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oops, didn't know about gain, volume trouble

Rotel75

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Just learned about gain/impedance/voltage recently.. having volume issues.

Here's what I have:
- PC with Lyrion Music Server (USB out)
- SMSL SU-1 (2V RCA out)
- STR12A Cary SLP-90 tube preamp clone (9x gain, 47k input impedance, unknown output impedance, RCA)
- Fosi V3 mono (input impedance RCA 25k, XLR 5k)
- MB Quart 800 (90dB efficiency, 4 Ohm)

It sounds great to me. I try to keep the sources at 100% if possible.
But at the preamps lowest volume setting (001/128) it's already loud.
What helped a bit was using the XLR input of the V3 mono (adapter).

I guess the preamp gain is too high in my case. I measured up to 11V AC with a simple meter.
Should I replace the preamp with a DACpre?

When SU-1 is connected to V3 mono directly, I had to set the source to 15%.
What if it resets to 100% by mistake? :eek:

I could get less efficient speakers I guess ;)

Should I have gotten an amp with volume control?

I like the relais/resistor+remote volume on my preamp.
It should be possible to use it separately, skipping the tube part.
Would solve my gain issues, right?

Is there a "best place" to do volume control?
- digital source / software
- dac digital
- dac analog
- preamp input
- preamp output
- amp input
- amp output
 
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What gain setting are you using with the Fosi RCA input? Make sure the switch is set to 25 not 31.

Does it make a difference?
 
One option, if you think the main issue is the high sensitivity of your speakers (which seems reasonable), is to add XLR Attenuator Adapters to the Amps - there's a range of attenuation (essentially fixed volume reduction) available. These also protect somewhat if your DAC suddenly resets to 0dB, which is unlikely but possible.
 
I found this info in the manual:

So the input sensitivity is 110mV which would make the volume control on the preamp extremely sensitive to movement at lower volume settings.

A pair of attenuators to reduce the level from the DAC would help here.

You could also use the volume setting on the PC to reduce the level, but I don't know how many bits would be lost.


1734699953890.png


Link to manual: https://caryaudio.com/wp-content/uploads/2013/06/SLP-90.pdf
 
What gain setting are you using with the Fosi RCA input? Make sure the switch is set to 25 not 31.

Does it make a difference?
The 25dB setting was better than the 31.
Using the XLR (20dB) input is even better. I could go up by 10% at the source.
 
As your other question - "best place to change volume" - this is one of those "should be simple but if you look at it, it isn't" things :)

This is a nice thread https://audiosciencereview.com/foru...distortion-propagate-through-my-system.33358/

There are technical answers (variants on "it depends") but I'd adjust volume in the place that makes most sense to you, for ease of use!
I read through that a few weeks ago.. wow o_O

By signal integrity... I would say the later you reduce the volume the better.
But of course, the (pre)amp with input switching is the most conventional and convenient place I guess.
 
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I found this info in the manual:
So the input sensitivity is 110mV which would make the volume control on the preamp extremely sensitive to movement at lower volume settings.
A pair of attenuators to reduce the level from the DAC would help here.
You could also use the volume setting on the PC to reduce the level, but I don't know how many bits would be lost.
Link to manual: https://caryaudio.com/wp-content/uploads/2013/06/SLP-90.pdf

I wonder how much the clone is the same... they look a little different :p
 

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I wonder how much the clone is the same... they look a little different :p
Yeah, the term clone seems to mean something different in 21st Century hifi component marketing than it does in my line of work.


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PS I was oh-so-tempted to try for some sort of gain... loss dad joke in the context of this thread, but I resisted.
Oops, I guess I didn't resist very successfully.
:cool:
 
The 25dB setting was better than the 31.
Using the XLR (20dB) input is even better. I could go up by 10% at the source.
The XLR input impedance is too low for most tube preamps. You'd be better off adding a passive volume control or attenuator at the input to the preamp. Something simple like the Schiit Sys.

Like most tube preamps it has far too much gain for modern sources.
 
Just learned about gain/impedance/voltage recently.. having volume issues.

As others have suggested, a pair of passive attenuators on the input (or output) of the Preamp.

Something like These allow you to select 10, 15 or 20dB of attenuation.
 
