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Preout

Optimum Pre-amp Volume Levels

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Hi everyone.

 

In my system, I noticed I can't really turn my preamp up more than 9 o'clock without it getting too loud.  I can digitally turn the signal down on my dac but I lose resolution. That's why I bought the pre amp, to keep the full signal. And it does sound way better.  

 

So I am wondering, for my listening levels, in a small room and monitor speakers is my 150w into 8ohm amplifier just too much for what I need?   

 

I am looking at getting a new amp and wondering if I choose a low power but still high quality amp, will I be able to then turn my pre amp up to round 12oclock where I have read that it will sound best allowing fuller signal through to the amplifier?  I want to achieve the best sound I can at around 85 DB listening levels.

 

Thanks.

 

 

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I am a complete novice on gain, but this might be a cue for discussing buffers such as the Pass Labs B1 Buffer Preamp, which might be a less expensive option and assuming your current amp is perfectly OK except for this issue. Such things can go before or after your preamp. In other words, you might have a wider range of options here.

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They are PMC Tb2i's. 90db. 

 

I think if I could sum up my original post, for argument sake. Would replacing the 150w amp with a 15w amp mean the volume knob on my preamp would go up to achieve the same level of DB? Or would nothing change?    

 

Thanks.

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Oh thanks for that link Neurone they look like a good solution! Do they degrade sound quality much?

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Posted (edited)

It’s the gain match between your two components as both are set high at the factory, a little rare for things to happen at 9am volume so howabout 8am.

 

Sometimes the problem is the other way around where you need it at 1pm volume to sound normal.

 

The RCA attenuators mentioned above would fix it.

 

If you look into to the gain value specs of the new amp it will give an idea compared to your current amp. There would likely be two factors going significantly down to a 15w amp, one being the gain setting and the other the ten times drop in power. You may not know exactly until you connect them up, it’s likely to play a lot lower volume.

 

90dB efficiency speakers are about average and not make big difference but the 15w amp may struggle to drive it depending on the impedance match. The speakers are rated at 8 ohm impedance so friendly enough and most low powered amps should work, likely to need about 11-1pm volume for normal listening levels. The room size will be a factor also as the speaker needs to fill it out.

 

Also, why do you want 85dB levels as many audio room average levels can be around 70-80dB(A) although if you are measuring at 85dB with no weighting mentioned it’s likely to be closer to what I mentioned in A-weighting which is how humans hear sound and relate closer to the dB value and your quoted figure.

Edited by Al.M

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Posted (edited)
26 minutes ago, Preout said:

Oh thanks for that link Neurone they look like a good solution! Do they degrade sound quality much?

People who've tried them said that unfortunately they do. You're just adding yet another mechanism for attenuating the signal. Turning the digital volume control down would probably do less harm.

 

You need to find the specs of how much gain your preamp and power amp provide separately before making any choices from here.

Edited by Ittaku

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Ok, I'll have a look into those specs.  Makes me think, an amplifier with adjustable gain control would be a very desirable product.   

 

If I were to try the inline attenuators, would you put them between the dac & preamp, or the amp & preamp?  

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Just now, Preout said:

Ok, I'll have a look into those specs.  Makes me think, an amplifier with adjustable gain control would be a very desirable product.   

 

If I were to try the inline attenuators, would you put them between the dac & preamp, or the amp & preamp?  

You can never have enough volume 😁   
between the pre and power 

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Just now, Preout said:

If I were to try the inline attenuators, would you put them between the dac & preamp, or the amp & preamp?  

There will be differences between the impedance match between dac & preamp versus preamp & amp so the amount of attenuation will vary. If you have those figures, the best way is to put it between the two components with the biggest difference in impedance - i.e. the biggest magnitude difference between output impedance on one and input impedance on the other.

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Ok, spec of my preamp.  

 

Marantz 7 Tube Preamp

Frequency response: 20Hz to 20kHz

Total harmonic distortion: 0.1%

Gain: 64.5dB (MM), 22.5dB (line)

Signal to noise ratio: 80dB (MM)

Valve complement: 3 x ECC83/12AX7

 

Belcanto S300 Amp

 

Power Output: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300W/channel into 4 ohms, 150W/channel into 8 ohmsMinimum Load: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 ohmsFrequency Response: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+/-0.5dB 20Hz-20KHz, all loadsTHD+N: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.01%, 1W, 1KHz, 4 ohmsIMD (CCIF): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.002%, 1W, 14:15KHz, 4 ohmsOutput noise: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90uVRMS A-weighted 10Hz-20KHzVoltage gain: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27dB (single ended or balanced input)Damping factor: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .>1000Output Impedance at 100Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .<8 milliohmsDynamic Range: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111dBInput Voltage for Max Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5VrmsInput connections: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Single-ended RCA or balanced XLRRCA input impedance: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10KohmsBalanced input impedance: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20KohmsOutput connections: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-sets WBT 5-way safety binding postsStandby Power: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10WSize: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8.5”x3”x12”, 216mmx76x305mm (WxHxD)Weight: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9lbs, 4Kg

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Sorry about the vomit of info on the amp, I was trying to trim out the non important info but was hard on my phone.

