LK155 Posted July 14, 2011 Share Posted July 14, 2011 Been thinking about some kind of stand for my amp. Wanted to get it up off the floor a bit, but without losing any of the low frequency response associated with it sitting on the floor. In fact, I wanted to see if the lows could be augmented somehow. Researched a bit and found an interesting product called the Sound Enhancer, which unfortunately is no longer available. But the concept looked reasonable (route the sound waves coming off the back of the speakers through a folded horn, projecting out the front of the box) and I decided to build my own version. Voila. This is more of a prototype than anything else, a proof-of-concept contraption. It cost me all of $5 (had to buy a box of wood screws), as it was built from scrap wood I had lying around. Mostly 1/2" plywood, which doesn't really give you that fine-furniture look. Used a piece of MDF shelf stock for the piece the amp sits on, as it already had a nicely rounded and finished front edge. The black around the opening is just sticky-backed weatherstrip foam and is intended to provide a seal between the back of the amp and the box opening. I think it's going to take about 3 layers of this stuff to make an effective seal. The triangular piece you see is a brace connecting the back, the sloping part of the horn, and the bottom. The amp just sits on the stand like this.....still lots of room for rear switch access and tube ventilation. I didn't tip the amp back nearly as far as the Sound Enhancer models do, just enough to aim the speakers towards my head rather than my knees. To my astonishment, the thing actually works. It increases the volume of the amp significantly (not what I was after, but it's not a bad thing either). Using a drum machine for a source, my SPL meter shows the box adds about 9db to the level. Fortunately, the increase is nowhere near that drastic when a guitar is the source. But it definitely colors the amp's sound. Not sure how to describe the difference except to say that it seems fuller and somehow has more clarity. Here's a sound clip: http://soundclick.com/share.cfm?id=10851530 The first 20 seconds are with no stand, just the amp sitting on the floor. The last 20 seconds are using the amp sitting on the stand, with absolutely nothing else changed: same guitar (H535), same pickup (neck), same pot settings (all maxed), same amp volume and tone settings, same mic position, same recording level. I'm going to experiment a bit with insulation material on some of the box's inner surfaces. Want to tame some of the volume increase without giving up the increased low frequency response. I might also reduce the size of the horn's front opening. So this is a work-in-progress. Was a fun project. If I can get it tuned to my satisfaction, I may just build another version using something more presentable, like cherry or maple. If any of you HOC'ers are interested, I could probably build you one for, oh, about $5000. Link to comment Share on other sites More sharing options...
JeffB Posted July 14, 2011 Share Posted July 14, 2011 Thats completely awesome. Can hear a difference in sound as well. Nice work. Link to comment Share on other sites More sharing options...
DetroitBlues Posted July 14, 2011 Share Posted July 14, 2011 That looks really nice...I can't wait to hear the sound clips when I get home. Link to comment Share on other sites More sharing options...
big bob Posted July 14, 2011 Share Posted July 14, 2011 Great job, I love a DIY... Link to comment Share on other sites More sharing options...
mars_hall Posted July 14, 2011 Share Posted July 14, 2011 I would be interested in where the mic was relative to the cone in each set of recordings. Just from listening, I would expected you had a more straight line (center of the lobe) to the mic on the 2nd half of the recording, since it appears to have greater high-frequency response. The 2nd half having more high-end is opposite of what I would have expected, since the horn should have provided more phase cancellation of the higher frequencies. Link to comment Share on other sites More sharing options...
