Thank you, guys, for your kind words. 🙂
It is true that it is very unlikely that we run out of wine down here: last night we tried to reduce the nation's reserve tasting some carménère réservé at a party but we ostensibly failed to do so
Though I did not yet made ABAB comparison with this VSSA (and the PS has provision of connectors to bypass the "charge-transfer" switch) because the module was previously installed at my work station which was relegated to the patio by a mightier power than mine 😀 , in every ocasion that I did this mod previously, be it on a low power or be it on a high power circuit, the results were the same: increased transparency with all the accompanying benefits. 😎 The circuit could be improved, as everything, but I lack the knowledge to do so. For example, the ground is still connected directly (which is OK I think with the use of my ballanced power mains TX) but maybe could benefit of some inductance between C1 and C2??... at the risk of a resonance tank? 🙁
https://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNNMTjNZETYmyPJy0liipFm0?feat=directlink
This circuit was the reason why I was reluctant to buy SMPS before, but now that I bought some, I will be able to tell if there is or if there is not need to insist in this approach.
Look instead at my speaker connector mod:
Now I have a question for the wise: can the VSSA be modded to work with quasi-complementary output??
The thing is that I have some Semisouth (enhancement) units lying around unused...
Thank you very much.
M.
It is true that it is very unlikely that we run out of wine down here: last night we tried to reduce the nation's reserve tasting some carménère réservé at a party but we ostensibly failed to do so
Though I did not yet made ABAB comparison with this VSSA (and the PS has provision of connectors to bypass the "charge-transfer" switch) because the module was previously installed at my work station which was relegated to the patio by a mightier power than mine 😀 , in every ocasion that I did this mod previously, be it on a low power or be it on a high power circuit, the results were the same: increased transparency with all the accompanying benefits. 😎 The circuit could be improved, as everything, but I lack the knowledge to do so. For example, the ground is still connected directly (which is OK I think with the use of my ballanced power mains TX) but maybe could benefit of some inductance between C1 and C2??... at the risk of a resonance tank? 🙁
https://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNNMTjNZETYmyPJy0liipFm0?feat=directlink
This circuit was the reason why I was reluctant to buy SMPS before, but now that I bought some, I will be able to tell if there is or if there is not need to insist in this approach.
Look instead at my speaker connector mod:
Now I have a question for the wise: can the VSSA be modded to work with quasi-complementary output??
The thing is that I have some Semisouth (enhancement) units lying around unused...
Thank you very much.
M.
Attachments
Correct way of bypass the diode ? advice please
In one of the previous post, LC recommend bypass the diode and the 10R for better sound .
Please see the attached picture.
Is this the correct way of doing it by using an 18G wire and soldered at these points.
thanks
kp93300
In one of the previous post, LC recommend bypass the diode and the 10R for better sound .
Please see the attached picture.
Is this the correct way of doing it by using an 18G wire and soldered at these points.
thanks
kp93300
Attachments
2nd point :
Can someone verified this ---- LC wrote it sound better without the 10 UF at C4 and C5 ??
thanks
kp93300
Can someone verified this ---- LC wrote it sound better without the 10 UF at C4 and C5 ??
thanks
kp93300
Correct wiring but see post #2526 nearly same as yours but maybe more cooperation to act as one 2mF (Same as Marc mean in post #3004).
See post post #1424, also most owners report best sound with 10uF film cap.
As general build helper index see post #2534 (Link: http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-254.html#post3653117).
Last edited:
Your VSSA missed SPL from speaker at +/-35V rails standard PSU, gets exiting to hear results by new +/-45V rails refreshed by Hi Freq secondary modulation and regulated, good soldering/building.
Hi gents
I m part of the group, now having 4 VSSA boards just awaiting some spare time 🙂
each VSAA will drive a single 8" woofer given for 13ohms (according to JBL LS 80 tech manual, LP filter removed)
+-45V should give 62W into 13 ohms with a peak current of 3amps only.
Id love to increase the PSU by few volts to juice theses damn 13ohms speakers as they should.
