A long time ago (in a galaxy... -- Ed), some of my first building experience (and much learning) was with the Bottlehead Foreplay preamp, which was $99 excluding base for the stock model, and had some upgrades available. I spent many hours modifying it, tube rolling, trying different attenuator options, different power supply arrangements, chassis damping, and pretty much every which way but loose to mess around with the thing. Part of my challenge was that I was using a high input sensitivity power amp with relatively high efficiency speakers -- a situation which persists today, albeit at a much higher level of performance than way back when. A few years ago I reviewed the Bottlehead SEX amp, and was thoroughly impressed with its performance, a musical, flexible, and enjoyable small integrated amp.
In late 2014 it was time to bottle things up
again and get some more goodies, and Bottlehead sent along review kits for the
Quickie and the Quicksand (a 4WPC battery-powered class D amplifier). These are
their two least expensive "active" components at $99 and $119 respectively ($20
off ordered together) but that's not a problem for me; I love a good bargain and
simple circuits can have a charm all their own. One of the charms of these
particular bargain components is in the top plates supplied; they can range in
color based upon what the acrylic supplier sends (a cost-control measure). I got
red for both plates, and I rather like the look of them (seen
The price of
Quick Quickie Overview
The Quickie circuit is the simplest you're likely to see -- a grounded cathode amplifier or "plate amp". This is one of the key building blocks of most tube circuits, and is present in most tube amplifiers in some variant or another. John Broskie of Glassware fame discusses this topology here.
The 3S4 is a pentode, wired as a triode in the Quickie and has a center-tapped cathode which runs with the two sections in parallel off a 1.4V 100mA supply, they can also be run series with 2.8V and 50mA. D cells give 1.5V when fresh which is a little hot but forgivable, and as they drain the voltage falls in a fairly linear fashion. You'll want to monitor voltage from the D cells (one per channel- dual mono heater supplies are necessitated by DHT operation); I have taken to checking it upon power up each time I listen. The high voltage.. (choke... higher) voltage supply comes from a quad of 9V batteries wired in series for 36V with alkaline batteries. Bottlehead indicates about 100 hours of battery life, I found that by about 25 to 30 hours of playback I had dropped the Duracell D cells to around 1.25V, which I deemed to be low enough to swap in fresh, but this may be on the low end of cell reliability, some other brands have seemed to fare better but I haven't tracked their timing as closely. Shutting down overnight will often recover a little voltage, too. During that same stretch the 9V Duracell Procell alkaline batteries I initially used dropped to about 8.35V per; not surprisingly they retain a longer life than the D cells which draw several times more power (100mA per cell @ 1.5V compared to about 4mA at 9V). Longevity will vary with brand and type, so your drain rate may be slower, or faster. Do buy your batteries online and Google the specific types you'll be getting, as you want high mAh (milliamp hours) batteries from a reputable company (that's not only Duracell or Energizer btw). Batteries are a high markup item at most retail outlets.
So, batteries come with two major drawbacks: additional operating expense and ongoing maintenance to ensure that you're getting appropriate voltage. Apart from portability batteries have two key positive aspects to their performance: they're typically quiet and relatively low impedance, both of which are very good things for a power supply. There is some variance in noise performance and impedance within the different cell types; from what I've seen good quality Nickel Metal Hydride (NiMH) rechargeable batteries having some of the best noise performance, with Alkaline batteries acquitting themselves very nicely but Nickel Cadmium and Sealed Lead Acid both potentially being a little noisier. I haven't found definitive noise testing data for batteries however.
More On Batteries
For the 9V batteries I wound up with 9.6V Imedion from Maha. They are pricey but high quality and the Quickie can handle extra voltage (and indeed eats it up). In circuit, fresh off the charger the Maha give 11.3V, driving the B+ up to 45V. The Quickie can handle the excess voltage and seemed to have a little extra pep in its step with this higher voltage. With the constant current supply in place, the plate voltage was about 31V and cathode was biased to 2.5V. After 5 to 6 hours they'd settled down to 10.3V, still a significant, and welcome, bump on the "high" voltage rail. They stay a little over 10 for quite a few hours, I haven't done the formal testing with them as I picked up 8 and just swap them out every once in a while so I never have to test nor worry about the 9V cells. The higher voltage than nominal is probably due to the low current demand- good high quality NiMH handle heavy loads much better than Alkaline (less voltage drop), and so at a handful of mA, they're loafing along and exceeding nominal voltage. The higher plate voltage also runs a little more current through the tube- not a bad thing (within reasonable limits).
D cells are a bigger challenge -- 1.2V from NiMH won't cut it, and 3V Lithiums are too much (one could regulate them down, or run the heaters in series instead of parallel if desired but that's another ball of wax). There are Nickel Zinc and RAM options, but neither are great. I am sticking with Alkalines and a replacement cycle, for the short term.
