motu
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I read somewhere that I could bias the diamond buffers for the low impedance of my CD3000, is that true, and how would I go about it?
Discrete PPA Diamond Buffer - Alternative DIY Take :)
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Sovkiller
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I don't know exactly about this particular latest version of Glassman (and that is why I stated that if this one is dynamically biased, as we don't know for sure) But I have heard a few of them (indeed I think I have tried all the buffers commercially available to the date, including some beta versions, and including the version that was inlcuded in the PPA2 board) ..... The PPA2 uses a regular LaRocco diamond buffer, which BTW was my first discrete buffer)
The dynamically biased ones are the best I have tried among them, and if this version of them are also Dynamically biased, I don't see why they should sound different or worst that the ones I'm using now....
| Originally Posted by BrokenEnglish al... you should listen first and judge later.. 
|
I don't know exactly about this particular latest version of Glassman (and that is why I stated that if this one is dynamically biased, as we don't know for sure) But I have heard a few of them (indeed I think I have tried all the buffers commercially available to the date, including some beta versions, and including the version that was inlcuded in the PPA2 board) ..... The PPA2 uses a regular LaRocco diamond buffer, which BTW was my first discrete buffer)
The dynamically biased ones are the best I have tried among them, and if this version of them are also Dynamically biased, I don't see why they should sound different or worst that the ones I'm using now....
steinchen
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I don't know the bias of the Glassman buffers, my PPA v2.0 is biased with the recommended 50 mA (110mV over 2.2Ohms).
Supply voltage is 30V for both amps.
Performance with K1000 is only SLIGHTLY better, not much. But that doesn't matter because for me the M³ is the King of the hill and is driving K1000 with a 30V PSU fine indeed. Therefore I'm not going to crank the parts up to their limits.
| Originally Posted by morsel What were the supply voltages and output bias currents for the PPA v1.1 with Glassman buffers and PPA v2 you tested? I find it hard to believe the Glassman buffers drive the K1000 better than the PPA v2 buffers if supply voltage and output bias are equal. For driving the K1000 you want as much supply voltage and output bias as possible. Choose a power supply and opamps that will handle 36V rails. Try some clip on heat sinks. |
I don't know the bias of the Glassman buffers, my PPA v2.0 is biased with the recommended 50 mA (110mV over 2.2Ohms).
Supply voltage is 30V for both amps.
Performance with K1000 is only SLIGHTLY better, not much. But that doesn't matter because for me the M³ is the King of the hill and is driving K1000 with a 30V PSU fine indeed. Therefore I'm not going to crank the parts up to their limits.
ppl
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If Detail is what you want without undue Brightness then i think the AD8065 is what you might like. If treble energy is really your desire then the AD-8610, if Bass is what your after the AD843.
| Originally Posted by BrokenEnglish can't imagine that, andy. same value: 100pf, same line (fkp2), higher voltage (1600v)... what's the problem? but don't worry... they'll be replaced by 1000v/100pf ones soon. the sound is not bad at all. i'd say, it's most likely markedly better than with the intersils inside. i'm sure, steinchen will elaborate on that as he'll be able to switch between his ic-buffered ppa and different discrete versions. within my rig the ppa has to compete with the wna ha (lm6171 inside). to keep it short: the glassmaned ppa offers a better tonal balance whereas the wna ha still is the champion in terms of detail and (after the last mods) accurate and deep bass-reproduction... well... at least for the moment... pre-burn-in... |
If Detail is what you want without undue Brightness then i think the AD8065 is what you might like. If treble energy is really your desire then the AD-8610, if Bass is what your after the AD843.
BrokenEnglish
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thanks, ppl - good to have you around! hope some ad843 will arrive this week. would need to find a source for the ad8065 if the ad843 will not suit my taste. ok... step by step.
in the meantime, after some burnin and further mods (c1 replaced incl. some bypassing caps, gain reduced) the ppa sounds really great. still would prefer some more detail...
(if there only were a viable way to use the lm6171 in the ppa... hey.. i know.. it's only a dream.. )
| Originally Posted by ppl If Detail is what you want without undue Brightness then i think the AD8065 is what you might like. If treble energy is really your desire then the AD-8610, if Bass is what your after the AD843. |
thanks, ppl - good to have you around! hope some ad843 will arrive this week. would need to find a source for the ad8065 if the ad843 will not suit my taste. ok... step by step.
in the meantime, after some burnin and further mods (c1 replaced incl. some bypassing caps, gain reduced) the ppa sounds really great. still would prefer some more detail...
