I understand your concerns and yet I fail to see why you have to remove the op amp at all in order to test the module without it. Wasnt' it you who thought of taping into the modulator at the AC coupling cap point?
If you do you also have to keep in mind you're changing the topology by doing so, it's no longer an instrumentation amplifier with a high imput impedance, so you'll be hearing that change as well.
I assure you're not alone on the sound of the AD, but you know, one choses the lesser of all evils.
If you do you also have to keep in mind you're changing the topology by doing so, it's no longer an instrumentation amplifier with a high imput impedance, so you'll be hearing that change as well.
I assure you're not alone on the sound of the AD, but you know, one choses the lesser of all evils.
classd4sure said:
Yes I was but I actually wanted to use an external op-amp stage the same as whats on the UCD module that would be tapped into the modulator.
I'll try it without any op-amp, so I guess its ok to just wire my 22k Attenuator to the modulator, does any other components need to be fitted/added?
Ask JP just to be sure. I don't imagine their would be, but safest to ask he who would know. Input impedance will change to an unbalanced ~10K so .... I don't know if you're attenuator would load it adversely.
classd4sure said:
Thats why I wasn't really too keen to try it without any input stage, at least with an identical external circuit with dip socket it would have worked ok and gave me the right gain etc
SMD is ideal if your not wanting to try things out, these tiny op-amps can get damaged with heat on the legs so easy
I know the potential of the UCD module, it impressed me straight away with the standard NE5532, which is about the only time I thought this op-amp sounded ok, I know op-amps have an effect on the sound but the effect is huge with these amp modules
I have dual mono UCD power supply. If i use single ps. to op-amps, do i miss (possible) benefits of dual mono configuration or does good (?) PSRR of AD8620 playing role here?
Mmmmh, good question... i would guess even single Hi quality PS to opamps should outperform conventional dual mono common PS, even considering some possible loss in the soundstaging department.
(but that is because we want you to try it and tell us 😀 )
Update:
Dear Chris, you (and Bruno) were wright: those Y caps were injecting some HF garbage to ground that was felt as HF distortion. I remember that this brilliant HF ocurred when I was modding my superDAC. I was getting outstanding HF and Midrange and I (as usual) push further with another mod to its PS and got in exchange this nasty HF behaviour. I dind't go back because I heard other good things happen, you know how this is 🙁
I think the more extended amp' s HF response is the more prone to show this imperfection, obvious.
Well, now HF are better but not ideal. So please no Y caps on AC filters (mine are actually X1/Y2 so no complete loss)
I NEED A SCOPE! Concerning hot monoblock: the one that got hot is the one in wich the vertically placed PCB had the coil downwards. Maybe the upwards convective air flow is transmiting heat to the T piece. Instead, the other module's coils convects freelly to air (read top plate). I placed a big 6 mm DIY heatsink and it's cool now.
I hope this helps.
Mauricio
I'm going to get the input stage made on a couple of pieces of veroboard for the op-amps to save mucking about, , I've several different type duals to compare so it should be interesting
There will be small sockets on the output to allow for coupling caps or shorting links dending on the type of op-amp
I'll use offboard regs to power them up, with these I can adjust the voltage from 12 - 15v
Is this schematic for the UCD180 still the same appart from the input impedance?
There will be small sockets on the output to allow for coupling caps or shorting links dending on the type of op-amp
I'll use offboard regs to power them up, with these I can adjust the voltage from 12 - 15v
Is this schematic for the UCD180 still the same appart from the input impedance?
Attachments
Hi,
The imput impedance is 100K on that one. I know it was said it was wrong at the time it was posted, but at that time the module actually had 10K. 🙂
It's more right than not.
Might I suggest for a direct A/B to include the AD8620 on your board?
The imput impedance is 100K on that one. I know it was said it was wrong at the time it was posted, but at that time the module actually had 10K. 🙂
It's more right than not.
Might I suggest for a direct A/B to include the AD8620 on your board?
classd4sure said:
Cheers Chris
Yes, I want to include the AD8620, I'll start off with the AD8620 on the UCD board then remove the coupling cap links and fit the separate board with dip socket
The only thing is that the AD8620 will be using the regulated supply on the UCD and the dip will have a pair of LM317/337/tl431's so its not going to be that fair for the AD8620
The only other thing is to buy a couple more AD8620's and make a couple of little dip converter boards to fit in the dip socket
Opamps I currently have in dip are below, the board will be the same as the above schematic but using separate regs
AD826
OPA2227/2228
OPA2132
OPA2604
4 x opa627 (which I can convert to duals, they will also probably need more decoupling)
op275gp
NE5532
I'm not sure if any of the above would cause problems like oscillation etc in this circuit so if anybody has any advice it would be appreciated
Regarding the input inpedance should I fit 10k or 100k?
classd4sure said:
Chris-
Just a follow-up...
My new module has the same (apparent) CRD setup as the original. FWIW, I bought these modules directly from Hypex... shipping costs hurt, but I figured that JP's and Bruno's support here has earned them any extra margin that they make on direct sales.
As it turns out, my wife was in bed with the flu when the new module arrived, so I was not unduly tempted to power it up before taking a rest. I double checked it the next morning, everything was good, and she was able to enjoy some music the next day while she was out sick.
Thanks for the moral support and your help with grounding. All is well that ends well, and the amps sound great now. Most notably, the bass is a lot tighter than with the old B&K. It's been a couple of months since the B&K died, so I don't trust my audio memory much further than that. The bass, though, is definitely tighter.