Basics And Assembly
Some light grousing- I had glued up both of the alder bases from Bottlehead, which are the same size for the Quickie and the Quicksand, and let the Quickie work from the unfinished base while I put a nice Danish oil finish on the other base after a 220/320 sanding- higher grits and more sanding are advisable for a better finish, but I didn't want to go too far off the plans on this step, which call for only sanding to 220. After letting the base cure, I went to swap in the finished base for the unfinished, and had a rather rude awakening- the base was slightly smaller than its brother. I had to then trim a little extra length into the rabbet on an assembled and finished wood base, which I did with a knife and some care, but then had to re-finish that portion and whatnot- one of the few negatives I have to gripe about, the other being some chipping around the cuts on the acrylic plate. Neither were major issues but when you buy an inexpensive kit, some of these challenges are almost inevitable. I do advise test-fitting your top plates carefully before applying a finish.
Now, we're talking- the Quickie was going into a rig which
required high attenuation from the preamp, making it a major challenge for any
but the quietest preamps. The Quickie, apart from the microphonics, is very
quiet and tube self-noise is the only other issue you may face with some tubes,
and shouldn't be an issue in all but the highest gain/big amp systems. The
ringing noise, with all but one tube I tried was audible and excited
acoustically during music playback, but it is fairly benign.
One of my favorite bits of music to evaluate a new component with is Trevor Pinnock with "The English Concert" doing Handel's Water Music. This is a lush, rich recording that is tonally robust without being overwhelmingly ambient. The Quickie didn't disappoint as I settled in and was able to relax, close my eyes, and focus primarily on the music. Any errors the Quickie was making relative to my transformer attenuators (which are quite pricey, and worth it) were primarily errors of omission. I was giving up some air, resolution, definition, and a meaningful chunk of soundstage width; but what I wasn't giving up was any meaningful amount of musicality or dynamics with this recording. Some more challenging recordings did indeed tax the dynamics a little bit when going against something as nimble and dynamic as my TVCs, which are exceptional in that regard. In short, the Quickie, even before the addition of the CCS, performed quite well, with some shortcomings but a relatively clean presentation, with plenty of musicality and excitement.
Going through a variety of other recordings, I found that at higher volume levels there was some added glare relative to my reference transformer volume controls. Some of this seemed to be microphonics rearing its head, and the solution for this is often to swap tubes out to find a low microphonics pair. The PJCCS (more later) alleviated most of the perceived glare. The Tung-Sol that shipped with the pre were nice tubes, but I ordered some alternatives, NOS RCA and Mullards to try some alternatives and see if I could minimize microphonics. The microphonics issue seems to be more related to the excitation of an internal structure than to surface resonance, so simply damping the tube envelope will only help somewhat. The sockets can be mounted with O-rings to provide some damping, and there are other methods to mitigate resonance getting into the tubes but this review is focused upon a stock preamp. If you have a high sensitivity amp/speaker combo, some ringing is something you'll have to live with the stock Quickie, plain and simple. Out of 10 tubes I tried, from Tung Sol, RCA, and Mullard, only one stood out as being less microphonic than the others. Self noise was only a very minor issue, in this challenging system, with one of the ten having a whine at about 15 kHz that was loud enough (in this system) to be mildly problematic.
In short, the CCS is not optional if you want to get the
cleanest sound out of the pre. Some will prefer without, enjoying the stock
colorations, perhaps finding it more pleasant. I prefer the CCS in place and
would go so far as to say it's significantly better and more accurate that way.
While the addition of the CCS didn't get it to the level of the reference TVCs,
it did bring the pre much closer, and that's no small feat. The transformers,
raw, cost many times what the Quickie does even before switches, connectors or
Some Other Systems
I then decided to add in the subs in the main system, driven in parallel with the amp inputs forcing the Quickie to drive three channels of amp per output. This means a 9700 Ohm load or so for the Quickie, it was my hope that the sub amp input would act as a current sink for the ringing, and indeed, it did; the microphonics issue subsided a bit and became less of an issue in my rig. Unfortunately the lower load along with some extra cable capacitance (presumably) collapsed the soundstage back down. Within the more limited soundstage tonality remained good and dynamics were okay, but the Quickie was definitely happier into the higher 50kOhm load as it gave up a fair bit of resolution, space, and basically every audiophile term into this load. Cable capacitance wasn't out of the range of normal, being equivalent to about a 2.5 meter run of typical twin-axial audiophile cable. The good news is that it remained musical and enjoyable- the things that matter most.
So, making sure that I give this pre a very fair chance to
compete in a system more appropriate to its cost, I combined it with the
Bottlehead Quicksand amp, the other battery-powered Bottlehead device I was sent
for review. This combination, in my daughter's rig vs. a modest Audiosource A100
integrated amplifier was a huge upgrade, with two caveats. First, the
microphonic ringing was still an issue and is audible between notes. It's pretty
bandwidth limited to the resonant frequency so it's not a horrible thing, nor is
it extremely loud, but it's a problem. The second was that her CDP didn't like
an ungrounded pre/amp combo and so there were mains hum and buzz. Using a
portable source cured this, since the inexpensive Sony player was the culprit. I
didn't experience any of this noise when using the Quickie in the big rig. Some
systems may be problematic, though. But all that aside, the sonic quality of the
Quickie via the Quicksand was head and shoulders over the more powerful
Audiosource, exhibiting a more natural tone, better imaging, and a more
musically enjoyable presentation overall.
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