Guest HRB853370 Posted July 15, 2011 Share Posted July 15, 2011 Been thinking about some kind of stand for my amp. Wanted to get it up off the floor a bit, but without losing any of the low frequency response associated with it sitting on the floor. In fact, I wanted to see if the lows could be augmented somehow. Researched a bit and found an interesting product called the Sound Enhancer, which unfortunately is no longer available. But the concept looked reasonable (route the sound waves coming off the back of the speakers through a folded horn, projecting out the front of the box) and I decided to build my own version. Voila. This is more of a prototype than anything else, a proof-of-concept contraption. It cost me all of $5 (had to buy a box of wood screws), as it was built from scrap wood I had lying around. Mostly 1/2" plywood, which doesn't really give you that fine-furniture look. Used a piece of MDF shelf stock for the piece the amp sits on, as it already had a nicely rounded and finished front edge. The black around the opening is just sticky-backed weatherstrip foam and is intended to provide a seal between the back of the amp and the box opening. I think it's going to take about 3 layers of this stuff to make an effective seal. The triangular piece you see is a brace connecting the back, the sloping part of the horn, and the bottom. The amp just sits on the stand like this.....still lots of room for rear switch access and tube ventilation. I didn't tip the amp back nearly as far as the Sound Enhancer models do, just enough to aim the speakers towards my head rather than my knees. To my astonishment, the thing actually works. It increases the volume of the amp significantly (not what I was after, but it's not a bad thing either). Using a drum machine for a source, my SPL meter shows the box adds about 9db to the level. Fortunately, the increase is nowhere near that drastic when a guitar is the source. But it definitely colors the amp's sound. Not sure how to describe the difference except to say that it seems fuller and somehow has more clarity. Here's a sound clip: http://soundclick.com/share.cfm?id=10851530 The first 20 seconds are with no stand, just the amp sitting on the floor. The last 20 seconds are using the amp sitting on the stand, with absolutely nothing else changed: same guitar (H535), same pickup (neck), same pot settings (all maxed), same amp volume and tone settings, same mic position, same recording level. I'm going to experiment a bit with insulation material on some of the box's inner surfaces. Want to tame some of the volume increase without giving up the increased low frequency response. I might also reduce the size of the horn's front opening. So this is a work-in-progress. Was a fun project. If I can get it tuned to my satisfaction, I may just build another version using something more presentable, like cherry or maple. If any of you HOC'ers are interested, I could probably build you one for, oh, about $5000. I'll offer $5001.00 just cuz your an HOC member. BTW, I still the sound enhancers pop up in ebay! Link to comment Share on other sites More sharing options...
LK155 Posted July 15, 2011 Author Share Posted July 15, 2011 I would be interested in where the mic was relative to the cone in each set of recordings. Just from listening, I would expected you had a more straight line (center of the lobe) to the mic on the 2nd half of the recording, since it appears to have greater high-frequency response. The 2nd half having more high-end is opposite of what I would have expected, since the horn should have provided more phase cancellation of the higher frequencies. You're right on. When the stand was not being used, the mic was positioned two feet from the front of the amp, two feet off the floor. This is actually above the speakers' line-of-fire. I didn't move the mic, so setting the amp on the stand moved it closer to the mic by about 6 inches, higher by about 9 inches, and because of the slight tip-back, made the speakers more on-axis to the mic. So, yes, more high-end seems logical. What I should have done for both samples is to have the mic much further away from the amp, in order to minimize those positioning changes, and just turn up the amp volume to get a good signal level. Getting a high level in my relatively small music room is not a challenge, as the Vibrolux can generate over 100db with the volume on 3/10. I would suspect that more volume would accentuate the properties of the stand, since more air would be moving off the backs of the speaker cones and through the horn. Will have to try that. Link to comment Share on other sites More sharing options...
