Hotrodding the UCD modules

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#621
Julien_M said:



I installed all but the boot strap cap. I have a Panasonic FM in there. I find the FM's more neutral and transparent than the FC's. I don't plan in changing the bootstrap cap now.
All caps I installed fit perfectly on the PCB. They're all flush with the board.
The BlackGates are now starting to sound more neutral with more mid range definition. In my opinion, as they are now, they're a definite improvement over the Panasonics. The major improvement is in timbre. I find the midrange and highs to sound more natural. The sound stage presence had improve as well.
My next steps in the UcD amp is to change some bypass caps from Panasonic Polypropylene to Sonicap Gen II, and later change the output LC cap from a BC Component Polypropylene to a 0.47uF/200V Sonicap Gen II.
Finally, I intend to change the 4 bridges in my dual mono power supply with FRED bridges.
Click to expand...

How do the BGs sound after a bit more burn-in? May get some, where did you get yours? Partsconnexion?

Best regards

Gertjan
 
#622
ghemink said:


How do the BGs sound after a bit more burn-in? May get some, where did you get yours? Partsconnexion?

Best regards

Gertjan
Click to expand...


As of now, the BG's are starting to sound more coherent. I find them more transparent than the FC and more fluid, liquid (that could still be an artifact of break-in). My UcD400 amp have been on 24/7 since I installed the caps about 8-9 days ago.
I got mine from Michael Percy. But SonicCraft and PartsConnexion also sells them.
Hope that helps,
 
#623
Julien_M said:



As of now, the BG's are starting to sound more coherent. I find them more transparent than the FC and more fluid, liquid (that could still be an artifact of break-in). My UcD400 amp have been on 24/7 since I installed the caps about 8-9 days ago.
I got mine from Michael Percy. But SonicCraft and PartsConnexion also sells them.
Hope that helps,
Click to expand...


Thanks, it seems they need a long break-in, will get some as well.

Best regards

Gertjan
 
#624
UcD output cap mod question

Hi Gents/Ladies,

As has been mentioned in this thread, stacked film caps are motion sensitive. Has anyone tried giving an additional expoxy coating to one of the output caps (any make of stacked film) to make them better protected physically?

Just a thought for a cheap mod.

Regards,
Greg
 
#631
Gain Adjustment

lucpes said:
Sorry for repeating myself (posted the question a while ago in this thread, was not clear enough).

I'd like to decrease the gain of UcD400 to 4.55 voltage gain.
I was reading a previous post and I got confused.

Here's the factory values given by J-P: A=1000, B=560, C=1800 and D=8200, in the formula (1+2*A/B)*D/C

If I remove the 560 ohm opamp resistor altogether (setting the opamp to unity gain buffer) would the overall voltage gain be set to 4.55 or am I missing something? (B would be infinite in this case).
Click to expand...

Here's the official reply from JP:

This is correct!

If remove the 560 ohm resistor the gain will be 4.55x

Regards,

Jan-Peter
 
#633
Hi,

I have changed my 470uF decoupling caps to Panasonic FC 820uF 63Vdc caps.

While I was there I also replaced the bootstrap cap as mentioned above, Panasonic FM 220uF 25 volt cap.

I only did one module.

It didn't sound like they required breaking in. That harsh/raspy sound you normally get with new caps was totally absent.

I listened to them for a little while just for initial impressions, then I ran them through a good heating cycle to help speed any break in period.

Initially the high's were a little attenuated. Seems like a definite loss of microdetail, at first. I think in reality it's still all there, just not overly prominent anymore, as the 470uF's seem to peak from mids-highs, but lack bottom end something fierce. So it really makes you feel like you lost something.

On the good side, it demonstrates how anemic the bass was with the original caps. There's now much better low frequency extension, some real grunt. With unmodified amp you hear the sticks hit the skins and that's it, lacking the rumble. Now I have both and wouldnt' have it any other way.

It seems evident the orignal caps were chosen for a higher Q in the upper frequency range, making most vocals and most of the micro detail really stand out, leaving the low mids-bass rather anemic and the whole thing with a very "thin" sound.

I'm not 100% in love with the sound of the FC caps, but listening to them side by side I often find my ear attracted to the one with the FC caps.

I think there's also the possibility that 820uF just might be too big too, too bad I dont' have slightly smaller to test with, although I'm unwilling to give up that low frequency extension.

I guess in all I find them a slight improvement, but the moral of this story is, just change all your caps in one shot, this AB stuff sucks, they're both good just different, and I can pick out what each one does better but neither is perfect. I think the FC gives it a bit of a muffled/distant sound.

However, I think I have a trick up my sleeve that might cure that, in the form of a very special output filter cap. I'll post more about it once I've listened to it. I'm going to install on the other module at the same time as I replace the electrolytics on it.

Regards
Chris
 
#634
classd4sure said:
Hi,

I have changed my 470uF decoupling caps to Panasonic FC 820uF 63Vdc caps.

While I was there I also replaced the bootstrap cap as mentioned above, Panasonic FM 220uF 25 volt cap.

I only did one module.

It didn't sound like they required breaking in. That harsh/raspy sound you normally get with new caps was totally absent.

