Typo in my posting...it should read 12BZ7s not 12BX7s...sorry! |
I've been a tube head for about 30 years and I'm a bit of a DIYer. I'm QUITE impressed with my C-J CAV50. I've owned the "who's who" of tube amps (Cary, Jadis, VAC) as well as modified vintage and built from scratch tube amps. I also have several friends that are VERY experienced with DIY, vintage and the "who's who" amps. We were all BLOWN AWAY by the stock CAV50. I have to agree about the dark and sort of sluggish sound...but that can be cured (read on...) The amp comes from the factory "hard wired" for a 4ohm load; this is not optimum for all speakers. I found that re-wiring it for an 8ohm load makes the amp sound MUCH faster and not so dark. I also converted mine to TRIODE...a HUGE improvement in all areas. The amp is MUCH faster, more transparent, more liquid, and significantly more open. YES...just like with the output load this is VERY speaker dependent and will not work for everyone. BTW, both the output loading and the triode conversion are STOCK and RECOMMENDED modifications...I got the info directly from C-J! If you're good with a soldering gun you can do it yourself...you can take it to your local tech...or you can send it back to C-J for these conversions. Now for the not-by-the-book modifications. I replaced the coupling caps with AN copper-foil-in-oil...WOW! A HUGE improvement...it's hard to describe but the sound became more detailed, more transparent, more extended as well as more rich and harmonic. I also tried EVERY tube (vintage and modern) on the market. I found the LONG PLATE tubes for the input and phase splitter to sound best (more plate area...DUH). I ended up using my old favorite RCA "red base" 5692 to replace the 6SN7 in the driver position (I tried ECC32s, Sylvania 6SN7Ws and chrome tops...money was no object). I also replaced the 12AX7s with 12BX7s and the 12AU7 with a 12BH7...they have about TWICE the plate area and give the amp an effortless character that can't be compared (they are also QUITE cheap). I preferred them to the overpriced vintage Telefunken, Brimar and Bugle Boy long plate tubes that I was using. I wouldn't recommend these modifications to the faint at heart...I've blown a filament fuse a couple of times (these tubes require 2X the amperage). I've spoken to the techs at C-J and they assure me that I'm still WELL within the operating limits of the amp (the amp is built like a tank). All of my audiophile friends can not believe their ears when they hear my "humble" C-J integrated...it is a REAL mind blower! I'm planning on doing some more mods to the amp (such as replacing the diodes with high speed HEXFREDs). I've owned DHT SET amps and I've owned PP pentode and Ultra Linear amps...I now KNOW that PP Triode is the way to go for me...it has most of the liquidity and midrange of SET and most of the slam of pentode...I consider PP triode to be the best of both worlds! This may not be my last amp but this amp will ALWAYS have a place in my home. |
I also owned a CAV 50. My impression of the amp is, it's abit colored, and slow in the timing domain. It is kind of a dark sounding amp. Might marry well with a pair of brighter speakers. After carefull listening, it is not a bad amp for the money, but has a distinctive signature. I would think the JM lab mini utopias would want alittle more power than that to open them up. The VTL stereo 150 might be a good match for those speakers. I can't comment on the Tempest. Hope that is helpfull. |
Rooze, I've always found them to offer the best prices, and they're good to work with, if shorter than some on specific advice (C-J itself is outrageously expensive for replacement tubes). If you do the retube, let me know what you think after burn-in. |
Thanks Zaikesman for the advice on the retube. It's something I've been thinking about for a while. On your advice I've just emailed Triode Electronics for a quote.
Rooze |
Rooze, unless you listen fairly infrequently, it's time for you to consider a tube change, at least on the power tubes. It's hard to hear the slow degradation over time, but a fresh set will often be a shocker. Allow me to suggest Svetlanas, which were a major improvement over the Sovtek/EH tubes C-J stocks in my MV-55. While you're at it, I would also switch out the 12AX7's with Yugo EI's and the 6SN7's with Chinese, since neither are too expensive, and all can be had at good prices from Tiode Electronics online, with the EL34's tested and matched. But the power tubes are the main thing - just give 'em a week to burn in, and I'll bet you'll be marveling at the difference. Just my opinion, but one based on experience... |
Hi,
I've had a CJ CAV 50 in my system now for over 3 years. Still using the original tubes, and have to set the bias about every six months, it takes about 30 seconds.
This is a great sounding amp, I replaced a Krell 300i and have never looked back. |
My experience with the VTL IT85 has been excellent. This unit has many capabilities: pre-out, processor in, remote (volume and mute), headphone socket, and if you need more power, can be easily biamped with the ST85 (they are gain matched). The binding posts on the back for the speaker cables and the inputs are heavy duty and overbuilt, and the unit itself is very well built.
I compared the VTL to the new Ayre integrated, on a pair of Martin Logans, and the VTL won hands down. It was easy to hear the difference. Maybe because tubes go better with 'stats, I don't know. But I love the VTL IT85.
This was my first tube piece, so I was unsure about "biasing", but I just read the directions, got the recommended biasing meter, and had no problem. It was a lot easier than I thought it'd be.
I swapped out the tubes for NOS amperex bugle boys 7316, and telefunken 802s for the pre section, and man, this amp really sounds great. I was surprised at the impact, depth/fullness of the sound. |
Zaikesman is right on the warm up time.
I would suggest you do this: buy an older tube amp of the audiogon or bay like a Cary SLA 70, take it play with it, do the tweaky thing, experiment with tubes, and caps.
Figure out if this is the sound your after. You can re-wire the amp to go triode if you want. Thats why you buy an old used one. Figure out if this is where you want to be.
If your a set it and forget it guy, SS is you.
jeff |
Between the CAV-50 and the IT-85, I'd go with the VTL based on my demo of my own MV-55 against the ST-85 (these are the non-integrated versions of the same amps). Can't comment about with your speakers though, and biasing the C-J is easier since it doesn't require a separate multimeter. One note: I'm not sure what you mean about 'warm-up' time - tube amps generally don't require as many minutes to reach their best sound as do solid-state amps. If you're talking about how quickly they make sound, the answer is about 10 seconds. They sound OK after about 30 seconds, and sound their best after about 15 - 20 minutes - quite a bit shorter than the 60 - 120 minutes required by a lot of SS amps to sound their best. |
