When you touch the input, is it "the same" hum, but just louder? Or is it a different type/tone of hum or hiss? Typically when you touch an input you're hearing 50/60Hz hum. Sadly, it becomes pretty recognizable over time. 😀
Others will likely have to pick up from here, particularly if it gets down to diagnosis for faulted parts. Hope you get it solved!
See post #3609. I didn't have hum, but a dead channel.
Kevin Heem's suggestion to change out Q2, Q3 and Q4 fixed me up.
Aleph J has been making wonderful music ever since then.
Still have a hard time shutting my system down once I get started, the AJ really pulls it weight in the chain from CD to ears.
I ordered a few extras, let me know if you want a set and I'll send them to you.
I'm getting a 120Hz peak hum in the right channel according to my iPhone "spectrum analyzer".
as you said 60hz peak when touching+ input but the 120Hz peak persists.
Mazeppa: Thank you so much for the offer. I may take you up on that! I had it almost perfect at one time and hoping I can get back.
@Pavo - I need to check out the iPhone spectrum analyzer. 😀
I'll bow out, but the fact that the hum you're trying to eliminate is the 2nd harmonic of the mains frequency is interesting... at least to me. People with more knowledge of the circuit will need to pick up the baton. Hope you find a solution.
I'll bow out, but the fact that the hum you're trying to eliminate is the 2nd harmonic of the mains frequency is interesting... at least to me. People with more knowledge of the circuit will need to pick up the baton. Hope you find a solution.
ref. post 4347
i can see 4 cables coming out of the transformer (2 blue, 2 green).
where is your "mid point cable" (what colour?) ?
i can see 4 cables coming out of the transformer (2 blue, 2 green).
where is your "mid point cable" (what colour?) ?
A couple of silly suggestions:
1) Disconnect source and short the inputs on both channels. Compare hum/noise of both
channels and measure DC offsets of both channels (with inputs shorted).
2) Switch left and right inputs from source. Any changes?
1) Disconnect source and short the inputs on both channels. Compare hum/noise of both
channels and measure DC offsets of both channels (with inputs shorted).
2) Switch left and right inputs from source. Any changes?
I know this has been discussed before but I am looking for some new speakers to mate well with the Aleph J. Wharfedale Dentons at 86dB efficiency is part of the issue.
A new turntable with an extended bass response over my old one has caused the Aleph J to clip at moderately high volume levels; but only with music with really deep bass like Pink Floyd. The clipping isn't harsh, comes off as compression. Putting my backup amp in, an Adcom 545, gave better results at these higher listening levels.
A new turntable with an extended bass response over my old one has caused the Aleph J to clip at moderately high volume levels; but only with music with really deep bass like Pink Floyd. The clipping isn't harsh, comes off as compression. Putting my backup amp in, an Adcom 545, gave better results at these higher listening levels.
I'm driving a pair of old Vandersteen 2C speakers with my Aleph J. It seems to do quite well even with Pink Floyd and higher volume. I did increase the rail voltage slightly to about 25V, and the bias current is 1.8A total per rail. Dual mono 300VA transformers, 20V secondaries, CRCRC power supply.
Not that you don't have perfectly valid reasons for wanting another pair of speakers 😉
Not that you don't have perfectly valid reasons for wanting another pair of speakers 😉
Open Source Monkey Coffin
GitHub - mbrennwa/osmcdoc: Documentation for the Open Source Monkey Coffin
Sorry, but I need to step in here.
The Antek transformers do not have a center tap, just a pair of independent secondary windings. The purple wire is connected to an electrostatic shield between the primary and secondary windings, and is not suitable for use as a center tap. There are a couple configurations of rectification available, that will produce an audio ground node. The usual connections which are documented with the diyAudio PSU boards work well.
The calculator on this page would be helpful to determine your next speaker sensitivity based on your target listing level and amplifier wattage.
Loudspeaker:Sound pressure level and amplifier power (scroll down)
Efficiency and sensitivity conversion - loudspeaker percent and dB per watt and meter loudspeaker efficiency versus sensitivity vs speaker sensitivity 1 watt = 2,83 volt box chart - sengpielaudio Sengpiel Berlin
Thanks for adding much more clarification. I thought @mjf was asking about the shield. It never occurred to me re: clarifying that it is not a center tap.
Aleph J's max output "can be" usable up to 30 watt peak in my experience due to its rather soft clipping nature, and 25W is a conservative rating compared to some other amps' published spec. We should be careful about the catalogue spec, especially the speakers, the numbers are often way too optimistic.
DeVore Fidelity Orangutan O/96 loudspeaker Measurements | Stereophile.com
DeVore Fidelity Orangutan O/96 loudspeaker Measurements | Stereophile.com
The one I used was called Sonic Tools SVM. I even had to check the peak frequency of my toothbush (256Hz by the way) It's kind of cool: Sonic Tools SVM on the App Store
IRFP150 sonic qualities
Hi all,
I have been absent for 6 years, just getting back into building and audio in general. In 2013 I bought the J boards and some of the key components, but at that time I couldn't get the IRFP240 so I ended up with 50 pcs of IRFP150, and about that time is when life changed and I stopped all projects.
So now I am back, the thread has bloomed to 490 pages and there is a lot to catch up on. One thing I found is the Babelfish J thread which I have just started reading but it's a long thread as well.
Before I spend too much more time researching I wanted to ask if people who have built the Aleph J with the IRFP150, did you use 2 paralleled or one in place of 2? Also wondering if anyone who may have built both noticed any sonic difference between the 150's and 240's? Probably a tough question.
I now see that the IRFP240's are back in stock at Digikey but since I have made the investment in the 150's I'd like to use those, but if the 240 is the best way to go, I'll buy them. I want to use the boards I have already, it looks like the Babelfish J may use a different board.
Thanks everyone.
Cheers
Hi all,
I have been absent for 6 years, just getting back into building and audio in general. In 2013 I bought the J boards and some of the key components, but at that time I couldn't get the IRFP240 so I ended up with 50 pcs of IRFP150, and about that time is when life changed and I stopped all projects.
So now I am back, the thread has bloomed to 490 pages and there is a lot to catch up on. One thing I found is the Babelfish J thread which I have just started reading but it's a long thread as well.
Before I spend too much more time researching I wanted to ask if people who have built the Aleph J with the IRFP150, did you use 2 paralleled or one in place of 2? Also wondering if anyone who may have built both noticed any sonic difference between the 150's and 240's? Probably a tough question.
I now see that the IRFP240's are back in stock at Digikey but since I have made the investment in the 150's I'd like to use those, but if the 240 is the best way to go, I'll buy them. I want to use the boards I have already, it looks like the Babelfish J may use a different board.
Thanks everyone.
Cheers
OKay cool thanks for the quick reply. I am working my way thru your BabelfishJ thread, I suppose you could just please quickly answer one question for me, can I just put one IRFP150 in place of the 2 in the original J boards and leave everything else original as the J board was designed?
Cheers and thanks for the help!
Cheers and thanks for the help!