has anyone DIYed a Citation 2?

[jarthel]

1. I found a schematic from drtube.com BUT it doesn't provide voltage readings from various points in the schematic which is always nice when debugging a problem.

2. is a Citation 2 DIY useless if using something other than a Freed transformer?

3. any other advise/ideas?

thank you

[Sherman]

I purchased a Citation II assembly manual and schematic online for a few bucks. In the end, after some discussion here I decided not to build it. It was a consensus among more experienced people than I that a huge part of the Citation II "magic" is due to the output transformers.

Having said that, it appears that the James transformer, 4.5K (vs. 4.3 for the Citation, no real difference) 200mA 70 watt OPT seems to have the bandwidth required to recreate a Citation II. I can't say for sure because I haven't built one nor have I laid hands on the OPT, though I'm considering it for another proect).

If you decide to go ahead, please report back here as you build, I'd be interested in your results!

[Jim McShane]

Originally posted by Sherman
I purchased a Citation II assembly manual and schematic online for a few bucks. In the end, after some discussion here I decided not to build it. It was a consensus among more experienced people than I that a huge part of the Citation II "magic" is due to the output transformers.

Having said that, it appears that the James transformer, 4.5K (vs. 4.3 for the Citation, no real difference) 200mA 70 watt OPT seems to have the bandwidth required to recreate a Citation II. I can't say for sure because I haven't built one nor have I laid hands on the OPT, though I'm considering it for another proect).

If you decide to go ahead, please report back here as you build, I'd be interested in your results!

Let me point out a couple things - first off the Cit II OPTs are not 4.3K. They are about 3.2K. They have a resonant frequency as high as 450K, and have extremely wide frequency response - 2 to 150KHz at a couple watts. They are also very conservatively rated on power. 200 ma is not enought current to match the Cit II trafo - I've measured them passing over 325 ma. It's said they can handle a second pair of power tubes per channel, although I've never tried it.

Yes, the OPTs are very good - but that amp is not a one-trick pony. The power trafo will deliver 1.7 AMPS at 170 volts of B+. The 1 Henry choke has a DC resistance of 11 ohms. The amp is flat to the megahertz region (excluding the OPTs). Pardon the shameless plug, but with that trafo and my kits people are finding it's an amazingly good power supply.

The multiple loop NFB is also a major contributor to the fantastic performance.

So if you want to build a Cit II "clone" I'd say it'll be very good with a proper set of high quality wide bandwidth OPTs (even if they aren't as good as the originals). But what else makes it very good are some superb quality parts (read - expensive ) you need to use, and you have to be willing to build a much different circuit than most people would even consider. There isn't a triode in it anywhere, and it uses 32 db of NFB. Consider that in 45 years no one has ever built anything like it.

Also, my site has schematics and voltage charts for the II. I'd happily support an effort to buiild a clone (within my time limitations) as long as the OPTs didn't get pillaged from a working or rebuildable Citation amp.

[Bandersnatch]

Hey-Hey!!!,
I was hunting an output like the Cit.II's for a project. The choice came down to the Freed units from the HK, or possibly the 16431 Peerless as used in the Heathkit W6. I suspect they're pretty damn close in terms of specs. I'd rather the Freed because it doesn't have the extra long secondary of the Peerless needed for the 70V line service.

Anyhoooo...I have had Heyboer TX unwind and clone some outputs for me( the Peerless S-265-Q and S-271-S ) and my Cit.II will have one of its outputs unwound in similar fashion at some point if I can't find a single before that time...

If you're going to clone the circuit, it is a bit complex. As evidenced by the low damping factor SE amps, a lot of FB isn't needed given a linear circuit and resistive/constant impedance speaker load. Out spec-ing the Deuce will be difficult, but if that were the goal I'd be building/buying/listening to SS gear.
cheers,
Douglas

[Bandersnatch]

Originally posted by Jim McShane


Consider that in 45 years no one has ever built anything like it.

I'd add, "for commercial sale". I've seen or built an amp or two I'd be happier with.

That amp was an end of era design, by an exceptional designer. Sort of like the wooden Mosquito bomber. Speak to a man who has flown one, look at one sitting on the ground....it is Art incarnate, and exceptional for a lot of the same reasons.
cheers,
Douglas

[Eli Duttman]

Yeah, the "Duece" measures pretty good. Unlike mass market SS GUANO that measures great and sounds GHASTLY, the Cit. 2 sounds BETTER than it measures.

Among his talents, Stu Hegeman was a recording engineer. He knew what music really sounded like. That knowledge shows up his circuit designs.

[kevinkr]

The design information for the Citation II output transformer is out there somewhere, I sure wouldn't sacrifice a good one for this purpose, otoh I would say a fried freed (hehe) ought to be ok for this purpose if you can find them.

MFA built a bunch of 120W monoblocks with a quartet of 6550 (etc) per channel. I have as well and in this configuration the transformer is absolutely stellar. (4 chassis for stereo with fully regulated supplies.)

No restorable citations died for any of the amplifiers I built. I was lucky enough to find several sets of Citation II opts NIB on eBay in the late 1990's and bought several thoroughly damaged and incomplete chassis for the rest.

[Bandersnatch]

Originally posted by kevinkr
The design information for the Citation II output transformer is out there somewhere, I sure wouldn't sacrifice a good one for this purpose, otoh I would say a fried freed (hehe) ought to be ok for this purpose if you can find them.

hey-Hey!!!,
Just because the info is 'out there' doesn't mean it is available to me for the asking. The design info for the Peerless I took apart is out there as well. It was not available for the asking, so I took it apart. The information is there for the taking, housed in every example wound. I am going to do it to a few of the tertiary winding Chicago units as well. Those BO-series are some sublime bits of Iron.
cheers,
Douglas

[Sherman]

Originally posted by Jim McShane


...- first off the Cit II OPTs are not 4.3K. They are about 3.2K.

Jim,

Oops, I've been thinking of Dynaco MK IIIs the last couple days (saw one, only one unfortunately, at an 'antique' shop) so that 4.3 has been on my mind. (That's my story and I'm sticking with it! ) BTW James also has a 3.5K OPT and while the specs are impressive they don't come close to your measurements. But maybe, if the other stuff is done right they could still work.

I've spent some time (read hours) looking at your stuff and checking eBay and every place local I can think of for a Citation II in *any* condition that I could justify purchasing. So far it hasn't happened but if it does you'll have another customer!

Sherman

[Jim McShane]

Originally posted by Sherman


Jim,

Oops, I've been thinking of Dynaco MK IIIs the last couple days (saw one, only one unfortunately, at an 'antique' shop) so that 4.3 has been on my mind. (That's my story and I'm sticking with it! ) BTW James also has a 3.5K OPT and while the specs are impressive they don't come close to your measurements. But maybe, if the other stuff is done right they could still work.

I've spent some time (read hours) looking at your stuff and checking eBay and every place local I can think of for a Citation II in *any* condition that I could justify purchasing. So far it hasn't happened but if it does you'll have another customer!

Sherman

I see you are from the Chicago area too! I'm in Orland Park, if that's not too far maybe one day you can stop by and visit! It'd be great to meet you in person.