Right, but I'd go with 30 seconds, just to be sure. Shorting to ground is safe, breaking the signal line could cause noise.
Also shorting the buffer output does not add contacts to the signal path.
Also shorting the buffer output does not add contacts to the signal path.
Yes, be sure to use a low leakage timing capacitor (it will be large, RC ~ 20 Sec).
Normally closed (shorting) relay.
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Did you read the very good and complete manual of the ICE 700? It covers really anything I can think of. Please read!
This amp has a symmetric input buffer with 2x 47k ohm. The circuit is on page 24/46.
There is no problem (it is described in the manual!) to use a single ended pre amp. Just ground the cold (-) input and use the hot (+) input and you are done.
Any additional "buffer" is useless and would only degrade sound quality.
If for some reason you want to induce valve made distortion into this perfect amp, use a 1uF capacitor and put a gain 1 valve stage in front of it.
Sorry, this whole tread is based on wrong information.
If you get an older ICE module, like the 500, 1000 or 250, the input has no buffer and 8k ohms input impedance. These modules need a symmetric buffer to reach full potential. As far as I know the rest of the amps (700-500 etc) is mainly identical and "sound" is just as good.
All ICE amps are very good and if implemented right you will not be able to find something audible better. Off course, only if you are objective and ignore marketing hype.
This amp has a symmetric input buffer with 2x 47k ohm. The circuit is on page 24/46.
There is no problem (it is described in the manual!) to use a single ended pre amp. Just ground the cold (-) input and use the hot (+) input and you are done.
Any additional "buffer" is useless and would only degrade sound quality.
If for some reason you want to induce valve made distortion into this perfect amp, use a 1uF capacitor and put a gain 1 valve stage in front of it.
Sorry, this whole tread is based on wrong information.
If you get an older ICE module, like the 500, 1000 or 250, the input has no buffer and 8k ohms input impedance. These modules need a symmetric buffer to reach full potential. As far as I know the rest of the amps (700-500 etc) is mainly identical and "sound" is just as good.
All ICE amps are very good and if implemented right you will not be able to find something audible better. Off course, only if you are objective and ignore marketing hype.
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The 8k minimum input impedance is mentioned on p24 in the manual provided in the 1st post of this thread. Since he is intending to use a SRPP tube preamp as frontend, this is probably a bit low w/o a buffer...
Marcus
So would it be agreed that these modules would benefit from some unity gain stage to be driven buy both tube and SS preamps?
Dominic
Dominic
See the attached schematic. I made this schematic based on the design shown on the cathode follower page on the Valve Wizard sight.
The Valve Wizard -Cathode Follower
Let me know if I should change or add anything.
Thanks
The Valve Wizard -Cathode Follower
Let me know if I should change or add anything.
Thanks
I clearly stated, the 700 does not need a buffer or pre stage, it can only sound worse if you put something useless in front of it.
It already HAS A BUFFER STAGE!
Read the f***** manual!
The input has 47k Ohm impedance! Not 8k!
I know that "valve guy´s" are very religious. They believe that these old stuff has some magical abilities...
It already HAS A BUFFER STAGE!
Read the f***** manual!
The input has 47k Ohm impedance! Not 8k!
I know that "valve guy´s" are very religious. They believe that these old stuff has some magical abilities...
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I did read the manual, but the issue is I don’t understand everything in the manual, and not everything can simply be googled for every scenario either. That is what these forums are for. I did not know that the 47k resistors explicitly set the input impedance.
Yes, typo, meant ECC82/12AU7.
I attached a new copy.
Will this be ok?
I'm looking to get multiple opinions on it, and if this input buffer is completely unneeded I would forgo it. Turbowatch definitely thinks it isn't needed.
In know in the Stellar line from PS Audio, they use a "gain cell" in front of these modules. I'm assuming that circuit at least provides some unity gain as well as switching between balanced and unbalanced inputs without the need for a switch. This design along with some others led me to believe it is preferable to have a buffer in front of these modules, but maybe it isn't.
Thanks
I attached a new copy.
Will this be ok?
I'm looking to get multiple opinions on it, and if this input buffer is completely unneeded I would forgo it. Turbowatch definitely thinks it isn't needed.
In know in the Stellar line from PS Audio, they use a "gain cell" in front of these modules. I'm assuming that circuit at least provides some unity gain as well as switching between balanced and unbalanced inputs without the need for a switch. This design along with some others led me to believe it is preferable to have a buffer in front of these modules, but maybe it isn't.
Thanks
From the CF plate there should be a 10uF-50uf electrolytic capacitor to ground, to provide
a low impedance path for signal current.
Here is the input buffer of the 700asi-x.
The older 500ASP /250 /1000 did not have this buffer. You had to add a very stable, summetric (!) buffer to the circuit, otherwise a low impedance, changing over the frequency band was the result.
If you put one end at ground and feed it by a single ended pre-amp, the sound quality was compromised.
Exactly this missing buffer is the "Evolution" of the newer modules. Simpler to integrate.
You could put a good transformer like this (Lundahl) Lundahl 1545a Audio Transformer
at the input and drive it single ended (or balanced). Some manufacturers give the ICE amp their "special sound" with such add on´s. A valve buffer has the same effect.
The sound of the 700 does not get better with them, it just changes. You have to judge if it is for the better. IMO try the 700 without, first, invest the money in a nice housing and good connectors.
Ignore the 8k in the text. Look at the Schematic.
The older 500ASP /250 /1000 did not have this buffer. You had to add a very stable, summetric (!) buffer to the circuit, otherwise a low impedance, changing over the frequency band was the result.
If you put one end at ground and feed it by a single ended pre-amp, the sound quality was compromised.
Exactly this missing buffer is the "Evolution" of the newer modules. Simpler to integrate.
You could put a good transformer like this (Lundahl) Lundahl 1545a Audio Transformer
at the input and drive it single ended (or balanced). Some manufacturers give the ICE amp their "special sound" with such add on´s. A valve buffer has the same effect.
The sound of the 700 does not get better with them, it just changes. You have to judge if it is for the better. IMO try the 700 without, first, invest the money in a nice housing and good connectors.
Ignore the 8k in the text. Look at the Schematic.
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How about one of these? Looking to put one im front of 3e audio 3255 board
How about one of these? Looking to put one im front of 3e audio 3255 board
Great, thanks Turbo. I will research that transformer more tonight. I’m sure I will have more questions about it.