That sounds like the right thing. Most LF noise from a phono is around 10Hz.
What cartridge/arm/turntable do you use?
a thought occurred to me - if all 4 caps are removed the switch would be on/off - for stylus cleaning etc?
maybe loudness switch could be used for this?
maybe loudness switch could be used for this?
Yes, the loudness switch could be rewired, grounding both top ends of the volume control pot, to mute.
If you do this, permanently connect R27 and R28 from the volume control's loudness taps to ground.
Otherwise the action of the volume control will be altered, and it will be difficult to adjust for low volumes.
There are lots more easy ways you can improve the sound of your Dyna amplifier. I can write up a list of them,
if you're interested.
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for the original poster, an easy solution is to find a copy of the APT Preamp manual and copy the filter design therein.
mlloyd1
mlloyd1
Ok, here is the manual if you don't have one.
http://www.thehistoryofrecording.com/Manuals/DynaCo/Dynakit_SCA_35.pdf
The next change would be to replace the two C17 capacitors (one on each the power amp board)
with a 0.1uF orange drop rated at 100V or more, preferably polypropylene.
This will be larger than the original part.
Would you consider a new volume control? It would be more disassembly, but it could be combined with
rewiring the loudness switch for mute. Does your amp have push-on knobs, or do they have a set screw?
If you don't use the balance or tone controls, you could connect the volume control wipers directly
to eyelet 7 on PC10. Disconnect all the wires going to the parts in between that are bypassed, but
make sure that the bottom terminal of both channels of the volume control is still grounded.
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thanks -c17 only 16v i see- im interested- was original always too small?
volume pot change-no
i use tone controls a lot-cassette is often over bassy and cd but i dont use that much
was i correct in saying i could snip off the two remaining caps of the filter and use as on/off?
many thanks for your time and patience
volume pot change-no
i use tone controls a lot-cassette is often over bassy and cd but i dont use that much
was i correct in saying i could snip off the two remaining caps of the filter and use as on/off?
many thanks for your time and patience
The 0.1uF capacitors on the amplifier boards are 40 year old electrolytics, so they should be replaced,
and a 0.1uF polypropylene type will be better, but physically larger. They can still be placed on the board.
For the filter switch, replace C11, C12, C 13, and C14 each with wires.
The switch will now mute the audio when activated.
Nope, I'm referring to APT-Holman Preamp from 1980s.
Holman published some papers on phono preamp design that would be of interest as well.
I think there's links on this board somewhere; search around a bit.
regards,
mlloyd1
Holman published some papers on phono preamp design that would be of interest as well.
I think there's links on this board somewhere; search around a bit.
regards,
mlloyd1
hi and thanks my skills are limited to soldering -which is instructed by some one elses knowledge
How is your SCA-35 doing now?
Was it ever refurbished by replacing the electrolytic capacitors (2 large cans)?
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12 years ago i replaced them with a board bought from holland- i thought it sounded crap,
back then you could only buy the large cap from dynakit-after studying the situation and learning what caps do my super lateral brain said i could simply join together the 40 and 20- giving a 60/60 instead of the 50/50 required- so i bought two large ones and there still in there
Does the replacement board still sound worse than the original caps?
You could replace it now.
after about 90 hours the news caps bed in giving an amazing sound-it sounds exactly like that today so why change
the board could never match what the originals do- they are part of the sounds make up
everything else in the amp is original- i might be what is called a purist in the sense that i want to hear the designer original work- they are the geniuses
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