Sunday, August 29, 2010

Citation I Refurb - Final Assembly, Part II

Well, this is it.  Final Assembly - Part II.  After this post the Citation I rebuild project will be complete.  That won't be the end of my Citation audio posts.  But this post should do it for the rebuild.

The last phase of the Citation assembly is to attach the power supply assembly to the main chassis and then attach all the wires.  As I've said for the last few posts now, there's not much to it.  Simply follow the instructions in the manual step by step.  The power transformer is attached and the transformer wires are separated into three groups and routed as indicated in the manual.  The bundle of wires from the main chassis is routed through the grommet on the power supply bracket and the bracket is then attached to the chassis using the appropriate washers and nuts.  The following photo shows how the underside of the unit will look after these steps are completed.


All of the loose wires shown in the above photo now need to be soldered to their attachment points.  Again simply follow the instructions for dressing the wires and solder them to their final destination.  Lastly, the power cord is inserted into the back deck of the chassis and the white and black wires are connected to the indicated points.  That is it for the wiring.  You are done!  The underside around the power supply bracket after all the wiring is complete is shown in the following two photos.  You can see the two capacitors just to the left of the choke (or above, depending on the photo) have been dressed in an upright position as opposed to lying flat as they were before final assembly.  I am satisfied with the neatness of the assembly.


The following two photos simply show the top of the unit after all the wiring is complete.  You can see that I have installed the tubes before I have completed mounting all the final hardware (the front plates, knobs, bottom plate, top cover).  The tubes were installed so that the unit could be tested for correct resistances and voltages as specified in the Citation pictorial diagrams before mounting all the remaining hardware.


The three escutcheon front plates are loosely connected to the back plate.  The hexagonal spacers are attached and all of the plates are tightened.  The clear plastic power switch is installed next.  Finally, the front plate assembly is mounted to the chassis.  It's upside down, but the unit with the front plate installed is shown in the following photo.


Lastly, the knobs are installed onto the switch shafts.  The only thing of note on the knob installation is getting the milled indicator line on the knob pointing to the correct position.  For most of the switches that have discrete settings, like the function switch or the rolloff switch this is a simple matter.  For the loudness and balance pots you'll have to decide for yourself.  I installed my knobs so that they point at 12:00 when the pot is at the midpoint of its travel.  The following two photos show the completed Citation I pre-amp from the front and rear.

The second photo reveals that I have already installed the bottom plate and the rear cover.  In fact, there are a number of things to do before installing these two pieces.  There are a few steps in the assembly manual still to be completed before closing the unit up.  These involve powering the unit on, checking voltages and resistances, etc.

When I first powered my unit on the fuse blew.  Oh no! I thought.  All that work!  I don't know if the added capacitance in the power supply causes a greater initial current draw when the unit is powered on.  In any event, I decided to give it another try with a new fuse.  This time I installed a slo-blow fuse.  This was based on a similar experience I had with my Citation II amplifiers after they were rebuilt with beefier power supplies.  When I powered up this time the unit it stayed on.  Phew!  With the unit on I measured the voltages against the chart.  Everything checked out fine so at this point I can officially declare PROJECT COMPLETE.


The pre-amp was installed inside an original H/K walnut cabinet.  This cabinet has a few scratches and dings that need to be removed with a refinishing project.  However, I have my father's mint condition cabinet in storage just waiting to house a refurbished Citation I.  I will probably save it for when I refurbish my father's unit.  But because I have a blemish free cabinet I don't feel a pressing need to refinish this one at present.

So, what tubes did I install in the completed pre-amp?  I chose to use NOS Amperex tubes for the 12AX7 positions.  NOS Mullard 12AT7WA tubes were used in the line stage positions V3, V4, V8, V9.  These Mullards are the later model military tubes that are usually found boxed as CV4024.  For the V5 position I chose to use a relatively cheap RCA 12AT7 tube.  I was advised not to put an expensive tube in V5 because this tube only serves to light the power lamp and is used for the center channel line out.  If you don't use the center channel, then why waste a good tube?

