Tube line stage to odyssey amp THUMP

MONKEYWICKEDMONKEY · « **on:** 11 Nov 2020, 03:57 am »

I run a Quicksilver line stage preamp into my beloved Khartago. When I turn the QS on I get a big boom through the speakers. I leave the Khartago on 24/7 but the QS is biased so hot I can’t do that.

I’m rigging something together but am curious what the many tube line stage users do about this.

I like the QS but now regret not going Candela

Thanks.

Meicheng · « **Reply #1 on:** 11 Nov 2020, 04:03 am »

If you turn on the preamp first, and then the power amp, you shouldn't get any speaker thump. But you said you are leaving your power amp turned on. Can you turn-off your power amp and just let both preamp and power amp "warm up" for 15 minutes before listening to your system?

Dishman442 · « **Reply #2 on:** 11 Nov 2020, 04:38 am »

SWAG (stupid wild assed guess) do you have another input, unused, that you can choose before turning on the quicksilver?

FullRangeMan · « **Reply #3 on:** 11 Nov 2020, 04:48 am »

Quote from: Meicheng on 11 Nov 2020, 04:03 am

If you turn on the preamp first, and then the power amp, you shouldn't get any speaker thump. But you said you are leaving your power amp turned on. Can you turn-off your power amp and just let both preamp and power amp "warm up" for 15 minutes before listening to your system?

+ 1 on 15 minutes or even 30.
The safety standard of tube equips is that they should not be left on without the assistance of a trained adult let alone 24/7, few tube transformers can endure it.

MONKEYWICKEDMONKEY · « **Reply #4 on:** 11 Nov 2020, 05:07 am »

Quote from: Meicheng on 11 Nov 2020, 04:03 am

If you turn on the preamp first, and then the power amp, you shouldn't get any speaker thump. But you said you are leaving your power amp turned on. Can you turn-off your power amp and just let both preamp and power amp "warm up" for 15 minutes before listening to your system?

Klaus instructs to leave the amps on so I have been. Are people not doing that?

FullRangeMan · « **Reply #5 on:** 11 Nov 2020, 05:21 am »

Your power bill will

Certainly Odyssey amps are made tô endure it.

jjss49 · « **Reply #6 on:** 11 Nov 2020, 05:55 am »

i have a stratos, it sounds very nice ...especially for the cost - for a solid state amp it is pretty finicky though

am sure klaus would say well it is finely tuned machine, more ferrari than toyota, so one can live with some inconveniences, sensitivity to hum, huge size, leave it on 24-7 for best sound etc etc - now we add to the list if you have a less polished, but very good sounding tube preamp that thumps at turn on... well too bad...pick what is most important to you

makes me wonder if its worth it

ThePriest · « **Reply #7 on:** 11 Nov 2020, 07:21 am »

The usual recommendation is to turn the source on first, then pre amp, and power amp as the last.
When you turn on equipment 'upstream' of a turned on power amp (

) you get thumps.
I don't know your amp, is there a power save function? Or else, turn it off before you turn on your pre amp, then on again.

/The Priest

klaus@odyssey · « **Reply #8 on:** 11 Nov 2020, 11:22 am »

JJ, what are you talking about ???????

1. Yes, if done right, it should be optimized to the max
2. sensitivity to hum not more than most other amps....if there is a problem, then yes, it'll show you, just as others do as well.....and the funky thing here is that the better the ps 's are, the more of the issues they will show you...and our power supplies are awesome !!!!
3. 24/7 for best sound is pretty much ubiquitous to non tube amps...just a matter of power supplies being completely charged, so that is not unique to our amps either
4. $-wise it's about the equivalent of a 30 - 40 W. light bulb in idle...so it's not that expensive....however, your personal call if you want to do that or not.
5. The thump on turn on / off has nothing to do with any amp.....it's all in the preamp.

Is it worth it ????? Up to you, but don't blame the amp or any other components in your system should other problems arrive without understanding the issues first.....

Rusty Jefferson · « **Reply #9 on:** 11 Nov 2020, 11:42 am »

Turn off your amplifier(s) before turning off the preamp, and on after the preamp, or change preamps. You're going to damage your speakers.

MONKEYWICKEDMONKEY · « **Reply #10 on:** 11 Nov 2020, 03:27 pm »

I guess I had been doing it wrong all along.

Thanks

JackD · « **Reply #11 on:** 11 Nov 2020, 03:50 pm »

I have owned multiple Odyssey amps over the years with no issues with noise of any kind. Also currently own four different tube preamps from four different manufacturers and none of them cause a thump at turn on with the amp left on 24/7 as their are methods to design around that transient turn on thump. So in this case the issue is that particular preamp.

sunnydaze · « **Reply #12 on:** 11 Nov 2020, 03:52 pm »

Bit of a PITA, especially if access is difficult, but disconnecting the ICs from QS output before powering it on will prevent the "thump" from reaching the amp / speakers.