mars_hall Posted July 15, 2011 Share Posted July 15, 2011 What I should have done for both samples is to have the mic much further away from the amp, in order to minimize those positioning changes, and just turn up the amp volume to get a good signal level. Getting a high level in my relatively small music room is not a challenge, as the Vibrolux can generate over 100db with the volume on 3/10. I would suspect that more volume would accentuate the properties of the stand, since more air would be moving off the backs of the speaker cones and through the horn. Will have to try that. Not suggesting you do this, but thought I'd provide this for reference. When they characterize speakers for comparison in an anechoic chamber, they have the speakers/targets stationary and sweep a microphone in a 180 degree arc across the projected plane of the cone with identical input levels. Typically the arc is 1m out from the center. The arc stops in 10 degree increments for measurements and at each increment, the frequency is swept low to high with the results being recorded and plotted. What you could do though for grins and crude comparison, were you so inclined, would be to measure the distance from the top of the cone to the bottom of the stand (i.e. floor) with the amp in stand and place the mic at the midpoint of this height for recording at a fixed distance from the speaker. Record this. then repeat without the stand but having the amp sitting on books to elevate the top of the cone to the same previous height, while maintaining the same mic mid-point and distance. The axis would be off a bit, but the results would be a bit more accurate for comparative purposes. An idle mind can think of all sorts of things for others, not themselves, to do. ;p Link to comment Share on other sites More sharing options...
fxdx99 Posted July 15, 2011 Share Posted July 15, 2011 Nice job, Lyle. Love those BF Vibrolux's - great amps. And "fuller with more clarity"... oh yeh! Link to comment Share on other sites More sharing options...
LK155 Posted July 15, 2011 Author Share Posted July 15, 2011 Take 2. I put some sound-deadening material on the inner back and sloped part of the horn. It's called SONOPAN, a 7/8" thick paper-based product, and is what is installed between the wall studs and drywall in my room (had some left over). Also added another layer of sticky-backed weatherstrip around the entry. And tried to get a more consistent basis for the no stand/stand recordings. This clip has the first run through the progression without stand, but with the amp elevated and tilted exactly the same amount as the stand would have. The mic was positioned at the height of the middle of the cones, 1 meter away, aimed at the amp's midpoint. The only change on the second part of the clip is that the amp was sitting on the stand. I did some SPL readings again, and it appears the SONOPAN has eliminated most of the volume increase caused by the horn. And the increased low end is still there, which is good. Here's the clip...... http://soundclick.com/share.cfm?id=10854842 The differences between no stand/stand on this clip are very subtle. On the stand, the low-mids are better defined, with less shrillness overall. On my sample clip, I only played the low E string twice, so the increased low end isn't particularly noticable. I think the mic positioning is a factor too, because just sitting here noodling around, the bottom end is much more pronounced when using the stand. So not a huge difference, but 'fuller and with more clarity' just about sums it up. I know what you're thinking. Yes, I have too much time on my hands. Link to comment Share on other sites More sharing options...
JeffB Posted July 15, 2011 Share Posted July 15, 2011 nice chords can hear a little difference but they both sound good. Just a little different. Being in the same room would be a different listening experience again. Link to comment Share on other sites More sharing options...
Steiner Posted July 15, 2011 Share Posted July 15, 2011 Peter Minerex would be proud! This is a cool idea; well executed too. Link to comment Share on other sites More sharing options...
smurph1 Posted July 15, 2011 Share Posted July 15, 2011 Thats completely awesome. Can hear a difference in sound as well. Nice work. Yep..Sure is..You Da man!! Link to comment Share on other sites More sharing options...
smurph1 Posted July 15, 2011 Share Posted July 15, 2011 Great job, I love a DIY... Yeah..That looks WAY BETTER than my "Hillbilly Pedalboard"..LOL Link to comment Share on other sites More sharing options...
Trouble Posted July 16, 2011 Share Posted July 16, 2011 That's very cool and not at all what i was picturing from the title. The bar I'm playing at tonight we play on a slab outside and I usually set my amp on a stump at the back of the slab. I was expecting something like that when I read the topic description. Link to comment Share on other sites More sharing options...
FredZepp Posted July 16, 2011 Share Posted July 16, 2011 Very cool... I've seen those, of course, but how cool to craft one of these stands yourself. A very interesting post... pics, description, and clips. Thanks. There are all kinds of small details that you could work with to fine tune one of these. Link to comment Share on other sites More sharing options...
bolero Posted July 16, 2011 Share Posted July 16, 2011 hey that's cool!! I'm stuck with chairs & milk crates Link to comment Share on other sites More sharing options...
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