|
Post by freddypipsqueek on Oct 18, 2011 16:25:27 GMT
My second system uses a Ben Duncan phone-01. It has incandesent blubs to adjust the impedence. The output is a bit too high for the phones I'm using (HD555). I'm worried about messing with the blubs (I really don't understand them) so would a pair of attenuators (Rothwell type things 10db reduction) be OK as they would effectively lower the volume out of the amp.
|
|
|
Post by freddypipsqueek on Oct 18, 2011 16:52:22 GMT
For those who are interested - heres the inside of the amp. The blocks at the bottom of the page are the batteries. The knob to the left switches the charger on and off (with a mid step). I have not thought about the opamps . . .
|
|
|
Post by freddypipsqueek on Oct 18, 2011 16:55:38 GMT
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 18, 2011 17:57:01 GMT
I was curious about the torch bulbs in there so I was reading the same article Feddy just linked to. It states they are there to protect the BUF04s (which have no internal s.c. protection) from any short circuit or over loading. I then looked up the tech sheet for the BUF04 which indicates a proper protection circuit is required to do this... BUF04 tekky speccySo is the bulb set up a clever piece of design or a cop out? Freddy said the bulbs could also be changed/adjusted? for different output impedences, is that in the user manual? Not being picky (in case it reads that way) just curious.
|
|
|
Post by freddypipsqueek on Oct 18, 2011 19:17:28 GMT
I don't have the manual and I maybe totally wrong !! I often am.
|
|
|
Post by freddypipsqueek on Jun 6, 2012 9:15:19 GMT
I have made the mistake of unplugging my Phones 01 but not switching the unit off. After leaving it for 2 months the (lead acid) batteries have discharged fully and (I understand) are now ruined. They are not that expensive (£26 for the two) but it is a flaw in the design and I will look into whether replacing the lead/acid units with something else (such as lithium batteries) maybe better. The batteries are a key part of the amps design.
Anyway the amp sounds a little dull to me (I tend to prefer a brighter sound) and I wondered if (as the box is open) anyone has had any experience of the op amps and whether it is worthwhile replacing them with something else or whether there is anything else which would make an obvious upgrade.
The two to the left are ADT641 SSM2017 N266977 0. I assume these are part of the amplifier.
The four to the right are NDT729 BUF04G N29078 0.
|
|