kev
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Post by kev on Jul 13, 2016 19:48:33 GMT
I have an Ember II & a Little Dot Mk IV se & want to add tubes to my main setup. Is there any difference in the design of these headphone amps & a pre amp designed to drive a power amp? I know that the LD has a max output of 10 Volts, so I would have to be careful to keep the vol cntrl in the range of a 1V line level. My power amps are around 70K input Z & the LD output Z is 600 ohms, so that should be OK. Not sure about the Ember output levels. Do the gain settings on the Ember effect the pre out level? Any insight on the subject of using a headphone amp as a preamp is greatly appreciated. Thanks, kev
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Rabbit
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Post by Rabbit on Jul 14, 2016 17:19:09 GMT
Hi Kev. Welcome.
The Ember II is a hybrid. I'm not sure, but I think the Little Dot is a pure tube amp?
I don't think that the gain setting affect the output from the line out. Either Frans or Jeremy will need to get back to you on this to confirm but Frans isn't able to answer at the moment.
If the Little Dot puts out 10v, I'd be very cautious. You don't know what voltage you're sending out for what volume setting you have so it's guesswork.
I am very careful about Little Dots. I had a Little Dot II years ago that I really liked a lot with the Senn hd650. It got hot as hell but it had a lovely 'rubber band' type bass. Unfortunately, I switched on one da hand it did a massive indoor fireworks display for me which kind of froze me to my seat! It was rather spectacular and once it all went out, I had to throw it and the table that it was on out.
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kev
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Post by kev on Jul 14, 2016 20:07:56 GMT
Wow! I hope it's not a common thing. First time I have heard of such a thing. Any idea what happened? As far as the output voltage, I can run my source at full vol (1V) & measure the output of the preamp so I can set a maxvolume position on the volume control for 1V out. Then I should be able to use any source that comlys with line level spec. I am wanting to build a tube power amp, but my speakers are not very efficient, so an appropriate powered amp would be expensive. Actually, I think I would prefer a tube in the gain stage & SS in the power stage to maintain good tight bass. Anyway, thanks for the warning, I will tread lightly around the LD. BTW The spec for Ember II says maxoutput voltage is 15.7V rms @ 300 ohms. A quick look at the Ember schematic shows that the gain jumper & output resistance are common to both the headphone & pre out. IIRC the pre amp out is taken off at the headphone jack.
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Rabbit
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Post by Rabbit on Jul 14, 2016 20:59:25 GMT
My Little Dot got so hot that I was unable to touch anything metal when it was on. When it finally blew, it was quite spectacular.
You know, if Jeremy doesn't turn up here, it might be a good idea to ask him about the line out. I used mine a while back into some active speakers and I had no problems. Mine is a MK 1. I moved house to a much smaller place and decided not to put speakers up in the front room so I don't use the Ember as a preamp any more. It sounded extremely good though.
Frans isn't around at the moment so he can't get back with regards to this but Jeremy might turn up.
He's pretty good at returning email answers on the Garage1217 site.
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kev
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Post by kev on Jul 14, 2016 21:26:24 GMT
My Little Dot got so hot that I was unable to touch anything metal when it was on. When it finally blew, it was quite spectacular. You know, if Jeremy doesn't turn up here, it might be a good idea to ask him about the line out. I used mine a while back into some active speakers and I had no problems. Mine is a MK 1. I moved house to a much smaller place and decided not to put speakers up in the front room so I don't use the Ember as a preamp any more. It sounded extremely good though. Frans isn't around at the moment so he can't get back with regards to this but Jeremy might turn up. He's pretty good at returning email answers on the Garage1217 site. I'm not surprised that the LD worked with powered speakers. It's output pobably exceeds the spec for line leven & that's usually what powerd speakers want to see. I would assume that you had to keep the volume control away from >12 o'clock or lower the source level. Although, I don't actually know the max output of the LD 1 amp. Regards, kev
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Rabbit
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Post by Rabbit on Jul 15, 2016 6:29:57 GMT
Oh no, Kev. I used the Dot with headphones. I was just warning about heat in them.
I was thinking about the Ember and remembered that the vol pot does indeed affect the line out on the v1. Not sure what was done to v2 though.
Either Jeremy or Frans will spot this though, although you'll do no harm trying it as long as the pot stays down and you tweak it up.
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kev
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Post by kev on Jul 15, 2016 21:48:25 GMT
Oh no, Kev. I used the Dot with headphones. I was just warning about heat in them. I was thinking about the Ember and remembered that the vol pot does indeed affect the line out on the v1. Not sure what was done to v2 though. Either Jeremy or Frans will spot this though, although you'll do no harm trying it as long as the pot stays down and you tweak it up. I had a response vanish? Anyway, I think I said Oh, I see an Ember. Yes the vol cntrl works on both outputs. That's because the pre out comes off the headphone jack, so anything upstream of that is common to both. I had a peek at the schematic, so now I can see that the gain jumper will effect the preamp out as well. As does the output resistor selection. Just have to play around & see which sounds best I guess. Since the Ember output voltage can be as high as 15V, I may reduce the level of my source so I can have more travel on the Ember volume cntrl & still keep it under 1V. My power amps don't want to see more than 1V, which is pretty standard as a line level spec. Regards, kev
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Rabbit
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Post by Rabbit on Jul 16, 2016 6:01:59 GMT
You know, the disappearing post once happened to me!! I then wondered whether I'd actually pushed the send button....
Then I thought that I must be losing my marbles!!
Come to think of it, you are right. I used to drive some active speakers from it and I did control the volume from the Ember. I set the volume on the speakers to a lower level and had a very long phono lead to my armchair, so I could adjust it without getting up!!!
I never found it a problem though.
I also adjusted the source level so that the max didn't send my speakers into distortion. (If I could)
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solderdude
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measureutternutter
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Post by solderdude on Jul 24, 2016 19:01:32 GMT
The Line-out of the Ember has an output 180 Ohm output R and max output voltage of 3.2V. The line-out is an attenuated version of the output signal (0.18x = -15dB)
This is enough to drive all power amplifiers and the low output R ensures a high bandwidth and nor problems with low input resistances found in some amps.
In the Ember-II the output R setting has a small influence in the output level on the RCA (on high output R setting the output level is 1dB lower than when set on low R)
The input attenuation jumper influences the overall gain but has no influence on the maximum output voltage.
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