(if there only were a viable way to use the lm6171 in the ppa... hey.. i know.. it's only a dream.. )
Sovkiller
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I second the AD8065 for details it is a hell of an OPAmp, that makes me remove my beloved OPA637BP from it, later on listening carefully the AD843, I'm still burning them, I think I will end with those, but not sure yet, if you get the AD8065, and you are affraid of mounting them yourself, I will do it for you in a heartbeat.
I was even thinking in conforming a PPA rolling pack.....for all the PPA lovers, let's see....other to consider is the AD744....
| Originally Posted by BrokenEnglish thanks, ppl - good to have you around! hope some ad843 will arrive this week. would need to find a source for the ad8065 if the ad843 will not suit my taste. ok... step by step. in the meantime, after some burnin and further mods (c1 replaced incl. some bypassing caps, gain reduced) the ppa sounds really great. still would prefer some more detail... (if there only were a viable way to use the lm6171 in the ppa... hey.. i know.. it's only a dream.. ) |
I second the AD8065 for details it is a hell of an OPAmp, that makes me remove my beloved OPA637BP from it, later on listening carefully the AD843, I'm still burning them, I think I will end with those, but not sure yet, if you get the AD8065, and you are affraid of mounting them yourself, I will do it for you in a heartbeat.
I was even thinking in conforming a PPA rolling pack.....for all the PPA lovers, let's see....other to consider is the AD744....
Glassman
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for AD744 there's an important trick though, you can skip their own output stage and connect the buffers there instead, some modifications on PPA board are neccessary of course.. this is probably the most meaningful use of opamps when paired with discrete buffers.. I'm getting AD744 soon personally.. I will provide details on how to modify your PPA for running these with bypassed output stage with my buffers..
as for the dynamical biasing rumors out there.. I can only tell you that mine have these properities: cascoded input stage without additional parts used to accomplish this and the second thing is that the output transistors never shut down as they are connected to constant current sources, again without any additional parts used.. call it as you like, it's up to you, one thing is clear though - these are not the usuall Diamond Buffers like my first generation ones or the original Triad modules, which are now integrated on PPAv2 board..
as for the bias, there is 25mA flowing through the output emmiter resistors plus about 6.5mA due to the constant current sources, that is indeed less than those 50mA you have in PPAv2 and still find them doing better job then PPAv2, I'm pleased
as for the dynamical biasing rumors out there.. I can only tell you that mine have these properities: cascoded input stage without additional parts used to accomplish this and the second thing is that the output transistors never shut down as they are connected to constant current sources, again without any additional parts used.. call it as you like, it's up to you, one thing is clear though - these are not the usuall Diamond Buffers like my first generation ones or the original Triad modules, which are now integrated on PPAv2 board..
as for the bias, there is 25mA flowing through the output emmiter resistors plus about 6.5mA due to the constant current sources, that is indeed less than those 50mA you have in PPAv2 and still find them doing better job then PPAv2, I'm pleased
ppl
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No the AD843 was the Flavor of the month about 5 years ago on these forums and has only made a comeback recently. If you like punch and bass dynamics this is the Op-Amp you want.
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Holy Mollie I don’t know how 50 mA was the recommended Bias for the PPA V2 The PPA is a portable amp and the V2 Buffers are intended for low bias current operation. The useable Bias range is 10-30 mA above 30 mA you are over biasing the output stage of the V2 MY recommended Bias is 15-25 mA.
As you increase the Bias current the Maximum available voltage swing is reduced because of the Voltage Drop across the emitter resistors in the current mirrors go up with Increasing bias current. At 50 mA you are probably losing + or – 2 volts of available output swing just from the voltage drop across the Current mirror resistors. The K1000 are 120-ohm headphones that require lots of output voltage to drive so any loss in available output voltage will reduce the dynamic range you can obtain, thus I recommend a lower bias setting like 20 Ma and see if you now don’t get adequate loudness. Personally I have used amps powered by two series connected 9-volt batteries and have had no problem with driving them, However am sure you were listening way louder than I was.
Quote:
I’m am not a big fan of the LM61 series of op amps thay make great Virtual ground drivers however they sound spitty and with so much grain that its IMHO a waist of time to make these work in the PPA when so many other better sounding devices are available that work great In the PPA. The LM61 series of op amps mate well with the softer sounding BUF634 IC buffers but that’s about the only combo I liked with them.
