Which amp should I rebuild and use? Eico ST70, Scott 222D, Big Knight, or Fisher 800C

loomis

bland
So...

I have to make a decision to rebuild one integrated tube amp and sell off the others. Which one would be the one that you would keep and use daily, and why?

1) One pristine Eico ST-70.

Pros: This was built by an engineer. Would be very easy to work on because it's wired so cleanly. Great output transformers on these.

Cons: Are these considered to be stable designs? I thought I read somewhere that there were some bias issues or something? Needs loudness mod etc done. Moreover, 7591's are expensive. Are there reliable usable and cheap Russian or Chinese 7591's now?


2) One Fisher 800c.

Pros: Restored, it's the most valuable of the bunch. It's also the most attactive. I seem to recall it has the best phono stage of the bunch but I could be wrong.

Cons: Same 7591 concerns. Also, I don't listen to FM much. Out of my league to try to align any FM stuff should it be out of whack. Missing cover.


3) Scott 222 something. (I'll have to check but I think this one is a 222D and has 7189's in it)

Pros: Pretty well-loved and popular amplifier. Attactive. Seemigly easy to work on. I think it has a headphone jack. 7189's mean less power and less heat, which is good.

Cons: missing cover. Not as "high-end" and the other 3 amps.


4) The Knight KA-95.

Pros: 4x EL34 amp. UL output transformers I believe. Mullard 5-20 design. Probably the best amp I own. Dual 5AR4 Mullard rectifiers too.

Cons: Early circuit board may be hard to work on. Might be a little overkill for me. Decent amount of power use and heat creating. Heavy. Missing a knob I'll never find a replacement for.


Thoughts? Thanks
 

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Hahaha....less heat for the 7189 Scott? I guess you haven't powered it up yet. I bet you could heat a small cabin with that,

If the choice were mine I would pick for cosmetic condition among the eico scott or fisher
 
7591's aren't a big deal now. The Russian ones work well. EH are solid, but fat bottles. Tung-Sol makes one that is the right size, though there aren't a huge number of reports on it yet since its fairly new. Someone on here has a set and says they sound good, though I can't recall who it is.


Of them, the Eico will probably be the easiest one to make run. It was a kit to begin with, and yours looks to have been well built. Those two things make it worlds easier to work on.

If the Fisher is restored, I wouldn't have qualms about it. I get the thing about not using the tuner though. I have a Sherwood receiver that I use about half of it's tube compliment on. The rest are tuner tubes, just sitting there cooking.

That Knight looks like a pretty cool amp, but i bet its a royal SOB to work on. A quad of EL34's jammed in that close, plus early circuit board construction? Hoo baby. Thats the kind of thing I'd fool with for the challenge of it, but I'd probably cuss at it the whole time. Also I seem to recall Knight info is few and far between, so you might be screwed on documentation.
 
I vote for the the one that matches your ability and experience. The easiest likely is the the EICO as it was designed for a novice to build. The most complex being the Fisher as it is a receiver and maybe the hardest would need the Knight due to those early pcb that tend to become contaminated and the traces are fragile to heat.

As for sound, I do not know the Knight so not not comment. I will say the EICO has some nice enough iron and when we built them using aftermarket parts vs the kit parts they responded very positively and the cost was worth the resulting improvements. There is some discussions about modding them but, I would suggest first doing a stock rebuild. We never experienced any of the issues the mods are suppose to address.
 
I'm kinda with you guys as well I think, as I'm also leaning towards rebuilding the Eico since it's seemingly easiest to work on, and was already cleanly built to begin with.
 
I guess it will depend somewhat on what you want out of this. Fun; different audio experience, increased worth, etc.

- You say the Fisher is restored and you do not use FM much, so I would leave that as a usable integrated and eye-candy for now while you make headway on one of he others.

- The EICO does have a lot of space that allows easy working, plus there are well documented updates & improvements on the web. The amp cover stands relatively tall so it will take all new production 7591 tubes. When all is done though, it is a good sounding, relatively powerful heavy amp - but not much to look at and you already have a 7591 push-pull unit you can play in the Fisher.

- The Scott will give you less power but the detail and sweetness of the 7189 (EL84 class) tube will be something different to experience with your music vs. the 7591 you already have in the Fisher.