I understand the main limitation is due to BC550/560 and the BF545 is protected by a serial resistor reducing branch voltage, but then this resistor also drops the supply seen by the BC550/560 , right ? 🙂
In this context where the curent in the ALFET will not be critical due to 13ohm load, can you advise on the very utmost value of the V RAIL to avoid burning the BF545 and BC550/560 ?
anyother thoughts welcome, cheers
I m part of the group, now having 4 VSSA boards just awaiting some spare time 🙂
each VSAA will drive a single 8" woofer given for 13ohms (according to JBL LS 80 tech manual, LP filter removed)
+-45V should give 62W into 13 ohms with a peak current of 3amps only.
Id love to increase the PSU by few volts to juice theses damn 13ohms speakers as they should.
I understand the main limitation is due to BC550/560 and the BF545 is protected by a serial resistor reducing branch voltage, but then this resistor also drops the supply seen by the BC550/560 , right ? 🙂
In this context where the curent in the ALFET will not be critical due to 13ohm load, can you advise on the very utmost value of the V RAIL to avoid burning the BF545 and BC550/560 ?
anyother thoughts welcome, cheers
You seem to be an obvious candidate for balancing/bridging with those 13ohm woofers. Just buy another 4 modules 🙂
You first and on your own but seems to be possible with +/-50V by replace BC550C/BC560C with BC546C(B)/556C(B) and replace R7, R8 with 10 k, 1206 resistors. Reference for this is post #2012 (Link: http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-202.html#post3571191). BC546C/556C is obsolete but see this link for chance to get them http://www.diyaudio.com/forums/soli...ugh-hole-pcb-build-thread-24.html#post3709279 or use the B grades.
Also as suggested go bridged, see post #1660 http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-166.html#post3539303 and search member metallicus69 posts in this thread.
NO! Sorry to disappoint you 🙁
Each BC input transistor sees almost one rail voltage. What happens on the BF545 CCS does not matter for the bipolar too much in regard to the Vce voltage.
think for the PNP, for example: B is at GND level via input resistor (10k). E will be polarized at +0,5V (approximately) by the 2,4mA CCS and C will be at V- rail voltage minus (Vbe of VAS) minus 120mV (drop on the 10 OHM VAS Re resistor). So approximately V- rail voltage will be the PNP Vce, because the drop on the 10 OHMs resistor can be considered negligible when compared to rail voltage.
Symmetrical, the NPN will see V+ rail voltage, really independent of what's happening on the current source, and hence limiting the rail voltages to what the input transistors can tolerate.
The only way to go up will be to change input bipolars with higher Vce tolerant ones, but you might lose some sweet spot parameters, and thus you might break the egg (as previously was so poetically designed this VSSA).
Or you can maintain the egg intact and go balanced. High impedance loads are good candidates for that.
Good luck!
Last edited:
thank you , the idea of bridging is very elegant but with 4 woofers thats a bit overkill and the quiescent current would generate 130W heat just for the 8 modules... lol
yes the 546/556 is a safe option which I ll consider as this are TH TO92 easy to solder
yes the 546/556 is a safe option which I ll consider as this are TH TO92 easy to solder
oops you are right metallicus69, each trani see the vrail , as the Voltage at the junction of the ccs and 2m2 cap is a virtual ground around +-1v... forgot that
Woofers ? Vssa will not make the difference in low frequencies, any amp (and don't forget cheap Class D ones) will do the job as well.
You don't want to bridge amps ? Parallel speakers.
6 ohms will be just perfect for any amp.
But, please, reserve Vssa to mediums and trebles where they will be like a fish in water.
Right! As you have said in the previous post, the serial resistor is to protect the JFET in the CCS by dropping the VDS to tolerated values (otherwise the FET will see the opposite Vrail voltage and that's too much).
I fully agree with Esperado, to use a 1,5MHz bandwidth amplifier just for woofers is a bit of an overkill! They won't sound bad of course, but it's just like you will use a racing horse for farming 🙂
Cheers!
good feedbacks guys, but for some reason, the cutoff frequency between the woofer and the horn is chosen by JBL at 2500hz, which is mid-high right ? so VSSA might be appropriate, hopefully 🙂
...and one of the 2 woofer is cut at 400hz , thats why I keep them separated and not paralelled
Well, it is not far from my future set-up.
One sub, powered by a Class D amp.
Two speakers from 30 to 1500Hz (FC) powered by 200W (cfa because i have them) amp, two horns, 1500 ->20 000 powered by VSSA.
There is no obvious advantage to use a current feedback amp at 1500 Hz or 2500 Hz. Any good amp can make the job.