Peter,
I´m getting really interested building an Aleph-X instead of Aleph 2´s but still have some questions:
1.What happens when you use this circuit with an unbalanced source? Reading the user manuals from X-150 etc. there´s no note that this will worsen the sound/power or anything else. There´s just the usual shorting pin between -IN and ground.
I will eventually build a new balanced preamp but can´t do everything at the same time.
2. I assume that just like with a normal Aleph you can play around with the ac-current gain to get more power into lower impedances (have to feed my Thiels and 10A bias (total) with +-15V supplies is about the maximum my heatsinks will allow for)
william
I´m getting really interested building an Aleph-X instead of Aleph 2´s but still have some questions:
1.What happens when you use this circuit with an unbalanced source? Reading the user manuals from X-150 etc. there´s no note that this will worsen the sound/power or anything else. There´s just the usual shorting pin between -IN and ground.
I will eventually build a new balanced preamp but can´t do everything at the same time.
2. I assume that just like with a normal Aleph you can play around with the ac-current gain to get more power into lower impedances (have to feed my Thiels and 10A bias (total) with +-15V supplies is about the maximum my heatsinks will allow for)
william
I had my reservations too about using it single ended, but it came out that it is no problem at all. I grounded the negative input through the capacitor. In case of my high pass filter (at 120Hz) I used .12u caps on both inputs. The negative input (on the amp) connects to ground through the cap. Shield (from interconnecr) goes directly to the ground). Both caps have to have the same value, otherwise hum is observed. Also the grounding cap acts as a filter too, so the value has to be adjusted for that.
I also tried 100k resistor (input to ground) before the cap, and it influences the sonics: somehow cleans the sound, making everything more focused.
I think the caps at the input are pretty important, because although my preamps have 0V DC on output (one is AC coupled the other has servo), when I short either cap DC offset appears at the output (even on the cap to the ground).
Here's additional info copied from other thread:
>Somebody did really nice pictures of this boards (I like the schematic's bacground ). I think the most tricky part will be choosing proper value for source resistors. It would be nice to aim at 0.5V drop, yet current is pretty much dependent on the heatsinks (if you want to keep them at 50 deg C). I have 4 pairs per side and used the value of 0.56 ohm, yet I had to lower the current and the actual drop is around 0.42V. The feedback cap I'm using is 10p, yet the square wave looks better with 5pF. It's silver mica from Digi-Key. I'm using 4k7 sources to output DC comp resistors and the value of 100ohm (10W Dale) for absolute DC offset correction resistor (otput to ground). The offset is very stable so I think those values are pretty much correct. I'll try today to omit the 100ohm resistors and see what happens. I didn't use lag capacitors (didn't even try to put them in a circuit). Most of the values of the resistors are according to the circuit posted by rtirion. I used 220k resistor in the feedback loop, 33K input to ground resistor. Initially I had 68K, but Nelson advised me that lower value is prefferable. My gain is around 26dB.
I noticed that input caps have big influence on DC offset. Initially I was using 2uF and -3dB was at 8Hz. I'm using now 0.06uF for high pass filtering at 120Hz (for bi-amp system). The values of the caps had to be the same on both sides. If I placed 0.06 on positive input and 2uF coupling negative input to ground, I got hum. Also my BOZ has a cap at the output, yet when I shorted the cap on posistive input the offset jumped to 300mV.
When I shorted the negative input to ground cap the offset jumped to something like 1V.
I'm using thermistors between the cap banks and they work pretty well. Also I have soft recovery diodes from Dig-Key and 0.33u caps across ea. (this was tha value I had at hand).<
As to your question on current gain, I believe it adjusts the same way as the regular Aleph. But I don't have to tell you this, you are an expert in this field and I keep copies of all your posts on that subject.
I also tried 100k resistor (input to ground) before the cap, and it influences the sonics: somehow cleans the sound, making everything more focused.
I think the caps at the input are pretty important, because although my preamps have 0V DC on output (one is AC coupled the other has servo), when I short either cap DC offset appears at the output (even on the cap to the ground).
Here's additional info copied from other thread:
>Somebody did really nice pictures of this boards (I like the schematic's bacground ). I think the most tricky part will be choosing proper value for source resistors. It would be nice to aim at 0.5V drop, yet current is pretty much dependent on the heatsinks (if you want to keep them at 50 deg C). I have 4 pairs per side and used the value of 0.56 ohm, yet I had to lower the current and the actual drop is around 0.42V. The feedback cap I'm using is 10p, yet the square wave looks better with 5pF. It's silver mica from Digi-Key. I'm using 4k7 sources to output DC comp resistors and the value of 100ohm (10W Dale) for absolute DC offset correction resistor (otput to ground). The offset is very stable so I think those values are pretty much correct. I'll try today to omit the 100ohm resistors and see what happens. I didn't use lag capacitors (didn't even try to put them in a circuit). Most of the values of the resistors are according to the circuit posted by rtirion. I used 220k resistor in the feedback loop, 33K input to ground resistor. Initially I had 68K, but Nelson advised me that lower value is prefferable. My gain is around 26dB.
