LDR Active Preamp - does it exist?

Nguyen, the amps 4v sensitivity is the problem, try this, email the manufacturer and ask is there any way of getting the amps sensitivity to 2v or even 3v will do. It may be a simple thing like change the input tube for a higher gain one.
If not you could get someone to build this simple buffer that has gain, parts would be around $10 http://www.diyaudio.com/forums/attachments/analog-line-level/341197d1365395103-preamp-buffers-simple-idea-buffers.gif

I Just looked at you input tube 6SN7 it is a very low gain tube of 20. A tube tech should be able to reconfigure this for a higher gain tube of say 40 or so with a different input tube.


Cheers George

Thanks George. I asked Grant Fidelity but did not get the answer I want to hear.

It is suggested that the amp Shuguang S845MK need to match with preamp Shuguang S200MK. The preamp spec is kinda freaky:

Input impedance: 100kohm
Input Power Voltage: ≤150mV
Output Voltage: more than 3V, maximum 10V
Output impedance: less than 10k ohm

Duc

The Lightspeed LDR is wonderful provided your source and amplifier are appropriate for a zero gain, zero buffering preamp.

Either find a source that outputs closer to 4V, find an amp whose sensitivity is closer to whatever output voltage of your source, find another way to either add gain or lower sensitivity, or get an active.

I happen to think the Burson Buffer is a reasonable try to add gain to your system. It's actually what you're looking for, isn't it? An active, with gain and LDR volume control. The Burson Buffer adds 6db gain, and your Lightspeed LDR acts as volume control.

Having said that, an LDR is not the only means to deliver great sound, I happen to think the Coincident Statement Linestage and TRL Dude are better than the Lightspeed. But if your source and amplifiers are appropriate, I'd agree that there may be nothing better at the price point of the Lightspeed LDR.

What do you think - One alternative to solve the issue is to buy a match preamp. The match preamp specification is a bit worrysome for me because it output voltage is minimum 3V and max at 10V. I guess the reason it matches with the amp 4V input is because the preamp can deliver high voltage. The potential caveat is the preamp is less likely to compatible with most of other amplifiers. Preamp output at minimum 3V seems too high that may cause damage if the amp input voltage less than 3V?

After lightly reading this thread I thought I would comment on it. I have the Burson buffer and the Lightspeed LDR. It is a outstanding combo. It would solve your high input voltage issue. Just put it before the Lightspeed and after your source. I think you would be extremely happy with it, but each one has his own preferences. I got my buffer from Chris Johnson at Parts Connecxion and he told me that this Burson is the Cadillac of buffers. Have fun.