Crossovers for F2 Use
And could you please point that light over here too...
I have read Papa's paper on the subject of crossovers for current source drive and have thoroughly confused myself. A friend is building me a very nice F2 (obviously a very good friend) which I am going to use with my Hammer Dynamics Super 12 pair (made by me). I do love the way they sound with my little Grommes PHI-26 SET - Alan Kimmel is really something - but I feel the F2 would take it to another level all together.
The Super 12 crossover is attached below. I am getting some advice that it will work fine, but my understanding is that if used as is the current drive will not work as intended, or the crossover will not function as intended, or both. Is there a soul here kind enough to sketch me out a crossover that will work? I admit I can't figure it out.
The idea is to crossover to the super tweeter at 9700hz or so. The notch filter might be less necessary with the current drive, but it would be nice to know how to include it just in case.
Thank you for hearing my plea,
Clark
Vix said:
And could you please point that light over here too...
I have read Papa's paper on the subject of crossovers for current source drive and have thoroughly confused myself. A friend is building me a very nice F2 (obviously a very good friend) which I am going to use with my Hammer Dynamics Super 12 pair (made by me). I do love the way they sound with my little Grommes PHI-26 SET - Alan Kimmel is really something - but I feel the F2 would take it to another level all together.
The Super 12 crossover is attached below. I am getting some advice that it will work fine, but my understanding is that if used as is the current drive will not work as intended, or the crossover will not function as intended, or both. Is there a soul here kind enough to sketch me out a crossover that will work? I admit I can't figure it out.
The idea is to crossover to the super tweeter at 9700hz or so. The notch filter might be less necessary with the current drive, but it would be nice to know how to include it just in case.
Thank you for hearing my plea,
Clark
Super 12 Crossover Schematic
OK, I have failed to attach the image so here is a link to a review where it appears.
http://www.enjoythemusic.com/magazine/equipment/0600/super12.htm
Clark
OK, I have failed to attach the image so here is a link to a review where it appears.
http://www.enjoythemusic.com/magazine/equipment/0600/super12.htm
Clark
Ultimately you will have to sit down and work it out, likely through
trial and error. The examples in the "Crossovers for Current Source
Amplifiers" will help, but they are not ready-mades for any
particular speaker. If you like to play, you're all set. If you just
want "plug and play" you might be disappointed.
trial and error. The examples in the "Crossovers for Current Source
Amplifiers" will help, but they are not ready-mades for any
particular speaker. If you like to play, you're all set. If you just
want "plug and play" you might be disappointed.
Onward!
Mr. Pass,
Thank you so much for your reply. I am indeed more naturally inclined to tweaking and fiddling than plug and play and I am sure my post does look foolish. My apologies. Your thoughtful and well researched examples do point the way, but I was still intimidated by "Capacitors become inductors and vice versa..."
I have decided to go with separate amps for the 12" and the tweeter. I will use a conventional triode amp for the tweeter and of course the F2 for the Hammer Dynamics Super 12. I already have the third order network to keep lower frequencies from the tweeter. I am assuming from the examples in your paper that a 2.2 micro farad cap across the terminals of the full range will reasonably block the signal over 9700hz or so. The frequency need not be exact and I calculate 2.2 to be close enough. I will also try it without anything and see how it sounds just rolling off naturally. The Zobel currently residing there obviously has to go.
I hope the notch filter will not be necessary as the Super 12 has minor problems that way next to small Lowther and Fostex cones. I expext the F2's current drive will straighten it out enough to ignore. If not, I will fiddle on!
I have been on vacation and away from the internet; I am sorry to have to delay my response.
Thank you again for your reply (and for your wonderful design), I am honored,
Clark
Mr. Pass,
Thank you so much for your reply. I am indeed more naturally inclined to tweaking and fiddling than plug and play and I am sure my post does look foolish. My apologies. Your thoughtful and well researched examples do point the way, but I was still intimidated by "Capacitors become inductors and vice versa..."
I have decided to go with separate amps for the 12" and the tweeter. I will use a conventional triode amp for the tweeter and of course the F2 for the Hammer Dynamics Super 12. I already have the third order network to keep lower frequencies from the tweeter. I am assuming from the examples in your paper that a 2.2 micro farad cap across the terminals of the full range will reasonably block the signal over 9700hz or so. The frequency need not be exact and I calculate 2.2 to be close enough. I will also try it without anything and see how it sounds just rolling off naturally. The Zobel currently residing there obviously has to go.
