[Northman]

Greetings, all.  I have to admit that I have only the vaguest understanding of voltage and impedance. Can I use a passive preamp between a BDA2 and a thirty-year old 3B?

Thanks!!

[Blueshound]

Ultimately that depends on the actual model of preamp that you have in mind and its' specifications. No one can give you a reasonable answer unless you provide info on which preamp model and a link to its' specifications. It would also be helpful to know how you expect your system to benefit.

If you refer to a fairly typical passive preamp, e.g. a Townshend, there should be no issue, except perhaps if you intend to use the preamp to drive long interconnects into the amplifier, or such uses that most passive preamplifiers are not well suited to.

Brian

[Northman]

Thanks for the reply, Brian. As you can tell, I don't know much about passive preamps.

I'm setting up a relatively high-end headphone system. I've got the streamer, DAC, and headphones, and I'm looking at headphone amps. I've also got an old 3B and some speakers not in use, and I'm pondering integrating them into the system. The familiar way to accomplish this is to use a headphone amp with pre-outs that can serve as a preamp for the speaker amp. However, there are a few features that I want, notably balance control and remote, that are quite hard to find in a headphone amp. So I'm wondering whether a passive preamp like the Khozmo Dualmono would work. That unit would give me balance and a remote, and it would give me considerably more choice in headphone amps. It has a pair of outputs, so presumably I could run cables to both amps (and presumably I'd need to have one of the amps turned off or disconnected at all times--an inelegant solution).

Thus for the speakers I'm looking at: streamer > BDA2 > dualmono > 3B > speakers

Would that work? I don't want to spend a lot of money on an active preamp. There are other solutions. I could probably use the Roon dsp/volume, eg. Mostly I'm interested in learning more about passive preamps.

I'm afraid I can't figure out how to embed the Khozmo link.  https://khozmo.com/product/dualmono-without-input-selector-rca-xlr/

[Blueshound]

Their website doesn't seem to provide full specifications. Re: your question, one critical spec is output impedance.

I'd suggest that you contact the manufacturer, describe for them what you're hoping to accomplish, including driving the Bryston amplifier. Be sure to include for them the input specifications for the Bryston amp, particularly the input impedance. If the amp has both XLR and RCA inputs, give them input impedance and voltage requirements for both input types.

You should also ask your other question re: using both pairs of outputs and having them connected at the same time - is there anything you should know about this?

Hope this helps.

Brian

[Northman]

That's very helpful, Brian. I appreciate that you took the time. I'll see what they say. Many thanks!

[REDGUUZ]

Hi,

This discussion in https://www.diyaudio.com  might be helpful:

https://www.diyaudio.com/community/threads/help-with-passive-volume-attentuator-passive-preamp.381539/

It seems that at the applicable/common  impedances /millivoltages (AES/EBU) for the  supplying DAC and the receiving Main Power Amp

a 10KOHM potentiometer is suitable to allow the full bandwidth of the music to pass.

A suitable commercial device could be IMO be choosen e.g.:

https://www.ebay.com/itm/163699238488

or

https://www.polsenaudio.com/product/13673/Polsen-VCP_2-Passive-Stereo-Volume-Controller-for-Powered-Speakers

or

https://www.amazon.nl/Nobsound-Precision-Controller-Preamplifier-HiFi-versie/dp/B07GRRS8SD/ref=asc_df_B07GRRS8SD?mcid=d2e99bd9f2253f3eb57ae90a61609c92&tag=nlshogostdde-21&linkCode=df0&hvadid=709885038928&hvpos=&hvnetw=g&hvrand=5096078920107036464&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9103803&hvtargid=pla-1154552841560&psc=1&gad_source=1







 

[Northman]

Thank you, @Redguuz. I thought I'd posted a response but it seems to have disappeared. Suffice it to say that I appreciate the time that you and Brian took to help me!