Ian
361 posts
Jun 19, 2016
12:38 PM
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Some of my harps blow bend really easily... like butter, regardless of the key, whilst some are really tricky.
Whats the optimum gapping etc for an easy blow bend?
Please note I am not confusing overblows with blow bends.
Cheers!
Last Edited by Ian on Jun 19, 2016 3:28 PM
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SuperBee
3869 posts
Jun 19, 2016
3:06 PM
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Great question that I still wonder about.
My best advice is to carefully observe those which you find easy and try to replicate that. If it works, cool. If it doesn't, take another look and see if there is some other factor beyond the gaps.
I've been doing this for several years and still find 9 and 10 reeds can be hard to get just right. But I get serviceable top ends now. Still have some better than others though, especially the 10 and 10 half step.
But careful observation is a good start. The position of the draw reed relative to the blow reed is a big factor.
I tongue block the blow bends up as far as 10 blow on the D harp, and maybe set the reed a fraction wider as a result. But I've found the gaps at the tip are not always the biggest factor. As in, there is a range which work fine. But the overall set up of the reed is important. It's not uncommon to find twists in reeds. Getting those out...shims, counter pressure. Sometimes a new reed. And reeds off centre in the slot. Also not uncommon. Even in Suzuki. I'm not talking about parallel alignment, although that also can be a factor. I mean a reed closer to one side.
Working with the tiny reeds is not so easy. They are stiff and also delicate.
But observation and replication is the starting point I think
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Ian
362 posts
Jun 19, 2016
3:31 PM
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Thanks for the advice sb.
Glad it's not just me. I have a couple of seydels and hohners that can hit all the blow bends pretty easily, one hohner in C is particularly easy, even the two steps in the 10, I'll try to analyse the gap etc on that and see what the deal is. Like you said though it's hard working with such small reeds ...
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SuperBee
3870 posts
Jun 19, 2016
3:48 PM
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I dread it sometimes...I get a D harp someone specifically wants me to fix the 10 blow on...shudder...
But...
The more i do, the better i get with it.
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Killa_Hertz
1608 posts
Jun 19, 2016
6:54 PM
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I suck at blow bending, but i also haven't put a ton of time into it for i don't have much use for the top notes. I really only play second positon right now. So they are relatively useless to me at this point.
But yes i would say observe the good ones. And tinker.
Remember that the reeds are relational. So if you move the blow reed it effects the draw reed. And the reed your using to bend on the blow bend is the draw reed.
I'm sure you know that, but incase you didnt.
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SuperBee
3871 posts
Jun 19, 2016
7:55 PM
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Sometimes maybe the shape of the reed plate is in issue. You may have a super flat comb...or not...and maybe the reed plate is not super flat but deforms when you attach it to the comb...so what you thought you did to the reed no longer looks that way...but you can't quite see it when assembled.
Anecdote: my A crossover, when I first got it. I don't remember the problem but I had it apart presumably to adjust a gap.
Put it together and one of the reeds in the 2nd chamber wouldn't sound. Took it apart, adjusted. Put it back on the comb, held covers in place and played. Great. Put the bolts in. Wtf? Same problem.
A bit more to and fro and I realised that it was all good until I inserted/tightened the cover plate bolt, rear left.
Pragmatic me, just left the bolt out, but clearly there was either the comb or reed plate deformed when I tightened that bolt. I've never addressed it and I think it's 5 years later...must go back and take a look now I've learned some more...
But the point..that sort of thing is probably happening to various degrees quite often, and sometimes at the top end. Maybe it accounts for some cases where no end of reed adjustment seems to get it right.
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Bike&Harp
13 posts
Jun 19, 2016
8:04 PM
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Those high blow bends on #10 are really rough on higher key harps! On my C i can get them good but on the D it's really hard to get them and to get them in tune is a bear! I can get them on the other high holes but 10 is sooo hard.