-Bill
Hi Bill,
Thanks alot for the update, glad to hear it all worked out and sounds great.
Cheers,
Chris
Thanks alot for the update, glad to hear it all worked out and sounds great.
Cheers,
Chris
I've now got some of those SST511 CRD's which I want to try on the output of the AD8620 before I try the external input board which I've built
Just a quick question, theres two pads for the SST511's on each UCD module for each of the dual op-amps output.
Do I have to fit one of the CRD's on each of the outputs or just on one output?
I remember Bruno mentioning that its tied to the negative rail, I just want to be sure before I fit them
So basically do I fit 1 or 2 to each module?
Cheer🙂
Just a quick question, theres two pads for the SST511's on each UCD module for each of the dual op-amps output.
Do I have to fit one of the CRD's on each of the outputs or just on one output?
I remember Bruno mentioning that its tied to the negative rail, I just want to be sure before I fit them
So basically do I fit 1 or 2 to each module?
Cheer🙂
Ok so I've fitted them, 2 on each module, if its wrong please let me know.
I've got to be honest I didn't expect much of a difference
HOW WRONG CAN SOMEBODY BE😱
I was actually getting ready to just write off the AD8620 and just fit in the external input section to try out the other op-amps and I'm so glad I've tried this mod, that midband colour I didn't like before seems to have totally gone, the bass seems deeper, the soundstage more focused, the sound is far better altogether😕
How can fitting these CRD's make such a difference, could somebody please explain? is it just my hearing
It also seems a lot more revealing so if your source is bright it may not suit anybody
Can somebody else please try this mod and post their results just to put my mind at rest that I'm not going mad😀
Is it possible the psu caps or something has just burnt in
I've got to be honest I didn't expect much of a difference
HOW WRONG CAN SOMEBODY BE😱
I was actually getting ready to just write off the AD8620 and just fit in the external input section to try out the other op-amps and I'm so glad I've tried this mod, that midband colour I didn't like before seems to have totally gone, the bass seems deeper, the soundstage more focused, the sound is far better altogether😕
How can fitting these CRD's make such a difference, could somebody please explain? is it just my hearing
It also seems a lot more revealing so if your source is bright it may not suit anybody
Can somebody else please try this mod and post their results just to put my mind at rest that I'm not going mad😀
Is it possible the psu caps or something has just burnt in
t. said:Ok so I've fitted them, 2 on each module, if its wrong please let me know.
I've got to be honest I didn't expect much of a difference
HOW WRONG CAN SOMEBODY BE😱
I was actually getting ready to just write off the AD8620 and just fit in the external input section to try out the other op-amps and I'm so glad I've tried this mod, that midband colour I didn't like before seems to have totally gone, the bass seems deeper, the soundstage more focused, the sound is far better altogether😕
How can fitting these CRD's make such a difference, could somebody please explain? is it just my hearing
It also seems a lot more revealing so if your source is bright it may not suit anybody
Can somebody else please try this mod and post their results just to put my mind at rest that I'm not going mad😀
Is it possible the psu caps or something has just burnt in
Great!
Ok, and now try to feed the op amps with an auxiliary power supply. This will be the next step in sonic improvement…. 😉
Cheers,
Jan-Peter
Jan-Peter said:
Thanks Jan,
You guys at Hypex are crafty regading this CRD mod😉 I'm still honestly shocked what difference it made, I was so close to chucking out the AD8620! it seems to have paid off trying this mod before jumping in with different op-amps
So is it honestly worth using an auxiliary supply as well as the CRD? I've already built two separate boards based on this
(Kindly posted by Roger) I use dual schottky rectifiers etc with a separate transformer rather than the zeners
I also have ALW super regs
Cheers,
Leo
Attachments
Your welcome...... 😉
The auxiliary power supply must be a seperate power supply. Connect the GND of the auxiliary power by the UcD400 GND and NOT by the high power supply......
Good luck!
Cheers,
Jan-Peter
Jan-Peter said:
Great🙂
I'll post my results as soon as I can get it up and running
If your still there Jan-Peter a quick question and sorry to go off topic, would I be ok to use the 470uf 50v BC136 caps in my UCD180's? the voltage is 41v for my UCD's (never goes higher than 44v), I know a few others asked about using the BC136's but I'm not sure anybody has tried them with the UCD180, I'll obviously keep those standard bypass caps to help with the low ESR but would these BC136 cause any problems? I've never liked the Panasonic FC's and have found the BC136 much better when used in other applications
Cheers,
Leo
The BCC136 is a very good capacitor. A rule of thumb is to go to 80% of the rated voltage. For testing I would not be so afraid, we have very good experience with the BCC136. Although we could not use it so close in production, personally I would also do it for my home made UcD180. (….hm, to tell you the truth I am the pround owner of serial number 1 and 2 of an UcD700AD… 😉 )
Cheers,
Jan-Peter
Cheers,
Jan-Peter
Jan-Peter said:
Thanks again Jan-Peter, you've been most helpful🙂
UCD700! lucky you although I think my neighbour would not be too impressed with that amount of power in my room😉
Anyway I wish you good luck with the UCD700's, that should be ideal for the guys with big rooms and the speakers to match, I see you've added things which gives the user more freedom to tweak with the UCD700 and itsd full of BC136's too
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