Mid-March 2007


Bella EXtreme 3205 Signature Vacuum Tube Power Amplifier
Tried and True and Updated Too!
Review By Nels Ferre
Click here to e-mail reviewer

  Back when I wrote for another website, I owned a JoLida SG502 integrated amplifier. While it wasn't in the same league as the amplifiers that resided in my reference system, I had planned to use it as a reviewing tool, and also as the cornerstone of a second system. The second system never materialized and I eventually sold the amplifier. Life has a funny habit of throwing curve balls when one least expects it. I sold my home in the suburbs of Orlando and bought a small one-bedroom condominium downtown.  I no longer needed the large tube monoblocks that I had been using for the last several years. I did not have the space for them nor required the large amounts of power they afforded. I also could not ignore the issue of heat. In my old home, it was not an issue, but in my new smaller digs, the amplifiers could easily raise the ambient temperature by more than a few degrees.  It was clear that I was going to buy another amplifier, and I gave it considerable thought. I knew my new amplifier would be tubed, as my favorite amplifiers that I have previously owned, both pre and power, have been tubed.  Other than that, I was unsure.

My mind kept wandering back to the JoLida SG502, but I knew that was not going to be my long-term solution. While the SG502 is a fine lower priced amplifier, it does not have the resolution that I require. Also,  it is not really an integrated amplifier, but rather a high gain power amplifier fronted  by a passive preamplifier.  Passive preamplifiers aren't preamplifiers at all; rather, they are just a volume control, input switching, and the associated wiring. Theoretically, this is great: no active circuitry means less between the listener and the music. Unfortunately, passive preamplifiers pose their own challenges. First, the output impedance of the source component will affect the frequency response of the power amplifier. Second, passive preamplifiers tend to be finicky when it comes to interconnect cables. Life is too short to stress over output impedance or interconnect cables; I just want to get into the music.

Hold on, did I say high gain power amplifier?  Yes, I did.  Hmmmm, what if....

Enter Bill Baker
Bill Baker has been a JoLida dealer since 1994, coincidentally, the same length of time that JoLida has been manufacturing audio components.  Bill determined early on that the JoLida amplifiers, with their high quality German transformers, were (and are) excellent values, but with some work, could be improved. He has been modifying JoLida integrated amplifiers and components, among other brands, since 1997. Other companies modify JoLida components, but to the best of my knowledge, Bill has been at it longer than anyone, making him a pioneer of sorts (pun intended.) When it comes to JoLida gear, I doubt if anyone outside the factory is more knowledgeable. The JoLida factory had several hundred of their original "A" series 502 amplifiers in storage. Most of them had minor cosmetic blemishes (more on this in a bit.)  Bill made an agreement to buy all of them for modification purposes. Currently in "B" series iteration, there are a few differences between the two series of amplifiers: the "A" series is clad in a dark charcoal gray metallic with exposed transformers, the current "B" series is clad in champagne or silver (depending on vintage) and the transformers are underneath a decorative cover. Additionally, the parts quality has been upgraded over the "A" series, although not nearly to the level of the parts that Bill utilizes in his modifications.  The very  latest  versions of the "B" series amplifiers also use LEDs for tube biasing, similar to the setup used by Conrad Johnson.

I called Bill and asked him if my idea was feasible. Could he take an A series integrated amplifier and turn it into a power amplifier by removing the volume, balance, and input switches, along with the associated wiring? Of course, I'd want the amplifier upgraded while he was in there. "No problem" was his response. It turns out that I wasn't the only person that had made the request. In the months since,   Bill has shifted away from modifying the JoLida integrated amplifiers to turning them into power amplifiers: integrated amplifiers are now the exception. The Bella EXtreme name came into being in late 2006.

The Bella EXtreme 3205 Signature
The Bella EXtreme 3205 Signature ($1600) is rather conventional. It is a push pull pentode class AB design using a pair of 12AX7s as the input tube, and a pair of 12AT7s as the driver tube.  It can use a variety of output tubes, depending on the end user's taste. Use either EL34 or KT77 output tubes for a rated output of 50 watts per channel. Use of the KT88 or 6550 output tube will generate 60 watts per channel.  Not only do the different tubes affect the power output of the amplifier, but they will also determine the sound of the amplifier as well as each of the 4 tube types will sound distinctly different from one another. This allows the end user to use the tube that matches their taste, as well as their system, for best performance. Try that with a solid-state amplifier!

Is there anything earth shattering in the design? No. It is a tried and true circuit, similar to both vintage and current designs from countless manufacturers, but has been updated with higher quality parts than what was originally installed at the JoLida factory. Additionally, the power supply has been fortified.  There are those that believe that upgrading parts makes no difference, that a well-designed circuit is all that matters. One manufacturer, whose designs and equipment I highly respect, calls upgraded parts (as well as cables) "foo foo dust." The only "foo foo dust" being sprinkled is that parts don't matter: just because they measure the same doesn't mean they are the same. I would have thought that idea to have died back in the 80's, a time when some of the worst sounding, but great measuring, "hi fi" components were foisted on an unsuspecting public. Both circuit design and parts quality is equally important for good performance.

