Preamp ideas for a pair of Fisher 100 monoblocks

[nickdinatale]

After dabbling with my pair of 100 monoblock projects for months, I think I'm just about done and ready to put them to use, but alas, I don't have a proper preamp. Originally I had intended to use my Fisher 500c as a preamp, but very quickly realized the jacks on the chassis that I had taken for granted as pre-in/out were reverb in/out. I also have a Fisher Ambassador V console, but the preamp in the receiver section is only set up for ceramic carts it seems.

So I guess I'm looking for suggestions for preamp pairings that may go well with these. I really don't have a ton of money to spend on one (unless I sell/trade one of the aforementioned units), but I'm open to any good ideas, or anyone with input that has practical experience with Fisher monoblocks. Looking to hopefully stay vintage and tube powered, but I was also considering building some sort of clone.

 

[primosounds]

I mostly use a Cary AE3 which is a single 6sn7 per channel. It is a very minimalist type of preamp with no TC or Phono stage and has 3 selectable inputs all line level.

 

[larryderouin]

Nick. The preamp on the Ambassador is set up for a MM cart. It's the same design that Fisher used in their receivers and above the BOTL consoles. Pull your headshell off the Type "A" and you'll most likely find a Pickering V-15 or Type U38 cart, which are both MM.

 

[dcgillespie]

Another thought that's in line with your original thought: Convert the Reverb In/Out jacks to Pre Out/Power Amp In jacks as was part of my original Fisher 400 project. As presented for that receiver, the modification would work equally well for the 500C and 800C as well. The schematic is given in that thread to perform the modification, and the end result is a true low impedance preamp output that would drive your Fisher 100s nicely. It even still leaves the internal power amps free for other duty or bi-amping if that that's your game. And, when you want to use your 500C as a stand alone piece, just reinsert the jumpers and you're back to normal operation of the receiver, with the added benefit that the setting of the volume control no longer affects the HF response of the power amplifier section, as it did in the original design. Compared to buying a preamp for your 100s, this approach would cost you very little $$.

Dave

 

[gadget73]

I'd personally be tempted to knock together a power supply and use the preamp from the Ambassador just so I'm not putting hours on the 500C's output tubes.