Bee: Yes i heard a tech guy say that on a video. You adjust something and play the harp with the covers off and then the act of screwing the covers on could just deflect the plate enough to throw the adjustment off! aaaaargh!
Last Edited by Bike&Harp on Jun 19, 2016 8:07 PM
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Killa_Hertz
1609 posts
Jun 20, 2016
5:26 AM
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Yes i mentioned that in the other thread. Make sure you get your reed plates and combs as flat as possible.
And do this obviously Before you do the reedwork.
Even with everything flat you still have to be careful not to overtighten.
You can also Make small adjustments with the harp together if you have to.
The thing i find the most bothersome is cross hole leakage. Meaning the plate is bowed in between the 2 and 3 hole (for example) so the leakage isn't from the issue of the harp, but rather from inside. It's annoying. But these are the things you can fix with a relatively small amount of work.
BLOWBENDS ... I practice my blow bends on my low harps. The upper octave on a low C plays just as easy as the low octave on a regular C. For what is Worth.
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Ian
363 posts
Jun 20, 2016
3:26 PM
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Yeah it's definitely only a problem in a few of my harps. I struggle, probably as most do with anything above a D, but it's a bit hit and miss with the others.
I've opened the gaps a bit on one seydel in C that was being tricky and that seems to be easier now. I think it was so tight it was choking, as if to overblow...
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Bike&Harp
14 posts
Jun 20, 2016
8:11 PM
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How do you get reed plates and combs flat? I've heard people talking about this but i don't know what they mean really. Aren't the plates properly flat when you get a decent quality harp? What about SP20 combs? Those are plastic you can't do anything to them can you? Like i say i've heard of this but don't know about it. LOL!
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SuperBee
3872 posts
Jun 20, 2016
8:45 PM
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Some plates are pretty flat, some are bowed. They are made of brass or 'German silver' and the manufacturing process subjects it to enough pressure to bend it a bit, and some parts of the original blanks were probably less than dead flat to begin with.
We're talking tolerances here. Most harps are fine but some are not.
Reeds are a much bigger deal than combs and plates. But sometimes when a reed just won't behave, maybe the flatness of the plate/comb is a factor. I think air leaks resulting from this are less significant than deformities which affect how the reed relates to the slot, generally. But it's only a hypothesis.
Last Edited by SuperBee on Jun 20, 2016 8:46 PM
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SuperBee
3873 posts
Jun 20, 2016
11:44 PM
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I mean air leaks are important and the bigger they are, etc
And I was thinking don't worry about sp20 and other 'hollow comb' harps, because you can't effectively 'flatten' the comb. But the question of reed plate 'distortion' could still be in play.
I've had harps in here done up so tight I thought I might strip out the head (trying to take them apart) Doing them up too tight is really bound to cause trouble I think
Last Edited by SuperBee on Jun 20, 2016 11:46 PM
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Killa_Hertz
1619 posts
Jun 21, 2016
5:09 PM
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Flattening reed plates.
https://youtu.be/N19__ef5_D4
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Last Edited by Killa_Hertz on Jun 21, 2016 5:09 PM
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Bike&Harp
15 posts
Jun 21, 2016
6:28 PM
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Killa: Thanks man that helps me out a lot. I never knew how to do this. I'd heard people talk about it but i was never sure what they meant and how to actually do it.
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SuperBee
3878 posts
Jun 21, 2016
6:46 PM
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Yeah, that stuff doesn't do much for a hollow comb harp IMHO. I mean, yeah do it by all means but it won't make your sp20 or other hollow-comb harp play better as far as I can tell. Solid combs, yep ok, I can see the case.
But..."I think"..The real reed plate flatness problems are things that sandpaper won't fix. Those front-to-back bows is where the action mainly is...that's what I'm thinking right now. For sure there are little bumps that you can get out with paper and I'm sure there's an incremental benefit, but I don't think it's such a big deal. Really. It's easy to do so of course why not do it...but I'm not sure what it really does or tells you. Whereas the plates that have bows which remain or change when screwed to the comb might actually have a real negative impact on reed performance.
