yes, tuning of a ported speaker is critically dependant on the source impedance it sees.
This can be from long/short cables and/or thin/thick cables and/or low damping/high damping factor.
Very short cables and high damping factor will sound very different from long cables and low damping factor.
Salas, have you been thinking in placing bypass capacitors right next to the transistors of the preamplifier section? I mean the 4x 2SK170. Would it bring any noticeable difference?
I haven't seen it in too much in discrete desings, only in opamps, where they are neccesary. I suppose you will have an explanation for that if you don't put them.
I haven't seen it in too much in discrete desings, only in opamps, where they are neccesary. I suppose you will have an explanation for that if you don't put them.
Here is a remote control Remote Control DIY kit PCB that is recommended on the very first page of this LightSpeed Attentuator. One caveat though, I have not read the Lightspeed thread so there may be a better solution enclosed.
Regards,
Dan
A week or so back I said I put up some pics of my dcb1 build....
So I'm using:
shunt resistors: ~7R (68r//68r//10r)
variety of LEDs to get the voltage somewhat correct.
4 inputs and I ignored the other 2 positions
6pos 2 pole switch, using 1 set of pole for relay selection and the other pole to switch the LEDs for the front panel
$10 21 step attenuator from ebay. FWIW, I think this sounds better than the valab one.
Tried to get a lightspeed working but it sounded thin to me, most likely was my build rather than a problem as such with the LS
Using PRP for the audio resistors (thanks teabag) although very little difference noted.
Using wima 0.22uF in the cap positions behind the terminal blocks.
Whole thing housed in a case of a dead CDP, with damping added to the case. The circuit itself is mounted on a 3mm alu plate (which serves as heatsink for the fets).
Circuit ground separated from safety earth via 69er diodes paralleled with a 0.01uf cap and 10R 3W resistor.
Home-made knobs on the oak front panel.
All wiring to the board is navships silver in teflon, and I used some dip sockets with the wire just shoved into them - very handy for a board tweaked as often as this one.
Fran
So I'm using:
shunt resistors: ~7R (68r//68r//10r)
variety of LEDs to get the voltage somewhat correct.
4 inputs and I ignored the other 2 positions
6pos 2 pole switch, using 1 set of pole for relay selection and the other pole to switch the LEDs for the front panel
$10 21 step attenuator from ebay. FWIW, I think this sounds better than the valab one.
Tried to get a lightspeed working but it sounded thin to me, most likely was my build rather than a problem as such with the LS
Using PRP for the audio resistors (thanks teabag) although very little difference noted.
Using wima 0.22uF in the cap positions behind the terminal blocks.
Whole thing housed in a case of a dead CDP, with damping added to the case. The circuit itself is mounted on a 3mm alu plate (which serves as heatsink for the fets).
Circuit ground separated from safety earth via 69er diodes paralleled with a 0.01uf cap and 10R 3W resistor.
Home-made knobs on the oak front panel.
All wiring to the board is navships silver in teflon, and I used some dip sockets with the wire just shoved into them - very handy for a board tweaked as often as this one.
Fran
Attachments
Thanks for sharing your build. Nice enclosure front, Fran. I like when a circuit looks so messy but you know that, despite that, it sounds perfect and flawlessly. No commercial attitude, just DIY.
How does it sounds this cheap sttepped attenuator? Maybe I'll order one as a spare. Have you compared it to any other type of pot?
What I wouldn't do is to use silver in teflon and then attaching it to a dip socket. A better way to go is soldering it.
How does it sounds this cheap sttepped attenuator? Maybe I'll order one as a spare. Have you compared it to any other type of pot?
What I wouldn't do is to use silver in teflon and then attaching it to a dip socket. A better way to go is soldering it.
Thanks guys,
all my builds are like birds nests inside!!
On the connectors with silver in teflon - regiregi, you are correct, soldering would be far better. However, I've had this board in and out of there at least 20 times so I needed some decent means of being able to connect and disconnect without damaging solder pads etc.
I've compared that pot to the valab one from ebay (supposedly better mechanical quality) and the LS (my crapy implementation) and then with an alps blue. This cheapo from ebay was the best of those. Never had fancier stepped/sweep pots like shallco, dact, noble or the like.
Sounds great though, best I've had, and its going to a friend of mine for a full review in the next week or so. The idea is that he will review it as if it was a commercial product **except** for the cosmetics!!!!
Fran
all my builds are like birds nests inside!!
On the connectors with silver in teflon - regiregi, you are correct, soldering would be far better. However, I've had this board in and out of there at least 20 times so I needed some decent means of being able to connect and disconnect without damaging solder pads etc.
I've compared that pot to the valab one from ebay (supposedly better mechanical quality) and the LS (my crapy implementation) and then with an alps blue. This cheapo from ebay was the best of those. Never had fancier stepped/sweep pots like shallco, dact, noble or the like.
Sounds great though, best I've had, and its going to a friend of mine for a full review in the next week or so. The idea is that he will review it as if it was a commercial product **except** for the cosmetics!!!!
Fran
Last edited:
Nice build, Fran. Especially I like idea about used enclosure and oak font panel.
If you turn board 180 and maybe little to front, you can make very short wires from pot to buffer and don't cross it with AC wires from transformer. I think it may improve sound quality and noise floor a bit.
If you turn board 180 and maybe little to front, you can make very short wires from pot to buffer and don't cross it with AC wires from transformer. I think it may improve sound quality and noise floor a bit.
I took mine over to a friend who is an all commercial hi-fi guy. He compared it to his $3500 Sonic Frontiers pre amp. He basically said that the differences were so minor that with a bit of reduction in humm in my B1 that they would be comparable. Pretty crazy how Nelson's simple designs well implemented are sonically comparable to pieces costing 3.5 times the cost.