I wouldn't have thought the Jadis had a problem here. 100 watts, speakers 92dB sensitive, 8 ohm compatible. Should easily get over 110dB cleanly at a metre, enough for most people ...What you're hearing is headroom.
Frank
I wouldn't have thought the Jadis had a problem here. 100 watts, speakers 92dB sensitive, 8 ohm compatible. Should easily get over 110dB cleanly at a metre, enough for most people ...What you're hearing is headroom.
Gary-you mentioned this to me before and the idea sounds very good. What doesn't sound good is trying to keep two Defy 7 amps running and in tubes. Now we would be talking about $1,600 to retube the amps and that cost will never go away and willl probably go up. I do think the secret to the Jadis amps is their output transformers. They are works of art and they are massive. The output transformers on the Defy 7 look like they belong on a 300 watt amp. I assume the Defy 7 is mainly Class A because of having 6 KT-88 tubes per channel and only claiming to have 100 watts of output power. Most tube amps that had 6 KT-88s per channel would be rated for at least 200 watts per channel.
microstrip-I don't think it matters with regards to push-pull or parallel single-ended. The point holds true for either type of amp. You are never going to get two output tubes to match perfectly, let alone 12. I am dealling with 6 per channel. I buy the best tubes I can and as matched as they can be. They are not perfectly matched. They are just *close.*
Lower noise floor = less masking, better resolution of the subtlest details at lower volume. It's no surprise that the Phase Linear does this well. I wouldn't be surprised if that cymbal was clearer as the volume comes up, too. Clipping and metal tweeters make harsh bedfellows. What you're hearing is headroom. An amp that can drive your speakers hard without even getting up out of its chair. In my view, there can't be too much headroom, and there really is no substitute for it. The only question in my mind is what was wrong with the Pass Labs?
Welcome to the dark side. Next up? Active. Bwahahahahaha!!!!!!!!!!!!!!!!!!!!
Tim
The Defy 7 is class AB. Do not give-up on it, it is and excellent amplifier. I used mine with SED 6550c , that cost me around usd 600 for a complete re-tubing in europe. Did you ever listen to it using the matching JPL preamplifier? I do no doubt that your Counterpoint is a very good preamplifier, but I only realized how good the Defy 7 was when I matched the two.
Match pair in pushpull is more important than SE. even parallel in SE still only single one still better than two of them if they can have same power out put, at least lower the cost, my transmitting tube 805 NOS stuff, do not have the re-tube problem, I think they can last longer than my lifetime because they were designed in CCS on military and industrial grade but we only use 1/2 of it's ICAS standardAlthough it is not clear for me if your are addressing pushpull amplifiers or paralleling several tubes to get a composite tube with lower plate resistance and higher current capability, I should refer that paralleling tubes per si is not a bad thing. We have two important parameters in power tubes - plate current versus bias voltage and transconductance. If you select and match the tubes you can get a composite tube with very good characteristics. Each of my VTLs have 12 6550C tubes - I select them in a way that the sum of the tranconductances of the push side
equals the one of the pull side.
Tim, my speakers are very efficient and should be a fairly easy load for any amp. I don't think I am hearing headroom issues. The Jadis is very powerful. 6 KT-88 tubes per channel will do that for you. The Phase Linear has twice the power, but as we know, that only translates into another 3dB of sound output. I certainly agree with you that you can never have enough headroom. Hell, maybe I will end up with a pair of McIntosh 501 amps. I'm just a little humbled right now. It's not over yet. I will listen tonight and gather some more information. I just can't believe that I'm seriously comparing an old Phase Linear amp to a Jadis amp.
You're right, Mark, that was a knee-jerk reaction to tubes not to that specific amp. Call it expectation bias! So, you've got a big, hefty tube amp that sounds good, and you've got a big heft vintage SS amp that sounds good. No need to be humbled; you've just discovered that it's all good. No need to be very surprised either. Bob Carver was pretty brilliant. In any case, it sounds like you're having fun.
Tim
Tim-The Phase Linear 400 Series Two amp is not really big or hefty. I can carry it with one hand. The power output is hefty though. And I do believe that Bob Carver is a very smart and talented engineer. After the C-500 amp, Bob came out with his line of magnetic power supply amps that I was never fond of. Remember the first Carver Cube amp? The C-500 amp represented the last amp that Carver designed with a *regular* power supply that used a common type of power transformer.
The Jadis new was around $8K I think. I paid $2600 to the original owner and was damn glad at that price and condition. I don't know what the Phase Linear amp sold for new. I paid $385 for mine, and that was a little high, but mine had just been gone through by a really good tech and the filter caps were replaced and the amp works perfect. That was worth a little more money in my book. I just can't believe that I'm comparing the two. Normally I would be turning up my nose right about now.
Headroom is the secret of life.
Tim
Steve, what's your motto? Isn't it something to the effect: am I hearing something that is better or I am just hearing something that is different?
Headroom is the secret of life. There should be enough headroom in those two amps with the sensitivity of those speakers that, operating at moderate volume levels, the audible differences between them should be negligible. If not, then either A) one of them does not have as much headroom as its ratings would imply or B) Somebody has designed for something other than a flat frequency response.
Tim
In 1975 I had a Phase Linear 400 driving dual Large Advents, with a Phase Linear 4000 pre-amp (remember the Auto-Correlator?) My first "hifi" system.
A friend of mine had the Carver C-4000 Auto Correlator preamp and it was dreadful. The over-achieving NAD 3020A used as a preamp only was much the better sounding. It didn't look as cool, but it sure sounded better. I assume your 400 was the first one with the VU meters?