Well it's close but no cookie
The JC-2 to FE hum persists. The Mini2496 DAC direct connection is still completely silent. I got a second DAC (Weiliang DAC-5) operational yesterday and it also produced a hum. That was reduced by 80 -90% after connecting it to the new monoblock build. That low level hum does not increase with higher volume levels and is almost completely masked with any volume increase.
But here is the kicker - the Mini2496 DAC to JC-2 to Hafler 120 is completely free of hum. Music plays cleanly and and not distorted.
So it appears the JC-2 to FE connection is still the issue. I'll investigate the ground paths on the Mini DAC to see how it differs from the JC-2 and the DAC-5.
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FE readings:
Left signal ground at the RCA to the Right signal ground at the RCA. = 0.5 - 0.7 Ohm
Mini2496 readings
Left signal ground at the RCA to the Right signal ground at the RCA. = 0.0 Ohm
Mini2496 to FE amp = 0.9 Ohm
JC-2 to FE amp = 2.6 Ohm
Mini2496 to JC-2 to Hafler 120 = NO Hum - music plays properly.
The mystery continues............
Attachments
Trimmers adjusment
Hi, after spotting this thread I bought the same kit from another ebay supplier. Got the schematics but no instructions about trimmers adjustment. May I ask you to send me the documentation you have about it?
Thanks for your help
Hi, after spotting this thread I bought the same kit from another ebay supplier. Got the schematics but no instructions about trimmers adjustment. May I ask you to send me the documentation you have about it?
Thanks for your help
Thanks Mr. A.
I've been trying to clean up a couple other projects first, but plan to clear the desk and dig into it soon. One new discovery is when the mini is fed with optical there is no hum. When the BNC is used there is some noise. That seems to confirm the issue is related to grounding.
I'm also going to order duplicates of the surface mount items in case I find hidden solder bridges or damage from excessive heat. I'll report my progress.
I've been trying to clean up a couple other projects first, but plan to clear the desk and dig into it soon. One new discovery is when the mini is fed with optical there is no hum. When the BNC is used there is some noise. That seems to confirm the issue is related to grounding.
I'm also going to order duplicates of the surface mount items in case I find hidden solder bridges or damage from excessive heat. I'll report my progress.
The gain and the compensation are crotically tied together.
Yes, you can change the gain, but then you must accept that you need to skills to reselect all the compensation components to give the same stability, or better.
The output has relay isolation. This ensures no start up, nor shut down, noises from the speaker.
If you read the MyRef Threads you will find all the information there.
Sorry KP, I don't have any additional information. I decided to wait till the final build and see if the hum was unique to my RC build. Nobody else has reported the same issue with the Fremen Edition RC amps.
The Pre itself is top shelf in my opinion and provides more gain than I can use. It works beautifully with the beta FE and several other flavors of MyRef amps. I have no reservation about recommending the kit to potential builders as the sound it produces is super clean and sweet. The switching and volume control elements are determined by user choice. Both discrete and integrated configurations can be applied.
I'll report back after the FE FV is done.
The Pre itself is top shelf in my opinion and provides more gain than I can use. It works beautifully with the beta FE and several other flavors of MyRef amps. I have no reservation about recommending the kit to potential builders as the sound it produces is super clean and sweet. The switching and volume control elements are determined by user choice. Both discrete and integrated configurations can be applied.
I'll report back after the FE FV is done.
The gain and the compensation are critically tied together.
Yes, you can change the gain, but then you must accept that you need to skills to reselect all the compensation components to give the same stability, or better.
The output has relay isolation. This ensures no start up, nor shut down, noises from the speaker.
If you read the MyRef Threads you will find all the information there.
repost to correct error in original post.
I have purchased a couple iterations of the JC-2 that you are talking about (1.2 and 1.6) and built both of them with PRP resistors and changed all caps to better quality ones except the supply caps which are really good (the BC ones).
