Remote-controlled tube preamp

[ohshitgorillas]

My main setup currently consists of a recently serviced Hafler DH500 and a pair of modded Magnepan MG12--both Craigslist scores--with a Marantz SR7500 as a preamp. Long story short, I think one thing that would take this system from great to incredible is the addition of tube sound in the form of a preamp--not necessarily the warm, gooey sort of tube sound but rather the more linear, lively tube sound with enhanced soundstage/dynamics/extension.

I'd like to keep this project at below $500 total. I'm also not terribly proficient at DIY yet, I've only ever built a Bottlehead Crack and am halfway through buliding an AMB sigma25 PSU (just need to add things to the case), so something in kit form is strongly preferred. I would also like to keep this project below $500, if possible.

So what's the big deal? I've got the Bottlehead Smash and the Transcendent Sound Grounded Grid kits to choose from! Why involve diyaudio readers?

I require remote control. Seriously, I have a rather large living room and I am lazy as hell.

I don't suppose there are any less-than-$500 tube preamp kits with remote control in the world, so I see this as my two options:

1. Build an AMB LCDuino/delta1/delta2 and splice in a tube line amplifier in place of their solid state line amp. I think building all three AMB kits would come out to around $200, which would leave plenty of room for a good preamp.

The issue here: I see plenty of tube line amp kits and PCBs on eBay--even Grounded Grid knock offs from Hong Kong, admittedly tempting given my graduate student salary--but it's difficult to assess their ultimate quality. Are there any highly regarded tube line amp kits out there that would be compatible with the AMB gear? I hear the Aikido is pretty good.

2. Build a Bottlehead Smash and implement some kind of high-quality remote control system for less than $100. The key word here is high-quality... which is something that I, as a newbie to this sort of thing, have a hard time assessing. Any recommendations regarding a good IR-controlled stepped attenuator system OR just an IR-controlled motor that would adjust one of the Smash's pots.

For reference, the input impedance of the Hafler DH500 is 43kohm.

 

[Koifarm]

I use often these type of volume controls.

MV04 Motorized Remote Volume Control with Input Selector Kit | eBay

And ad a tubebuffer of your choice, i like the 6n16 or 6n6 in srpp/cathode follower setup.

Ronny

 

[gofar99]

I have used the V02 version as well. All digital with relay switching volume. (no analog pots). I had problems with some of the older V04 units as they were cranky from time to time and when interfaced with high gain circuits introduced noise through the grounding system they used. I stopped using them about three years ago so they may have changed since then. YMMV

 

[Koifarm]

Hello Bruce,

i used several of these kits with no problems. Because of the small housing i used, i always desolder the motorpot and solder the cables straight on the potmeter. Maybe that is why i do not had noise problems.

Ronny

 

[gofar99]

Thanks for the info...I'll give it a try.

 

[Koifarm]

Some inspiration.

http://www.ebay.nl/itm/Assembled-Re...242?pt=LH_DefaultDomain_3&hash=item33a189a7ba

 

[mrgreenjeans]

I'm build speakers but I'm new to everything else. I like what I see so far but I'd want to make sure I didn't sacrifice SQ too much. I want to build a preamp too. Only tube pre that I've used is the Audio Research LS16? I would be amazing to be able to build something that sounded as good as that. Now if volume control can be remote controlled, why not a remote input selector? Or is that does that introduce too much compromise? I'm also into making everything look great. With all the amp housings with heat sinks on ebay, I think that's now more possible than ever.

 

[Koifarm]

The kit above has also 4 channel remote input selector and remote on/off.

 

[Eric]

Koifarm: That is the same remote unit that I am using in my BA-3 preamp. My approach is a bit of a Frankenstein's Monster implementation, but the remote unit works well for input switching and volume control. I have a different implementation where the pot is used to control voltage to an LDR volume control and the relays are used to drive another set of relays on a hacked up DCB1 board, thus the MV-04 is completely out of the signal path in my pre. It increases the implementation overhead, but keeps the signal path short and sweet.

 

[Koifarm]

Hi Eric, i do not see why replace the pot for other electronics. we have done listening test with the volume contol and with just 4 resistors and a wire. Nobody heared any difference.

 

[Eric]

It was a choice driven by an existing project-in-progress that changed part way through and I wanted to preserve the time/money/effort already invested. It was not necessarily an active choice about sound quality... Call it an end result of an overly extended project life cycle.

 

[JonesySA]

Some inspiration.

15W Regulated PSU DC Linear power supply LPS 5V 6V 7V 9V 12V 15V 18V 24V | eBay

Great build. What are your thoughts on the source/volume control. I noticed you used the following:
Assembled Remote ALPS motor Volume control preamplifier board + Standby board | eBay

Was it better than the MV04?
Many thanks

 

[gofar99]

Hi Looking at the two types it seems the one is a variation of the other. Both use the same setup, with the addition of the "standby" board in the one. I suppose it lets the rest of the circuit sleep. I have never needed that sort of feature so I can't tell how useful it is. Perhaps it saves power. But since the consumption is quite low, it may be a moot point.