Anybody got any experience with a really good harp amp? One of the guitar players in my band has inherited the harmonica duties and I'd like to try and make him a nice one.
What makes a good one?
What is the best type of speaker? Closed or open back? It seems to me that closed back might overdo the bass side of the equation...
The only schematic I've found purporting to be for a harp amp is a little "Princeton" type of affair offered in kit form by our brother-in-Christ, Ken Weber. And, of course, the '59 Bassman is supposed to be the end-all etc., but I'm looking for something a little more portable and not quite as loud. Maybe in the Deluxe range. We sometimes play big clubs but no stadia yet.
I've been told that the big bottles make good harp-amp-tubes, and even the 807 has been mentioned. My thinking, such as it is, leads me toward a single-ended amp.
Any thoughts on the subject?
Dave
Good Harp Amp?
Moderators: pompeiisneaks, Colossal
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titanicslim
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Good Harp Amp?
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)
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CaseyJones
- Posts: 856
- Joined: Fri Mar 17, 2006 1:29 pm
Re: Good Harp Amp?
Sonny Junior from Darn Sarf (down South for those of you without a drawl) builds a killer tweed Bassman set up for harp. Or check out Meteor (Komet for harp?!) from upstate New York.
There are a couple things to remember when working on a harp amp:
Harp players like old fashioned high impedance mics like Shure controlled reluctance or controlled magnetic elements. That's a CR86 element. They're hot as hell, the hottest guitar pickup is wimpy by comparison. These guys can get by with 12AU7s for the first preamp stages to tame the gain. OR use a 220pf snubber on V1 to exorcise the squeal.
Oddly enough bass amps work well. It may be counterintuitive but you don't want ANY top end to speak of, the amp should drop off sharply above 3.5 to 4khz. Too much top end makes it uncontrollable. Volume before feedback is the name of the game.
These guys are hyper traditionalists for the most part. There may be a hundred or so ways to skin a cat so to speak but they only want to know about ten of them.
There are a couple things to remember when working on a harp amp:
Harp players like old fashioned high impedance mics like Shure controlled reluctance or controlled magnetic elements. That's a CR86 element. They're hot as hell, the hottest guitar pickup is wimpy by comparison. These guys can get by with 12AU7s for the first preamp stages to tame the gain. OR use a 220pf snubber on V1 to exorcise the squeal.
Oddly enough bass amps work well. It may be counterintuitive but you don't want ANY top end to speak of, the amp should drop off sharply above 3.5 to 4khz. Too much top end makes it uncontrollable. Volume before feedback is the name of the game.
These guys are hyper traditionalists for the most part. There may be a hundred or so ways to skin a cat so to speak but they only want to know about ten of them.
Re: Good Harp Amp?
Hi Slim, I mod some amp's for harp, it's not that hard to do, you have to kill the input by adding bigger resistor's, those bullet mic's are hotter than H*LL ! LOL ! Just like Ol' CasyJones was talkin about !
They feedback easily if you don't hold the input back, the next thing is to get rid of a bunch of high's, on a B/F delux that normally has a 250 PF treble cap, I may endup with a 750 PF cap, maybe more, an .047 mid cap, .1 bass cap, on some Gibson's where I find a .01 coupling cap between stage's i'll up that to .02 mf to get more bass responce, if you play chromatic you may want more trble, just decrease the size of the treble cap to get more,
for less gain i use 5751's, 12AU7's,and i find Mullard's nice and dark, Amperex's strong and brighter, you can lower the voltage to your pre/amp tube's by adjusting your b+ dropping resistor's, plus adjust your Plate resistor's and cathode value's, i do find the 25 MF cathode cap's to be ok for harp, and bias to get the breakup at the vol. level you need !
