Hi everybody,
I found that SL-10/CAS-1 for a good price, and they work very well! I use them with my Infinity Quantum 3. I'll recap them later, since I spend too many time and money to recap/refoam/fix the Infinities.
Now, my problem is that volume control is too sensitive: on first position it's already too loud. (I use a NAD C521).
Is there something wrong, or do I have to build an attenuator? Also, I have too much bass and subs, but maybe it's a Quantum 3 characteristic...
What do you think?
I found that SL-10/CAS-1 for a good price, and they work very well! I use them with my Infinity Quantum 3. I'll recap them later, since I spend too many time and money to recap/refoam/fix the Infinities.
Now, my problem is that volume control is too sensitive: on first position it's already too loud. (I use a NAD C521).
Is there something wrong, or do I have to build an attenuator? Also, I have too much bass and subs, but maybe it's a Quantum 3 characteristic...
What do you think?
Try this after each CD line output, with R1=10k, and R2=1k.
http://www.electronics-tutorials.ws/attenuators/attn8.gif
If it works better, you may need a different volume control.
I restored an SL10 back in 2010 and wrote about my experience here:
http://www.diyaudio.com/forums/pass-labs/162305-restoring-threshold-sl10.html
I discuss a couple of different ways of reducing the gain in that thread.
I posted several pictures of that restoration here:
Threshold SL-10 preamplifier schematic and an introduction - www.thresholdlovers.com
---Gary
The line stage has about +28dB gain, so it's no wonder you have gain to burn on CD.
The volume control is 22k, so if you replace the 1k in series with it with a higher value,
that will burn some of the excess gain. To reduce the overall line stage gain to +14dB,
change the 1k resistors to 86.6k (or a near value), using 1% tolerance parts.
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Here is:
The pot is ok, 22K, not stepped but "detended", as says the schematic.
First, I'll try my SME/Garrard/Ortofon 540 MKII, and check if the gain is also a problem. Then I will probably change the serial resistors if needed.
Later I'll change the caps for Elna Silmic II , and maybe others low values for styroflex or something... A lot of suggestions on internet.
Do I have to re-set the trims? What is the procedure?
The pot is ok, 22K, not stepped but "detended", as says the schematic.
First, I'll try my SME/Garrard/Ortofon 540 MKII, and check if the gain is also a problem. Then I will probably change the serial resistors if needed.
thank you, I found your posts about... very helpful!
Later I'll change the caps for Elna Silmic II , and maybe others low values for styroflex or something... A lot of suggestions on internet.
Do I have to re-set the trims? What is the procedure?
Ok, I finally replaced the 18K2 with 4K7. It's a bit better, but It's still loud on second position... Maybe I will add the divider mod.
Next step will be to recap everything...
Last owner build a device which can be called "idiot proof delayed switching module" (with two LM555 and two e-relays). Do I really have to wait 60'' before switching on power amp? Would 30'' be enough?
Next step will be to recap everything...
Last owner build a device which can be called "idiot proof delayed switching module" (with two LM555 and two e-relays). Do I really have to wait 60'' before switching on power amp? Would 30'' be enough?
Ok,
-I've changed elkos on both SL-10 (Silmic II) and CAS-1 (tantalums for Silmic II and Nichicon FG). There is a big difference, although I couldn't describe it, excepted that I recovered some lost bright... I let the 6 big 6900µF for later, I spend too much money for now.
-I set offset as described by Zen Mod. I measured about 1mV.
-I cleaned big Waters volume pot (see post #8): in fact, it is a stepped attenuator! on each detent the brush stops on a pad, which is connected to the the resistive material by a track. The brush never touches the resistive material (conductive plastic). I forgot to make pictures, but have a look on this. It's a modular system easily demountable by layers. After clean, I have no more cracks.
But after that, I still have a small hum on left channel. I noticed it after changing the feedback resistors, but maybe it was already present before. It comes from SL-10, after volume. Any idea?
-I've changed elkos on both SL-10 (Silmic II) and CAS-1 (tantalums for Silmic II and Nichicon FG). There is a big difference, although I couldn't describe it, excepted that I recovered some lost bright... I let the 6 big 6900µF for later, I spend too much money for now.
-I set offset as described by Zen Mod. I measured about 1mV.
-I cleaned big Waters volume pot (see post #8): in fact, it is a stepped attenuator! on each detent the brush stops on a pad, which is connected to the the resistive material by a track. The brush never touches the resistive material (conductive plastic). I forgot to make pictures, but have a look on this. It's a modular system easily demountable by layers. After clean, I have no more cracks.
But after that, I still have a small hum on left channel. I noticed it after changing the feedback resistors, but maybe it was already present before. It comes from SL-10, after volume. Any idea?
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