As others have suggested, a pair of passive attenuators on the input (or output) of the Preamp.
I'd suggest the input side of the pre because typically something like I suggested is 10K on the input side which is a bit low for a tube preamp to drive at its output, but is absolutely fine on the input side.

Other ideas could be attenuator pads at the input side of the pre; you could do these at the output side but the preamp needs to "see" a decently high input importance to the pad, say 50K, if you do that, which really rules out something like the Sys (I mean it'd work, it just wouldn't be optimal). It's also worth thinking about subwoofers - if you intend adding a subwoofer, typically their input impedance is too low for a tube preamp and you'd probably be better off using speaker level connections to the sub.
 
There are a lot of suggestions in here about attenuators, which is good because sometimes your source volume might go to 100% randomly, it happens.

That said, the theoretically correct advice for gain staging is probably overkill for most home listening. It's really important in recording, but nobody will die if you get it wrong at home, especially in a situation like this.

Unless you're hearing noise, and especially with all of your downstream gear set lower, I don't think there's any practical issue with lowering the volume digitally.
 
There are a lot of suggestions in here about attenuators, which is good because sometimes your source volume might go to 100% randomly, it happens.

That said, the theoretically correct advice for gain staging is probably overkill for most home listening. It's really important in recording, but nobody will die if you get it wrong at home, especially in a situation like this.

Unless you're hearing noise, and especially with all of your downstream gear set lower, I don't think there's any practical issue with lowering the volume digitally.
Also very true.
 
Thanks for all the tips.

I finally got the Monacor attenuators and put them between DAC and preamp. The connectors are nice and tight.
With -10bB setting, everything worked fine. The volume range was about 20 steps higher.

I then tried the attenuators between preamp and amps.
This would also helps when listening to other sources like CD player.

I gave up using the V3M XLR inputs (possible impendance issue).
With the RCA 25dB setting, I'm now at 15dB I guess.

I'm an elecronics noob.
Which part of the V3M is doing the gain?
If it's an op amp.. could I get/use one with less gain?
 

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Thanks for all the tips.

I finally got the Monacor attenuators and put them between DAC and preamp. The connectors are nice and tight.
With -10bB setting, everything worked fine. The volume range was about 20 steps higher.

I then tried the attenuators between preamp and amps.
This would also helps when listening to other sources like CD player.

I gave up using the V3 XLR inputs (possible impendance issue).
With the V3M RCA 25dB setting, I'm now at 15dB I guess.

I'm an elecronics noob.
Which part of the V3M is doing the gain?
If it's an op amp.. could I get/use one with less gain?
You may want to use some really short extension RCA cables to use with these attenuators.
The combined attenuator+RCA length there acts like a lever even with the smallest touch,that's not a good idea for the connectors or the gear connected to them.
 
Thanks for all the tips.

I finally got the Monacor attenuators and put them between DAC and preamp. The connectors are nice and tight.
With -10bB setting, everything worked fine. The volume range was about 20 steps higher.

I then tried the attenuators between preamp and amps.
This would also helps when listening to other sources like CD player.

I gave up using the V3M XLR inputs (possible impendance issue).
With the RCA 25dB setting, I'm now at 15dB I guess.

I'm an elecronics noob.
Which part of the V3M is doing the gain?
If it's an op amp.. could I get/use one with less gain?
I would look for a tube specialist who knows the circuitry in the preamplifier and can reduce the gain there. Maybe it can even be switched using resistors.
That would also reduce the amplified noise, to the extent that it is audible at all.
 
A real Cary SLP90 has input "gain" controls and a "listening level" control. The way this works is basically a volume control in front of a volume control. I've tried implementing this with other tube preamps with too much gain and it works well, but with the caveat that it doesn't reduce noise at the output. You could get someone to do this for you; it doesn't involve modifying the actual preamp circuit (which will change it's sound). You can have them install a small stereo pot inside the case which you can set and forget.

I assume the clone doesn't have this arrangement which explains why you can't find a comfortable volume setting.
 
The Aliexpress shops sometime allow you to choose the basic value of the volume control (25/50k etc).
But I got my preamp used. I guess I could just add two more resistors if I knew where and what value.
I couldn't find the HIFI Audio ZZ-2311V128-1 product/manual.
1738073393436.png
 
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