As an example, although not music related, let's say my Editor lends me his Ferrari for a day. I'll return it to him with new shocks, brakes and tires, all professionally installed by the garage at the local Super Wal-Mart. Do you think the car will perform as the engineers at Ferrari designed it to perform? Will my Editor ever lend me his car again? Of course not, but the parts fit so it shouldn't matter... or so believe the naysayers.

I'm not saying that high quality parts can fix a poor design or that higher performance can be achieved by slapping in parts at random in a good design. It takes a lot of measuring as well as listening:  Bill told me it took him nearly two years to get the amplifier voiced the way he wanted. At the end of the day, the JoLida SG502 is not really modified: it is re manufactured.  Here is a description of the work done on the amplifier, lifted directly from the Bella EXtreme website:

Audience AuriCap Film capacitors used in the coupling position.

•        SoniCap Gen II film and foil capacitors used for the signal ground.

•        Mills non-inductive resistors are utilized in the grid stop locations

•        Dale/Vishay 1 watt metal film resistors throughout the circuit.

•        Dale/Vishay 3 watt 1% resistors used at the beginning of the input circuit.

•        High quality Panasonic low ESR capacitors make up the filter capacitor banks in the power supply for great dynamic control.

•        Power supply filter bank capacitors bypassed with high voltage SoniCap capacitor.

•        Fairchild "Ultra Fast - Soft Recovery" diodes used in the power supply rectifying stage.

•        Dale 5 watt non-magnetic resistors used at the cathode locations.

•        Dale 3 watt 1% resistors used in the bias stage.

•        High quality 22 gauge copper wire used for the input signal.

•        Side mounted power switch for a clean look.

•        Chassis: High grade steel - metallic charcoal

•        Face plate:  Solid Cherry or Black Walnut - 1/2" thick, Aluminum (Black or Silver)

•        Tube complement: 4 pieces EL34 or 6550 / 2 pieces 12AX7 input tubes / 2 pieces 12AT7 driver tubes

•        Warranty: 1 year parts and labor / 90 days on supplied tubes.

•        Warm-up time: 10 minutes

•        Recommended break in period: 200 hours musical signal

As you can see, it is not really a JoLida at all anymore. The amplifier has changed from a mostly Chinese sourced amplifier with German transformers with final assembly Stateside, to a mostly American amplifier, with German transformers, and a few Chinese ancillary parts.  The only parts that remain from the original design are the transformers, chassis, tube sockets, bias pots and the IEC power inlet socket.  Everything else is replaced. The front panel is covered with the customer’s choice of black or cherry finished walnut. Black or silver aluminum is available as well. Custom finishes, including powder coating, are available at an additional charge.

All amplifiers are burned in on the test bench for 2 hours, and reside in a test system playing music for an additional 12 hours before being double boxed for shipment. Because each amplifier is rebuilt by hand, expect a build time of 30 to 45 days for the amplifier to be delivered, depending on Bill's workload. I mentioned that most of the amplifiers have minor cosmetic blemishes. It took me a bit to find the blemish on mine. It has a dime-sized imperfection in the paint finish on the top right side of the amplifier, just in front of the 12AT7 driver tube. The imperfection is not really noticeable unless the light is "just so." As far as I am concerned, it is all about the music; the flaw is slight.  I am not going to concern myself with it.

Listening
Setting up the Bella EXtreme 3205 Signature was a snap. I had it up and running within 30 minutes, including biasing the output tubes. For novices, the amplifier comes with an excellent set of instructions, which can also be viewed on line at the Bella EXtreme website. The amplifier was shipped with Russian Sovtek 6550 output tubes, which remained in use for the entire review period. The rear of the amplifier is equipped with one pair or RCA input jacks, 1 pair of speaker ground connections, and 2 pairs of speaker hot connections, 4 Ohm and 8 Ohm, which correspond to the taps used on the output transformers. My Infinity Kappa 6.1s have a nominal impedance of 6 ohms, so I used the 4-Ohm outputs for the duration of the review.

The original JoLida SG502 integrated amplifier has the sound that tube detractors detest: warm and woolly in the bass, a midrange glow, and slightly rolled off in the upper frequencies. Personally, I don't have a problem with this, especially in a lower priced component. I believe it is far better to err towards a warm, relaxed sound than a bright, etched presentation, which some mistake for detail.  The Bella EXtreme 3205 Signature is a completely different beast after the rebuild. The first thing that struck me was the silence: no hum, no hiss, and no buzz. This tube amplifier is dead silent. I would not hesitate to use this amplifier with high efficiency horns.

