarded, but definitely a personal preference based on playing posture. While it might be a deciding factor for one buyer, it could be completely irrelevant to the next.
  10. powerbass


    Nov 2, 2006
    western MA
  11. Jake deVilliers

    Jake deVilliers Commercial User

    May 24, 2006
    Crescent Beach, BC
    Owner of The Bass Spa, String Repairman at Long & McQuade Vancouver
    Eric posted that link in the second post of this thread!

    That 'study' is as full of holes as their 'study' of bridge adjusters. In the immortal words of Wayne Gretzky, its "a crock of crap!"

    However, Arnold Schnitzer's thoughtful comparison (also in Post #2) is an informed essay on the topic. Really, I think only a builder with many years of experience even begins to be qualified to address the question.

    It takes a long time (and an open mind) to see the arcs that connect the different attributes of stringed instrument construction because of the lack of continuity between one instrument and the next.

    This piece of wood sounds completely different from that one, even though they both may be, say, Sitka Spruce from Haida Gwaai, let alone the differing shapes of the arching and re-curve, the graduations of the top, the shape, weight and frequency of the bass bar, etcetera...
  12. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    My flatback just happened to be the best sounding pizz bass in the shop on the day I bought her. If there was a carved back bass that sounded as good at the price I might have made another choice, considering long term maintenance concerns. That said, no problems at all in five years. Basses break. Buy the one you like, humidify it in the winter and sleep well.
  13. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    And I live in Kansas where the saying is, 'if you don't like the weather be patient because it will change tomorrow'. 60 on Sunday and 10 yesterday.
  14. Lee Moses

    Lee Moses

    Apr 2, 2013
    I don't think I've ever lived anywhere where some form of that wasn't a common saying. In Texas it was typically, "If you don't like the weather in Texas, just wait a few hours...you will."
  15. hdiddy

    hdiddy Official Forum Flunkee Supporting Member

    Mar 16, 2004
    Richmond, CA
    I think this is a great point. It also explains why I've heard that some people complain about Flatbacks are too nasal. it's probably because they're dampening the back.
  16. MikeCanada


    Aug 30, 2011
    Toronto, ON
    Any of the experiments I have heard of where people try to make similar instruments except for one variable (I knew a violin maker that experimented with treating her wood in various brine mixtures) usually yeild, "I did what I could to keep everything the same, but there's just too much variation in the wood." Long story short, the violin experiment was pretty much a bust. The maker said that although she kept all the graduations the same on each instrument, even though each of the tops came from the same log, some needed different graduations because the wood just responded differently. I think she ended up taking them all apart and re-graduating. She said she learned a lot by trying to make four exact copies, but anything she "learned" about treating the wood was negligible.

    It makes sense that it's really difficult to isolate the "results" of a flatback from a roundback from the individual instruments. Attack, tone, projection, and a bunch of other factors that we attribute to one back or the other are very easily influenced by the setup of the bass, strings, and technique, and are all pretty subjective. While you can often get multiple players to agree one particular bass is "a cannon" every single one of those players might speculate a different reason for it. And every one of them might be right. If we had figured out that a rib depth of 8 1/2" tapering to 6" with a roundback, violin corners, 42" string length and a lion head instead of a scroll was the recipe for "bass CANNON", then bass likely would have been "standardized" like violins and cellos largely have been.

    On the flip side, not everyone wants a cannon, and preference is very qualitative, not quantitative. As much as I would like a definitive list of characteristics, pros and cons, etc. and I really don't like "every bass is different" as an answer, it might be the only right answer. If/when I do commission a bass, I will have to consult with the maker and cross that bridge when I get there.
  17. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    This has been an interesting discussion. I'll refrain from commenting on the acoustical studies. I have so much to say that I'd rather pass. :)

    Answering the fundamental (pun intended) question really comes down to the ratio of between to within variances. Now in English. Suppose, for the sake of argument, that there are true, underlying differences along some relevant dimension between flatback and roundback basses. How could you tell? In order to see the differences, the variance within a group of flatback basses and within a group of roundback basses along the dimension of interest would have to be small (enough) relative to the variance between groups of basses on that same dimension. Good luck!

    We all know that there is huge variance among flatback basses and among roundback basses. I gotta agree with Jake here. The only real shot you have here is to consult luthiers who can draw on their experience with huge sample sizes and who can say that, "in general," flatbacks tend to have these characteristics, while roundbacks have those characteristics. Any individual exemplar might or not fit expectations based on that.
  18. jmpiwonka


    Jun 11, 2002
    the easiest thing to do here imo (and especially soundwise), play the basses you're interested in and choose the bass that you connect with.

    as for stability, it seems it's pretty much accepted opinion that roundbacks are more stable than flatbacks.

    if you're having an instrument made, then it'd be best to ask the builder what they feel the differences are in their roundbacks and flatbacks.
    also ask them about the stability of the instruments.

    btw, i do think the link to the AES page is probably the best explanation out there. it's the one that seems to make the most sense to me atleast.
  19. bucephylus

    bucephylus Supporting Member Commercial User

    Aug 18, 2002
    General Manager TecPadz LLC
    Well, almost nothing is the same from instrument to instrument, IME. So, I would personally go with trying individual instruments for what I was after and pretty much ignore the construction on the back vs response and tone of the individual instrument. My 0.019 cents anyhow.

    That said, I have discussed this aspect of the construction at some point in the distant past with Steve Reiley. His position was that from the stability standpoint, using proper bracing etc techniques, either construction could be equally "stable," whatever that is; and allowing for the vagaries of instrument to instrument variation, climate variability, and user care. Those things aside, Steve's view was that the flatbacks tend to have a bit more projection capability with the back acting more like a trampoline, while the carved backs tend to be a bit more complex and darker.

    Don't know if that helps, but, that's my understanding.
  20. MikeCanada


    Aug 30, 2011
    Toronto, ON
    Well said Dr. This why I am hoping to hear from some luthiers on this topic, even if their responses boil down to "tend to" "often" "general" type comments about characteristics. I don't want to call out specific makers/shops because I don't think it is fair to put them on the spot like that, but there are a few out there that offer the "same" instrument with a roundback or a flatback option. Although there are plenty of other variables at play here as we have discussed, it isn't a huge leap for me to assume that those makers/shops have at least a few vague characteristics they attribute to one or the other.

    From what I have gathered in browsing the websites of many different makers/shops, it is standard practice for a player commissioning an instrument to have a fairly in depth conversation about what they desire in the bass that results from that commission. Obviously some of those are aesthetic choices like individual tuners vs. plates or lighter and darker finishes. Some of them are more "practical" choices like string length, D vs. Eb necks, and/or an extension, which do have their tonal repercussions as well. Makers also talk about the characteristics of wood selection, and how there are differences between Maple, Poplar, Willow, and other woods for backs and sides. I understand that how a top is graduated and how an instrument is setup are two of the most agreed upon factors in what the end result sounds like, my curiosity extends to some of those other less agreed upon factors.

    It makes sense to talk to the specific maker about what they feel the differences are on their instruments. I was hoping to get a few of them to chime in here. In the "basses already made" market, playing as many of them as you can and deciding on the bass that best meets your needs, regardless to some preconceived notion that flatbacks sound like this or roundbacks sound like that is very sound advice. In the "I'm considering commissioning an instrument and this is one of several choices that I will have to make that could impact the bass that results from those choices" market, it would be nice to have a few characteristics to help make some of those decisions.

    Maybe I'm extremely paranoid about commissioning an instrument and the resulting bass not being "the one" for me. Maybe a commission isn't for me?