I mean...I can play a chromatic with no wind savers and it just takes some more air. And I think the tiny gaps from a slightly uneven plate to comb mating are less significant than that.
But if the plate moves, changes shape when you bolt it to the comb...that's gonna change the relationship of the position of reed to slot...potentially. And that is gonna have a direct effect on how that reed plays...
But I'm speculating. It's a new thought for me, that I'm still dealing with...I haven't really tested it much yet, I'm just thinking that 'reed plate flatness' is possibly a slightly different issue to what you get from sanding
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Killa_Hertz
1621 posts
Jun 21, 2016
9:04 PM
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Well heres the deal. I straighten my plates the best i can before flat sanding. I even get inbetween the slots if its off in there.
Then as you start to sand, Make a few passes and then check the pattern on the bottom. This will tell you where your still off. The spots that arent scuffed are your high spots. So fix that accordingly and sand again, but in a different direction so it leaves a distinct pattern over the old one incase you somehow raised a new spot that was previously low enough to get sanded.
Anyways repeat this until you have no more high spots. Then give it a good sand in a figure 8 pattern then spin 180 degrees and figure8 again. Repeat as needed to get a good flat surface, being careful not to push the reeds in thru the slot. If they get sanded the tuning is obviously shot.
I go from 180-220ish Up to 400-600ish. So you end up with a decently pollished bottom .. flat plate. Do this to the comb aswell. Make sure it's flat. Dont put uneven pressure in it. After you do this enough times it can be done in a few minutes. But take your time the get used to it and dont rush.
This will (believe it or not) make a pretty big difference if done right.
Flatsanding along with a little reedwork will make a Night and Day difference in your harp.
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SuperBee
3879 posts
Jun 21, 2016
10:57 PM
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Yeah, I know...I've lost track of how many I've done...but I'm just not convinced. I always do the reed work anyway...and when I replace a solid comb, or put a new reed in a plate that's going on a solid comb (without divots) I have to sand the plate to remove the rivet bumps. But you know, I've worked on a heck of a lot of harps now, and I'm ambivalent on the topic of 'flat sanding' as a performance enhancement technique. I do expect there'd be an improvement but I'm just not sure how much. I've never taken a harp and 'only' flat sanded. I think that's what I have to do.
I'll have to find a harp I can test it on. I'm just not quite sure how to test 'only' flat sanding, without changing anything else, and I'm also not sure how to measure the difference.
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SuperBee
3880 posts
Jun 21, 2016
11:09 PM
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I think for the purpose of experiment...I have to use one of these marine bands I have which are on the original comb. But if I remove the reed plates I might bend them. I need a harp that's already screwed together so I can just take the Reedplate off and sand it, then put it back. I have some promasters but they are all terrible and I'm sure that flat sanding won't make enough difference to detect. I think it has to be a harp which is at least playable but could be better. I can't think what I have that might fit the bill. MS blues harps maybe?
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Killa_Hertz
1622 posts
Jun 22, 2016
2:59 AM
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I think the promasters might be the perfect thing. Because apparently the big beef with the promasters are
1 the saw marks on the aluminum comb
2 the leakage between holes 2 & 3 that really kills the bottom end response.
I find that Alot of my Manjis have the leak between the 2 & 3 reedslots. It totally kills the harps bottom end. With this fixed and the right reedwork, its like a new harp
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SuperBee
3881 posts
Jun 22, 2016
7:55 AM
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These promasters are not worth a pinch of shit. I think sanding the plates would make sfa difference to them. Like...they're beyond understand of how bad a harp can be. Just dreadful.
So I can try flat sanding a Reedplate. And use original comb. Then throw that thing in the ballast box, and use a Zajac comb which I have all ready to go.
But I have to do this without touching the reeds.
Or...I can try and get the reeds right...