I listened to them for a little while just for initial impressions, then I ran them through a good heating cycle to help speed any break in period.

Initially the high's were a little attenuated. Seems like a definite loss of microdetail, at first. I think in reality it's still all there, just not overly prominent anymore, as the 470uF's seem to peak from mids-highs, but lack bottom end something fierce. So it really makes you feel like you lost something.

On the good side, it demonstrates how anemic the bass was with the original caps. There's now much better low frequency extension, some real grunt. With unmodified amp you hear the sticks hit the skins and that's it, lacking the rumble. Now I have both and wouldnt' have it any other way.

It seems evident the orignal caps were chosen for a higher Q in the upper frequency range, making most vocals and most of the micro detail really stand out, leaving the low mids-bass rather anemic and the whole thing with a very "thin" sound.

I'm not 100% in love with the sound of the FC caps, but listening to them side by side I often find my ear attracted to the one with the FC caps.

I think there's also the possibility that 820uF just might be too big too, too bad I dont' have slightly smaller to test with, although I'm unwilling to give up that low frequency extension.

I guess in all I find them a slight improvement, but the moral of this story is, just change all your caps in one shot, this AB stuff sucks, they're both good just different, and I can pick out what each one does better but neither is perfect. I think the FC gives it a bit of a muffled/distant sound.

However, I think I have a trick up my sleeve that might cure that, in the form of a very special output filter cap. I'll post more about it once I've listened to it. I'm going to install on the other module at the same time as I replace the electrolytics on it.

Regards
Chris
Click to expand...


Sounds interesting, keep us updated on the output caps as well. I plan to put 100V FC caps 680uF on some of my modules. The 100V caps are the ones with the lowest loss factor. I can't really complain of lacking bass with the standard caps, however, will see what those FCs do.

Gertjan
 
#637
I replaced the 470uf CHEMI-CON KMG caps in my UCD180 with the BC136's.
I noticed some oscillation with things like cymbals through my ribbon tweeters and the sound was slightly mechanical so I mounted the caps underneath the board with the supply leg short and fitted a 0.5R and then tried a 1R to the leg that goes to earth on each cap, now the oscillation has gone but it still sounds slightly mechanical, its strange but it reminds me of a transistor SS amp😱

I'm going to give them a few more hours to burn in and if it does not improve the original KMG's are going back in
I would not say that there is much more detail with these caps, the bass seems thinner
I don't have my scope handy so can't check to see if the BC136's are causing any more problems regarding stabillity
At least trying these caps has satisfied my curiousity🙂
 
#638
t. said:
I replaced the 470uf CHEMI-CON KMG caps in my UCD180 with the BC136's.
I noticed some oscillation with things like cymbals through my ribbon tweeters and the sound was slightly mechanical so I mounted the caps underneath the board with the supply leg short and fitted a 0.5R and then tried a 1R to the leg that goes to earth on each cap, now the oscillation has gone but it still sounds slightly mechanical, its strange but it reminds me of a transistor SS amp😱

I'm going to give them a few more hours to burn in and if it does not improve the original KMG's are going back in
I would not say that there is much more detail with these caps, the bass seems thinner
I don't have my scope handy so can't check to see if the BC136's are causing any more problems regarding stabillity
At least trying these caps has satisfied my curiousity🙂
Click to expand...


Hi,

At first I strongly considered putting the original caps back too. I wouldn't now. They've broken in a little more and the high's no longer seem attenuated, there's a certain dip in response around low-mids but I find the others peak so it's OK.

The original caps have a far greater "tizzy" metallic sound and that's completly gone with the FC's, a very welcome change, along with the increased rumble, does not sound thin at all anymore and even more realistic. I've still yet to do the CRD mod.

I guess I recommend you try the FC's but get a few different values like ~600, ~820, ~470.

I'm going to change the caps on the other module right now and slap on my new filter cap too, I've some high expectations for it too.

Regards,
Chris
 
#639
classd4sure said:



Hi,

At first I strongly considered putting the original caps back too. I wouldn't now. They've broken in a little more and the high's no longer seem attenuated, there's a certain dip in response around low-mids but I find the others peak so it's OK.

The original caps have a far greater "tizzy" metallic sound and that's completly gone with the FC's, a very welcome change, along with the increased rumble, does not sound thin at all anymore and even more realistic. I've still yet to do the CRD mod.

I guess I recommend you try the FC's but get a few different values like ~600, ~820, ~470.

I'm going to change the caps on the other module right now and slap on my new filter cap too, I've some high expectations for it too.

Regards,
Chris
Click to expand...


Cheers Chris,

I'm going to let it run all night into a pair of 8R loading resistors 😀
The cymbals still are sounding a little odd but hopefully after a good run in it should improve, I'll try the different value FC caps.
Was your original caps the brown KMG types too Chris? I noticed some UCD180's had blue sleeved caps

Whilst on the subject of caps does anybody know if there is any suitable 680nf caps available from Farnell or RS that would be better than that boxed yellow polyester on the output?
If I'm going to be ordering some FC's I may as well order the output caps at the same time, it looks like there is a footprint for 5 and 7mm caps

Thanks,
Leo
 
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