My primary concern is that since the B1 isn't a 'good fit' in my current system when paired with my Aleph 5. How will it be with the F5's I'd like to build?
I have the appropriate film caps on hand so I can try that soon.
Regards,
Dan
Those things can't be gauged if someone does not have experience with the sound in your room. There is a thread about impressions from F5 I think. Try the films, and also try the B1 driving the GC. Maybe from those combinations we understand more where to turn. What is the sensitivity and impedance of the speaker system?
Tried a lower cost valve amp once and it didn't perform that well. Once again, the gainclone is the best to date.
Regards,
Dan
B1 finished
Hi out there,
have finished one DCB1 some days ago. Voltages are around 10V In my testsetup it drives a modded Helder TA2020 amp (on Sigma11 PSU) very very very well. Sound is open, detailed and holographic soundstaged on my old Tannoy Monitors. Of course Bass would be better with a stronger amp, but the rest is almost perfect. Looking foreward to getting my FE126 horn back and hearing this combination. Will link photos later.
Cheers Ernst
Hi out there,
have finished one DCB1 some days ago. Voltages are around 10V
In my testsetup it drives a modded Helder TA2020 amp (on Sigma11 PSU) very very very well. Sound is open, detailed and holographic soundstaged on my old Tannoy Monitors. Of course Bass would be better with a stronger amp, but the rest is almost perfect. Looking foreward to getting my FE126 horn back and hearing this combination. Will link photos later.Cheers Ernst
Hi out there,
have finished one DCB1 some days ago. Voltages are around 10V
Cheers Ernst
A little update, recall I was having problem with getting functional +ve half when I attempt to use the Fairchild FQA12P20's in the place of the IR IRFP9240's.
I received the IR's and dropped them right in last night. The +ve half was measured much closer to the norm, the only thing that I had to do was to re-adjust the 5-LED string which was right on 9V for the Fairchild and was too high (9.88V) for the IR.
The Fairchild FQA19N20C's are TO-3P's which work perfectly, but for more symmetric look, I replaced the N-channel's with IR's IRFP240's. One thing that I observed with this change was that the R1 voltage dropped quite significant. With stock R1 (68R // 68R), it only measured 1.467V vs a little over 2.0V with the Fairchild.
Anyhow, here are the latest measurements in stock form:
+ve side
B+ = 9.74
Volt R1 = 1.648
Volt 3 LED's = 5.4
Volt 5 LED's = 9.1
-ve side
B- = -9.67 (Same measurement when I used the Fairchild)
Volt R1 = 1.467
Volt 3 LED's = 5.4
Volt 5 LED"s = 9.01
For some reasons, I don't quite get what most fellow DIYers had:
1. the +v/-ve differentiation s not even close to 0.5V (absolutely value). B+ and B-
are almost symmetrical.
2. B+ and B- are somewhat lowered than the typical 10.9 and -10.5.
3. voltages across R1 are even close to the 2.0 strike mark, but this can be easily
cure by lowering the R's. I have done some experiment to find out what R's to
get 125ma which is still good for bare MOSFETS without heatsink.
If anyone sees anything alarming, please point that out.
Thanks!!
I received the IR's and dropped them right in last night. The +ve half was measured much closer to the norm, the only thing that I had to do was to re-adjust the 5-LED string which was right on 9V for the Fairchild and was too high (9.88V) for the IR.
The Fairchild FQA19N20C's are TO-3P's which work perfectly, but for more symmetric look, I replaced the N-channel's with IR's IRFP240's. One thing that I observed with this change was that the R1 voltage dropped quite significant. With stock R1 (68R // 68R), it only measured 1.467V vs a little over 2.0V with the Fairchild.
Anyhow, here are the latest measurements in stock form:
+ve side
B+ = 9.74
Volt R1 = 1.648
Volt 3 LED's = 5.4
Volt 5 LED's = 9.1
-ve side
B- = -9.67 (Same measurement when I used the Fairchild)
Volt R1 = 1.467
Volt 3 LED's = 5.4
Volt 5 LED"s = 9.01
For some reasons, I don't quite get what most fellow DIYers had:
1. the +v/-ve differentiation s not even close to 0.5V (absolutely value). B+ and B-
are almost symmetrical.
2. B+ and B- are somewhat lowered than the typical 10.9 and -10.5.
3. voltages across R1 are even close to the 2.0 strike mark, but this can be easily
cure by lowering the R's. I have done some experiment to find out what R's to
get 125ma which is still good for bare MOSFETS without heatsink.
If anyone sees anything alarming, please point that out.
Thanks!!
How much AC secondary you got when it works at 125mA?
Many people get enough asymmetry from that trick on plus side reg's Jfet under leds but it helps offset too. How are your offsets? If you want to listen with symmetry and decide, go read the first post from using the hypno as a shunt reg thread in psus section. There is an easy trick to go orthodox.
Many people get enough asymmetry from that trick on plus side reg's Jfet under leds but it helps offset too. How are your offsets? If you want to listen with symmetry and decide, go read the first post from using the hypno as a shunt reg thread in psus section. There is an easy trick to go orthodox.
The AC secondary is irrelevant for the CCS. I have a 15-0-15 toroid running behind a variac. I started with 12VAC and raised slowly to 100% (15VAC), the voltages across the R1's remained the same as the numbers in my previous post. However, I could raise the current to 125ma on both sides by adding a 14R to the -ve side and a 17R to the +ve side. The -ve is easier to make, the resulted R is about 10R which I have quite a few in my parts bin. The +ve is kind of a little tricky, I need a 12R which will have to be made up from whatever I have.
I read that the DCB1 was designed to be asymmetrical between the 2 rails, and I did read the use hypno thread about how to bring it back to symmetrical. I was just surprised that mine came out so close to symmetrical with stock DCB1 circuit and wonder anything wrong.
I hope I will have some time this afternoon to wire up the rest and to do a listening test in the stock form and go from there
I read that the DCB1 was designed to be asymmetrical between the 2 rails, and I did read the use hypno thread about how to bring it back to symmetrical. I was just surprised that mine came out so close to symmetrical with stock DCB1 circuit and wonder anything wrong.
I hope I will have some time this afternoon to wire up the rest and to do a listening test in the stock form and go from there
One way to get closer than norm, is to have a weaker idss JFET in the plus side. Another way is if the particular Leds are stiff and don't translate easy to significantly more Vf for 5-10mA running current differences. Those Jfets do work both ways but the unorthodox way is normally stronger for self current and worse for regulation. In hot rod CCS currents environment the subjective benefit in THD profile is filled out by the stronger tone and details. In Blue the orthodox will be standard since its reinforced everywhere for hotrod. But unorthodox it helps tone with small currents. Helps with offset too if the audio fets are not that well matched also. Did you measure your offsets BTW?
Salas... offset appears to be +1mV, -3mv... so 4mV. Good, yes
Wiring should be done today or tomorrow. Thanks for your help, as always.
Left channel + 1mV, right channel -3 mV so 1 mV and -3 mV. No adding of parameters of both channels !
What trick ?
Salas, I can not read/understand this post !
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