Portlandmike said:
Mike,
Sounds like you are getting similar results as I am. While I do like the stronger bass of the FC's the M's seem more natural and musical to me. I may get yelled at for this 🙂 But from my experience and reviews of UCD based amps is that they are not the most "ballsy" or dynamic amps in the world. They have good dynamics and can be improved with some tweaking. I sometimes think this is part of what people are trying to impove with the FC caps.
Let me know your thoughts with the 470 ufd cap if you try it. I thought it gave me the best soundstage of all the caps I have tried. In fact I may switch back to it. Unless someone finds a better cap for this spot. The sibilance or "sssss's" you hear may be the caps needing more break in?
One thing I found using caps larger than 470 ufd is you can get a slight grunge? or something in the mid's. With the 1000ufd M cap's, bypassing them with a .01 FKP seems to clear this up. Also impoving the overall transparency. This didn't work with the larger FC cap's though. In fact it seemed to make them sound worse.
Hope this helps.
Mike2 said:
Mike2,
I agree with you that the UcD's are not that dynamic. In fact, the one thing I miss over my previous amp, the only one I feel really bests the UcD, is its not as live sounding as that amp. The stage is excellent, but the dynamics or what I find to be that convincing "live" sound of the is not there. Quite laid back. I sometimes wonder if its not the op amp. My experience has been that discrete is usually best when done right. I don't have my previous amp to test the AD8620 on though, so..... I'll wait to see.
thanks for info on your experience. Its very helpful, and when two agree, it helps me trust my ear. Your comments make me think trying say a ~0.33u with a ~25mohm series shunt across the 470u socket might damp the HF resonance a bit with lower ESR's.
When I did simulations, the resonance of the 470uF socket with very low esr caused a wopper of a resonance in the several Mhz range because of the ceramic bypass cap. Bruno has 5mohm in series with that which is I guess optimized for the yeago's.
I ordered, but there back ordered, some quite expensive .47uF 100V X7R's for the ceramic replacement. I suspect with those you could increase the 5mohm a bit thus damping out the resonance a bit more while having more fast charge availible to damp those spikes you see.
So do you find the 1000uF M's the favorite?
Do you or anyone know where the feedback RC's are?
I haven't traced it but I fear they are under the epoxy
Best Regards,
Mike
As I understand it they are under the epoxy. Too bad, it would have been a good place to try silver mica caps.
classd4sure said:
And decent resistors, which I think may be part of the dynamics issue.
You know, if you soak epoxy in water for several hours, it just peals off!
Mike
Portlandmike said:
And decent resistors, which I think may be part of the dynamics issue.
You know, if you soak epoxy in water for several hours, it just peals off!
Mike
You're kidding??
For me, it depends. My UCD400 based system is a bit laid back and diplomatic in sonic presentation. OK with me for now because it is so revealing with my "balanced power" device 😎
Anyway I thought about doubling the PS capacitance from 20mF to 40mF per monoblock and see... (Sikorel, of course)
That is, while we get the Rubicon ZL 😉
My humble "active" system on the contrary is verry dynamic!
I wonder how many forum mates are using UCD's on that kind of system.
All the best.
M.
classd4sure said:
Chris,
Not really. There are a couple of things I detest under that epoxy.
One is ceramic caps in the signal path, one is plane old Vbe biased current source designs. Any one of these would cause most serious audio designers to blow chunks, although it seems the audio world is for the most part still in the dark about current sources.
Each of those things I've found has a profound affect on sound. To the degree that I'm quite amazed it sounds as good as it does, but on my system I'd give it a 9 for image and stage and about a 4 for live dynamics. The more I get used to the amp, the more I find myself missing the dynamics rather than enjoying the staging. I want both.
By the way, for clarification, what I'm talking about when I say dynamics may not be what others call it. Its the temporal quality to an instrument that makes it sound like its right there in the room. Its totally seperate from staging as I have heard in audio equipment that did and didn't stage well.
If there is a better word for this, I'd love to increase my vocabulary for audio.
Maricio, My beef is that in an identicle system, the UcD isn't as live dynamically.
Best Regards,
Mike
Mike:
Presence??? Do you mean the "solidity" of the instrument's sound? Plus notes' decay...
You know I am monothematic: 🙁
clean power for this revealing amp.
Enter power filtering/isolation.
Otherwise, noise will obscure the difference between instrument and black backstage.
Just MHO.
Presence??? Do you mean the "solidity" of the instrument's sound? Plus notes' decay...
You know I am monothematic: 🙁
clean power for this revealing amp.
Enter power filtering/isolation.
Otherwise, noise will obscure the difference between instrument and black backstage.
Just MHO.
Micro-dynamics man! It's what gives it life, spatial imagery, holographic resonances... I think it's an intrinsic part of the soundstage though, helps give it depth and definition.
Portlandmike said:
I ordered, but there back ordered, some quite expensive .47uF 100V X7R's for the ceramic replacement. I suspect with those you could increase the 5mohm a bit thus damping out the resonance a bit more while having more fast charge availible to damp those spikes you see.
So do you find the 1000uF M's the favorite?
Do you or anyone know where the feedback RC's are?
I haven't traced it but I fear they are under the epoxy
Best Regards,
Mike
I would not mess with that 5mOhm resistor, I think it is used to monitor the rail current. If you increase that resistor, your amp will likely shut down at a lower current.
