preamp with integrated amp ?

[tubeampking]

Boy I do love this site!! You have all been so helpful to me...thanks.
For my next ?? I am using two Grommes LJ4 in my listening room and have put a tube driven stereo preamp in front of it to make the input signal hotter. It definitely gives the output some great punch, but I'm wondering what, if any, damage it could cause. I am using the radio inputs on the Grommes. The preamp is a Little Bear P3 running a pair of Raytheon 2C51 at 180 volts. What say you all? :scratch2:

 

[spicer]

Boy I do love this site!! You have all been so helpful to me...thanks.
For my next ?? I am using two Grommes LJ4 in my listening room and have put a tube driven stereo preamp in front of it to make the input signal hotter. It definitely gives the output some great punch, but I'm wondering what, if any, damage it could cause. I am using the radio inputs on the Grommes. The preamp is a Little Bear P3 running a pair of Raytheon 2C51 at 180 volts. What say you all? :scratch2:

I'm not sure the reason for your concern. The preamp output is signal only, no DC component... unless there is a malfunction. Same with the input on the power amp. A malfunction would be a leaky coupling capacitor in the preamp output circuit and even then it would be blocked by the input capacitor of the power amp. There are no interconnect issues to worry about between these units assuming they are properly constructed.... no hot, power line on the chassis kind of thing. Sounds like a fun system.

 

[tubeampking]

Claification

What I meant by making the input signal hotter is to boost it to get more overall volume and punch...which it does. Without the preamp, the result is unimpressive, but with it....wheeee!!! Thanks for the input...:yes:

 

[cademan]

You won't really cause any damage, you will usually just get a little more distortion and sometimes over the top tone coloration. A preamp running into an integrated amp can work ok except that you are adding another preamp in the chain along with the original integrated amplifier with its existing preamp.

The Little Bear P3 looks to have a single control so it is more likely a gain control rather than a so-called volume control. When you are using it to boost your signal, you will normally experience above normal hiss.

It won't hurt the Little Jewel amplifiers, but if you really wanted to get adventurous, take the output of the Little Bear and wire it directly into the first grid of the input tubes of the Little Jewel amplifiers. This way you would bypass the volume and tone controls on the Little Jewel amplifiers. It might even sound better than the way you are using them now.

 

[spicer]

What I meant by making the input signal hotter is to boost it to get more overall volume and punch...which it does. Without the preamp, the result is unimpressive, but with it....wheeee!!! Thanks for the input...:yes:

I see... just more drive, read signal voltage available from the preamp output. In no way is that a concern for your power amplifier with regard to the output of a preamp. Apparently the power amplifier's sensitivity is such that it needs the input level supplied by the preamp. Most power amplifiers are units dedicated to providing voltage gain from preamp level output... 700mv to 1.2 volts in for rated power output.... sufficient to drive output devices, tube or transistor, as current amplifiers to the limit of the supply voltage. These units have a fair amount of headroom built into them so they operate easily within their limits. Sounds like your power amp needs the preamp level input. The line level... that of source devices like tape decks, CD players, audio from Video devices, etc. are at line level... generally 300mv, not enough to adequately drive a power amp to it's normal operating levels. That's one of the reasons why they need a preamp... besides providing selection, processing like tone controls, the preamp provides necessary voltage gain to drive the power amp.

 

[tubeampking]

" but if you really wanted to get adventurous, take the output of the Little Bear and wire it directly into the first grid of the input tubes of the Little Jewel amplifiers. This way you would bypass the volume and tone controls on the Little Jewel amplifiers. It might even sound better than the way you are using the m now. "

So could I wire one of the other RCA inputs directly to the grid of the VI tube? Looking at the schematic, it would have to be V2 in order to bypass the volume and tone controls. I am aware that stringing two preamps can create noise, but I can control that with the gain of the Little Bear. I keep it under half, then adjust the LJ volumes for listening level. No discernible hiss at moderate volume levels.

 

[spicer]

" but if you really wanted to get adventurous, take the output of the Little Bear and wire it directly into the first grid of the input tubes of the Little Jewel amplifiers. This way you would bypass the volume and tone controls on the Little Jewel amplifiers. It might even sound better than the way you are using the m now. "

So could I wire one of the other RCA inputs directly to the grid of the VI tube? Looking at the schematic, it would have to be V2 in order to bypass the volume and tone controls. I am aware that stringing two preamps can create noise, but I can control that with the gain of the Little Bear. I keep it under half, then adjust the LJ volumes for listening level. No discernible hiss at moderate volume levels.

I'm sorry... I read the thread title than from the text of your first post was thinking pre amp into power amp. I see it is pre amp into integrated, which has it's own preamp. Still won't matter, as was mentioned, set the volume controls of the two amps for the best sensitivity with the least amount of hiss. Overall you'll just have more gain available... might have a very low source that needs it.

 

[cademan]

So could I wire one of the other RCA inputs directly to the grid of the VI tube? Looking at the schematic, it would have to be V2 in order to bypass the volume and tone controls.

Can you post the schematic? You can also tap into or alligator clip to the center lugs of the volume controls.