I noticed that input caps have big influence on DC offset. Initially I was using 2uF and -3dB was at 8Hz. I'm using now 0.06uF for high pass filtering at 120Hz (for bi-amp system). The values of the caps had to be the same on both sides. If I placed 0.06 on positive input and 2uF coupling negative input to ground, I got hum. Also my BOZ has a cap at the output, yet when I shorted the cap on posistive input the offset jumped to 300mV.
When I shorted the negative input to ground cap the offset jumped to something like 1V.
I'm using thermistors between the cap banks and they work pretty well. Also I have soft recovery diodes from Dig-Key and 0.33u caps across ea. (this was tha value I had at hand).<
As to your question on current gain, I believe it adjusts the same way as the regular Aleph. But I don't have to tell you this, you are an expert in this field and I keep copies of all your posts on that subject.
Here's how I mounted caps. I paralleled Silvertone silver foil with Jensen copper foil (paper in oil type) for positive side and Silvertone with MIT RTX for negative side. I didn't have enough of Jensen caps. Although people say good things about those Jensens, I'm not totally satisfied, they seem to be heavy sounding with not too much detail and all voices sound kinda low. If I wouldn't parallel with siver cap (which BTW is great)< I wouldn't use Jensen at all.
Attachments
And here are the amps. Most of you've seen those chassis before, yet, they deserve their spot in this thread. I find this type of chassis design very attractive both visualy and practically. Normally I stack them one on top of the other. And the inspiration comes from original Alephs. Thank you again Mr. Pass for all your contributions to DIY Audio world.
Attachments
Must say I was wondering about the same thing.
It is Peter's work that makes me keep trying to make the internals neater on my amps - even though no one will see them!!!
You are really something else when it comes to DIYAudio...
You must be crap at something? You don't even seem to be a nasty person!!!
Well done...Again!
Gaz
It is Peter's work that makes me keep trying to make the internals neater on my amps - even though no one will see them!!!
You are really something else when it comes to DIYAudio...
You must be crap at something? You don't even seem to be a nasty person!!!
Well done...Again!
Gaz
Rarkov said:
You must be crap at something? You don't even seem to be a nasty person!!!
There is one thing I'm crap at...I can't commit myself to full time job.
I'm using 2 amps per channel. What you see here is one channel. Bottom amp is Aleph X and it feeds tweet and mids. Top one is A75 used for subs. I have two (12" and 15"), that's why two cables.
Peter Daniel said:
There is one thing I'm crap at...I can't commit myself to full time job.
I'm using 2 amps per channel. What you see here is one channel. Bottom amp is Aleph X and it feeds tweet and mids. Top one is A75 used for subs. I have two (12" and 15"), that's why two cables.
If you don't commit to a job sometime, you will have to result to more frugle components.
Has anyone gone as far as make a Fruglephile(tm) amplifier? Dave?
As for the large speakers, what do you crossover the 12" and 15" at? They are quite interesting looking.
--
Brian
Peter
Regarding the polarization of Your inputcaps.
I found this description on the "Super E-Caps" from BlackGate on the site http://www.referenceaudiomods.com/bgecaps.html
quote:
--------------------------------------------------------------------------------
Canceling resonance frequency by using the characteristics of Black Gate-N
Jelmax has developed a new system which uses a pair of two BG-Ns of the same voltage and capacity in such a way that their internal inductances (L) canceled each other by utilizing the mechanical characteristic of the BG-N using a rolled pair of electrode foils of the same area and same mechanism set fact to face, and thereby, allows the pair to function as a single ideal capacitor called “Super E-Caps”.
--------------------------------------------------------------------------------
I posted this and a little more on the X SOZ thread the other day, I bring it here just i case You didn´t se it.
Regarding the polarization of Your inputcaps.
I found this description on the "Super E-Caps" from BlackGate on the site http://www.referenceaudiomods.com/bgecaps.html
quote:
--------------------------------------------------------------------------------
Canceling resonance frequency by using the characteristics of Black Gate-N
Jelmax has developed a new system which uses a pair of two BG-Ns of the same voltage and capacity in such a way that their internal inductances (L) canceled each other by utilizing the mechanical characteristic of the BG-N using a rolled pair of electrode foils of the same area and same mechanism set fact to face, and thereby, allows the pair to function as a single ideal capacitor called “Super E-Caps”.
--------------------------------------------------------------------------------
I posted this and a little more on the X SOZ thread the other day, I bring it here just i case You didn´t se it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.