I use Super's, Bassman's, Vibraverb's, Delux's for most of the guy's i deal with,
a S/E amp will not have much headroom for any Chromatic stuff, but would be great for the dirt,
Closedback would have booming bass, might be a problem,
for the best tone i've seen, the low wattage, Smooth cone speaker's from weber work great, Alnico 25 watter's seem to be what these guy's like, the darker the better, stay away from those that say screaming high's, your harp is loaded with plenty high's,
Only a few have anything on the web, most are just learning how to put vid's and mp3's up, here's 1 guy i've built 3 amp's for, I wish he had better video's up, but you can check him out,
http://profile.myspace.com/index.cfm?fu ... =246066421
Johnhenry
They feedback easily if you don't hold the input back, the next thing is to get rid of a bunch of high's, on a B/F delux that normally has a 250 PF treble cap, I may endup with a 750 PF cap, maybe more, an .047 mid cap, .1 bass cap, on some Gibson's where I find a .01 coupling cap between stage's i'll up that to .02 mf to get more bass responce, if you play chromatic you may want more trble, just decrease the size of the treble cap to get more,
for less gain i use 5751's, 12AU7's,and i find Mullard's nice and dark, Amperex's strong and brighter, you can lower the voltage to your pre/amp tube's by adjusting your b+ dropping resistor's, plus adjust your Plate resistor's and cathode value's, i do find the 25 MF cathode cap's to be ok for harp, and bias to get the breakup at the vol. level you need !
I use Super's, Bassman's, Vibraverb's, Delux's for most of the guy's i deal with,
a S/E amp will not have much headroom for any Chromatic stuff, but would be great for the dirt,
Closedback would have booming bass, might be a problem,
for the best tone i've seen, the low wattage, Smooth cone speaker's from weber work great, Alnico 25 watter's seem to be what these guy's like, the darker the better, stay away from those that say screaming high's, your harp is loaded with plenty high's,
Only a few have anything on the web, most are just learning how to put vid's and mp3's up, here's 1 guy i've built 3 amp's for, I wish he had better video's up, but you can check him out,
http://profile.myspace.com/index.cfm?fu ... =246066421
Johnhenry
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titanicslim
- Posts: 131
- Joined: Sat Mar 11, 2006 7:52 pm
- Location: Joplin, MO
Re: Good Harp Amp?
Good info, guys- thanks a bunch! 
That gives me a lot to think about, but it helps give me a direction in which to start. I'll be sure and try to include testing something like a 20 watt Fender bass amp.
Are tube rectifiers helpful in producing the desired tones? Seems to me I've heard something about bloom and sag being considered but...
Also, what about reverb, trem. etc.?
Dave
That gives me a lot to think about, but it helps give me a direction in which to start. I'll be sure and try to include testing something like a 20 watt Fender bass amp.
Are tube rectifiers helpful in producing the desired tones? Seems to me I've heard something about bloom and sag being considered but...
Also, what about reverb, trem. etc.?
Dave
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)
Re: Good Harp Amp?
Dave,Sometime's i put a S/S rect. and a tube on a switch for some guy's that want it, Benny like's the sag of a tube rect. and lower voltage on the preamp for blues,
reverb, trem, delay, I've seen it all used, got 1 guy that use'a an Arion SR-1 Chorus pedal, he get's like a Hammond B-3 type sound out of it, More are less i bet the sky's the limit on what you can or can't do,
Have fun,
Johnhenry
reverb, trem, delay, I've seen it all used, got 1 guy that use'a an Arion SR-1 Chorus pedal, he get's like a Hammond B-3 type sound out of it, More are less i bet the sky's the limit on what you can or can't do,
Have fun,
Johnhenry
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CaseyJones
- Posts: 856
- Joined: Fri Mar 17, 2006 1:29 pm
Re: Good Harp Amp?
Speaker setups: Most of the harp players I've built stuff for like 8" speakers. LOTS of 8" speakers! Mix 'em up. A mix of old ceramic Jensens and alnico Jensens work well. Or buy some Weber Sigs 'cuz the Jensens have become stupid expensive, I watched a Fender labeled Jensen go over $200.00 on eBay as a replacement for a Champ. Weber will sell you something better for $35.00 plus shipping so what's the point?
Semi-open back cabinets work well unless you can't find a spot onstage where the rig won't feed back. One jazz harp player I know uses a modded Twin, he tells me his hands go numb because he has to cup the mic so tight!
Harp players have driven the blue frame Eminence 1028 alnicos with paper voice coil formers out of sight. Again, a mix of alnicos and ceramics are the way to go, you want alnico for early speaker breakup then ceramic for some definition.
