I am having a hard time finding a .25 amp slow-blow fuse to fit a Cooper Bussman holder. It takes 1 1/4 X 1/4 or 6.3mm X 32mm fuses. I am in the states so need 125 volt rated. Can find plenty of 250v rated fuses in this size and I am wondering if 125 volt power I should use .5 Amp slow-blow? I need to buy a holder and fuses for my VSPS power supply so I am open to suggestions, would like to stick to Mouser to save on shipping.
good evening.
i would like to as a few questions if that's ok.
i'm planning on buying a Denon DL103r as my new cart and i have read a good part of your threads regarding the phonoclone being designed to run with the Denon and i have come to a decision that i would like to build one. i'm also after a headphone amp till funds permit me to build some power amps at a later date.
my questions:
can the phonoclone and the headphone amp (sapphire) be powered from the same power supply?
would it be possible to add to the headphone amp to give it function as a pre-amp so come the time i can use it to feed the power amps?
you touch on the fact that the B-board could be used as a headphone amp, is this the case?
is there a way to make the headphone amp specific as regards the ratings of my headphones which are beyerdynamic 770 pro 80ohm?
i'm handy with a soldering iron but i know nothing about electronics so is there a complete 'build it for dummies' tutorial on how to build and test and what tools are required for testing?
i know that's a lot of questions but i'm keen on building my own gear
i would like to as a few questions if that's ok.
i'm planning on buying a Denon DL103r as my new cart and i have read a good part of your threads regarding the phonoclone being designed to run with the Denon and i have come to a decision that i would like to build one. i'm also after a headphone amp till funds permit me to build some power amps at a later date.
my questions:
can the phonoclone and the headphone amp (sapphire) be powered from the same power supply?
would it be possible to add to the headphone amp to give it function as a pre-amp so come the time i can use it to feed the power amps?
you touch on the fact that the B-board could be used as a headphone amp, is this the case?
is there a way to make the headphone amp specific as regards the ratings of my headphones which are beyerdynamic 770 pro 80ohm?
i'm handy with a soldering iron but i know nothing about electronics so is there a complete 'build it for dummies' tutorial on how to build and test and what tools are required for testing?
i know that's a lot of questions but i'm keen on building my own gear
In order of appearance,
Yes. Yes. Not really. Yes. and No.
You should be able to share the power supply.
Any headphone can double as a preamp without modification.
The B-board is of limited use as a headphone amp, since it has unity gain.
No special modifications are needed for 80 ohm 96 dB headphones, that's a "generic" spec.
The kits come with instructions but a basic level of familiarity with electronics and electronics is assumed.
Yes. Yes. Not really. Yes. and No.
You should be able to share the power supply.
Any headphone can double as a preamp without modification.
The B-board is of limited use as a headphone amp, since it has unity gain.
No special modifications are needed for 80 ohm 96 dB headphones, that's a "generic" spec.
The kits come with instructions but a basic level of familiarity with electronics and electronics is assumed.
Getting close to completion. It has taken me a lot longer than I expected but that is normal for me. I checked every resistor twice before populating the boards and triple checked every solder joint as I cleaned the joints with alcohol. I did find one joint that did not receive solder the last check. I guess being a little anal pays off. Other than speakers and crossovers this is my first piece of solid state electronic gear.
My VSPS 300 is up and running.
My VSPS is up and running. After a minor mishap, wired right channel output at the board out of phase, it is settling down nicely after a few hours of play. The sense of depth is very good and bottom end is filling out. I am not missing any detail but seem a little too smooth but I think that is due to my output caps the Obbligato Gold, they will probably take some time to open up. Right now I am feeding it with a tuner through a reverse RIAA attenuator box to give is some on time for a few days.
Other than the output caps the only other change I made to the board is to increase gain to 48-50 DB.I believe R3 is 2.7k and R2 is 330 ohm if I have that order right. I am getting some NOISE that may be power line noise with the signal turned up. I have the power supply case grounded to the line neutral on a shielded power cable but did not connect the shield of the cable to the PS case. I have 3 wires out to the preamp box: ++, --, and the common. The ground for the turntable is connected to the ground connector of both boards and the case itself. The RCA plugs were not grouded to the case and are floating. Before I installed the final op amp both boards were reading identical or within a few tenths of a volt on the suggested + and - pin outs following the suggested checks before install IC1 in their sockets. I may be getting stray EMF from the tube preamp on the shelf below and I can get some change moving the position of the preamp and VSPS but doesn't eliminate the noise. I can say that it is not noticeable with music playing. I did use a power switch with a led in it and wonder if that could be it? Could swapping the position of the wires that feed the diode bridges ( the two wires from the transformer secondaries ) make any difference?
My VSPS is up and running. After a minor mishap, wired right channel output at the board out of phase, it is settling down nicely after a few hours of play. The sense of depth is very good and bottom end is filling out. I am not missing any detail but seem a little too smooth but I think that is due to my output caps the Obbligato Gold, they will probably take some time to open up. Right now I am feeding it with a tuner through a reverse RIAA attenuator box to give is some on time for a few days.
