Passive vs. Powered Pre Amp — Skip the Power?

T

tedp

New member
Joined
Aug 13, 2014
Messages
8
I'm planning to get the Job 225 amp. I can't decide if I need a powered preamp like the Job pre2, or if I'd be ok with a passive preamp like the Schitt Syst.

My only source will be my computer, run through a dac, and I would guess that I dont need any additional gain.

Thoughts?
 
My preference always is an active preamp. If you don't mind tubes, the Primaluna preamp seems like a great match
 
Thanks Joe

I was initially thinking the same thing, but I was chatting with someone at Schitt and they were making the case for a passive amp. Here's what they said:

In general, the less stuff you have in the chain, the better the sound—hence passive preamps. If you don’t need the gain of a traditional preamp (and you usually don’t, with line-level signals), then it’s best to go passive.
Click to expand...

My set up has a computer source which will never be more than a couple feet away, so it's unlikely that would introduce much impedance.
 
There is no substitute for experiencing it for yourself. You could try it and if you like it, that's great. You'll probably gain some detail and resolution doing it that way.

tedp said:
Thanks Joe

I was initially thinking the same thing, but I was chatting with someone at Schitt and they were making the case for a passive amp. Here's what they said:



My set up has a computer source which will never be more than a couple feet away, so it's unlikely that would introduce much impedance.
Click to expand...
 
I have the STP-SE, that I bought just for the JOB, and while I will agree with the reviewers that it is quiet, dead neutral and has a wide soundstage it was missing something for me. I have been running tube preamps with either tube or SS amps for almost twenty years. I remembered that I had an as new Anthem Pre-2L in the "audio storage closet" that I hadn't used in almost ten years. It is based on the circuit of the Sonic Frontiers Line 3 which sold for well over $3000 almost 15 years ago. It has switchable gain on the board at 8, 16 or 24 db. I pulled it out of the box, stuck in a quad of Amperex Bugle Boys, set the gain at 8db and took it for a spin. To my ears it is yes not as linear, but it brought the "meat" back to the music. 8db gain is right on the borderline as you get some tube hiss within a foot of the speakers that I don't get with less sensitive amps. To me it was worth the hiss I can't hear from more than a foot away to have the "soul" of the music back. Today I packed the Anthem up to send back to Chris Johnson at Parts Connexion, to change out that known problem Noble volume pot with an Alps. My only other choice with the JOB was to put the STP-SE back in. Again while it is dead neutral, to me the excitement is gone. If I were you I would look at the Primaluna, unless you can find a used STP-SE to try at a good used price like I did.
 
Jack said:
Schiit's passive is only $49 so what do you have to lose?
Click to expand...

Good point, I'll give it a shot.

Side note, does anyone have strong feelings about volume knobs that use stepped attenuator vs. a potentiometer?

The Sys uses a potentiometer, but some people seem to be really hyped on stepped attenuators.
 
Jack said:
I have the STP-SE, that I bought just for the JOB, and while I will agree with the reviewers that it is quiet, dead neutral and has a wide soundstage it was missing something for me. I have been running tube preamps with either tube or SS amps for almost twenty years. I remembered that I had an as new Anthem Pre-2L in the "audio storage closet" that I hadn't used in almost ten years. It is based on the circuit of the Sonic Frontiers Line 3 which sold for well over $3000 almost 15 years ago. It has switchable gain on the board at 8, 16 or 24 db. I pulled it out of the box, stuck in a quad of Amperex Bugle Boys, set the gain at 8db and took it for a spin. To my ears it is yes not as linear, but it brought the "meat" back to the music. 8db gain is right on the borderline as you get some tube hiss within a foot of the speakers that I don't get with less sensitive amps. To me it was worth the hiss I can't hear from more than a foot away to have the "soul" of the music back. Today I packed the Anthem up to send back to Chris Johnson at Parts Connexion, to change out that known problem Noble volume pot with an Alps. My only other choice with the JOB was to put the STP-SE back in. Again while it is dead neutral, to me the excitement is gone. If I were you I would look at the Primaluna, unless you can find a used STP-SE to try at a good used price like I did.
Click to expand...

I always found my STP-SE always sounded best with tube amps, vs SS to SS
 
Chris

I only tried mine with the Music Reference RM-10 for a short time, not really long enough to form an opinion yet. Do intend to re-visit that combo again though. The MR amp has an input sensitivity of .95 mv so should be a good enough match and might provide more midrange meat.
 
I've never been able to get a passive to work as well as an active. If you can run the passive at full volume, it sounds fine. But as you turn it down, it seems like bass impact and dynamic punch both go away.

I like detail as much as anyone else, and have yet to hear a passive that has more. Some come very close, but IME equipment matching is paramount as passives are often a lot more sensitive to cables as the impedances involved are higher.

Some passives are lower impedance -10K- to get around this problem, but some sources are not happy driving that kind of load at all. Some are- so setup and matching is everything when it comes to successful use of a passive control.
 