My buddy with the wall o' 8"s uses an old Masco P.A. head. I'm not up on Masco but I believe his is a late version that used 6L6s and miniature preamp tubes. The Masco is a cool amp, harp players have driven the prices up on them a bit but they're still dirt cheap compared to any flavor of vintage Fender. It's a P.A. amp so it's intended for use with a high impedance mic to begin with. It's cathode biased so I told him to swap the 6L6s for 6V6s, he also has a small arsenal of alternative preamp tubes. At jams there are guys who show up with their Sonny Juniors, they end up takin' turns playin' through the old Masco and all those little speakers.
Semi-open back cabinets work well unless you can't find a spot onstage where the rig won't feed back. One jazz harp player I know uses a modded Twin, he tells me his hands go numb because he has to cup the mic so tight!
Harp players have driven the blue frame Eminence 1028 alnicos with paper voice coil formers out of sight. Again, a mix of alnicos and ceramics are the way to go, you want alnico for early speaker breakup then ceramic for some definition.
My buddy with the wall o' 8"s uses an old Masco P.A. head. I'm not up on Masco but I believe his is a late version that used 6L6s and miniature preamp tubes. The Masco is a cool amp, harp players have driven the prices up on them a bit but they're still dirt cheap compared to any flavor of vintage Fender. It's a P.A. amp so it's intended for use with a high impedance mic to begin with. It's cathode biased so I told him to swap the 6L6s for 6V6s, he also has a small arsenal of alternative preamp tubes. At jams there are guys who show up with their Sonny Juniors, they end up takin' turns playin' through the old Masco and all those little speakers.
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titanicslim
- Posts: 131
- Joined: Sat Mar 11, 2006 7:52 pm
- Location: Joplin, MO
Re: Good Harp Amp?
Hey, I've actually got an old Masco! It's the ME-8. Pretty small (one 6L6) but still in one piece. Maybe I'll try it with harp before I scavenge it for parts!
Another thing I'll try is a cheap Celestion "MG" twelve-inch guitar speaker. Avatar was selling them super cheap a couple of years ago. Not much bass but their deficiencies actually work out pretty well for acoustic guitar. Might be worth trying in a harp amp.
Thanks!
Dave
(Hey, wait a minute! Casey Jones... John Henry... Titanic Slim...
Where the hell's Pecos Bill?)
Another thing I'll try is a cheap Celestion "MG" twelve-inch guitar speaker. Avatar was selling them super cheap a couple of years ago. Not much bass but their deficiencies actually work out pretty well for acoustic guitar. Might be worth trying in a harp amp.
Thanks!
Dave
(Hey, wait a minute! Casey Jones... John Henry... Titanic Slim...
Where the hell's Pecos Bill?)
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)
Re: Good Harp Amp?
Last year I built a 40 harp amp w/ reverb for a guy. I used a modified self-balancing parahprase PI as described in one of Gerald Weber's books to kill feedback. Works like a charm! When I get home today I'll try to remember to post an old Fender schematic and circle the resistor you substitute with a pot to make the feedback killer.
Rich Gordon
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
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titanicslim
- Posts: 131
- Joined: Sat Mar 11, 2006 7:52 pm
- Location: Joplin, MO
Re: Good Harp Amp?
Thanks Rich- I appreciate that! Even though I've never heard of one, it sounds like a good thing to haverfgordon wrote:Last year I built a 40 harp amp w/ reverb for a guy. I used a modified self-balancing parahprase PI as described in one of Gerald Weber's books to kill feedback. Works like a charm! When I get home today I'll try to remember to post an old Fender schematic and circle the resistor you substitute with a pot to make the feedback killer.
Dave
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)
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David Root
- Posts: 3540
- Joined: Fri Aug 04, 2006 3:00 pm
- Location: Chilliwack BC
Built One for Myself
Just finishing up a modified 5E7 tweed Bandmaster, with cathode bias pretty much to Class A. V1 & V3 are 12AY7s, 150V B+, V4 12AX7 (PI), 330V B+, pair of KT66s about 350V plate. Rectifier (V7) is a 5U4GB Oversized iron for cleaner bass and more of it. Kept the cathodyne PI. Hope to get about 25W out of it. V1-V4, V7 are all NOS.
I replaced the Normal channel with the Mic input from a Gibson GA40, so I can have Fendery triode tone and also greasy Gibson 5879 pentode tone. V3. Separate inputs, not footswitched.