Other than the output caps the only other change I made to the board is to increase gain to 48-50 DB.I believe R3 is 2.7k and R2 is 330 ohm if I have that order right. I am getting some NOISE that may be power line noise with the signal turned up. I have the power supply case grounded to the line neutral on a shielded power cable but did not connect the shield of the cable to the PS case. I have 3 wires out to the preamp box: ++, --, and the common. The ground for the turntable is connected to the ground connector of both boards and the case itself. The RCA plugs were not grouded to the case and are floating. Before I installed the final op amp both boards were reading identical or within a few tenths of a volt on the suggested + and - pin outs following the suggested checks before install IC1 in their sockets. I may be getting stray EMF from the tube preamp on the shelf below and I can get some change moving the position of the preamp and VSPS but doesn't eliminate the noise. I can say that it is not noticeable with music playing. I did use a power switch with a led in it and wonder if that could be it? Could swapping the position of the wires that feed the diode bridges ( the two wires from the transformer secondaries ) make any difference?
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I believe I got it. I think I created a ground loop at the switch. The switch has three tabs: power in, power out and neutral. Instead of neutral I connected the house wiring ground to the neutral tab and jumped after it to ground the chassis with the neutral connection, more 2am foggy logic I will fix it in the AM and report back.
I have what appears to be 120HZ noise I cannot get rid of. Should the metal cases of the diode bridges be grounded to the PS? Lifting the ground and reversinf polarity do not affect the noise. Using a Avel Lindberg 250VAC toroid with 25 amp bridges. Shielded power cable to the PS and same to the VSPS but the shield is not connected to ground. Moving the VSPS in reference to other components did not make a difference. Tried adding ferrite cores to power lines with no result. Everything is plugged into a low budget home theater surge suppressor that is new but no effect on CD player or tuner. Tried removing the VSPS PS and plugging it into the wall to no effect. Any suggestions?
I believe you are asking have I tried using a shorting plug at the inputs to rule out noise entering there. I have not. Easy enough to try but I have used the same turntable and cardas phono cable with a few different preamps with no problem. I have searched this forum for other such reports and there are a few mentions it doesn't seem to be commonplace. The noise seems to be something that could be a related noise existing or riding on the house wiring. I knew I should has used another transformer other than a toroid, they work well as transformers but are poor filters. One other thing that I will be addressing the next few days is changing the output coupling cap. The one I am using I come to finnd out does not work well in low voltage circuits, the tech at partsconnexion says the Obbligato gold caps need to have some current through them to work well, consequently the sound is waaaay to bass heavy.
I will try to short the inputs, if anyone knows this is not to be done please let me know.
Walt
I will try to short the inputs, if anyone knows this is not to be done please let me know.
Walt
Did you check your phonocable, is it still in position at your arm base (if it uses a 5p-din at your arm base it could slip out a bit and cause hum). Do you have a earth wire connected between VSPS and your recordplayer? If so remove it if not try one.
Ronald.
I check the phono cable and it is secure. I did some initial checks for continuity and at the phono cable I check good from the base of the tonearm to the ground plug. In checking the VSPS 300 shows good from + on all phono plugs back to the solder connection at the boards, I checked the gound points and the common wire coming from the power supply and get continuity at all - connections on input and output and all ground points on the rca's. The ground for the turntable is good and shows good to the chassis. All - points show good back to the common also. I assume I am looking for something common to both channels because both have the noise. I am bringing the unit downstairs to mount the stock caps in place of the Obbligatos.
Installed the Rapport cap that came with the kit. I tried and took a wire from the TT ground lug and connected it to the grounded PS chassis and the noise is all but gone. This is easy enough to remedy, I could connect the shields and run a wire from inside the VSPS to the inside of the ground lug. Is this kosher? Is it an indicator of something else I should address?
With the help of Richard I was able to troubleshoot my noise problem and it all related to the wiring of a switch I purchased from Radio shack without instructions included on how to wire it in. Apparently I was not the only one with a problem because numerous others complained of it. I followed one persons suggested wiring but if I read the reviews further down I would have realized the wiring in that fashion was flawed.
Anyway I want to make some observations on the sound of the VSPS 300 after a a few hours of brake in. I was taken back with the sound I was hearing. Initially using the Obligatto Gold output caps the sound was way too bass heavy and almost muffled. I switched to the stock caps and after a few days the sound opened up and the best way I could describe the character was dense and powerful, very dynamic. The exact opposite of many highly regarded but polite stages. Far better than my Ray Samuels Nighthawk. I ordered Hovland Supercaps based on what was hearing and will report back when they have some time on them, pricewise they are around the cost of Mundorf Supremes. They were designed to be used as coupling caps and work well in low voltage circuits and are very clear with well defined deep bass.
Walt
Anyway I want to make some observations on the sound of the VSPS 300 after a a few hours of brake in. I was taken back with the sound I was hearing. Initially using the Obligatto Gold output caps the sound was way too bass heavy and almost muffled. I switched to the stock caps and after a few days the sound opened up and the best way I could describe the character was dense and powerful, very dynamic. The exact opposite of many highly regarded but polite stages. Far better than my Ray Samuels Nighthawk. I ordered Hovland Supercaps based on what was hearing and will report back when they have some time on them, pricewise they are around the cost of Mundorf Supremes. They were designed to be used as coupling caps and work well in low voltage circuits and are very clear with well defined deep bass.
Walt
