Tube Pre Amp into SS Integrated amp

[niceshoes]

I have a Rotel RA313 integrated amp that doesn't have a pre out/main jacks.

I want to experiment with a "tube" sound. Is there potential to damage anything by running the tube pre-amp into the Aux or Tuner line inputs on the integrated? And what should I do with the volume controls?

Is a tube pre-amp likely to change the sound much when connected in that way? Source will be airport express airplay.

Thanks for your knowledge

 

[highfigh]

I have a Rotel RA313 integrated amp that doesn't have a pre out/main jacks.

I want to experiment with a "tube" sound. Is there potential to damage anything by running the tube pre-amp into the Aux or Tuner line inputs on the integrated? And what should I do with the volume controls?

Is a tube pre-amp likely to change the sound much when connected in that way? Source will be airport express airplay.

Thanks for your knowledge

The Aux and other line inputs are designed to receive about 1-2VAC of input signal, not the varying level from a preamp although, if you can match the level from the preamp to that of another source, it should be OK as long as you leave the volume control where it has been set.

Will you hear a difference? Maybe. Preamp tubes are capable of wide frequency response, just like solid state and the characteristics that endear themselves to many people won't be heard unless certain conditions are met. Most of the differences people like are from output tubes and especially when they're on the verge of distortion, especially guitar amps. However, that's different- here, we're REproducing the sound and when a guitar amp is used, it's for sound production.

If your music files are low resolution MP3, nothing will help the sound. If your files are 192KHz or higher, AAC, FLAC or the highest quality possible, it should sound good but again, it might not be a noticeable difference unless the tube preamp needs service- it's highly unlikely that it will be a night & day difference for the better.

 

[niceshoes]

Awesome, thanks highfigh.

So you're saying if I want to adjust the volume I need to either do it at the source, or on the integrated amp?

I'll give it a go and let you know if anything blows up

 

[markw]

So you're saying if I want to adjust the volume I need to either do it at the source, or on the integrated amp?

Consider this: You'll be feeding the signal through two preamp stages, both with volume controls. You'll probably want to set (and forget) the volume on one or the other and use only one volume control on a regular basis.

Also, the output impedance of the driving device is usually lower (1/10) than the input impedance of the next stage. Generally,, a 1:10 ratio is considered ideal. No explosions, but it may or may not affect performance.

 

[Mark of Cenla]

I would leave the volume set on the preamp and change the volume on the amp. That is what I do in my car with the mp3 player. If you turn up the preamp too much, it will cause distortion. Peace and goodwill.

 

[highfigh]

If you do this, changing the level on the preamp will eventually give you that heavily over-driven sound guitar players use, but it probably won't be the sound they search for. Find the level on the preamp that's the same as other sources and NEVER change it. Use the volume control on the integrated, if you do this.

 

[Poultrygeist]

I've always had excellent results using tube preamps with ss and class D integrated amps. The accepted practice is to max the pot on the integrated amp while using the preamp to control the volume.

In this picture I'm using the silver Nobsound 12AX7 preamp paired with the $10 TPA3116 integrated amp and a $22 Pyramid regulated power supply ( lower right ).

Haven't seen any posts here on the incredible TPA3116 but on other forums it's all the rage.

 

[niceshoes]

Well I went ahead and hooked up the tube amp to my SS. After some research I discovered my tube pre-amp (little bear P5) is actually a buffer designed for line level. I ended up connecting it to my new Rotel RA 11 after I realised it wasn't going to blow anything up

It works, whether it sounds different or better I can't say without just yet.

Following Markw's advice above I set the pre-amp to the same volume level as other line inputs and left it there. Poutrygeist is suggesting to handle volume in the exact opposite way so I'm not sure what to make of that. Surely running an integrated amp at 100% volume all the time isn't ideal?

 

[Poultrygeist]

The difference between a tube buffer and a tube preamp is the preamp has gain.

You might want to roll the tubes as most gear from China comes with horrible tubes.

I put Telefunkens in my Nobsound and the improvement was dramatic.

 

[slipperybidness]

Well I went ahead and hooked up the tube amp to my SS. After some research I discovered my tube pre-amp (little bear P5) is actually a buffer designed for line level. I ended up connecting it to my new Rotel RA 11 after I realised it wasn't going to blow anything up

It works, whether it sounds different or better I can't say without just yet.

Following Markw's advice above I set the pre-amp to the same volume level as other line inputs and left it there. Poutrygeist is suggesting to handle volume in the exact opposite way so I'm not sure what to make of that. Surely running an integrated amp at 100% volume all the time isn't ideal?

You need to reconsider your view on the "volume knob".

It is really a "gain knob", as long as the "gain structure" is set in a manner that gets to your desired sound output level without clipping, that is the only real concern here.

For my power amps, I typically leave the gain maxed out, and control the volume with my pre-amp. I only adjust the gain down to solve any problems like too much gain causing noise to get amplified until it is audible, or clipping at peaks.

 

[highfigh]

You need to reconsider your view on the "volume knob".

It is really a "gain knob", as long as the "gain structure" is set in a manner that gets to your desired sound output level without clipping, that is the only real concern here.

For my power amps, I typically leave the gain maxed out, and control the volume with my pre-amp. I only adjust the gain down to solve any problems like too much gain causing noise to get amplified until it is audible, or clipping at peaks.

It's NOT a gain knob, it controls the input level- gain is fixed by the circuit design.

 

[slipperybidness]

It's NOT a gain knob, it controls the input level- gain is fixed by the circuit design.

OK, fair enough.

If you want to get the best technical description, then most "volume knobs" are really "input attenuators", at least in the classic topology.

You are right, it isn't a "gain knob", because gain is set and fixed by the circuit. However, I still think it makes sense to consider it as a "gain structure adjustment knob" in this particular situation.

What is important is that the gain structure is at a reasonable level to be amplified without clipping or amplifying the noise floor.

 

[highfigh]

OK, fair enough.

If you want to get the best technical description, then most "volume knobs" are really "input attenuators", at least in the classic topology.

You are right, it isn't a "gain knob", because gain is set and fixed by the circuit. However, I still think it makes sense to consider it as a "gain structure adjustment knob" in this particular situation.

What is important is that the gain structure is at a reasonable level to be amplified without clipping or amplifying the noise floor.

EXACTLY! That's why AVRs and some other pieces have an indicator for -dB around the knob. The noise floor is what it is and if the control must be set at a point where noise is heard, something else needs to be changed.

'Gain stages' is an OK name, but it would be helpful if the manufacturers would add some indicator for the point where the preamp reaches its known clean output level and power amps to have a clipping indicator.

Ultimately, it's only what the name implies- it's a volume or level control.

 

[Ibbz]

Can I use a Little Dot Mk II as a pre amp with my current set up which is an iMac connected to a TEAC A-H500 using 3.5mm jack to The phono LR in for that Tube sound? (In CD in using CD direct mode? Or Aux?)

I use the LDii as a headphone amp currently. And the speaker from the TEAC are BW 601 s2.