Need a Preamp/Amp!
- Thread starter team_tsp
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team_tsp
Active Member
Hey so I went with the A23 amp. The local dealer helped me unbox and test it while at his store to make sure there weren't any immediate issues 
When I brought it home, it does have a small buzz / hum, but it's only noticeable within a few inches really. Standing about 1-2 feet away, and the buzz / hum mixes in with ambient noise. Overall I seem to be having much better luck with this unit, even without it being plugged into the Emotiva gadget (which I'll probably try to return).
But I have a new question about the amp and my preamp (2100).
The A23 has gain knobs on the back, and the manual says it's ideal to set them to max. However, I noticed that when I use the remote control for my 2100 to change the volume, a buzzy hiss sound comes out of the speakers. I think the motor that turns the potentiometer is leaking noise into the circuity (which apparently was a problem on the P5 as well).
The 2100's manual states to set your amp's gain level down to where you can use the potentiometer in a certain range for typical listening, which is supposed to be the cleanest range for the potentiometer. When following those instructions, I set the gain on the A23 low enough so when I change the volume via the 2100's remote, the hiss no longer comes through the speakers.
My question is, does it matter from a sound quality perspective where the amp's gain level is set, or not really? Like I'm not sure if the 2100's potentiometer is having an issue, or if having the A23's gain set to max is amplifying typical noise too much?
When I brought it home, it does have a small buzz / hum, but it's only noticeable within a few inches really. Standing about 1-2 feet away, and the buzz / hum mixes in with ambient noise. Overall I seem to be having much better luck with this unit, even without it being plugged into the Emotiva gadget (which I'll probably try to return).
But I have a new question about the amp and my preamp (2100).
The A23 has gain knobs on the back, and the manual says it's ideal to set them to max. However, I noticed that when I use the remote control for my 2100 to change the volume, a buzzy hiss sound comes out of the speakers. I think the motor that turns the potentiometer is leaking noise into the circuity (which apparently was a problem on the P5 as well).
The 2100's manual states to set your amp's gain level down to where you can use the potentiometer in a certain range for typical listening, which is supposed to be the cleanest range for the potentiometer. When following those instructions, I set the gain on the A23 low enough so when I change the volume via the 2100's remote, the hiss no longer comes through the speakers.
My question is, does it matter from a sound quality perspective where the amp's gain level is set, or not really? Like I'm not sure if the 2100's potentiometer is having an issue, or if having the A23's gain set to max is amplifying typical noise too much?
I am big on gain level control.
If I were you, I would turn the amp controls to off, play your most favorite loud music, turn the preamp up to midway (50%), then slowly turn up the amp levels until listening levels are ideal for serious listening. Once done the preamp with have lots of range for your ideal listening levels, the amp will be set lower, and the noise will be lower.
It can be difficult to set the two amp knobs perfectly so the are matched. If you have a multimeter you can set it to AC volts then measure the actual voltage at the outputs while playing a singe wave test tone and merely adjust one of the knobs until the outputs measure identically.
If I were you, I would turn the amp controls to off, play your most favorite loud music, turn the preamp up to midway (50%), then slowly turn up the amp levels until listening levels are ideal for serious listening. Once done the preamp with have lots of range for your ideal listening levels, the amp will be set lower, and the noise will be lower.
It can be difficult to set the two amp knobs perfectly so the are matched. If you have a multimeter you can set it to AC volts then measure the actual voltage at the outputs while playing a singe wave test tone and merely adjust one of the knobs until the outputs measure identically.
MakeMineVinyl
Well-Known Member
Your new amplifier has more overall gain than you need, and when you turn that gain control fully up, you are over-amplifying the noise from your preamp. As a rough setting, set the amplifier gain controls to the 2:00 o'clock position (match them as closely as possible), which in gain terms is about 10dB less level than if they were fully up. That setting should get you into the ballpark. You can raise or lower them together as needed depending on how loud you listen. For the best system noise ratio, set these gain controls so that at max volume on your preamp, the system is playing just a bit louder than you will ever listen, using a variety of program material. That way, you are only using as much gain as absolutely needed, and none is being wasted in amplifying noise.