- The Knight offers the option of the EL34 tube sound. It does look to have UL taps and nothing much weird looking in the schematic except a PEC in each channel tone circuit, that should be easy to replace with discrete components. I had a similar sized KN-775 (but different circuit). The working space will be somewhat cramped but might be well worth the effort with the different tube selection options available for EL34. The knob should not be a biggie as they look to be similar to some of the ones on the Knight KP-70 tape preamp, which can often be picked up inexpensively (with the added bonus of having 7-8 12AX7, 12AU7 type signal tubes, often Mullard or other Euro types).

KP-70:
normal_Knight_Preamp_1.jpg
 
DSC_0198 by mhardy6647, on Flickr

The EICO ST70 is a very good (if kind of homely) amplifier with very good output transformers. There are, as the OP implies, some well-known and readily rectified (no pun intended) design "issues" -- it's big and simple inside; easy to work on (EDIT: although, in the interest of disclosure, I didn't rehab mine; Gary Kaufman did!).

I think the Scott 222 family are my favorite Scott amplifiers. I have a 222C and think it is a dandy amp -- if the power output is adequate for the OP's needs, and he really only wants to choose one the Scott is my sentimental favorite.

All in all either the Scott or the EICO'd be my top choice.

The 800C is a wonderful receiver, and very straightforward (the amp part, at least) to rehab -- but it wouldn't be my first choice -- just because it is a receiver. If the OP wants only an amp, do an amp (IMO)!

I'd love to have one of the Knights, but I have zero experience with this amplifier -- if it is built on a PCB, which I think it is, I'd consider that a negative (after decades of heat/cool cycles, I wonder what kind of shape the board and its traces are in, plus I prefer point-to-point wiring philosophically).
 
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I have never heard the term "chockablock" before!

The Eico. Probably overall everyone's first choice, but man is it ugly. The Scott is so much better looking in my opinion.

Well I've got to start ordering parts soon... better make a decision soon lol.
 
Hahaha....less heat for the 7189 Scott? I guess you haven't powered it up yet. I bet you could heat a small cabin with that,

If the choice were mine I would pick for cosmetic condition among the eico scott or fisher



Is that the case for ALL the old Scotts? Just wondering, since I would like to one day try one with my current mains.

One thing to consider is whether or not you're a headphone-listener. The Fisher *00C series models have an excellent-sounding headphone-output. I splurged on a pair of Grado RS2's because of that thing (And I had no problems with the sensitive Grados). I love my 800C. My only major complaint is that damn volume pot/on·off switch. When it gets old worn-out, the channel-balance gets squirrely as you turn the volume up/down. If you have already dealt with this or have not experienced this problem, then by all means, go with the 800C.

The tube Fishers also happen to be a great match for the old Wharfedale speakers. I use my 800C to power my oil-capped alnico W90's. The 800C got a recent compliment of Westinghouse 7591's and RCA 12ax7's, plus I gave the wood case a little TLC treatment, and that combo knocks really gets it done for me and several other AK'ers.
 
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That Eico looks to have been partly rebuilt, or using better components than usual. And as others have said to have been well-built. If the power reservoir and filter caps are good/replaced, there's not much to change. But the outputs aren't UL. My experience of my ST40 is that it's nice, but not amazing.

I also personally prefer the sound of the EL84 to 7591 and EL34 tubes, so I would incline towards the Scott (also not UL, though).

I'd hang onto the Knight, if necessary for a rebuild on a easier chassis. Here's the schematic: http://oldtech.net/Amps.html
 
I have never heard the term "chockablock" before!

The Eico. Probably overall everyone's first choice, but man is it ugly. The Scott is so much better looking in my opinion.

Well I've got to start ordering parts soon... better make a decision soon lol.

oh, it's butt-ugly... but it is a bit more powerful than the Scott. The Scott 222 family is awfully nice, though...
 
The Eico is not a winner in the looks department, but when I close my eyes to listen to music, I really don't care what the box it comes out of looks like. I've got Bogen gear too, and its not exactly winning any beauty contests. It sounds great though.
 
Follow Steve Lafferty's and Dave Gillespie's ideas on mods to the Eico ST70, and it'll absolutely blow away the others, AFAICT. They show how to get over DOUBLE the factory power output, and better low bass output (less distortion) at those power levels, if you're willing to go far enough with it...

http://www.tronola.com/html/st-70_hotrod.html

Regards,
Gordon.
 
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