My final photo for this project is shown below.  This is my system.  Placed on top is a Music Hall MMF-7 turntable on the left alongside the new Citation I.  Down below you can see two Citation II amplifiers.  Both have been completely refurbished using all of Jim McShane's kits and parts.  At present I only have one amplifier in use.  The intention is to use both amplifiers.  I haven't decided yet if I will bi-amp them with my Joseph Audio speakers or wire them as monoblock units.  The shelving unit is from Salamander.


Time Spent: ~4 hours

So ends the project.  I hope there are Citation fans out there who enjoyed reading this blog.  This project was a lot of work, but I enjoyed all of it.  I hope there were things to be learned for everyone who visited.  What's next?  I don't think I'll be doing a second Citation I right away.  I have a couple of Citation II amps that I may work on next.  But, the very next thing on my list is to hook this new pre-amp up to my system and see how it sounds.  I hope you check back from time to time to read my report.

Once again, thanks to everyone for stopping by and reading.  Goodbye for now.

1 comment:

  1. Mike,

    I recently started to enjoy listening on a completely rebuilt Citation II. What differentiates the work of the technician who rebuilt this unit from nearly everyone else is that since he works from the schematic, he found the wiring instructions of HK to be quite unhelpful. Written for amateur kitbuilders, those instructions have become more and more inappropriate once the virtues of direct point to point wiring can show what Hegeman's circuit is capable of. So, off went the turret boards and "on" went direct point to point wiring with scrupulous observation of the schematic. Adjustments were made for the higher line voltage and better, same-value parts not in the picture when the kit was first issued.

    The net result is an amplifier that doesn't have "the neatness" that appears to be a cosmetic mine-is-neater-than-yours point of pride, but one that works infinitely better due to shorter connections and careful attention to radiation, heat dissipation and component-induced fields. One difference that's immediately apparent is the improved path for air convection uncluttered by heat dissipation barriers and free standing components clear of contact with convection-blocking boards. Even with high grade, appropriately de-rated parts, heat contributes to component deterioration, so my technician attended as much to longevity of service issues as he did matching and confirmation of values, voltages, and current.

    Yes, the amp looks different from underneath as it's minus the boards, but there is less audible grunge caused by excessively long leads, cable and wire bundling, and part crowding.

    It continues to puzzle me why owners who rebuild and customize their C II's haven't taken on this additional approach to open up the unit to the full capabilities of Hegeman's circuit. There's a point beyond which eye candy makes little sense, especially from the listener's perspective. I am not a proponent of the ugly but sounds beautiful approach, but my ears are better sensory devices for the quality of a performance, including its magical moments, than are my eyes. For me, the test of enjoyment has meant listening with my eyes closed, as I do at live concerts. The stage on the C II is immense; better than any of the other tube amps I've owned in over 55 years of listening, and some have been ludicrously expensive. Tube rolling makes a difference of course, but first and foremost comes the circuit itself. With removal of the turret boards, the unit's much easier to trouble-shoot, and if tweaking is the interest of some owners (it isn't mine) that's more intelligently accomplished with an open architecture than with one limited by a fifty-year-old ease of kit building technology.

    I'm not an antiquarian, but there are things from the "keep it simple school" of engineers with good ears that make sense to my listening pleasure. One of them isn't to be ruled by "newest is better" in all instances. This is a true classic, as were some of the classic speaker designs of the same period. Of course, many of them produced great spectral balance, but didn't image well. In my case, I went out ten years "newer" for a stock set of DQ 10's. The test is listening with one's eyes closed, and with this amp, a good table and cartridge, and a good pre, the grade on my personal test is pretty high. The rest of what's missing isn't as important as being able to mentally fill in the gaps with one's knowledge of the music and the performers.

    Happy listening.

    Roger N. Meyer
    rogernmeyer@earthlink.net

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