I measured with Neutrik analizer and reponse is regular from 25 Hz to 20KHz. My room is very large (5.5m x 10.5 ) and I've very regular reponse since 300 Hz. The reinforcement of boundaries give me very good bass freqs and the lowest mode (about 16Hz)of the room, is excited by my amps. The bass cabinets are builded in a different way: I used RPG diffusors in all the not parallel walls and filling fiberglass in the resting walls.Using the minimum absorbing materials the sound is more vivid and better the dynamics.The RPG breaks the standing waves and preserve the life of music.The bass are in infinite baffle configuration, and the very gentle slope (less than 12 dB/oct) give me extended,controlled and very quick basses.
X-o freqs are 100, 400 and 2500 Hz. Low pass filter of woofer is made eletrically by the preamp, is fully bal and implemented on the ccs x bosoz, and 2nd order Bessel.
The hi pass of mid woofers is 2nd order realized with mechanical cut of enclosure and the output cap of bosoz. The low pass is a 2nd order Linkwitz Riley (2LR) with a Mundorf Zero Ohm coil in serie with the speakers, to preserve the damping factor of the amps.
The midranges bandpass is 2LR again with "balanced structure" ; the coil and capacitors in serie are not both on a single rail, but one on + and the other one on -. In this way the mids are "quasi"floating respect to amp and to other loudspeakers; imho it sounds better
than both on a single rail.Very important is use only Mundorf Supreme in serie, cause this caps give the best soundstage than ever. The AMT is cutted with again a 2LR. I don't use attenuation , cause the loudspeakers are choosen with (circa) the same sensitivity.
X-o freqs are 100, 400 and 2500 Hz. Low pass filter of woofer is made eletrically by the preamp, is fully bal and implemented on the ccs x bosoz, and 2nd order Bessel.
The hi pass of mid woofers is 2nd order realized with mechanical cut of enclosure and the output cap of bosoz. The low pass is a 2nd order Linkwitz Riley (2LR) with a Mundorf Zero Ohm coil in serie with the speakers, to preserve the damping factor of the amps.
The midranges bandpass is 2LR again with "balanced structure" ; the coil and capacitors in serie are not both on a single rail, but one on + and the other one on -. In this way the mids are "quasi"floating respect to amp and to other loudspeakers; imho it sounds better
than both on a single rail.Very important is use only Mundorf Supreme in serie, cause this caps give the best soundstage than ever. The AMT is cutted with again a 2LR. I don't use attenuation , cause the loudspeakers are choosen with (circa) the same sensitivity.
2SK170BL Idss
Testing jfets for the pre-pre. The measurements are a bit strange.
Tested over 10 2sk170bl jfets and they all measured 8.75 Idss exactly.
Some went to 8.76, then dropped to 8.75. They all arrived from the same shipment. The power source was a 9v battery.
Is it normal for so many to have the same Idss?
I'm not complaining, but has anyone else seen this happen before?
Testing jfets for the pre-pre. The measurements are a bit strange.
Tested over 10 2sk170bl jfets and they all measured 8.75 Idss exactly.
Some went to 8.76, then dropped to 8.75. They all arrived from the same shipment. The power source was a 9v battery.
Is it normal for so many to have the same Idss?
I'm not complaining, but has anyone else seen this happen before?
Although, it's a shame and most likely not the same case here, but I can share my experience getting similar results. It's just that my DMM was turned to mV instead of mA. Reaction was the same: „How's is this possible to have that kind of matching?"
That's it!! Thanks!
Follow this with your DVM in mV maybe it will be stabler in your case. Let time after you had touched each JFET or better use a tool so it will not get or keep your fingers warmth. During measurement wait until the rate of climb is minor or set a limit same for all. Say 2 minutes.
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Thanks Salas! It does sort of stablize after 30 seconds or so, then the climb is slower.
I've been recording the reading when it stay on the same value for 10-15 seconds.
Will that get me close or should it stop complete?
Two more questions.