Frequency wise, the Bella EXtreme 3205 Signature is very balanced, but those who generalize that all tube amps are light on bass, and loose and flabby with what bass they do have will be in for a shock. Spinning on the SOTA as I write this is "Mrs. Vanderbilt" from the 1998 reissue of Paul McCartney and Wings 1973 release Band On the Run. [EMI LP 7243 99176 1 3]  I've listened extensively to this album since I bought it years ago, Paul's bass work keeps tearing me away from the keyboard.  Far from thin and flabby, it is very full and EXtremely tight, succinct. On some recordings I may want just a bit more bass, but that really depends on the recording. I believe a change to KT88 output tubes may be perfect in this regard. I have had reliability issues with the KT88 in the past (their internal structure is not nearly as robust as the 6550) so I have not tried them in this amplifier.

Clarity excels in all aspects of the amplifier's performance. Jimmy Page's acoustic playing on "Tangerine" from Led Zeppelin III [Atlantic/Classic LP SD7201] is absolutely gorgeous, the attack and decay of the notes totally natural and believable. Room ambiance and background sounds on the album also come through in spades. The amplifier excels with acoustic music.

The Bella EXtreme 3205 Signature can rock too. The first two Flaming Lips albums have been re released on colored (and clear) vinyl. Their first album, Hear it Is on white vinyl [Plain Recordings LP 111] has been in heavy rotation since I bought it a couple of months ago. Recorded in 1986, it is a mixture of hard rock, punk, and one can hear a bit of the "future" in the album...grunge. Not particularly well recorded, it is a blast to listen to nonetheless. It is easy to place the musicians on the stage, close your eyes, and imagine a live show (complete with a Peavy PA system.) Sometimes loud, sometimes gritty, and never polite, the Bella EXtreme helps convey all of the excitement cut into the grooves.

When it comes to tubes, everyone expects lushness in the midrange, and the Bella EXtreme Signature does not disappoint, if the recording calls for it. If you like Ry Cooder's project Buena Vista Social Club, you may want to check out Charanga Cakewalk's Loteria de la Cumbia Lounge. [Triloka/Artemis CD 82050]  This recording has midrange lushness and smoothness galore. The vibraphone is incredibly recorded, and the musicians can easily be pinpointed along both the width and depth of the stage. Amplifiers don't image, sorry, but they can alter the signal and detract from the soundscape and soundstage in the recording.  The Bella EXtreme 3205 Signature doesn't do that.

Maybe that is what I like best about the Bella EXtreme 3205 Signature: it gets out of the way of of the music. As I was writing this review, the Promitheus Audio TVC Line Stage ($320 plus shipping) showed up on my doorstep from Malaysia. A review is in progress, so I won't say much, except that when it stood in for my current reference, the Sonic Frontiers SFL-1 Signature (originally $1995) I had a completely different sonic experience. This tells me that the Bella EXtreme 3205 Signature is generally uncolored, and puts a minimum of influence on the music. I listened to J.J. Cale's Naturally [Mercury CD 830 042-2] and thoroughly enjoyed it.  Although far from a reference quality recording, I do enjoy the music. I can't remember a time, with any system, that I have enjoyed this disc more than with the Promitheus/Bella EXtreme combo.

Conclusion
After living with the Bella EXtreme 3205 Signature for several months, I continue to be impressed with its performance. It is a good value, and can satisfy critical listeners. Because it can be used with a variety of output tubes, it can easily be configured to the listener's taste and system. What I find most exciting, however, is that this level of performance can be achieved for such a relatively reasonable sum. It's price puts it within reach of many listeners, including those who want to move up from the offerings at the mass merchant stores.  Well done!

Specifications
Type: Vacuum tube stereo amplifier

Tube Complement: four 6CA7/EL34 or 6550/KT88 power output tubes; two 12AX7 input tubes, and two 12AT7 driver tubes

Recommended Bias: 35-40mV / 45 mV maximum (EL 34 power tubes) 
45-50mV / 55mV maximum (6550/KT88 power tubes) 

Maximum Power Output: 75 wpc at 8 ohms, 1KHz (EL34 tubes)
85 wpc at 8 ohms, 1KHz (6550/KT88 output tubes)

Rated Output Power: 50 wpc at 8 ohms, 25Hz to 70KHz (EL34 tubes) 
60 wpc at 8 ohms, 25Hz to 60KHz (6550/KT88 tubes)

Frequency Response: 13Hz to 80kHz (+ 3dB; 0dB)

Distortion THD: Less than 1% at 50/60 W output, 28Hz to 15KHz

Circuit Type: Ultra Linear, Class AB

Input Impedance: 100Kohms 

Input Sensitivity: 500mV at 1KHz and 8 Ohms for 50 watt output 
600mV at 1KHz and 8 Ohms for 60 watt output

Output Impedance: 4 Ohms and 8 Ohms

Negative Feedback: Less than 5dB

Noise and Hum: 85dB below rated output

Dimensions: 17 x 15 x 7.5 (WxDxH in inches)

Weight: 40 lbs.

Warranty: 18 months, 90 days on supplied tubes

Price: $1550 with EL34 tubes, $1600 with 6550 tubes

Company Information
Response Audio Co., LLC
112 Carl Street
West Corners
Endicott, NY 13760

Voice: (607) 785-3440
Fax: (607) 785-3800
E-mail: Response34@aol.com
Website: www.bellaEXtreme.com