You can choose any voltage version you find practical given your already available voltages. The 5V one just draws more current than its higher voltage coil versions. Read the datasheet and use a dropping resistor in series to each so to burn that 1.1V extra. Says how many mA each type draws. The rest to calculate is by simply using Ohm's law.
Ok, I was lazy and used an online calc, datasheet says 140mW nominal power, coils resistance 178 Ohm, 5 Volt = 28mA.
Dropping 1.1V requires a 36 Ohm resistor.
Ill get the parts ordered once I know which upgraded resistors to buy for R1 R5 R6. The costs and crazy, I may just start with metal film versions for now?
Cheers
Ian
I couldn't find all the correct values from HiFi collective, in the end I bought the lot from farnell with the relays. At least I am swapping out basic carbon for 1% metal film....
Sent from my Amazon Tate using Tapatalk
Sent from my Amazon Tate using Tapatalk
I know them from the FSP where they were clean but not harsh. Not as clean as foil, not as tonally deep as tantalum. Balanced.
Hi Salas /all.
I have installed the 1% metal film resistors from Farnell instead of carbon comps.
The sound is smoother and taken a little edge off.
Very pleased, and a welcome improvement, at some point I will replace with better, just waiting for Merlin to finish playing 😉
I wanted to check the frequency response of the Itch, can I connect my laptop and use the 20-20 frequency sweep on the Hifi News record to produce a meaningful test?
I have Audacity on linux?
Next job is to fit the input relay circuit, I only have a 3 x 6 cm space in between RCA's.
Any matrix layout tips or suggestions?
Many thanks
Ian
I have installed the 1% metal film resistors from Farnell instead of carbon comps.
The sound is smoother and taken a little edge off.
Very pleased, and a welcome improvement, at some point I will replace with better, just waiting for Merlin to finish playing 😉
I wanted to check the frequency response of the Itch, can I connect my laptop and use the 20-20 frequency sweep on the Hifi News record to produce a meaningful test?
I have Audacity on linux?
Next job is to fit the input relay circuit, I only have a 3 x 6 cm space in between RCA's.
Any matrix layout tips or suggestions?
Many thanks
Ian
With the HFNRR record you will see the cartridge response and the subsonic arm-cart resonance "hill" through the Itch when using the full band track and FFT software. To see only the Itch response when using a PC or otherwise electronically generated live signal you will need an inverse RIAA circuit (sometimes called Anti-RIAA also) to locate between the generator and the Itch's inputs. Like those Hagerman Audio Labs is known for but you can DIY one too when having confirmed value parts. As for small "prototype PCB" eBay is full of them in many sizes for very cheap. Since you will probably need to trim for exact size anyway why not taking a piece out of a bigger one from Maplin using your side cutters. Just wire the connections with very small lengths of single core, maybe taken from UTP strands, and make a short central connection for all the cable shields involved in each channel. Use easy to work with in small spaces, easily bending coax, like RG174.
That is for delaying power amp's output connection to loudspeaker or for delaying some internal power line I believe. We were talking small matrix prototyping boards to put together his own two TT input switcher with mini high quality relay.
Hi Salas,
Fitted the relays and switch, works like a dream!
No thumps or pops switching, no hum etc.
I managed to fit the matrix board between the RCA's, so was able to keep signal wires about an inch long.
No photos as it was late when finished and just had a quick listen.
Many Thanks
Ian
Fitted the relays and switch, works like a dream!
No thumps or pops switching, no hum etc.
I managed to fit the matrix board between the RCA's, so was able to keep signal wires about an inch long.
No photos as it was late when finished and just had a quick listen.
Many Thanks
Ian
Congrats! Maybe also photos some time if possible because some members would love to build a reliable input switch between two systems as well I suppose.
On further listening I have introduced hum, and a LR channel swap.
So lid off and time for photos!
I have checked the diagram Salas provided, and the circuit switched between channels. The output from the Itch is swapped?
The hum issue.
I grounded the input RCA shell via shielded cable to Itch input, at the copper circuit ground that goes to SSHV ground. I used the shield of the black input cable, Hot L to V1 Pin 2, Hot R to V1 Pin 7.
The pink wire is non shielded, only used for the short run from RCA to relay, could this be the cause?
Maybe a ground loop?
Thanks for any help.
Ian
So lid off and time for photos!
I have checked the diagram Salas provided, and the circuit switched between channels. The output from the Itch is swapped?
The hum issue.
I grounded the input RCA shell via shielded cable to Itch input, at the copper circuit ground that goes to SSHV ground. I used the shield of the black input cable, Hot L to V1 Pin 2, Hot R to V1 Pin 7.
The pink wire is non shielded, only used for the short run from RCA to relay, could this be the cause?
Maybe a ground loop?
Thanks for any help.
Ian
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