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Help with Pre-amp purchase

DaWoofer

DaWoofer

Super Member
Is it best to run a single stereo pre-amp with a balance control for dual-mono tube amps with a single volume control? Or run two mono pre-amps? I'm looking for a tubed pre-amp for my Heathkit W4-AM's. I have one Heathkit mono pre-amp already but don't want to purchase another if this is not the route to go. I would think that a single volume and a balance control would be the best way to go in case the amps are not quite perfect in their outputs. Any insight would be greatly appreciated.
 
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Either will work fine but I personally find a pair of mono preamps is a real pain constantly having to adjust both to match the levels on both channels. Most folks would prefer a setereo preamp with either a balance control or levels controls per channel.

Craig
 
I just went to your website before I posted this thread but did not see any listed there. I'm leaning towards PrimaLuna although its just a shot in the dark for me.
 
Yea I don't have a preamp offering yet. I just have so little spare time to develop one. It's in the plans but stopping to design and build it means no income while doing so. That is a hard pill to swallow when you at least 4 months back logged with work.

I may have a nice preamp of mine for sale in the very near future. I already offered it to someone and I'm waiting to hear back now.

I can't comment on the sound PrimaLuna I've never heard the preamp they make just a few of the amps. I think the amps could be much better but the build quality is very good. Most of the short comings of the amps are the output transformers which would not be an issue with the preamps.

Craig
 
This is just my opinion, and would be what I'd do, so take this advice with a grain of salt.

If your have a pair of mono vintage tube amps, you have the starter for a very nice system. If you haven't rebuilt then yet, you should seriously consider doing so for the life of the amp, and as an added benefit you WILL have an improvement in sonics. If you have two identicaly rebuilt monos, and you're using basically the same tubes in both of them, I would expect that their output should be basically the same. This would probably reduce your reliance on a balance pot, which is just another thing in the signal path that has an opportunity to suck.

I am not a big fan of vintage preamps, by and large. Nor am I a fan of tone controls, effects buttons, or any other frequency "helping" circuits. Unlike vintage amps, who's strength lay mainly in their very nice output transformers, a vintage preamp is all circuit dependent. I believe modern preamps are the way to go. You could start with the simplest/cheapest route and do just a passive volume control, you could build one of the many excellent kit offerings out there by the likes of Bottlehead, Hagerman, and others, or you could do more advanced DIY and start from scratch. The parts in the preamp that I would not scrimp on for sure would be the attenuator, and the source select mechanism. You can do one of many passive attenuation options with resistors, or even use something like an autoformer. This will result in a "stepped" control, which might seem like a compromise, but will actually be able to keep the channels more closely matched than say two infinately variable pots with wipers, which can be as much as 3dB off in some cases! Granted, there are some nice pots out there, too, but I'm talking cheap! If you do get a vintage preamp, remember that it'll have to be rebuilt for the same reasons a vintage amp would have to be.

Again, these are all mutterings of a probably deranged person! Sounds like a nice starting place you're in, no matter what route you take! Good luck, and let us know how it goes! :yes:
 
DaWoofer said:
Which preamp are you speaking of for sale?
Click to expand...

Its a one off custom job that I ordered as a semi kit from Mapltree Audio in Canada. It is a version of his Ultra 4A SE in fact my mods and suggestions are where the SE version came from. I about drove Lloyd the owner nuts with special power supply and other requests. I then went hard at it tweaking it to my liking. I sold it to Dave McDonald (Dmax) after I went to a Juicy Music BBX. He then (two years later) purchased a BBX from me and I took the mapletree back in on trade... I have vintage Scott preamp that I use in my second system that I went nuts modifying so I have no use for this one. This preamp uses 12SN7 for the line stage with cathode follower output (I installed the much sought after Mil Spec black plate 12SX7's for these). It has a phono section that uses 12SC7's. The preamp is stuffed full of Auricaps and other high end components like Black Gates for cathode bypassing and so on. The power supply is in a separate box (this is where I really went nuts) is tube rectified (6X5GT) choke loaded and has like 4 times the filtering of the stock offering by Mapletree.

Here is a picture
 

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I see an upgraded Bottlehead on that auction site for 250.00. I thought that was a pretty good deal. Both of the W-4's have been in systems recently and supposedly work fine. I am going to put a full compliment of matching tubes in before I fire them up. I'm strongly debating on the homemade variac for this purpose.
 
Craig- I refreshed and their it is. Strange. Thats a sweet looking set-up. Are those seperate volume controls? What are the other two for, inputs?
 
DaWoofer said:
Is it best to run a single stereo pre-amp with a balance control for dual-mono tube amps with a single volume control? Or run two mono pre-amps? I'm looking for a tubed pre-amp for my Heathkit W4-AM's. I have one Heathkit mono pre-amp already but don't want to purchase another if this is not the route to go. I would think that a single volume and a balance control would be the best way to go in case the amps are not quite perfect in their outputs. Any insight would be greatly appreciated.
Click to expand...
I think either way you go is fine. Some people would be very envious of what is effectively a "dual monoblock" preamp. I have separate volume controls on my Manley Stingray, and I don't find it inconvenient at all.

But I'd also understand not wanting that hassle, and wanting the convenience of a single volume control and a balance control.

So, either way you go is fine.
 
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