PSz. said:Thank you for your replies, I think I've got a bit more learning to do.
any specific places I might look?
havin fun
PSz.
follow this article
variable impedance amp
It doesn't sound as good as a current source, Class A, no neg. fb- amp.
Last week end, I have finished the 3-way active crossover for my loudspeaker system. The cut are at 500 and 3500 LR 12dB slope, so I have made some tests with a GC arranged as current amplifier. I already tested it alone with the passive crossover, but because of the many peaks and deeps due to the passive crossover, the listening result was not very good. The tonal balance was preponderant on the midrenge frequency, so that the mid bass was a lot behind and the deep bass very present, due the resonance of the closed box. The high was very good one.
Now I have been able to test the single ways, so, leaving unchanged the problems on the bass, I have seen (listened) that the results on the mid and the tweeter are extraordinary. The latter sounds better with the current GC than the Zen V4, while the mid (to which I have added one RLC cell for the resonance and a RC cell for the inductive zone) seems to sound the same with the two amps. Next week and, I'll try to add a 1hom resistor on the source of the Zen and take off the feedback resistor, so to have a zen transonduttance, and compare it with the GC on the high and mid frequencyes.
If results will be as espected (Zen better then GC) in the Christmas holydays I will build a mini V4 (36V reg 1.5A bias about 15 watts in 6hom) dedicated to the tweeters while the maxi V4 (44V reg 2.4A bias) will be left on the mid range.
Ciao.
Now I have been able to test the single ways, so, leaving unchanged the problems on the bass, I have seen (listened) that the results on the mid and the tweeter are extraordinary. The latter sounds better with the current GC than the Zen V4, while the mid (to which I have added one RLC cell for the resonance and a RC cell for the inductive zone) seems to sound the same with the two amps. Next week and, I'll try to add a 1hom resistor on the source of the Zen and take off the feedback resistor, so to have a zen transonduttance, and compare it with the GC on the high and mid frequencyes.
If results will be as espected (Zen better then GC) in the Christmas holydays I will build a mini V4 (36V reg 1.5A bias about 15 watts in 6hom) dedicated to the tweeters while the maxi V4 (44V reg 2.4A bias) will be left on the mid range.
Ciao.
I got it.
This afternoon I have modified my V4. 221 ohm on the gate of Q4, take off R3 and C12, added 1 ohm 10W on the source of Q1, and regulated R4 for the DC set. R1 is 1.5 ohm. I have 1.85V on the new resistor (that is to say 1.85A bias.) The temperature of this resistor is about 65 °C.
I didn't touch the aleph CCS.
Everything works fine.
No oscillation at the output. Z out is about 81 ohm (I measured it on a 100W 7.5 ohm resistor). The gain is about 10 (or 20 dB) on a 6 ohm resistor (22.5dB on 8 ohm).
How does it sounds? Well respect to the last test that I made, the situation is different. Now the mid range sounds much better respect to the normal V4, while swopping it on the tweeter and the current GC on the mid I can listen for sure a less better mid and no differences on the high freq. I think that is due to the fact that working the mid from 500 to 3500 Hz, the ear is much more sensible, while up to those frequencies, the less sensitivity of ear doesn't seems to make big differences (while I was modifying the V4, I tried to listen without the tweeters, and I have to say that I could also live without it, just taking off the low pass filter on the 2" dome mid).
The mid with the modded V4 sounds with more punch and much more clear (cable should be trasparent to a trans amp) and just a little bit deeper.
Having said this, I think that I will not build another V4 for the tweeter, but maybe a V5 for the low freq, on which a GC with 8 ohm Z out (costant power?) is actually playing with.
Ciao.h
This afternoon I have modified my V4. 221 ohm on the gate of Q4, take off R3 and C12, added 1 ohm 10W on the source of Q1, and regulated R4 for the DC set. R1 is 1.5 ohm. I have 1.85V on the new resistor (that is to say 1.85A bias.) The temperature of this resistor is about 65 °C.
I didn't touch the aleph CCS.Everything works fine.
No oscillation at the output. Z out is about 81 ohm (I measured it on a 100W 7.5 ohm resistor). The gain is about 10 (or 20 dB) on a 6 ohm resistor (22.5dB on 8 ohm).How does it sounds? Well respect to the last test that I made, the situation is different. Now the mid range sounds much better respect to the normal V4, while swopping it on the tweeter and the current GC on the mid I can listen for sure a less better mid and no differences on the high freq. I think that is due to the fact that working the mid from 500 to 3500 Hz, the ear is much more sensible, while up to those frequencies, the less sensitivity of ear doesn't seems to make big differences (while I was modifying the V4, I tried to listen without the tweeters, and I have to say that I could also live without it, just taking off the low pass filter on the 2" dome mid).
The mid with the modded V4 sounds with more punch and much more clear (cable should be trasparent to a trans amp) and just a little bit deeper.
Having said this, I think that I will not build another V4 for the tweeter, but maybe a V5 for the low freq, on which a GC with 8 ohm Z out (costant power?) is actually playing with.
Ciao.h
Unfortunately, the tradeoffs on efficient drivers lean towards loss of bass extension. Four string basses (assuming normal tuning) have a low E at 42Hz. That's hard enough to hit with less efficient speakers--go to more efficient ones and you tend to lose the bottom octave. I can't remember any figures off the top of my head, but bass cabinets are already pretty efficient compared to home gear.