I hope the notch filter will not be necessary as the Super 12 has minor problems that way next to small Lowther and Fostex cones. I expext the F2's current drive will straighten it out enough to ignore. If not, I will fiddle on!
I have been on vacation and away from the internet; I am sorry to have to delay my response.
Thank you again for your reply (and for your wonderful design), I am honored,
Clark
Or do I have that "double backwards" and it would be a .13mh inductor and not a cap to lower the upper limit of the pass band to 9700hz to the woofer?
This is not a crossover but a limiting filter so an inductor would still block higher frequencies and a capacitor lower frequencies? In parallel with the terminals of the driver, of course.
Clark
This is not a crossover but a limiting filter so an inductor would still block higher frequencies and a capacitor lower frequencies? In parallel with the terminals of the driver, of course.
Clark
F2 gain issue
Folks,
I dont like to usually ask for help, but I got stumped.
One of the F2 chanels I built p2p seems to work fine, measure exactly like the other, but there is little gain for output to the speakers. The other seems fine, and normal, considering the gain.
I cant crank it up more than a wisper.
I swapped the speakers and inputs, no love.
I suspected something wrong with the signal resistors, but they all check out. continuity test between parts seems right, both FETS warm up same as the others. I set drain to ground voltage to 12v. Before I tear it apart and start over, anyone have any idea what I may have wired in backwards (dont say resistor)?
Otherwise I think I will take apart R1-12 and C1 and Q1 then re-wire.
Mike
Folks,
I dont like to usually ask for help, but I got stumped.
One of the F2 chanels I built p2p seems to work fine, measure exactly like the other, but there is little gain for output to the speakers. The other seems fine, and normal, considering the gain.
I cant crank it up more than a wisper.
I swapped the speakers and inputs, no love.
I suspected something wrong with the signal resistors, but they all check out. continuity test between parts seems right, both FETS warm up same as the others. I set drain to ground voltage to 12v. Before I tear it apart and start over, anyone have any idea what I may have wired in backwards (dont say resistor)?
Otherwise I think I will take apart R1-12 and C1 and Q1 then re-wire.
Mike
F2 gain issue
Both seem to measure 21.5v DC once hooked up to the boards (24.5v unhooked supply). This is measured at R23-26 to ground, or across C5.
If I remember right, ZTX B to ground is ~16v. Where I did measure, all the voltages seem similiar on both channels. I suspected they would not. If there is smarter place to measure here I will. I built a mirror of the right channel, I imagine I may have hooked up something wrong, or there is a busted part, or in my luck, a bad joint. I've had a few of those in my time...
Nelson Pass said:
Both seem to measure 21.5v DC once hooked up to the boards (24.5v unhooked supply). This is measured at R23-26 to ground, or across C5.
If I remember right, ZTX B to ground is ~16v. Where I did measure, all the voltages seem similiar on both channels. I suspected they would not. If there is smarter place to measure here I will. I built a mirror of the right channel, I imagine I may have hooked up something wrong, or there is a busted part, or in my luck, a bad joint. I've had a few of those in my time...
F2 gain issue
I did some more measurements since I still cannot find a wiring error.
Q1 on 'good gain' channel is Gate 6.6V, Drain 12V, Source 2.17V
Q1 on ' bad channel is Gate 6V, drain is 12v, Source is 1.6V.
Q2 measure the same on both channels.
20V gate, 12v drain, 16v source.
I am unsure if the lower voltage is the direct cause of the low gain, but I haven't much else to go on. I measured the voltages of the following, but came up with the same value on both channels.
some of the spots I have little contact area to measure on, so I have yet to study all the resistors.
R7-12 Source resistors .85v
R2-6v
R3-6v
r6-6v
Not sure if these matter,
R21 10v
R17-18 6v
I dont think C1 is an issue here, but cant measure it without some mechanical effort.
THe question I have, does anyone suspect a particular component here? If the passive components match, should I replace Q1 since it is the only thing that measures different?
I did some more measurements since I still cannot find a wiring error.
Q1 on 'good gain' channel is Gate 6.6V, Drain 12V, Source 2.17V
Q1 on ' bad channel is Gate 6V, drain is 12v, Source is 1.6V.
