A potential advantage could be the isolation you get via the transformer, i.e. no ground loops. Be sure to bypass the red-brown input caps if you use an input transformer, otherwise you will have two time constants affecting your low-end response. Make sure the input transformer is of high quality (Luhndal, Jensen, etc.) and has a flat response at the low end down to at least 20 Hz.
Kurt
Kurt
Thanks Kurt - the added isolation would be an advantage.
Not knowing how the input stage of the UCD works, I am wondering whether it performs better (lower s/n ratio?) with a balanced source.
If there were advantages to be had, and those advantages outweighed the disadvantages that would come with sticking a transformer in the signal path, then it would be worth doing.
Anyone understand the inner workings of the UCD enough to comment?
Not knowing how the input stage of the UCD works, I am wondering whether it performs better (lower s/n ratio?) with a balanced source.
If there were advantages to be had, and those advantages outweighed the disadvantages that would come with sticking a transformer in the signal path, then it would be worth doing.
Anyone understand the inner workings of the UCD enough to comment?
I discussed to the guys at Hypex a while ago as I had the idea on how to connect a transformer. As I thought the amp could be used with its input OP and capacitors removed like an instrumentation-amp, ie with the transformer secondary balanced. Zin of the UCD is then 3,6kohm. Senstivity is 9Vrms.
I see the attraction in bypassing the opamp on the UCD, but that's not what I'm looking to do. I'd like to know if the on-board input stage performs better with a balanced input signal - if so, it may be worth adding a good unbalanced to balanced transformer before the UCD module. You say you doubt that it would be worth it. I'm grateful for your input, but am really looking for someone who fully appreciates the workings of the UCD input stage to comment.
You may well be right
The UcD180 HG has a LM4562 bipolar opamp at its input. The input impedance is 100k on each input. If you bypass the caps, as I suggested earlier, the windings of your input transformer will reduce the original 100k resistance to a small fraction, which should result in lower input offset. Not that this is a problem in the original design, but lower is always better.
There is at least one amp manufacturer who uses the UcD with an input transformer; unfortunately I can't find the link anymore. Some will say the sound improves, others will disagree. I'm using mine dc-coupled, i.e. without the caps and without a transformer. Only you can decide which configuration you like best.
By the way, there is a huge thread on the Hypex UcD on this forum, maybe a search will reveal additional info on the benefits of an input transformer.
Kurt
There is at least one amp manufacturer who uses the UcD with an input transformer; unfortunately I can't find the link anymore. Some will say the sound improves, others will disagree. I'm using mine dc-coupled, i.e. without the caps and without a transformer. Only you can decide which configuration you like best.
By the way, there is a huge thread on the Hypex UcD on this forum, maybe a search will reveal additional info on the benefits of an input transformer.
Kurt
As already stated the main advantage of a transformer is isolation. If you dont have ground problems you probably dont need it. IMO anything in the signal path thats not necesary is a bad idea. You will be adding some distorion, eq, noise etc. you will color your sound (more or less depending on the tranies). Some people like the color. And good transformers are expensive.
I want to run it directly by one of those: Audio Note Kits - L3 Remote Pre-Amplifier It has a gain of about 10x and the output impedance is 13 Ohms, so it can drive about anything.
I have build the DAC4.1 from them recently and I am blown away by it's performance. (and I had quite a few good DAC's before)
It has a gain of about 10x and the output impedance is 13 Ohms, so it can drive about anything.I have build the DAC4.1 from them recently and I am blown away by it's performance. (and I had quite a few good DAC's before)
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.