Gertjan
maxlorenz said:
For me, it depends. My UCD400 based system is a bit laid back and diplomatic in sonic presentation. OK with me for now because it is so revealing with my "balanced power" device 😎
Anyway I thought about doubling the PS capacitance from 20mF to 40mF per monoblock and see... (Sikorel, of course)
That is, while we get the Rubicon ZL 😉
My humble "active" system on the contrary is verry dynamic!
I wonder how many forum mates are using UCD's on that kind of system.
All the best.
M.
I`m using them in active speakers, in fact I`m still using UcD180 for mid and high. Replaced the standard output caps with 2x330nF wima MKP2 in parallel. This made the sound more laid-back in my feeling. Sound is further away and/or less connected to the speakers. I feel that is a good thing and maybe subjectively interpreted as less dynamic?????
Gertjan
Portlandmike said:
I also totally agree with that, my UCD180 had orginally the NE5532 fitted, although those op-amps was far from perfect I thought the amp sounded dynamic with a decent soundstage, I fitted the AD8620 and to be honest was disapointed, the dynamics reduced a fair bit, the mids had a sort of hollow sound, it changed the sound altogether to be honest😕 its like I've now been trying to improve this by mucking about changing the output,decoupling caps,CRD mod etc to make up for it.
A discrete input stage would probably be much better if we can find something suitable
Great let's get started....
1. Should allow DC coupling
2. Should have a fairly high bandwidth
3. True differential input
4.
1. Should allow DC coupling
2. Should have a fairly high bandwidth
3. True differential input
4.
t. said:
Use an OPA2134 or OPA2132 (same with lower offset), its better than AD8620 at this place and less expensive.
.
stef1777 said:
Wouldn't mind trying that myself if I can get samples.
Anyone going for that who currently has the CRD mod should re-mod it so that it ties to the positive rail instead in order to preserve the full effect of it.
opamps?
I also have had the same type of experience with opamps. 5532 too noisy and grungy, just not open sounding. The 8620 leaves me yawning, no life. My personal answer is the same one Lars uses the, LM6172. This chip has problems with high frequency instability and ringing if not properly decoupled. It also has the added problem of high bias current requirements. This requires equal DC resistance to both input pins or you end up with excessive offset (Volts!). For using it with the UcD’s it requires the use of 2 coupling caps, one to break the ground connection to DC. With this done the offset is very good. The sound has the sparkle of the 8620 and is more dynamic than the 5532 but most important it makes music more enjoyable. Direct coupling is only possible with equal +/- DC resistance sources, very unlikely with single ended. Bottom line, it is so cheap in comparison to the 8620 you can afford the extra quality cap and the sound is so much better who cares!
Roger
I also have had the same type of experience with opamps. 5532 too noisy and grungy, just not open sounding. The 8620 leaves me yawning, no life. My personal answer is the same one Lars uses the, LM6172. This chip has problems with high frequency instability and ringing if not properly decoupled. It also has the added problem of high bias current requirements. This requires equal DC resistance to both input pins or you end up with excessive offset (Volts!). For using it with the UcD’s it requires the use of 2 coupling caps, one to break the ground connection to DC. With this done the offset is very good. The sound has the sparkle of the 8620 and is more dynamic than the 5532 but most important it makes music more enjoyable. Direct coupling is only possible with equal +/- DC resistance sources, very unlikely with single ended. Bottom line, it is so cheap in comparison to the 8620 you can afford the extra quality cap and the sound is so much better who cares!
Roger
Sorry hit the button twice.
There must be a way to delete a second message like this but I don't know how.
There must be a way to delete a second message like this but I don't know how.
I can't say I would miss the AD8620, I've tried this op-amp in other units like cdp's etc and never liked its signature
I wish I never fitted this in my UCD180 to be honest.
It has been recommended if we was going to go dicrete it would be best to use something like a folded cascode design.
All we need is a suitable circuit, any idea's🙂 failing that it looks like another smd dual op-amp, either way the AD8620 is going to be removed out of my amp soon
I wish I never fitted this in my UCD180 to be honest.It has been recommended if we was going to go dicrete it would be best to use something like a folded cascode design.
All we need is a suitable circuit, any idea's🙂 failing that it looks like another smd dual op-amp, either way the AD8620 is going to be removed out of my amp soon
Re: opamps?
What sort of coupling caps would you recommend if using the LM6172 Roger? Auricaps? although they are a bit big
I've got to sort something with my UCD, I'm not listening to it much lately, the music just isn't there, damn AD8620
Theres also the AD826 which has been recommended a couple of times by various people
sx881663 said:
What sort of coupling caps would you recommend if using the LM6172 Roger? Auricaps? although they are a bit big
I've got to sort something with my UCD, I'm not listening to it much lately, the music just isn't there, damn AD8620
Theres also the AD826 which has been recommended a couple of times by various people
Re: Re: opamps?
If you want to stay with small caps who will fit, you can try these ones:
Black Gate NX Hi-Q 47uF
Rubycon NA 47uF or 100uF
Silmic II 47uF
Better to stay with coupling caps for security reason.
.
t. said:
If you want to stay with small caps who will fit, you can try these ones:
Black Gate NX Hi-Q 47uF
Rubycon NA 47uF or 100uF
Silmic II 47uF
Better to stay with coupling caps for security reason.
.
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