Cabinet is the 5E7 cab but depth is an inch or so deeper for a bit better bass.
Two Weber 10A125 w/Alnico plug magnets, one Weber 10F125 ceramic magnet, each 12 ohms in parallel for 4 ohms. Some builders believe harp amp speakers need to be in parallel, not series-parallel.
I will probably have to tweak the bypass and coupling caps, and the treble tone circuit, but they are all quite a bit bigger than for guitar. PI coupling caps are 0.22 uF, for example.
I did a lot of research on the web. there are several good harp amp forums out there. Bruce at Mission Amps in Denver is a real guru harp amp designer and builder.
Haven't cranked it up yet, but that is coming.
I replaced the Normal channel with the Mic input from a Gibson GA40, so I can have Fendery triode tone and also greasy Gibson 5879 pentode tone. V3. Separate inputs, not footswitched.
Cabinet is the 5E7 cab but depth is an inch or so deeper for a bit better bass.
Two Weber 10A125 w/Alnico plug magnets, one Weber 10F125 ceramic magnet, each 12 ohms in parallel for 4 ohms. Some builders believe harp amp speakers need to be in parallel, not series-parallel.
I will probably have to tweak the bypass and coupling caps, and the treble tone circuit, but they are all quite a bit bigger than for guitar. PI coupling caps are 0.22 uF, for example.
I did a lot of research on the web. there are several good harp amp forums out there. Bruce at Mission Amps in Denver is a real guru harp amp designer and builder.
Haven't cranked it up yet, but that is coming.
Re: Good Harp Amp?
In the attached schematic, I've circled in red a shared resistor in the PI. If this resistor is substituted for a pot, either 100k or 50k plus 10k tail to ground, the pot becomes the feedback killer.
What you will find is that, for any given microphone, if the speaker phase is correct, with respect to the mic, then turning this control can kill feedback without changing volume. You might have to reverse the speaker leads to make it work.
When I built that harp amp, I cranked the amp and pointed my cheapest Radio Shrek mic right at the speaker to really get it howling--then I turned the control and the feedback instantly stopped.
As Gerald Weber explains it, this Self-Balancing Paraphase PI doesn't amplify both sides of the wave symmetrically. According to him, this control affects the magnitude of one side of the wave. Thus, if speaker phase is right with the controlled side of the wave, turning the control drops half the wave and kills feedback.
I've never scoped it to see if all that is true. I do know that the circuit works!
What you will find is that, for any given microphone, if the speaker phase is correct, with respect to the mic, then turning this control can kill feedback without changing volume. You might have to reverse the speaker leads to make it work.
When I built that harp amp, I cranked the amp and pointed my cheapest Radio Shrek mic right at the speaker to really get it howling--then I turned the control and the feedback instantly stopped.
As Gerald Weber explains it, this Self-Balancing Paraphase PI doesn't amplify both sides of the wave symmetrically. According to him, this control affects the magnitude of one side of the wave. Thus, if speaker phase is right with the controlled side of the wave, turning the control drops half the wave and kills feedback.
I've never scoped it to see if all that is true. I do know that the circuit works!
You do not have the required permissions to view the files attached to this post.
Rich Gordon
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
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titanicslim
- Posts: 131
- Joined: Sat Mar 11, 2006 7:52 pm
- Location: Joplin, MO
Re: Good Harp Amp?
Rich
How do you like that! It happens I've already printed out the 5D3 layout and schemo. I've been staring at them for a few nights now and had just about decided on that one for the harp amp. Hoodoo, man, that's what it is.
Now, are you just running from the PI to the wiper of this "feedback killer" pot, and the output bleeding to ground, or does that connect back into the circuit?
Is this the basis of the 40 watt harp amp you mentioned? What is needed in our case is about 20-25 watts, but I should be able to get that with Deluxe Reverb iron. I'm just assuming here, having never dealt with the Deluxe family before.
Thanks! And thanks David (et al!) That Bandmaster looks really interesting. Any further info you could send (regarding iron, mods etc.) would be very welcome I've had Mission Amps website bookmarked for some time but have only seen a rather nice looking 5E3 kit there.
Dave
How do you like that! It happens I've already printed out the 5D3 layout and schemo. I've been staring at them for a few nights now and had just about decided on that one for the harp amp. Hoodoo, man, that's what it is.