I recently tested the JC-2 V1.6 against my DCB1, JC-80, Aleph P2.0 and some Tube buffers. We were 7 audio freaks to do the comparison. We also did compare different sources and amplifiers (All DIY).
Although the JC-2 sounds good I would not compare the sound stage to the DCB1 and JC-80 and Aleph P2.0 which better the JC-2 on almost all levels. The JC-2 has tendencies of sounding a bit clinical at parts but you won't find a better pre for the price, that I'll admit.
The Aleph P2.0 here sounds really good and has 128 stepped attenuator built in. We tested this one as well.
MOSFET SE preamplifier plus volume control 128 steps ! | eBay
The JC-2 on eBay is a very good preamp but hold your breath since I saw a new iteration of it that will be coming out soon and be much different and supposed to sound much closer to the original one.
Ciao!
Do
I recently tested the JC-2 V1.6 against my DCB1, JC-80, Aleph P2.0 and some Tube buffers. We were 7 audio freaks to do the comparison. We also did compare different sources and amplifiers (All DIY).
Although the JC-2 sounds good I would not compare the sound stage to the DCB1 and JC-80 and Aleph P2.0 which better the JC-2 on almost all levels. The JC-2 has tendencies of sounding a bit clinical at parts but you won't find a better pre for the price, that I'll admit.
The Aleph P2.0 here sounds really good and has 128 stepped attenuator built in. We tested this one as well.
MOSFET SE preamplifier plus volume control 128 steps ! | eBay
The JC-2 on eBay is a very good preamp but hold your breath since I saw a new iteration of it that will be coming out soon and be much different and supposed to sound much closer to the original one.
Ciao!
Do
Very interesting Dominic. There may be some system differences but my impression is opposite yours - adds warmth if anything. I haven't heard any of the other pres you mention, but as much as I have resisted, with all the accolades there is probably a DCB1 build in my future.
I'm building a couple Pass power amps basically for comparison to the MyRef FE, and it appears it may be necessary to take the same approach with some other DIY preamps. The small one/two tube kits have always attracted my attention but I'm not sure if stepping up to something more sophisticated might be a better path.
I'll also add that when I started this thread I wasn't getting the SPL I wanted. I believe that was still the stock beta version of the FE amps. With the current RC build and a few upgrades the need for a lot of gain has diminished. For the past several months I've just been using the volume slider in JRiver through a DAC. My desire is to bypass that software chunk in the system so a discrete volume control will be needed again.
Please let us know when the new JC-2 version shows. If it has anywhere near the "bang for the buck" the current kits offer I be on-board. After the FE Final version is done it might be a good time to check out all the new volume control offerings.
I'm building a couple Pass power amps basically for comparison to the MyRef FE, and it appears it may be necessary to take the same approach with some other DIY preamps. The small one/two tube kits have always attracted my attention but I'm not sure if stepping up to something more sophisticated might be a better path.
I'll also add that when I started this thread I wasn't getting the SPL I wanted. I believe that was still the stock beta version of the FE amps. With the current RC build and a few upgrades the need for a lot of gain has diminished. For the past several months I've just been using the volume slider in JRiver through a DAC. My desire is to bypass that software chunk in the system so a discrete volume control will be needed again.
Please let us know when the new JC-2 version shows. If it has anywhere near the "bang for the buck" the current kits offer I be on-board. After the FE Final version is done it might be a good time to check out all the new volume control offerings.
Hi Bob,
Just wanted to share with you that I have changed all signal cabling to PTFE silver and RCA to CMC silver and this made much of an improvement on the JC-2. Still not a DCB1 but the sound is not clinical anymore. It is much warmer but in a good way.
Still I can't wait to get my hands on the new JC-2
Ciao!
Do
Just wanted to share with you that I have changed all signal cabling to PTFE silver and RCA to CMC silver and this made much of an improvement on the JC-2. Still not a DCB1 but the sound is not clinical anymore. It is much warmer but in a good way.
Still I can't wait to get my hands on the new JC-2
Ciao!
Do
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