It's a sad fact of life that the literature on bass cabinets tend to use the phrase "useable bass," which translates as the -10dB point; the 'real' rolloff (i.e. -3dB) is up around 50, 60, or even 80Hz, and this is from 15" and 18" drivers. Tens and smaller drivers fare even worse.
Yes, you can play through home audio type drivers, but you quickly exceed Xmax, even with the puny power supplies they use in bass amps. They depend on the collapsing rail as a crude limiter. Go to hi-fi amps (I use an old Hafler 500 sometimes) and you're likely to rip the driver apart. The best compromise is to use pro speakers with hi-fi amps, but every bass player craves that last, forever unobtainable octave.
Guitar players have it easy.
Grey
It's a sad fact of life that the literature on bass cabinets tend to use the phrase "useable bass," which translates as the -10dB point; the 'real' rolloff (i.e. -3dB) is up around 50, 60, or even 80Hz, and this is from 15" and 18" drivers. Tens and smaller drivers fare even worse.
Yes, you can play through home audio type drivers, but you quickly exceed Xmax, even with the puny power supplies they use in bass amps. They depend on the collapsing rail as a crude limiter. Go to hi-fi amps (I use an old Hafler 500 sometimes) and you're likely to rip the driver apart. The best compromise is to use pro speakers with hi-fi amps, but every bass player craves that last, forever unobtainable octave.
Guitar players have it easy.
Grey
Hello all,
I'm a bass player and the cabinet I used for larger gigs (I sold it because I presently lack a band which plays regular larger gigs, or any band for that matter) had 2 15" speakers, they were made by RCF, the L15/554K. Those speakers had an efficiency of about 103,5dB (don't remember precisely), for two speakers that would mean 109,5dB/1Watt/1Meter. Coupled to a 700Watt amp, you could say that it was decently loud. It also did produce a lot of low end, unlike most of the 4x10" cabinets.
But I don't think MikeW meant a bass amp, and for guitar you don't need a lot of power. Hell, you can get into lot's of trouble with your neighbours when using your Fender Champ "to it's limits", and that's about 5 watts.
Greetings,
Jarno.
I'm a bass player and the cabinet I used for larger gigs (I sold it because I presently lack a band which plays regular larger gigs, or any band for that matter) had 2 15" speakers, they were made by RCF, the L15/554K. Those speakers had an efficiency of about 103,5dB (don't remember precisely), for two speakers that would mean 109,5dB/1Watt/1Meter. Coupled to a 700Watt amp, you could say that it was decently loud. It also did produce a lot of low end, unlike most of the 4x10" cabinets.
But I don't think MikeW meant a bass amp, and for guitar you don't need a lot of power. Hell, you can get into lot's of trouble with your neighbours when using your Fender Champ "to it's limits", and that's about 5 watts.
Greetings,
Jarno.
You can get 15" pro drivers with Fs of 40 ish Hz.
Aanother plus is they are likely to be able to tolerate a bunch of amps through them.
A pair would certainly be close to 100 dB/watt/meter at 4 ohms.
I think more bassists than guitarists would prefer a clean sound.
Especially acoustic bassists.
How do you make a current amp sound like an overdriven tube amp? I guess with the right preamp or stomp box?
Aanother plus is they are likely to be able to tolerate a bunch of amps through them.
A pair would certainly be close to 100 dB/watt/meter at 4 ohms.
I think more bassists than guitarists would prefer a clean sound.
Especially acoustic bassists.
How do you make a current amp sound like an overdriven tube amp? I guess with the right preamp or stomp box?
Oi! Just what I need...a servo bass rig.
The overdrive question is easy--tube preamp. For extreme circumstances, cascade one into another. My personal preference is the Alembic F1-X, but that's just a repackaged Fender front end; not particularly difficult to DIY. Use a couple of 12AX7s and a handfull of caps and resistors and you're there. Go look it up in the Aspen Pittman book. Your choice: Showman, Twin, old Bassman, etc. The trick is to make it rugged enough for the road. I went ahead and bought a used Alembic rather than drop money on a strong chassis, etc.
Despite thirty or forty years of claims that manufacturer X's circuit sounds "like tubes," there's still no substitute for the real thing.
Grey
The overdrive question is easy--tube preamp. For extreme circumstances, cascade one into another. My personal preference is the Alembic F1-X, but that's just a repackaged Fender front end; not particularly difficult to DIY. Use a couple of 12AX7s and a handfull of caps and resistors and you're there. Go look it up in the Aspen Pittman book. Your choice: Showman, Twin, old Bassman, etc. The trick is to make it rugged enough for the road. I went ahead and bought a used Alembic rather than drop money on a strong chassis, etc.
Despite thirty or forty years of claims that manufacturer X's circuit sounds "like tubes," there's still no substitute for the real thing.
Grey
GRollins said:
Hey Grey-
Maybe we should take this offline, but Mr. Gerald has been wanting to put his servo on a bass amp rig for yrs... Someting to play with and try? I agree with him and think it would sound great.
Currently I use his stereo servo on a pair of 15" woofers flat from 125 to 20 in 1.25 cu ft enclosures. The servo is suppose to be accurate to 800 hz but I think Mr Erath just extended that to 2K or something.
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