Now, are you just running from the PI to the wiper of this "feedback killer" pot, and the output bleeding to ground, or does that connect back into the circuit?
Is this the basis of the 40 watt harp amp you mentioned? What is needed in our case is about 20-25 watts, but I should be able to get that with Deluxe Reverb iron. I'm just assuming here, having never dealt with the Deluxe family before.
Thanks! And thanks David (et al!) That Bandmaster looks really interesting. Any further info you could send (regarding iron, mods etc.) would be very welcome
I've had Mission Amps website bookmarked for some time but have only seen a rather nice looking 5E3 kit there.Dave
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)
Re: Good Harp Amp?
Dave,
Just replace the resistor with a pot, say 110k, with wiper to ground, and one end of the pot to the board.
In the amp I built, I did a 50k pot with a 10k to ground from the wiper, but, in retrospect, I think the control would have a greater range of effect if it was just the 100k pot.
Just replace the resistor with a pot, say 110k, with wiper to ground, and one end of the pot to the board.
In the amp I built, I did a 50k pot with a 10k to ground from the wiper, but, in retrospect, I think the control would have a greater range of effect if it was just the 100k pot.
Rich Gordon
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
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titanicslim
- Posts: 131
- Joined: Sat Mar 11, 2006 7:52 pm
- Location: Joplin, MO
Re: Good Harp Amp?
Has anyone ever seen something like this?
[/img]
[/img]
It's the brainchild of a French harp player (Yes, that's right. He plays the French-harp) He calls it the i-mic. Like the i-mac- get it?
I made mine with a Perrier bottle and a grape juice jug. Instructions are here: http://www.planetharmonica.com/ph2/VE/TMI-micUK.htm though I scarcely think anyone on this board really needs them.
I'm just about finished putting my 5D3 together. Can't wait to plug this little guy in.
Dave
[/img][/img]It's the brainchild of a French harp player (Yes, that's right. He plays the French-harp) He calls it the i-mic. Like the i-mac- get it?
I made mine with a Perrier bottle and a grape juice jug. Instructions are here: http://www.planetharmonica.com/ph2/VE/TMI-micUK.htm though I scarcely think anyone on this board really needs them.
I'm just about finished putting my 5D3 together. Can't wait to plug this little guy in.
Dave
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)
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titanicslim
- Posts: 131
- Joined: Sat Mar 11, 2006 7:52 pm
- Location: Joplin, MO
Re: Good Harp Amp?
Well, I've got the 5D3 circuit hooked up but all I'm getting so far is some fairly bizarre 'boating. I've switched the OT primaries and that didn't do it.
The PT is a Fender Deluxe Reverb reissue unit and I used the (series?) heater wiring shown in the Fender schem/layout here:
http://www.schematicheaven.com/fenderam ... _schem.pdf
Here are a few pho9tos:
[IMG
768]http://i175.photobucket.com/albums/w157 ... CF0836.jpg[/img]
[IMG768]http://i175.photobucket.com/albums/w157 ... CF0834.jpg[/img]
[IMG768]http://i175.photobucket.com/albums/w157 ... CF0835.jpg[/img]
[IMG768]http://i175.photobucket.com/albums/w157 ... CF0837.jpg[/img]
Unless you see something I've missed, I'll rewire the heaters tonight. I just thought I'd try it this way since these Fender charts have never failed me in the past. Oh, well...
Thanks!
Dave
The PT is a Fender Deluxe Reverb reissue unit and I used the (series?) heater wiring shown in the Fender schem/layout here:
http://www.schematicheaven.com/fenderam ... _schem.pdf
Here are a few pho9tos:
[IMG
768]http://i175.photobucket.com/albums/w157 ... CF0836.jpg[/img]
[IMG
768]http://i175.photobucket.com/albums/w157 ... CF0834.jpg[/img]
[IMG
768]http://i175.photobucket.com/albums/w157 ... CF0835.jpg[/img]
[IMG
768]http://i175.photobucket.com/albums/w157 ... CF0837.jpg[/img]
Unless you see something I've missed, I'll rewire the heaters tonight. I just thought I'd try it this way since these Fender charts have never failed me in the past. Oh, well...
Thanks!
Dave
The denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of the blood. - Logan Pearsall Smith (1865 - 1946)