Passive preamps have one major advantage. Noise. There isn't any.
However they have several disadvantages. You can't use long cables, they are hard to mate with some equipment, should be used with high impedance amps - low impedance amps don't like them at all. Most of the ones I have seen have been limited to only a couple of inputs, but I'm sure there are ones that have a good selection.
Impedance matching is probably the biggest issue though.
I've built, and sold both active and passive preamps, and have used both personally. I go for active every time. Active preamps just do the job better.
 
Schitt Sys output impedance: 5k ohms maximum

Job 225 input impedance: 51k ohms
 
The input impedance (resistance really, its just a volume control after all) is 10K. Can your source drive 10K properly?
 
Dave Slagle's TVC may blow some of these myths out of the water

Try one for yourselves

Bruce
 
I am familiar with TVCs! None of what I have mentioned thus far is myth, and is not about TVCs. TVCs are a different kind of volume control, and not surprisingly, have their own set of issues, although generally speaking I think they can perform better than PVCs.

Dave did not believe me when we had a conversation about loading and how if the transformer is not loaded correctly, it will not express its turns ratio correctly either- instead will tend to express its inter-winding capacitance (Much to his credit, when he discovered that I was correct he conceded that immediately, which, IMO is a mark of integrity). And that is the chief issue with TVCs- depending on the unit, the load for the transformer varies with the setting. This results in distortion (ringing) at some settings and a lack of flat bandwidth (due to the inter-winding capacitance taking over as the chief coupling means). As a result, TVCs are quite variable, some excellent and some underwhelming depending on how well this is addressed.

In both the cases of PVCs and TVCs, I see them as really good examples of how badly designed some active line sections are if the passive or transformer unit comes out on top. So far I have yet to see either technology top the preamp in my system. But it is driving 30 feet of balanced interconnect cable and that might have something to do with it.
 
Atmasphere, you beat me to it. I've only ever seen two examples of a TVC. One very expensive, who's frequency response varied quite a bit depending on how it was loaded (both source and load). However I know of one TVC that is coupled to an active preamp stage that works quite well. The TVC was designed to run a specific load and had quite good charcteristics, but did exhibit a bit of well damped ringing. Again not for everybody, but may be worth a try.
Schitt Sys output impedance: 5k ohms maximum
Click to expand...
Interesting how a 10k pot can have a 5k maximum output impedance. Am I missing something here.
 
atmasphere said:
I am familiar with TVCs! None of what I have mentioned thus far is myth, and is not about TVCs. TVCs are a different kind of volume control, and not surprisingly, have their own set of issues, although generally speaking I think they can perform better than PVCs.

Dave did not believe me when we had a conversation about loading and how if the transformer is not loaded correctly, it will not express its turns ratio correctly either- instead will tend to express its inter-winding capacitance (Much to his credit, when he discovered that I was correct he conceded that immediately, which, IMO is a mark of integrity). And that is the chief issue with TVCs- depending on the unit, the load for the transformer varies with the setting. This results in distortion (ringing) at some settings and a lack of flat bandwidth (due to the inter-winding capacitance taking over as the chief coupling means). As a result, TVCs are quite variable, some excellent and some underwhelming depending on how well this is addressed.

In both the cases of PVCs and TVCs, I see them as really good examples of how badly designed some active line sections are if the passive or transformer unit comes out on top. So far I have yet to see either technology top the preamp in my system. But it is driving 30 feet of balanced interconnect cable and that might have something to do with it.
Click to expand...


Ralph, Pardon my inference re the Myth--poor choice of words-- I'd probably say minor anomalies that crop up with Passive V Active debates?-- Rest assured I know your products( first heard at my dear Friends Dave and Kumiko Magnan's house so many moons ago-ha!)

plus the excellent rooms you man at the shows my opinion has not changed. Your competent replies and honesty to

educate us "non engineer minded Philes!"is both enlightening and forthright--a rare trait I might add from some designers Long may you continue with Gusto!-- we're all ears!

Yes I know Dave too --quirky/eccentric but his heart is in the right place--if a little over the top for the mainstream crowd--ha!

Your comments noted and absorbed for future--thank you

Bruce
 
I use the W4S SE preamp and I think it works great with the Job 225, which I also own. In fact, Srjaen Ebaen from 6 Moons also stated (in an email to me) that he thought those two were a very fine pairing. Since the Job has such high gain and sensitivity, you need to be careful about the gain of your preamp which is why the Job Pre has only 3 db of gain. The transparency and neutrality of the W4S is a great match for the transparency and neutrality of the Job... if you like favor those characteristics. If the recording has "soul", then you should be able to hear it, providing your source and speakers are up to to the task. Personally, I am a bit leary of equipement that injects "excitement" into every recording. even if it does not exist, since it would seem to add something (coloration?) that was not there to begin with. Just like my whiskey, give it to me straight please! ; )
 
I've had the STP-SE almost since it came out. One of the reasons I like it is that I DIY amps, and this pre will hang well with both low and high gain amps. It easily starts passive, and if needed, slips into active if needed.

i use Zu Essence speakers (Druid Vs on order), so a 20 watt DIY Aleph J is medium gain for me. I plan some low watt tube amp builds, and my system should adapt well.

i also love the connectivity with this Pre, I have balanced out to both my speaker amp and headphone amp. Balanced in from phono pre and DAC.
 
You must log in or register to reply here.
Back
Top