Running a passive pre solution can be a bit iffy. What taper are you using? You should be using a logarithmic taper.
I'd suggest maybe building a Pass B1 as a preamp. Http://www.passdiy.com sells circuit boards with ready matched transistors.
Johan-Kr
I'd suggest maybe building a Pass B1 as a preamp. Http://www.passdiy.com sells circuit boards with ready matched transistors.
Johan-Kr
Last edited:
Hi all,
Thanks for the comment, I appreciate !
I think selector switch is probably not the problem here.
I have "Alps Blue" 10K that is logarithmic. Amp input is 100K
I know that running passive volume control could have some problems. I am still on a learning course with some of these stuff but trying hard to get it all with limited time resources.
I was thinking adding some buffering there but what would be the benefits of doing so? I have one LDR pre available (2nd hand , some groundin issues) thst could be included in the set if needed. I really don't need any added gain so passive / buffer would be the way to go
Thanks,
M
Thanks for the comment, I appreciate !
I think selector switch is probably not the problem here.
I have "Alps Blue" 10K that is logarithmic. Amp input is 100K
I know that running passive volume control could have some problems. I am still on a learning course with some of these stuff but trying hard to get it all with limited time resources.
I was thinking adding some buffering there but what would be the benefits of doing so? I have one LDR pre available (2nd hand , some groundin issues) thst could be included in the set if needed. I really don't need any added gain so passive / buffer would be the way to go
Thanks,
M
If you don't need any gain, I'd take a good look at the B1, or go for a stepped attenuator, instead.
I think some of your problem is that your source has too much output, so you simply have too much gain. At the normal volume, you may be running into problems with unlinearity at the potmeters bottom scale.
I have a 6-cannel amp, with two UcD180s and a UcD34MP, and if I conncect this to an old Dynamic Precision preamp and a Slimdevice Transporter, I end up with similar problems. The DP is equipped with separate pots, so with too much gain, the potmeters is too unlinear at the rock bottom. I got myself a pair of Rothwell attenuators to fix this...
Johan-Kr
I think some of your problem is that your source has too much output, so you simply have too much gain. At the normal volume, you may be running into problems with unlinearity at the potmeters bottom scale.
I have a 6-cannel amp, with two UcD180s and a UcD34MP, and if I conncect this to an old Dynamic Precision preamp and a Slimdevice Transporter, I end up with similar problems. The DP is equipped with separate pots, so with too much gain, the potmeters is too unlinear at the rock bottom. I got myself a pair of Rothwell attenuators to fix this...
Johan-Kr
Picture of the pot wiring connection please. Amp is balanced input so yo have to sort the negative lead and use just the positive and sheild.
Hi Johan & Troy,
I am sure some of my problems are because of my need for little added gain in my system and with my listening habits.
But does that explain the way the pot was acting when I tried the amp without attenuators? I mean the pot giving signal through when turned down. Also the sound was very bright without any bass really. Could this be related to the wiring of the pot as mentioned by Troy?
While using inline attenuators It did help. Though I had bit too much attenuation since I could easily move the pot to full without being too loud.
I will post an image of the wiring, at least a drawing later today. I'm sure it will help a bit.
Thanks for your suggestions and help.
M.
Apologises for possible typos. Phone keypad is pretty tiny...
I am sure some of my problems are because of my need for little added gain in my system and with my listening habits.
But does that explain the way the pot was acting when I tried the amp without attenuators? I mean the pot giving signal through when turned down. Also the sound was very bright without any bass really. Could this be related to the wiring of the pot as mentioned by Troy?
While using inline attenuators It did help. Though I had bit too much attenuation since I could easily move the pot to full without being too loud.
I will post an image of the wiring, at least a drawing later today. I'm sure it will help a bit.
Thanks for your suggestions and help.
M.
Apologises for possible typos. Phone keypad is pretty tiny...
Hi,
The amp case is bit tight for taking proper pics but here are some. I also made quick drawing how wiring is done. Hope it helps!
Sorry for Dropbox links..
https://www.dropbox.com/s/s74tuit0jmnlz99/_20161021_233828.JPG?dl=0
https://www.dropbox.com/s/g11zfnmguw6hu6r/DSC_1601.JPG?dl=0
https://www.dropbox.com/s/8hjhxq3dp2xiypq/DSC_1602.JPG?dl=0
The amp case is bit tight for taking proper pics but here are some. I also made quick drawing how wiring is done. Hope it helps!
Sorry for Dropbox links..
https://www.dropbox.com/s/s74tuit0jmnlz99/_20161021_233828.JPG?dl=0
https://www.dropbox.com/s/g11zfnmguw6hu6r/DSC_1601.JPG?dl=0
https://www.dropbox.com/s/8hjhxq3dp2xiypq/DSC_1602.JPG?dl=0
Just to clarify my drawing the amp module input terminal wiring is following (from right to left):
Hot - Gnd - Cold.
Audio ground has no connection to chassis ground. This also means pot ground lugs are not connected to chassis.
Br,
M
Hot - Gnd - Cold.
Audio ground has no connection to chassis ground. This also means pot ground lugs are not connected to chassis.
Br,
M
Last edited:
Without seeing the bottom of the pot the wiring looks correct so I would then say the pot impedance. Do you have another amp that you can test this input switch and pot on? And can you test just the amp section as a stand alone again?
Hi
i am building a 5 channel ucd180 ampd using the 1200a180 smps i have a few questions.
on the power supply from what i can make out the boot strap cable j1.5 & j1.1 (purple and grey from the hypex cable) are not needed?
also are both the ground cables j1.3 & J1.6 needed or just one of them?
on the ucd180 module
is the thin black wire on the hypex ucd cable which i think is pin 1 needed?
i want to be using RCA connectors for audio in rather than xlr so blue ( pin 4) goes to RCA and white (pin2) and black/shield (pin 3) goes to ground on the RCA Connector?
thanks
i am building a 5 channel ucd180 ampd using the 1200a180 smps i have a few questions.
on the power supply from what i can make out the boot strap cable j1.5 & j1.1 (purple and grey from the hypex cable) are not needed?
also are both the ground cables j1.3 & J1.6 needed or just one of them?
on the ucd180 module
is the thin black wire on the hypex ucd cable which i think is pin 1 needed?
i want to be using RCA connectors for audio in rather than xlr so blue ( pin 4) goes to RCA and white (pin2) and black/shield (pin 3) goes to ground on the RCA Connector?
thanks
Hi
For several months, I have been wondering about the possibility of connecting Philips UCD modules into a bridge (BTL mode).
Despite publicly available documentation for these modules, this connection is not clearly and clearly outlined.
While I can cope with simple diagrams, this configuration is beyond me. I will add that not only to me but also more
knowledgeable people, I asked on many forums and nothing.
Maybe here in the topic of UCD180 questions (a module similar in topology to UCD Philips), I count on the presence of such distinguished people as Jan-Peter
For several months, I have been wondering about the possibility of connecting Philips UCD modules into a bridge (BTL mode).
Despite publicly available documentation for these modules, this connection is not clearly and clearly outlined.
While I can cope with simple diagrams, this configuration is beyond me. I will add that not only to me but also more
knowledgeable people, I asked on many forums and nothing.
Maybe here in the topic of UCD180 questions (a module similar in topology to UCD Philips), I count on the presence of such distinguished people as Jan-Peter