My sonic preferences are detail but without the brightness and Glare. I think a lot of people mistake Brightness with Detail and in reality thay is very different, unfortunately most Solid-state electronics that are detailed are also bright. The AD8065 is the exception.
IMHO the FOTM is in actually real time tested classics that keep resurfacing as better ways to implement them are discovered or that after going though all the latest fads that people return to trusted old staples.
| Originally Posted by BrokenEnglish maybe the FOTM? 
|
No the AD843 was the Flavor of the month about 5 years ago on these forums and has only made a comeback recently. If you like punch and bass dynamics this is the Op-Amp you want.
Quote:
| Originally Posted by steinchen I don't know the bias of the Glassman buffers, my PPA v2.0 is biased with the recommended 50 mA (110mV over 2.2Ohms). Supply voltage is 30V for both amps. Performance with K1000 is only SLIGHTLY better, not much. But that doesn't matter because for me the M³ is the King of the hill and is driving K1000 with a 30V PSU fine indeed. Therefore I'm not going to crank the parts up to their limits. |
Holy Mollie I don’t know how 50 mA was the recommended Bias for the PPA V2 The PPA is a portable amp and the V2 Buffers are intended for low bias current operation. The useable Bias range is 10-30 mA above 30 mA you are over biasing the output stage of the V2 MY recommended Bias is 15-25 mA.
As you increase the Bias current the Maximum available voltage swing is reduced because of the Voltage Drop across the emitter resistors in the current mirrors go up with Increasing bias current. At 50 mA you are probably losing + or – 2 volts of available output swing just from the voltage drop across the Current mirror resistors. The K1000 are 120-ohm headphones that require lots of output voltage to drive so any loss in available output voltage will reduce the dynamic range you can obtain, thus I recommend a lower bias setting like 20 Ma and see if you now don’t get adequate loudness. Personally I have used amps powered by two series connected 9-volt batteries and have had no problem with driving them, However am sure you were listening way louder than I was.
Quote:
| Originally Posted by BrokenEnglish thanks, ppl - good to have you around! hope some ad843 will arrive this week. would need to find a source for the ad8065 if the ad843 will not suit my taste. ok... step by step. in the meantime, after some burnin and further mods (c1 replaced incl. some bypassing caps, gain reduced) the ppa sounds really great. still would prefer some more detail... (if there only were a viable way to use the lm6171 in the ppa... hey.. i know.. it's only a dream.. ) |
I’m am not a big fan of the LM61 series of op amps thay make great Virtual ground drivers however they sound spitty and with so much grain that its IMHO a waist of time to make these work in the PPA when so many other better sounding devices are available that work great In the PPA. The LM61 series of op amps mate well with the softer sounding BUF634 IC buffers but that’s about the only combo I liked with them.
My sonic preferences are detail but without the brightness and Glare. I think a lot of people mistake Brightness with Detail and in reality thay is very different, unfortunately most Solid-state electronics that are detailed are also bright. The AD8065 is the exception.
IMHO the FOTM is in actually real time tested classics that keep resurfacing as better ways to implement them are discovered or that after going though all the latest fads that people return to trusted old staples.
Syzygies
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Wow! You should write ad copy. If anyone ever nailed what I'm trying to sort out with my amps, you just did. I don't mistake Brightness and Glare with Detail, I just thought the hangover came with the booze. Now my Ety 4s and I have to buy yet another set of op amps
| Originally Posted by ppl My sonic preferences are detail but without the brightness and Glare. I think a lot of people mistake Brightness with Detail and in reality thay is very different, unfortunately most Solid-state electronics that are detailed are also bright. The AD8065 is the exception. |
Wow! You should write ad copy. If anyone ever nailed what I'm trying to sort out with my amps, you just did. I don't mistake Brightness and Glare with Detail, I just thought the hangover came with the booze. Now my Ety 4s and I have to buy yet another set of op amps
BrokenEnglish
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ppl, my fotm-remark was just a joke... a bow to gsferrari's fotm-threads those days...
in general i don't like such labels: we'd have to speak of of the opa627/637 and ad8610 as FOSYs (favor of some years) then...
reading your description of the sonic characteristics of the ad843 i have to guess, that those are not the ones for me...
Quote:
hm... hmmm... even if you mark it as a mistake, i prefer - along with my phones - brighter setups. i was used to listen to my music with maxed trebles on my really bad rigs for long years...