But I already know these harps totally suck...I dunno...I guess I'll try it and see if I come up with a better idea. Mr Kinya Pollard gave me an interesting idea today, which is to fit the promasters covers to a special twenty. He reckons that is a good combo.
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Ian
364 posts
Jun 22, 2016
10:14 AM
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I have one promaster in C which I got on Amazon dirt cheap. It's really good... I wouldn't buy any more as I think it's the exception rather than the rule, but it's ultra airtight and plays very well , barely needed gapping.
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Tiggertoo1962
150 posts
Jun 22, 2016
12:43 PM
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Bee - an MS BH would be the ideal harp to try it on. First one I got, I flat sanded the comb and draw plate without doing anything else, and found it made an appreciable difference. Been trying to gap it to my satisfaction since, but I just can't get it quite where I want it.
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One of the last of a dying breed.
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SuperBee
3883 posts
Jun 22, 2016
3:21 PM
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Hmm...I think I can't sand the comb in this experiment. Or I have to do both things to separate harps. My question is about the efficacy of reed plate sanding. If I do gapping as well, I don't know what made the difference. If I sand the comb and the reed plate I cant say how important it was to sand the reed plate. If I replace the original comb with a guaranteed flat comb, I need a reed plate without obvious bumps...I mean from the rivet heads. My suspicion is that the main reason to sand a draw plate is to remove the rivet bumps when replacing with a comb lacking divots to accommodate said bumps. My promasters are so old they are from before Suzuki began spot welding reeds. They are riveted.
I think this probably becomes incrementally more significant as the other opportunities for air to enter and exit a chamber diminish. Eg, gaps reduced, slots sized to smaller tolerances.
I know everyone fits a new comb or flattens their existing comb and sands thevreedplate as part of the deal and then says it made a big difference...I don't doubt that, I just wonder how much of that comes from the Reedplate.
And the more I think about I see my interest is really only incidental to a different question I'm thinking about which is related to the question of reed plate flatness (as distinct from 'smoothness'.
I've been thinking about this for a while...let me tell you about MasterHarp.
MasterHarp is a tuning table, prototyped and initially built by Dick Sjoeberg. The idea is you lay your Reedplate on the table and then can hear individual reeds and combinations by opening slider valves. In theory this allows you to tune chords and octaves without having to stop and move the work while you check progress.
The plate however plays differently on the table than when assembled on a harp. And my experience has been that there is no consistency in the variation. On reed may play 10 cents sharper on the table than on the comb. 3 reeds may play exactly the same on both, some may play lower on the table than the comb. And this varies from plate to plate. It's not predictable.
I came up with a workaround and the table is still a useful platform for me, but I can't tune chords on it very often so not quite what I'd hoped...but my interest is not in the usefulness of the tool, rather it's in understanding why the Reedplates behave the way they do.
I'm hypothesising it's about air leaks. I've seen plates on a comb also behave very oddly and inconsistently. And some plates I've had on the table almost do play consistently end to end. I suspect they are the flattest reeds.
Those who have used the Zajac 'French tuner', note what happens if there is an air leak...the reed plays quite a different pitch. On sp20 plates for instance you must ensure you cover the holes in the plate around certain slots. So there is a clue in that about the effect an air leak can have on tuning.
Basically what I'm saying is that when you sand a draw plate, there's a good chance that the pressure applied in the process distorts the reed plate and that what you see as a nice smooth shiny surface may not mean you have a nice airtight fit against the comb. Yes, there are the common low spots around 1 and 2 draw, and up the high end between chambers, and on harps with a cover plate groove there'll be a noticeable shadow...and you can work to smooth those down...I just doubt it is all that effective. What I'm saying is...probably if you think it's important, that may not be the place to stop and feel satisfied.
I'm not saying 'don't do it'. I'm just dubious that it's very effective in itself without other reed-plate flattening work. And I'm thinking about the best way to do that other work
Last Edited by SuperBee on Jun 22, 2016 3:24 PM
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