Q2 measure the same on both channels.
20V gate, 12v drain, 16v source.
I am unsure if the lower voltage is the direct cause of the low gain, but I haven't much else to go on. I measured the voltages of the following, but came up with the same value on both channels.
some of the spots I have little contact area to measure on, so I have yet to study all the resistors.
R7-12 Source resistors .85v
R2-6v
R3-6v
r6-6v
Not sure if these matter,
R21 10v
R17-18 6v
I dont think C1 is an issue here, but cant measure it without some mechanical effort.
THe question I have, does anyone suspect a particular component here? If the passive components match, should I replace Q1 since it is the only thing that measures different?
F2 layout
My pictures did not reveal an easy layout to follow. My wiring is not pretty either. I defer to others as more proper mentors.
I followed Hugz and vitalstates work to get it hooked up. Their layouts work.
Mine is on a perfboard like vitalstates.
I will use a matrix board or a PCB for my next amp (F5).
Getting things to not move was difficult for me. For one channel I put the ground bus on both sides to restrict movements.
I don't have it in the system to listen for noise. Just running off some radio shack full ranges in the basement. The channel without the problem seems fine. Just some diode noise if you listen closely. I think ground loops are a system problem, or issue with your house ground anyways.
Mike
nicoch46 said:
My pictures did not reveal an easy layout to follow. My wiring is not pretty either. I defer to others as more proper mentors.
I followed Hugz and vitalstates work to get it hooked up. Their layouts work.
Mine is on a perfboard like vitalstates.
I will use a matrix board or a PCB for my next amp (F5).
Getting things to not move was difficult for me. For one channel I put the ground bus on both sides to restrict movements.
I don't have it in the system to listen for noise. Just running off some radio shack full ranges in the basement. The channel without the problem seems fine. Just some diode noise if you listen closely. I think ground loops are a system problem, or issue with your house ground anyways.
Mike
My F2
Thanks to several members of this thread for advice.
This beast is up and running as a bass amp driving the Dick Olsher OB1 setup. Dick is on to somthing, as this does work much better than the Gainclone here. It seems to integrate better regardless of crossover freq and Crossover db.
The problem with the low output turned out to be the power clip lead or the speaker output terminal rubbing on chassis and grounding something out. Got them solidly away from the chassis and this worked well. Also seemed to occur if the power 0v was attached to far away from the speaker out + to ground.
The unit still smells quite strong when warmed up. I hope it's the high temp paint offgassing off the heatsinks. I may need to move the one ohmers well away from the PCB if it's burning the formelahyde smell off the perfboard. I cant tell. But works well. No hum at all. The first amp I have not needed to lift ground on.
Thanks to several members of this thread for advice.
This beast is up and running as a bass amp driving the Dick Olsher OB1 setup. Dick is on to somthing, as this does work much better than the Gainclone here. It seems to integrate better regardless of crossover freq and Crossover db.
The problem with the low output turned out to be the power clip lead or the speaker output terminal rubbing on chassis and grounding something out. Got them solidly away from the chassis and this worked well. Also seemed to occur if the power 0v was attached to far away from the speaker out + to ground.
The unit still smells quite strong when warmed up. I hope it's the high temp paint offgassing off the heatsinks. I may need to move the one ohmers well away from the PCB if it's burning the formelahyde smell off the perfboard. I cant tell. But works well. No hum at all. The first amp I have not needed to lift ground on.
twitchie said:
Is the purpose of C1 to filter out high frequency noise? Can another value be used successfully, like 0.1uF instead?
I made a big mistake in my layout and my 0.1uF MKP will fit, but the 1.0uF MKP is at least twice the size and won't fit :-(
You can use this to calculate:
f=1/(2*pi*R*C)
Stinius
Nelson Pass said:C1 effectively is loaded with 100K, so 1 uF gives a 1.6 Hz rolloff. .1 uF
gives 16 Hz. If you change the 100K to 221K, then the .1 uF will give you
7 Hz.
Thank you for the reply Nelson and thank you for the formula stinius - is that called a pi filter? (just heard the term before and taking a guess from the formula).
Since everybody seems to enjoy pictures, here's what I've built so far. If I can find the files, I'll upload the pdfs
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