... that's my personal auditive history. on your description, dr. ppl, i'll try to retrain my ears/cortex... huh... but please... i can't stand that bitter-sweet "opa forte" medicine anymore...
/edit: oh... just saw al's posting:
Quote:
thanks... that's a nice gesture! tell you what.. i'll wait until you've decided for the ad843 and then grab your ad8065
- if necessary at all... let's discuss it via pm then...
| Originally Posted by ppl No the AD843 was the Flavor of the month about 5 years ago on these forums and has only made a comeback recently. If you like punch and bass dynamics this is the Op-Amp you want. |
ppl, my fotm-remark was just a joke... a bow to gsferrari's fotm-threads those days...
reading your description of the sonic characteristics of the ad843 i have to guess, that those are not the ones for me...
Quote:
| Originally Posted by ppl My sonic preferences are detail but without the brightness and Glare. I think a lot of people mistake Brightness with Detail and in reality thay is very different, unfortunately most Solid-state electronics that are detailed are also bright. The AD8065 is the exception. |
hm... hmmm... even if you mark it as a mistake, i prefer - along with my phones - brighter setups. i was used to listen to my music with maxed trebles on my really bad rigs for long years...
/edit: oh... just saw al's posting:
Quote:
| Originally Posted by Sovkiller I second the AD8065 for details it is a hell of an OPAmp, that makes me remove my beloved OPA637BP from it, later on listening carefully the AD843, I'm still burning them, I think I will end with those, but not sure yet, if you get the AD8065, and you are affraid of mounting them yourself, I will do it for you in a heartbeat. |
thanks... that's a nice gesture! tell you what.. i'll wait until you've decided for the ad843 and then grab your ad8065
Sovkiller
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I don't think I will sell my 8065 unless I sell my PPA also, I want to keep a rolling OPAmp kit just for fun, and definitelly the 8065 will be part of it, even as I stated above, I'm planning on doing an OProlling kit for the PPA owners to try diferent approaches, not sure to what point it will be a good idea, and maybe I will loose some of the OPamps in the trial and error process, those are not as the tubes, they could be damaged easily by static charge, etc...
| Originally Posted by BrokenEnglish thanks... that's a nice gesture! tell you what.. i'll wait until you've decided for the ad843 and then grab your ad8065
|
I don't think I will sell my 8065 unless I sell my PPA also, I want to keep a rolling OPAmp kit just for fun, and definitelly the 8065 will be part of it, even as I stated above, I'm planning on doing an OProlling kit for the PPA owners to try diferent approaches, not sure to what point it will be a good idea, and maybe I will loose some of the OPamps in the trial and error process, those are not as the tubes, they could be damaged easily by static charge, etc...
bg4533
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I need to pick up 8065s. I tried the 8066 in a Pimeta with my old MS2, but I wasn't that impressed. I hope for better with the HD650 and PPA. They are so cheap I can't really go wrong.
Still haven't been able to try the AD843 in the PPA yet either. My isolation JFETS are at 10mA which isn't enough. I think I am going to socket an extra so I can try the 843.
So far I am pretty happy with the OPA627.
Also, I have shipped all of the buffer orders that were placed with me so far. Some yesterday, some today. I don't feel like sending individual PMs right now.
Still haven't been able to try the AD843 in the PPA yet either. My isolation JFETS are at 10mA which isn't enough. I think I am going to socket an extra so I can try the 843.
So far I am pretty happy with the OPA627.
Also, I have shipped all of the buffer orders that were placed with me so far. Some yesterday, some today. I don't feel like sending individual PMs right now.
Juergen
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I hadn't realized the US buffers were available. I have been watching for a Mall-Fi ad. How many do you have left?
| Originally Posted by bg4533 ... Also, I have shipped all of the buffer orders that were placed with me so far. Some yesterday, some today. I don't feel like sending individual PMs right now. |
I hadn't realized the US buffers were available. I have been watching for a Mall-Fi ad. How many do you have left?
ppl
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BrokenEnglish> I am sorry i did not wish to offend anyones sonic sensibilities i do understand your posistion.
BrokenEnglish
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no offense taken, ppl! your valuable hints are always welcome!
| Originally Posted by ppl BrokenEnglish> I am sorry i did not wish to offend anyones sonic sensibilities i do understand your posistion. |
no offense taken, ppl! your valuable hints are always welcome!
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