Stratos Question

Jim Lee · « **on:** 12 Jul 2005, 07:25 pm »

I have ordered a Stratos amp and will be using it with the Bottlehead Foreplay pre. If my present SS amp is on when I power up my Foreplay there is a loud thump or pop in the speakers. I am using MMG speakers made my Magnaplaner.
My question, will this noise cause a problem for either the amp or speakers and if so is there a fix for this problem. All suggestions will be appreciated.
Jim

MaxCast · « **Reply #1 on:** 12 Jul 2005, 07:44 pm »

This happens with mine too. Stratos and Forplay. If you turn on your preamp first and then the Stratos it should be eliminated. If you like to leave your Stratos on all the time you could turn it off just before you turn on the pre then turn on the stratos.

I don't know if it can be eliminated by a fix on the preamp. If no body know here you can try the bottlehead forum.

corwin99 · « **Reply #2 on:** 12 Jul 2005, 09:11 pm »

Hmm.. I do not have this problem with my bottlehead when I use it with my stratos, but you should be turning your preamp on first, especially if its tubed... waiting 20 seconds and then turning on the power amp. The stratos has a short delay (8 seconds??) before it turns on completely so its a bit better.

Initially i had a problem with my bottlehead doing this but it was because one of the tubes was no good.

If you installed a timer on the bottlehead to not pass any signal until after 20 seconds or so of being on might fix it if you want to turn it off while leaving the stratos on.

Eduardo AAVM · « **Reply #3 on:** 13 Jul 2005, 06:01 pm »

I have here a Foreplay design based pre and I do not have that problem...

speedcenter · « **Reply #4 on:** 13 Jul 2005, 10:16 pm »

Quote from: Jim Lee

I have ordered a Stratos amp and will be using it with the Bottlehead Foreplay pre. If my present SS amp is on when I power up my Foreplay there is a loud thump or pop in the speakers. I am using MMG speakers made my Magnaplaner.
My question, will this noise cause a problem for either the amp or speakers and if so is there a fix for this problem. All suggestions will be appreciated.
Jim

put a mute switch on your Foreplay. Solved my problem. A simple DPDT switch that routes part of the Foreplay output to ground via a small resistor is all it takes. Turn it off once the tubes come alive. There's a 50 V jolt coming from the stock Foreplay as the tubes reach temps and kick in. The only other solution to reduce the thump is to separate the heater from the V+ supply and first heat up the tubes, and then turn on the V+ supply. In any case, with a stock Foreplay, it's gonna thump.

Peter

speedcenter · « **Reply #5 on:** 13 Jul 2005, 10:17 pm »

Quote from: corwin99

Hmm.. I do not have this problem with my bottlehead when I use it with my stratos, but you should be turning your preamp on first, especially if its tubed... waiting 20 seconds and then turning on the power amp. The stratos has a short delay (8 seconds??) before it turns on completely so its a bit better.

Real Odyssey owners never power down their amps... I think that's what is at the core of the problem here.

Peter

Eduardo AAVM · « **Reply #6 on:** 14 Jul 2005, 01:15 pm »

Quote from: speedcenter

Real Odyssey owners never power down their amps... I think that's what is at the core of the problem here.

Peter

Hehehe, good point, nice way to express it...

hifishaggy · « **Reply #7 on:** 14 Jul 2005, 07:16 pm »

Found this on the bottlehead website from the designer, this might be the cause of the problem, they say there is a fix but I don't know what it is, though I am sure you could ask on the bottlehead forum. Here is what bottlehead says under the foreplay:

Any fine tuning involved?

The gain for each input in the Foreplay III can be adjusted by choosing the right resistor, so that all the various sources will use pretty much the same volume setting. Depending on the signal output of your source devices, and the sensitivity of your amplifier/speaker combination, choosing the right value may take an iteration or two. Some source devices produce enough ground loop current to create "pops" when switching due to the switched grounds; there is a modification to alleviate this problem, at the expense of slightly increasing the chance of ground loop hum. The preamp comes with serviceable old-stock tubes, but many - probably most - will try a few different brands to optimize the sonics for their system and ears. Those are the only "fine tuning" items that I am aware of.

KarlDL · « **Reply #8 on:** 18 Jul 2005, 01:22 am »

quoted Bottlehead tip has nothing whatsoever to do with the problem noted. appropriate fix is a mute switch or relay that doesn't connect the pre output until the tubes are warmed up and internal DC voltages have charged up to nominal levels. most any pre, tube or SS, is going to generate a "thump" at its output upon turn-on, absent a mute feature. the Tempest avoids this by means of a mute relay that turns on about a second or two or three after power is applied.

tube life is greatly enhance by NOT turning the pre off. if technically inclined, you may install a switch to allow plate HV on/off to conserve power. but the filaments suffer time-off-their-lives every off-on cycle. (in my day job, I deal with tubes that cost $30K to replace)

KDL

speedcenter · « **Reply #9 on:** 19 Jul 2005, 07:32 pm »

Quote from: KarlDL

tube life is greatly enhance by NOT turning the pre off. if technically inclined, you may install a switch to allow plate HV on/off to conserve power. but the filaments suffer time-off-their-lives every off-on cycle. (in my day job, I deal with tubes that cost $30K to replace)

well, I prefer the mute switch over leaving the tubes powered up: my tubes cost $300 to replace, but there's no way in hell I'll leave anything I built myself powered up when I am not around the equipment. I consider the power cycle life loss of the tubes my DIY audio equipment fire insurance fee.

Peter

BikeWNC · « **Reply #10 on:** 21 Jul 2005, 11:04 pm »

Quote from: KarlDL

tube life is greatly enhance by NOT t ...

So you leave your tube gear on 24/7? Even when you not at home or plan to be out for an extended time? It makes me a little nervous to think about those tubes aglow while I'm away.

Andy

wrayman · « **Reply #11 on:** 22 Jul 2005, 01:03 am »

I also have a tube pre and SS amp ( Stratos Extreme

) Hate leaving the pre on all the time, thinking of how much faster the tubes are gonna wear out

Started disconnecting the pre and shutting it down at night, then reconnecting when I want to listen. Luckily there is no pop or thump when I reconnect, making the procedure easier on the nerves.

Chow for now,
Mike

KarlDL · « **Reply #12 on:** 22 Jul 2005, 02:03 am »

The point is that cycling the tube filaments on and off is going to shorten life far more than leaving them on continously. I began my career in broadcast facility engineering back when much small-signal equipment still contained tubes. We seldom, if ever, shut it down and tube life was pretty good, measured in years, not months. Detailed, controlled studies on high-power tubes by the Voice of America and others, within the past 10 years, showed lifespan reductions of up to 70% from shutdown when not in use. Thoriated filaments are used in both high-power and small-signal tubes, so there is not a substantial physical difference that would suggest that small-signal tubes won't enjoy the same benefits of continuous heat. And empirical experience 30+ years ago supports that.

Speedcenter makes a rational point about safety concerns, which apply to some folks (especially those with inquisitive children or pets).

The approach of the prior post certainly covers the "thump" issue, but the deterioration of tube filament longevity remains.

John151 · « **Reply #13 on:** 22 Jul 2005, 02:25 am »

My Tempest has the HT bypass. I have found that I can turn off the Tempest when in HT mode, and not get the thump.