Problem is, sometimes that causes a loud hum / buzz. Depends on the amp. If it does, maybe disconnect them at the amp end? This will allow you to keep the amp warm, but I'd be slightly concerned about the eventual wear and tear on the connectors.

Rusty Jefferson · « **Reply #13 on:** 11 Nov 2020, 04:31 pm »

Quote from: sunnydaze on 11 Nov 2020, 03:52 pm

Bit of a PITA, especially if access is difficult, but disconnecting the ICs from QS output before powering it on will prevent the "thump" from reaching the amp / speakers.

Problem is, sometimes that causes a loud hum / buzz. Depends on the amp. If it does, maybe disconnect them at the amp end? This will allow you to keep the amp warm, but I'd be slightly concerned about the eventual wear and tear on the connectors.

Yeah, no. Don't disconnect the interconnects with the amplifier(s) on, ever. Especially solid state amplifiers.

sunnydaze · « **Reply #14 on:** 11 Nov 2020, 04:38 pm »

Quote from: Rusty Jefferson on 11 Nov 2020, 04:31 pm

Yeah, no. Don't disconnect the interconnects with the amplifier(s) on, ever. Especially solid state amplifiers.

Why not? Can damage occur?

I've done it many times with all different amp topologies. Sometimes loud hum or thump / popping sound occurs, sometimes it's dead quiet. Is it because these surges / noises can damage a driver?

richidoo · « **Reply #15 on:** 11 Nov 2020, 05:48 pm »

It's very common for tube preamps to put some unwanted voltage on their output when they first start up. That's why it has become audiophile lore to always start the preamp before starting up the amp, and reverse when shutting down, so the preamp antics can't harm the speakers.

The preamp will settle down after about 10 seconds of warm up, so many tube preamps have an automatic output mute during the first 30 seconds after turn on.

If you leave the amp on all the time to keep it warm, just turn it off for a minute while you turn on the preamp. The amp won't cool down in that short time.

Alternatively, you could mute/short the amp input externally, or lift speaker positive legs before starting the preamp if you didn't want to shut off the amp.

Nice system you got! I bet it sounds awesome....

richidoo · « **Reply #16 on:** 11 Nov 2020, 06:10 pm »

Quote from: sunnydaze on 11 Nov 2020, 04:38 pm

Why not? Can damage occur?

The hot cable unplugging causes a sudden change of voltage from whatever signal voltage was on the line to zero, aka "transient". The transient "pop" can excite any potential resonances in the system which can persist into a sustained oscillation. It usually starts at midrange frequency and climbs up quickly out of audio band, then you see smoke, flames or even sparks with aluminum ribbons. I've seen it twice. Once was with antique 200W OTL amps with the input cable deliberately pulled out by a cocky tech who just restored the amps and wanted to show off how stable they were (weren't.) The other was a popular tube DAC being shut off while connected to powered on Mac tube preamp and Mac SS power amp, very unexpected behavior, but quite a fireworks show from the aluminum ribbon tweeters! Its always a good idea to make sure downstream components are shut-off or muted before risking accidental transients. I've also heard two other components that used to be popular on AC start to oscillate for no obvious reason, luckily they could be unplugged before any damage. None were Odyssey!

sunnydaze · « **Reply #17 on:** 11 Nov 2020, 07:12 pm »

Thanks so much for the info.

I'll be more careful in the future!

klaus@odyssey · « **Reply #18 on:** 11 Nov 2020, 08:06 pm »

The posts are all pretty much right on the money...as for smoking a tweeter, add one more idiot: myself.
Last CAPfest I stepped on the IC's, bent the connector and as a result destroyed the Beryllium.....was a first, but happened.

Bottom line, give me 2 minutes with anything and it'll be done. Just taking a little care will go a long way.......

"Thanks Captain Obvious"

mdiehl · « **Reply #19 on:** 23 Nov 2020, 10:27 pm »

I have a Quicksilver line stage and do not experience any of these problems with my Kismet in Khartago case power amplifier. First, the Quicksilver line stage has a mute pause at the beginning. Second, I turn my volume knob down just to play it safe. But even if I don't turn the volume knob down, there is nothing more than an almost inaudible click when the line stage is ready for operation. Third, it has worked without any problems the entire time I put the Quicksilver into the system, which is about 4 years or so. Conclusion: I would check all the connectors to make sure everything is fine.