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Posted (edited)

No problem. Got the DAC output impedance somewhere? It's bound to be low. And the preamp output impedance? Bound to be relatively high.

 

My guess is between the DAC and preamp would be best.

Edited by Ittaku

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Guest jakeyb77

You need to look at the output impedance figure of your preamp compared to the input impedance of the amplifier. I think a 1:10 ratio is the magic number but others may know more 

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Guest jakeyb77

Is it possible to put a lower gain tube in the pre also?

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Ok, 

 

Bel Canto Dac3

 

Analog Section: Maximum Output • 4.5Vrms balanced XLR, 2.25Vrms RCA Output Impedance • 200 ohms balanced XLR, 500 ohms RCA Frequency Response • 20Hz-20kHz, +/- 0.5dB THD+N • <0.001%, 4.5Vrms balanced Out, 1KHz IMD (CCIF) • <0.0005%, 19:20KHz, 4 ohms Output Noise • 3uVrms A-weighted 20Hz-20KHz Dynamic Range •  129 dB A-weighted 20Hz-20KHz Idle power draw • 15 Watts 

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28 minutes ago, Ittaku said:

People who've tried them said that unfortunately they do. You're just adding yet another mechanism for attenuating the signal. Turning the digital volume control down would probably do less harm.

 

You need to find the specs of how much gain your preamp and power amp provide separately before making any choices from here.

I too have an interest in these and your comment is interesting as in Neurone's post where he provides a review reference in 2002 by the tnt-audio webzine reviewer Steve Davey (unknown to me) concludes by saying - "But the real test was whether there was any audible degradation in the sound quality. After a number of A/B testing sessions with and without the attenuators in place I could discern no change in signal quality". I suppose it's going to be a situation of trying them and establishing for yourself whether you are happy with the results. Their low cost luckily makes this an easy test.

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Guest jakeyb77

Marantz 7 output is 470 ohm. 

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3 minutes ago, Smp said:

I too have an interest in these and your comment is interesting as in Neurone's post where he provides a review reference in 2002 by the tnt-audio webzine reviewer Steve Davey (unknown to me) concludes by saying - "But the real test was whether there was any audible degradation in the sound quality. After a number of A/B testing sessions with and without the attenuators in place I could discern no change in signal quality". I suppose it's going to be a situation of trying them and establishing for yourself whether you are happy with the results. Their low cost luckily makes this an easy test.

I have no idea of the quality of resistors in the attenuators, but given the insane levels people go to in high end audio to use the finest components on earth in their signal path, and that this is going into the signal path, it's impossible for it to have no effect, but discernible effect is an entirely different question - people (allegedly) hear differences in their system with changes in the phases of the moon, so just knowing it's there they'll be sure it's affecting sound. The only instances I've seen of people using them on this forum they've said it degrades the sound, but best you just check for yourself.

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The attenuators come in 3, 6 and 12db.  Which one do I pick?

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One last thing missing - the preamp input impedance?

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Posted (edited)

Would go for 12dB attenuators given your observation that 9am volume is too much. If the 12dB translates to exactly that through the circuit, which I doubt, it is subjectively twice less the perceived loudness interpreted at your hears and brain, so should give at least double the affect.

 

Try the 6dB attenuators as well to give a half way result if you find the 12dB is too much.

 

I have used the RCA attenuators and the sound quality effect is minisculel to non-existent in my system and ears using Supratek tube preamp.

Edited by Al.M

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19 minutes ago, jakeyb77 said:

You need to look at the output impedance figure of your preamp compared to the input impedance of the amplifier. I think a 1:10 ratio is the magic number but others may know more 

1:10 is the minimum where even lower is better, something like 1:100. Putting the attenuators in there will raise the ratio which is why it can matter a lot, especially since he has a tube preamp which notoriously have relatively high output impedances.

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7 minutes ago, Ittaku said:

I have no idea of the quality of resistors in the attenuators, but given the insane levels people go to in high end audio to use the finest components on earth in their signal path, and that this is going into the signal path, it's impossible for it to have no effect, but discernible effect is an entirely different question - people (allegedly) hear differences in their system with changes in the phases of the moon, so just knowing it's there they'll be sure it's affecting sound. The only instances I've seen of people using them on this forum they've said it degrades the sound, but best you just check for yourself.

Hear, hear. And not to mention an additional RCA connection (i.e. about the worst kind of connection anywhere in audioland) per channel. That alone would trick my brain into thinking something sounds off.

 

Just dial down the digital volume control by 6-10dB and be done with it.

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4 minutes ago, Ittaku said:

I have no idea of the quality of resistors in the attenuators, but given the insane levels people go to in high end audio to use the finest components on earth in their signal path, and that this is going into the signal path, it's impossible for it to have no effect, but discernible effect is an entirely different question - people (allegedly) hear differences in their system with changes in the phases of the moon, so just knowing it's there they'll be sure it's affecting sound. The only instances I've seen of people using them on this forum they've said it degrades the sound, but best you just check for yourself.

I certainly would agree with you that by the very fact that they are in the signal path they "should" be anticipated to have a negative effect. They are inexpensive in audiophile terms and generally the quality of  Rothwell's products (principally their SUTs) are reasonable so sucking and seeing will have to be it for me.

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