I need some techy help in order a preamp--resistor values.

Usually the problem in cases like this is being scared to solder. But this is a kit. You're building it. So call em up, tell em exactly what you're doing. Not like they don't get these questions all the time. Then whatever they say, which you want to know even though it really does not change anything, because what you do is order the upgrade and try it both ways. Only way to know. Seems a waste to go to all the trouble of building and then not learn anything because you didn't swap and compare. Might as well have bought off the rack.

OK I'm not a fan of passive controls- so often I've seen them reduce bass impact and dynamic quality while otherwise seeming to be 'neutral'.
But having been in the industry for over 4 decades I can tell you that expensive resistors are expensive :)  Not only that but the lower the overall value of the control, the less effect they have.

If I were you I would see about auditioning first. If you are really stuck on a passive control, the best we have heard (and it really pains me to say this) is the Lightspeed. Its fairly cheap too as these things go.

But if it were me I'd do an active line stage before I used a passive. One problem not mentioned so much (particularly by manufacturers of passive controls) is that they are more susceptible to the variability of the sound of the interconnect cables themselves. Put another way, the lower the output impedance of whatever is driving the cable, the less you will hear the cable itself. Passives hive higher output impedances and thus often force you to audition lots of cables to find one that sounds right in your system- and even then, the only reason that cable is working is that you didn't find or hear about the one that works better than that.

JB, the Khozmo is a very nice looking piece of kit. I can't help you with advice regarding resistors, my concern is whether your amp would have enough gain to use with a passive line stage. You didn't mention that subject in the specs you listed.

I don't know how much this piece will cost you, but just yesterday I received from Modwright an SWL 9.0 Linestage, and it just put me over the top in the chase for the sound quality I've been trying to attain for all these years. As my Virtual System is listed, I really am "Done For Now".

By the way the unit I got was a trade in, which has a new upgraded power supply, tube board, and new MWI capacitors, all for $1450, shipping and tax included. The much, much better preamp you are seeking may not cost as much as you might think.

Good luck with your search for a preamp, regards,
Dan 

@jbhiller,

I would recommend you to check out Aric Audio. He can custom build anything to your exact needs. 

https://www.aricaudio.com/tube_gear.php

I have recently completed a project involving a custom 300B amp. Even though I only have about 100 hours on them, I can say without any hesitation they are the best tube or SS amps I ever owned. One would probably pay 3 times elsewhere to achieve this kind of performance and attention to detail. 

The Elekit TU 8600 amplifier already comes with a volume pot built-in, what you need is change it to a higher quality same value pot, use a line level sources selector as preamp.

https://www.goldpt.com/sw4.html

Wow! Fast responses--thank you. 

I can't find any specs on the Elekit's gain.  I'll email them. 

The kit is built and been in use for nearly 2 years. There's no fear of soldering here.  I was just looking for a reasonable suggestion/starting place. 

The reason I want a preamp is that I have 2 line level sources (Elekit has one line level input) and I can't live without a remote any more!  There--I admitted it. :)  There's not enough room for me to add in a motorized attenuator and I can't seem to figure out how to fit another set of line level inputs in back.  

This unit sounds wonderful.  So long as I don't push it too hard, it bests my Primaluna Dialogue Premium.  I just wish it had two inputs and a remote!

Aric is a great thought.  I've been curious about his work in the past. 

Atmasphere your suggestion intrigues me too.  As always, much appreciated. 

Jb, just FYI, the Modwright has a built-in remote volume control that is smooth and quiet, and raises (or lowers!) the volume in small enough increments that won't aggravate you with too large a jump in volume.

Dan

Thank you Dan!

I can’t find any specs on the Elekit’s gain. I’ll email them.

Power amp gains are often not specified, but they can be calculated from the specified maximum power capability and sensitivity numbers (assuming those numbers are reasonably accurate, of course).

Also, in the case of a tube amp having multiple output taps the gains of the different taps will not be the same.

In this case there are two taps, one designated for 4 to 6.3 ohm loads, and one designated for 8 to 16 ohm loads. The specs you provided don’t make clear where within each of those impedance ranges the 9.2 watt maximum output capability occurs. But given that the specs shown here indicate 9.2 watts into 8 ohms let’s assume it occurs at 8 ohms if the higher impedance tap is selected, and at 4 ohms if the lower impedance tap is selected.

Also, in this case it appears that sensitivity (i.e., the input voltage required to drive the amp to its rated maximum output) is being referred to as the "rated input," spec’d at 320 mv.

For the higher impedance tap:

9.2 watts into 8 ohms corresponds to about 8.58 volts.

8.58 volts/320 mv = a voltage gain of 26.8 times = 28.6 db.

For the lower impedance tap the gain would be around 3 db less than that, or about 25.6 db.

As I indicated those numbers could be a little different depending on the specific load impedance upon which the 9.2 watt figure is based. But given those results it’s safe to assume that the gain is fairly typical for a power amp (that in the majority of applications would be used with an active preamp), but is around 10 or 12 db less than is typical for an integrated amp. I would be concerned about that mainly if you are using a vinyl source.

Good luck. Regards,
-- Al

jbhiller

The Khozmo is a great passive, to mate it properly you’ll need the source that ’s feeding it’s input to be at least 500ohms or less in output impedance.
Then order a Khozmo 10kohm series/shunt, this will then also be a great match into your 50kohm input impedance Elekit amp which is as you stated 0.32v input sensitivity

BTW Elekit made good stuff, I've got one of their preamps here, and was impressed with quality of the kit and the sound. Still nowhere near as dynamic or transparent as a properly mated passive.
 
Cheers George

I am using a Luminous Audio Walker Mod Axiom II, and I feel it is invisible...meaning, I do not hear it. It works well with every source I have, as well as all of my amplifiers in my collection. If additional gain is not needed, passive is the way to go. Not to mention, Tim Stinson, is a man with excellent communications, integrity, knowledge, and wants nothing, but happy listeners.

I have owned several khozmo attenuators the best option is with the Vishay Naked resistors shunt remote for only 2 resistors are in the signal path on the output and the Vishay Naked are the lowest distortion and cleanest resistorsfor the application . You just buy it 
complete built it comes with the digital readout board and remote.
for around $400.

I’d check out the same kit avail from diy audio and parts connexion too. I believe they’ve already upgraded the resistors and the Lundahl transformers, which if you’re going to go as far as to build this kit, ya might as well do it right. 🎶🔊🙂

1. First, it's a level control, not a pre-amp.
2. It can also be an input selector.
3. I've used passives and a slew of actives for 40+ years. Each has a sound. Each interacts with cables and associated electronics. There is no free lunch.

SMD resistors have lower inductance and thus have a different sound than leaded parts. However, they require a PCB and a different switch and thus have a different sound.

Each passive topology has its proponents. Each has a different sonic characteristic dependent on the associated components and cables.

Most passives do not compensate for varied amplifier input impedance. Step levels will vary considerably making audition difficult unless one has the tools and skill necessary to match auditioning levels.

1. I've used passives and a slew of actives for 40+ years. Each has a sound. Each interacts with cables and associated electronics. There is no free lunch.

SMD resistors have lower inductance and thus have a different sound than leaded parts. However, they require a PCB and a different switch and thus have a different sound.

Each passive topology has its proponents. Each has a different sonic characteristic dependent on the associated components and cables.

^^ +1!