[rollo]

I think I need line level attenuation for my system, probably due to my efficient Zu speakers. Whenever I use my Avastar pre with either Ultravalve or FET Valve 400r, I really can't turn my volume knob much more than 9-10 o'clock, without blasting my room with sound. Fine volume control can be difficult.

I assume that the attenuator with be attached with the RCA interconnects between the pre and the amp? Can anyone give me the approx. dB attenuation that I should use?

Thanks.

    In line attenuators are OK. If it were me I would have AVA adjust the gain in your preamp.


charles

[Freo-1]

Actually we do have one passive preamplifier in production right now!

It is the front end of our Synergy Control Amplifier.

In this case we were able to achieve the necessary overall voltage gain by simply engineering a high gain version of our Synergy power amplifier circuits.  This is matched with a passive preamp secton with nearly identical functions as our Insight  SL preamplifier but without the active gain stage.

Since the loads the passive section needs to drive are well known to us and the input and circuit capacitance is very low (very short runs) the effects of loading are eliminated.  The functions this configuration cannot support are Line Out circuits and a RIAA phono option.  We can't expect the passive section to drive external equipment so no line outputs, and there just is not room in the chassis for a phono section, it is full of heat sinks, audio and regulated power supply circuits, and a humongous power transformer.

The sonic quality is excellent and it makes 100W/Ch and drives our inefficient speakers (Salk HT3 and B&W 801) just fine.

The price is $1799, lots less than the equivalent separates and with great musicality and no "compression" at all.

Regards,

Frank Van Alstine

It very well may actually sound better than a preamp/power amp combo.  There are less gain stages, no interconnects to worry about, and should have a slightly better noise floor.  This is what I have observed with the Pass Labs INT-150 vs. separates.   Honestly, the main reason for preamps back when was for phono RIAA equalization and signal boost.

[avahifi]

Yes, we can do that - - - take the line stage gain of an Avastar preamp down quite a bit.  We need to see the preamp here to do it as it requires changes on the circuit board, not an amateur project.

Its not expensive to do here, mainly shipping costs.  Call me about this if you want.

Frank Van Alstine

651-330-9871

[G Georgopoulos]

I was talking about the tube amp's gain potentaily adding noise. Not noise that may be present from the signal coming into the amp.

When I had an Atma-sphere amp and very efficient speakers, I employed attenuators that Atma-sphere supplies to lower the gain. That nicely lowered my noise floor.

Actually noise can come from many sources,then it becomes noise floor noise if you amplify it will become
louder...

[medium jim]

Actually noise can come from many sources,then it becomes noise floor noise if you amplify it will become
louder...

Certainly not the case in my system, noise...maybe a problem in yours? 

Jim

[pansixt]

I was amazed at the noise that I never really acknowledged, and that I now know I had from my old tired Mac SS preamp that I felt served me so well.

Since I hooked up the T-8 that I received from Franks Place, the quietness in the music has been very pleasing, direct and to the point accurate.
This includes recordings of which I know intimately and have heard versions live from artists that I know very well and even personally and in some cases
was there.

Now I know my meager system as it is presently cannot do proper justice to a live show. But it does not audibly add anything unwanted. At least not anything
that I or in one recent case, one of the performers themselves who was over the other day can determine. But we were also relying on memory from many, many moons ago.

Anyway, as close as we can get, sometimes just has to be good enough.

James

[trackball02]

Frank, I'm glad that you can alter the gain on the Avastar. I'll call you in a few days on how to get it back to you.

My only problem is that I will go into Avastar withdrawal. The unit is by far my most favorite piece of audio gear. It is on all of the time! It will be hard to part with it. Seriously.

[werd]

Ok

so its settled then. The source rules.....Yah.

[DustyC]

What amp do you have? How much gain does it have?

Bi-amped with Classe Audio DR-9 and DR-3's. I think the DR-9 needs 1.0v for full output and the DR-3's need 1.2v

[DustyC]

and any decent tech should be able to reduce the gain of your preamp simply by adding or replacing a resister in each channel...

doug s.

Yes, but that's a little like slowing down your car by dragging a trailer with flat tires.  Better to engineer in less gain in the first place. 

[DustyC]

Actually, depending upon your amp, a lot less gain.  There are many SET amps that reach full output with 1 volt or less.  Given the output of a typical CD player / DAC or phono stage you will always be in attenuation mode.  At that point the gain is useless.  So do you operate your volume control below unity gain? 

It's all a case of balance, knowing what each stage contributes can help determine if line stage gain is really necessary.

I'm sure the preamp is below unity gain unless I'm using phono and playing a recording from ViTaL Records (David Manley's old label). They seem to be cut at really low levels. Easy to get the volume up to about 1:30 or so. 

[doug s.]

Yes, but that's a little like slowing down your car by dragging a trailer with flat tires.  Better to engineer in less gain in the first place. 

i completely disagree.  it's more like slowing down your car by letting your foot off the gas.     change a resistor walue, or change the wolume pot, which is basically a waristor - there is no difference in the result.

doug s.

[avahifi]

Dusty C, there are many different ways to reduce gain.  The the two methods we would choose (perhaps in combination) could be, but not always, simply a change in the active circuit feedback loop and/or a voltage divider to reduce the level of the input signal.  Either or a combination of both will reduce signal level without screwing up the music and without "dragging the trailer".

Read up on basic electronics and try to keep your posts a bit more positive.

Frank Van Alstne

[G Georgopoulos]

Certainly not the case in my system, noise...maybe a problem in yours? 

Jim

Hi, no noise problem in mine!!!  it's dead silent 

[DustyC]

Dusty C, there are many different ways to reduce gain.  The the two methods we would choose (perhaps in combination) could be, but not always, simply a change in the active circuit feedback loop and/or a voltage divider to reduce the level of the input signal.  Either or a combination of both will reduce signal level without screwing up the music and without "dragging the trailer".

Read up on basic electronics and try to keep your posts a bit more positive.

Frank Van Alstne

Sorry about that.