Quad II passive preamp - remote volume control

[tzurby]

I use my Quad II power amps (feeding ESL57s) without a preamp. Just a switch for different inputs (CD, DVD, TV, Phono) and a pot (it is 2,5k, which seems to be wrong, as I just learned). The system sounds very good to me.

Now, I want to have a remote volume control. The PGA2311, which can be found on ebay fully assembled for around $100, could be one option. But it is not passive. And the impedance of the pot is not given. (I could ask the suppliers, but what exactly to ask?)

How about simply using a remote controllable Pot, like the motor ALPS 100k boards (for example ebay 142347424572)?

The technical defaults seem to be formulated here: Re: Passive Pre-amps and Quad II amps - JerryS - Amp/Preamp Asylum
But I do not understand what this means for the "passive preamp" (it is just a volume pot).

Also, from here I learned, that I would need pot of around 500k:
http://www.diyaudio.com/forums/tubes-valves/296346-quad-ii-issues.html

But, regarding ALPS, the highest value for impedance is just 100k.


Thanks

Ulrich

 

[audiowize]

You can't really ask these questions without discussing what your sources are.

The PGA2311 is a solid state preamp crammed into one chip.

The input impedance of the Quad II is very high. If you happen to want a powered subwoofer down the road, and you plan to feed it a line level signal, things change drastically.

For a passive level control, it's really important to look at the output impedance of each of your source components in conjunction with how long your cable runs are.

 

[tzurby]

Thanks for your response.
I thought the input signals do not matter as they are line level anyhow. It is (values according to the manuals):
CD-player: Sony CDP-228 esd (line out level adjustable). Output: 2V at 50K
DVD/Blu Ray: Sony UHP-H1. Output: 2 Veff/10 kOhm
Phono: Clear Audio Smartphone. Output: 12 V eff (1 kHz)
TV (Sat Receiver): Technisat Digit ISIO S2, Digital Twin-HD-Receiver. Output: 0,5 V r.m.s., 600 Ohm
I assume, I could also use the audio signal from the TV
TV: Panasonic TX-P37X25E. Output: 0,5 V[eff] (high impedance)

Also, I plan to reinstall my active Rel Strata (1st version) subwoofer. I want to use it with professional audio (German broadcast) distribution / split. amplifiers to have the normal and the bass signals split. For the Lawo/Delta V1082 the data are:
input impedance >5 K Ohm
output impedance 40 Ohm

Would this work with the ALPS pot or with the PGA2311 (I would need the pot values, right?)

Thanks

 

[audiowize]

The output impedance of your sources are extremely important. Your CDP-228 does not have a 50K output impedance. It would be in the trash if it did.

Sony is a little bit daft when it comes to actually publishing real specifications (a pair of ear buds I saw in an airport vending machine that advertised frequency response from 3Hz to 30kHz immediately come to mind), but reading between the lines, it looks like it's about 1K on the CDP-228ESD. The UHP-H1 looks to be in the same boat.

Why they can't specify the actual output impedance instead of an arbitrary load impedance will go into the stack of other questions that I have for Sony engineers.

The Clear Audio phono preamp has a more annoying absence of specifications. If we assume that there are opamps driving the outputs and a decent design, we can call that 1K too.

Your TV has real specifications, go figure! That's what you should expect out of your HiFi.

You should use an active preamp with the V1082. If anything, you could build the V1082 and the preamp into the same enclosure. Why do you want to use the V1802? It doesn't seem well suited to what you're trying to do.

 

[tzurby]

Regarding the Clearaudio phono preamp, I could not find any value for the output impedance. clearaudio electronic GmbH - smart phono V2, & smart phono headphone V2, Features, Preisgekronte Technik (I have the older version.)

Regarding splitter amps (V1082), this worked fine, at least to my ears. (I moved and want to set up my hifi anew. The V1082 were in a large 19 inch chassis for professional audio use - summing digital signals and feeding them to different outputs. I want to get rid of that.)
I could also the internal splitting amp, using the "high level inputs" and feeding the power amps with one of the "bass cut outputs". I did not use that because of very long cables necessary in my old set up. Now, the subwoofer would be situated much closer to the power amps. Nontheless it would be 2-3 meters of cables extra.

Now, would a 100k (motorized) pot work fine? Or should I go for the PGA2311?

Thanks

 

[audiowize]

Since the PGA2311 isn't a passive preamp, that will work better for what you're trying to do as the input impedance of most subwoofer plate amps is fairly low.