Let's talk preamp kits

airtime

Super Member
I mainly use a Conrad Johnson Classic 2SE that I love. So this post isn't about "going up a level" but more like something else to try and play with.

I was thinking a cheap preamp kit to add more tube like sound. Ok, let's not get into what the tube sound is. The CJ is EXTREMELY transparent and adds nor takes away anything - it does what a preamp should - preamp and burffer.

What kits would you recommend in the $500 range.

A kit using mainly the 12axt, no tone controls, simple, no 12AU7 or 6922, something that puts more "warmth" back into the equation.

I would use this mainly for my newer gear like a NAD C275BEE. Which gives me listening fatigue after 20 minutes.
 
Last edited:
Tubes4hifi, I have the SP9 kit. If you do your own chassis you can get the board kit for a lot cheaper.
Responds well to tube rolling and was a major upgrade to my system. Playing familiar music I hear details that I never knew where there.
I have a Aikido Octal tube kit that I'm collecting parts for. I found a great deal on the SP9 and this got shelved. Maybe this winter I'll finish it and compare.
Both the SP9 and the Aikido Octal have been compared to preamp's that cost in the 3 to 5K range. Great designs without the designer signature. Although both designers of the mentioned preamp's rate very highly in my book.

BillWojo
 
Last edited:
Bottlehead stuff also might fit the bill, though they run 12au7 tubes. I have one sitting here that I fixed. Sounds nice, not super tubey though if thats what you're after.
 
Hmm. Not a full kit, but there's the Aikido octal preamp board.
Ive been using an Aikido preamp using RCA 12au7 clear tops and like it. I should try the octal version at some point. There is a clarity to this design that I really like.
 
A friend built an octal Aikido. It's very good sounding. Not sure I'd call it tubey in the traditional sense.
 
Yes, I would recommend changing the input resistors on any solid state amps to better match the high impedance. Or a tube buffer. But not to many people would use a solid state amp with a PAS. The company Sound Values that took over the Dynaco name & inventory had sold preamps like you want. Retrovert has one. They got very good reviews and show up used, would also be easy to swap parts, I think it has a cathode follower for low impedance. Maybe PAS boards with a tube buffer board for your own custom kit. In Audio Amature there was a great remake of the PAS circuit with a buffer and B+ regulator. Vorhis mod could be hand wired in to your custom chassis. All depends on how time and effort is available. This stuff can take over your life.
 
I'm leaning towards a Bottlehead or a full PAS kit. Again, the purpose of this is to tinker. I'm not looking for the ultimate preamp.

Bottlehead's middle name is tinker and the PAS is the most worked on preamp in history. But don't worry I'm not buying a vintage PAS. Only the kits and parts and build my own chassis. So around the holidays I'll decide between the two.
 
I'm leaning towards a Bottlehead or a full PAS kit. Again, the purpose of this is to tinker. I'm not looking for the ultimate preamp.

Bottlehead's middle name is tinker and the PAS is the most worked on preamp in history. But don't worry I'm not buying a vintage PAS. Only the kits and parts and build my own chassis. So around the holidays I'll decide between the two.

Bottlehead seems a lot less about tinkering than it used to. Their products, which I still buy and use, are certainly subject to parts upgrades and and maybe putting a choke in the power supply and that sort of thing so there is some level of tinkering. But their lines are much more developed than they used to be when people were installing filters, regulated power supplies, dual power supplies, etc... etc... A lot of the best stuff is already incorporated. I would still recommend them to anyone but I just don't get the hardcore tinkering vibe from the Foreplay I days anymore.
 
Bottlehead seems a lot less about tinkering than it used to. But their lines are much more developed than they used to be. A lot of the best stuff is already incorporated. I just don't get the hardcore tinkering vibe from the Foreplay I days anymore.
I had a Foreplay WAY back in the day. I nick named it "the humming bastard". Never got that thing to stop humming.
 
I had a Foreplay WAY back in the day. I nick named it "the humming bastard". Never got that thing to stop humming.

Yea, I remember some posts along those lines... I had a FPII that buzzed like a hive but we managed to fix the problem, I think with a reverse recovery spike filter or some odd name like that (speaking of tinkering). My FPIII was trouble free and my Bee Pree is an astounding preamp. I love it and honestly never even think about upgrading it.
 
I have a Foreplay II sitting here that I did some work on. It had a nasty hum that I couldn't work out. Finally the C4S boards came out, and it started working right. Not sure what the problem was, but it did not seem happy with those installed. Works fine with two resistors though.

One thing about the way they did the heater to ground reference is sort of problematic though. Its run off one end of the heater string instead of being balanced. I changed that with a couple of 100 ohm resistors to make a virtual center tap. I did that at the same time as the C4S boards came out so I don't know if it would have hummed without it. It did hum with that setup and the C4S, but it was less than the stock setup.

I also just have general concerns about the construction of those things. The whole wood box not being shielded thing is a big one, but the fact that I can see noise on the scope if I get near the tubes is another. They really should have used shields on the tubes. A cap from circuit negative to the grounded metal plate wouldn't have been a bad idea either. I may have to experiment with that before it goes back home.
 
I have my original FP II with the C4S boards sitting on a shelf, one channel out. Maybe I should try pulling the C4S boards and do the cap to ground thing (what value?) & add some tube shields , then I could A/B the two units. I have the standard 100K Alps pots in the one I use now, I have considered going to a stepped attenuator. I had the sweetest whispers in the original, but I didn't like the 11 steps and clunky action. I guess if I end up with two working units I could put one on BT.
 
Ive been using an Aikido preamp using RCA 12au7 clear tops and like it. I should try the octal version at some point. There is a clarity to this design that I really like.

I'm thinking an Aikido build will be in my future. Sounds interesting.
 
Back
Top Bottom