If you want to get really anal, set the volume on your preamp to its "zero dB" setting, and set all "trim" controls to zero. Then play a video test disc, playing the 75dB pink noise test on one speaker at a time. Set up a sound level meter at your listening position, and set the gain controls on the amplifier for each channel so that the sound level meter reads 75dB. Do this individually for each speaker.
Or just set the gain controls on the amp for 2:00 o'clock and call it good.....
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D
Deleted member 133
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My go-to stereo power amp from 1978 for about two decades was the Hitachi HMA-8300. Besides having loads of power, it also had a large pwoer meter for each channel, and individual gain controls on the front panel. I did all the things Flint and rammis suggest whenever introducing a different pre-amp. Loved the flexibility. (Before it left the store with me when I bought it, I had a tech put in on the test bench to make sure the meters were calibrated as well as could be.)
I still have that amp (in storage) and am planning to have it checked-out in the shop and then put back into service for a system I'll put together for one of my daughters.
Jeff
I still have that amp (in storage) and am planning to have it checked-out in the shop and then put back into service for a system I'll put together for one of my daughters.
Jeff
team_tsp
Active Member
@JeffMackwood - Nice, I've always kinda wanted an amp with power meters I didn't even know Hitachi had made power amps, that's cool
@Flint and @rammisframmis - thanks as usual for the guidance! I did a rough calibration for now since I still need to finish organizing and setting everything up. Once I have everything set up I'll do a thorough calibration, and in preparation for that, I've got a couple more questions (go figure lol).
1. Subwoofer gain - Having set the A23's gain levels based on setting the 2100's volume knob set at 50%, I'm now finding that setting the gain on my SVS sub might be difficult. It seems I have to set the SVS' gain level close to minimum. Any slight adjustment (hair movement) of the SVS' gain knob makes the sub either really loud or really quiet. The 2100 has a sub-level knob, and for now I've turned that down quite a bit. Is that the way to go?
2. Channel & Sub level matching - I remember back on the S&V forums there were guides for this, and I may have saved a copy of those guides for my own notes (I'll need to check my notes). I also have a Radio Shack sound level meter (I don't have a multi-meter, but that's a neat idea and might borrow one from a friend):
I didn't even know Hitachi had made power amps, that's cool@Flint and @rammisframmis - thanks as usual for the guidance! I did a rough calibration for now since I still need to finish organizing and setting everything up. Once I have everything set up I'll do a thorough calibration, and in preparation for that, I've got a couple more questions (go figure lol).
1. Subwoofer gain - Having set the A23's gain levels based on setting the 2100's volume knob set at 50%, I'm now finding that setting the gain on my SVS sub might be difficult. It seems I have to set the SVS' gain level close to minimum. Any slight adjustment (hair movement) of the SVS' gain knob makes the sub either really loud or really quiet. The 2100 has a sub-level knob, and for now I've turned that down quite a bit. Is that the way to go?
2. Channel & Sub level matching - I remember back on the S&V forums there were guides for this, and I may have saved a copy of those guides for my own notes (I'll need to check my notes). I also have a Radio Shack sound level meter (I don't have a multi-meter, but that's a neat idea and might borrow one from a friend):
- Do you all recommend any particular (preferably free) software that can generate sine waves or pink noise? I figure I can load such software on my laptop and hook it up to my preamp to play the signals.
- And does the calibration process differ when using sine waves vs pink noise? Or do you use a combination of both?
team_tsp
Active Member
Gotcha, I'll look for something that generates pink noise, otherwise I'll try TrueRTA. Also any thoughts on my sub's gain level?
MakeMineVinyl
Well-Known Member
D
Deleted member 133
Guest
Not a bad looking amp. I found this pic online - with optional handles (which I have for mine - they come in handy given how heavy this thing is!)@JeffMackwood - Nice, I've always kinda wanted an amp with power meters
Deerhunter
Well-Known Member
Looks stout