On the Pre-Pre, it says 7mA and on the main phono it requires 8-8.5mA. Can the Pre-pre have any variance in Idss? My jfets now show Idss from 7.5 to 10.2 and everything in between. I have around 30 to play with and still haven't opened the remaining 10 pack yet. None of the jfets are exactly 7mA Idss, so far.
Finally, I want to use one 9 volt battery per channel. I was going to keep R1 and C2.
Will that be enough to power and filter the circuit?
Thanks for your help and patience.
Vince
I've been recording the reading when it stay on the same value for 10-15 seconds.
Will that get me close or should it stop complete?
Two more questions.
On the Pre-Pre, it says 7mA and on the main phono it requires 8-8.5mA. Can the Pre-pre have any variance in Idss? My jfets now show Idss from 7.5 to 10.2 and everything in between. I have around 30 to play with and still haven't opened the remaining 10 pack yet. None of the jfets are exactly 7mA Idss, so far.
Finally, I want to use one 9 volt battery per channel. I was going to keep R1 and C2.
Will that be enough to power and filter the circuit?
Thanks for your help and patience.
Vince
That will get you close. Only do the batch tests same day @ ~same room temperature. If it is a hot day use the aircon.
Yes, the pre pre can have some Idss variance but not much. I don't trust the stability and noise of battery chemicals over time and brands. I prefer the active filtering. ~15mA per channel is going to drain them fast also. But its your choice. See the noise floor of a pre pre I made recently without battery on electronics PSU only. 5mV output, 1VRMS=0dBV. I think its adequate.
Yes, the pre pre can have some Idss variance but not much. I don't trust the stability and noise of battery chemicals over time and brands. I prefer the active filtering. ~15mA per channel is going to drain them fast also. But its your choice. See the noise floor of a pre pre I made recently without battery on electronics PSU only. 5mV output, 1VRMS=0dBV. I think its adequate.
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Congrats Salas, very nice & neat work. Could you post more pics of insides & psu, are you using Nichicon Gold Tune in the pre-pre?
Unipolar (FET) SE no global feedback, SIMPLE like a tube amp. JFETs are silky. SE no loop FB is big soundscape.
Will show you a folded cascode first stage (more PSRR) & optionally JFET cascoded 2nd stage with B1 style output buffer version, to test also when feeling adventurous. 2SK170 don't have the low 1/f that BJTs got. If you ever find some 2SK369 to parallel for front end let me know (will bring bass noise down). SE ain't DC coupled symmetric servo with FB, still a Vendetta type CCT is, and its still JFET front end, EB style is the same, that would be the sound style to put against symmetric BJT, and saves you the input offset.
I hope I gave some clues.
P.S. Last but not least normalize the SPL with a meter even, when comparing anything, each one pre normally has different gain.
Will show you a folded cascode first stage (more PSRR) & optionally JFET cascoded 2nd stage with B1 style output buffer version, to test also when feeling adventurous. 2SK170 don't have the low 1/f that BJTs got. If you ever find some 2SK369 to parallel for front end let me know (will bring bass noise down). SE ain't DC coupled symmetric servo with FB, still a Vendetta type CCT is, and its still JFET front end, EB style is the same, that would be the sound style to put against symmetric BJT, and saves you the input offset.
I hope I gave some clues.
P.S. Last but not least normalize the SPL with a meter even, when comparing anything, each one pre normally has different gain.
Pear and oranges then
The quest for the magic ingredient for wide sound stage continue.
Tanks for clues I do understand topology and feedback have some to do with it but why?
Looking at it another way I wonder if phase response is efecting it.
Or maybe armonics (5th or 7th) ad the wide band of Simplistic.
Yes of course about SPL but level sems not to efect stage width.
I am alwayse feeling adventurous so Yes please.
The quest for the magic ingredient for wide sound stage continue.
Tanks for clues I do understand topology and feedback have some to do with it but why?
Looking at it another way I wonder if phase response is efecting it.
Or maybe armonics (5th or 7th) ad the wide band of Simplistic.
Yes of course about SPL but level sems not to efect stage width.
I am alwayse feeling adventurous so Yes please.
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