Review: Croft Micro 25 Basic Preamplifier

Review: Croft Micro 25 Basic Preamplifier, What a Bargain!


Official Website

Glenn Croft, most respected UK tube guru/auteur, amongst the last of a dying breed, has certainly been around. For the longest time, he has been making excellent tube products at bargain prices. Perhaps he is as famous for the unadorned looks of his creations as his legendary OTL amps (which I had the fortune of hearing at my friend mda's place; but apparently and unfortunately Croft doesn't make them any more). Some years ago, I almost bought his Vitale preamplifier, but it took my trip to the UK this year for me to finally acquire a Croft product.

Croft Micro series Preamplifers Croft has been using the term "Micro" for his preamplifiers on and off for a long time. The latest is the Micro 25 series, I suppose an anniversary designation. His current amplifiers are simply designated Series 7, a continuation of previous efforts. I learned about the current products through reviews of the Micro 25 Preamplifier and Series 7 Amplifier (Tone, TAS).

click pic to enlarge.

Micro 25 Basic

It must be emphasized that the product under discussion is the cheapest Basic version, not the regular version reviewed in the links above.

Built The box is OK, but packing material is quite a joke (I have no idea if export versions are different) - there is no foam or cardboard, instead consisting of crumpled paper (apparently compaction is achieved by stepping-on them, as shoe marks are evident). No manual is provided. The case is very basic, but slim and solid. Lettering is a bit smeared (don't know if it is better in the non-Basic version). The knobs are cheap plastic, but you can easily upgrade them for little money so that your unit looks like the non-Basic version(s). I have no problem with the utilitarian RCA connectors and toggle switches.

Power Supply Only 4 screws hold the cover. Once inside, I have even more admiration for the built. In the power supply, unusually there are two transformers (which are the same and appear in series). I wrote Croft and was informed one was for B+ and the other heater supply. At this price point, I applaud the presence of transistors for power regulation.


Preamp section is well isolated from the power supply and is truly compact. I have no problem with the basic volume pot and selector. Like all Croft preamps. the entire preamp section is hard wired through a basic terminal strip (which may raise eyebrows), with the bigger caps anchored to the chassis. Resistor and caps used are basic but of good quality. This unusual method of construction for sure guarantees very short signal paths, but may prove troublesome should modification is desired or service needed. I cannot decipher what cables are used inside. My unit comes with 2x JJ ECC83 for the phono section and a Sovtek 12AX7WB for the line section. Since the website says 5965 for the linestage, and since 5965 is not exactly the same as 12AX7 I am not sure what is the import on sound, I wrote Croft on this. I received this reply: "...later Basics like yours can only use the ECC83 in the line stage - the 5965 has a higher heater current. The ECC81 and 5751 are other options for the line stage....". Now, that settles it - the info on the website has not been updated.

Features

The separate volume controls for the two channels enable one to adjust for balance. The mute switch is useful for turn-on and -off, and also for phono users.

Caution! I must caution you on connection to the amplifier. Here, the Preamp Output is simply marked "Out". Adjacent to it is a "Line Out" which turns out to be what we would call "Tape Out". I mistook the latter for the preamp out and got full volume. Fortunately I was able to immediately shut down my amp so no damage was sustained. Also, as this basic model has no protective relay or auto-mute at turn-on, if you intend to use it with a transistor power amplifier you must wait a couple of minutes for the preamp to stabilize before playing music, or risk damaging your amp and speakers (tube preamps sometimes output DC at turn-on).

Sound-Round 1 in NYC

I first listened to the Croft in NYC, with the help of a step-up transformer (although the transformers look like they could easily be re-wired to 110V, I didn't do it).

Driven by Wavac MD-811A, sound through my reference highly sensitive YL 4-way horns was a bit rough at first, but settled quickly. The sound was forward, quite dramatic and palpable, equally adept through both the line and phono sections. However, a bit of amelioration/smoothing with old-stock tubes was needed, as the forward natures of both the preamp and the loudspeakers could sometimes be too much of a good thing. Swapping in RCA 12AX7s did the trick for me.

In that system, the Croft proved to be highly capable. Even with 100 db sensitivity, the preamp was commendably very quiet even when phono was used. Although with large orchestral material it did not match the Shindo Monbrison dynamically, it acquitted itself quite well, with particularly impressively clean bass. With jazz and pop material, the sheer presence was quite enjoyable. Although it did not quite yield the ultimate details and at times I could detect the thinnest veiling, somehow it gives life to instruments like few preamps can - they simply sound more real. That is quite an accomplishment. 

Sound-Round 2 in HK

Back in HK, I paired the Croft with another Wavac amp, the MD-300B. Sound through the Tannoy Canterbury though was quite a different thing. With the same tubes inside, the preamp sounded just a little too soft on attacks. Some of this has to do with tube rolling. I left the strong-sounding stock tubes in NYC, and did I wish I have them with me now! Some of this I think also has to do with the gain structure. In NYC, turning the volume pot just a wee bit got plenty loud. With the less sensitive Tannoy I had to crank it up some more, and as is sometimes the case with one-tube linestages (it partly depends on the design) the volume pot gets progressively insensitive. I swapped in some other tubes and got improved results. Also, in terms of the line section, the Croft benefits from stronger-sounding digital sources - low output and refined types may not suit. As for the phono section, it is excellent but not quite the equal of others that have better power supply.

What is interesting is that, with the Tannoy, and perhaps due to run-in, the Croft acquired a refinement that had escaped me at the start. The faithful rendition of instrumental timber is still there, but now more subtle sonic textures can be heard - indeed it can be quite refined with tube rolling, if that is what you are after.

Some musical examples. When I substituted the re-issue Marantz 7c everything moved backwards. In the Beethoven violin sonata from Argerich's Lugano 2011 set, both the violin and piano became more recessed into the soundstage; the piano grew more full bodied and the violin was sweeter. But I have to confess the sense of a live event was better conveyed by the Croft, even if the tones of both the violin and piano were leaner. Playing the vinyl of Ellington's Blues in Orbit, it was obvious the Marantz 7c had more oomph, though the Croft held up valiantly.

Conclusions

The Croft Micro 25 Basic turns out to be a little enigmatic, and that is one of the things I like about it. For a pittance it lets you go straight to the heart of the performance. It is also quite responsive to tube rolling. While its performance may differ a little from system to system, it is that rare thing, a bargain with a huge personality. The price is incredible - for the same money you cannot even buy a Chinese preamp with phono. If you are interested, think also of the higher models, the Micro 25 and the 25R; I wonder how much improvement they would bring?

Buying from the UK

Since Croft has no dealer in HK, those interested would have to buy from the UK. I bought mine from Divine Audio. Buying in the UK saved me shipping, but I had to pay the VAT and get the refund back later when I left the UK. The government red tape took quite a while, but I am pleased to report that I got the VAT back and salesperson Tim Chorlton was a tremendous person to deal with, even answering emails when off work! If you buy from HK, you don't have to pay VAT in the first place, and Divine Audio knows how it works. There are other dealers who ship out of the country, but I do recommend Divine. Check for prices as there has been a recent price increase, not reflected in some dealers' websites.