Rabbit
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Post by Rabbit on Dec 22, 2013 20:40:44 GMT
I was listening to a grotty download on a tablet today and connected it to the Ember from the headphone out so that I could listen on the HD650.
To my ears, it sounded congested and compressed. I lowered the volume on the tablet and it seemed better but very low in volume. So in desperation, I just stuck a Neco in as a kind of preamp.
The sound seems to have gained some more dynamic range. Tablet at just over half whack with the Neco at about half to three quarters and then using the Ember to control the volume.
Not good to have two amps in line but my crappy tablet sound seems to have become more lively as a result.
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Post by deireleire on Jan 6, 2014 11:20:27 GMT
Question on this pre 'buffer' amping. What would happen if one would place Frans' new filtered portable amp before the ember. Would the headphones receive a 'filtered' tuby sound or just a crappy sound?
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solderdude
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Post by solderdude on Jan 6, 2014 12:27:56 GMT
It would be tuby and thus crappy but would also be filtered.... which would mean.... crappy2. Or is 'crappy' negative by nature and minus x minus = positive ? I am confused.
I planned to make the PCB design and a proto in the last few days but a nasty flu changed those plans.
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Rabbit
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Post by Rabbit on Jan 6, 2014 16:33:02 GMT
The thing is that one amp into another means two lots of problems, I guess. I was just trying to raise the volume level from my tablet and one amp was giving enough, so I raised the input with the Neco. It's not hi fi at all but it was the only way to get the second amp to drive the 650 reasonably well tbh. The output from the tablet is very low.
I don't normally do it!!
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solderdude
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Post by solderdude on Jan 6, 2014 19:44:59 GMT
In fact there is nothing wrong with adding amplifiers in front of an amplifier to boost the signal to levels the last amplifier can handle.
An example: low output MC cartridge -> MC pre-amp -> RIAA amplifier -> pre-amplifier -> power amplifier. These are (or can be) all separate devices and some may or may not be battery fed.
After all most amplifiers themselves consist of various stages each increasing the gain.
consider this: low output MC cartridge -> MC pre-amp -> RIAA amplifier -> tube buffer -> pre-amplifier -> active XO -> power amplifier(s).
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Rabbit
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Post by Rabbit on Jan 6, 2014 20:56:53 GMT
Yes, that's how it works but purist types tend to turn their noses up when you pair two (in effect) power amps in series. The output level from the tablet was very low in comparison to a line out. I could turn the volume up to 100% but it was stressing the output from the tablet itself, so I just turned it back down and used the first amp to boost it to as close to 2v as I could guess from the vol pot setting on the second amp.
That way, nothing was running flat out which gave me the benefit (I think) of better dynamics on the HD650.
I guess the disadvantage is that one set of potential nasties is passed on to the second which amplifies them and adds them to the second amp's own nasties. However, the reality is that amps are pretty good really and it doesn't sound nasty at all!!
It was a kind of balancing act too, I guess, getting the S/N ratio as low as possible since tablets can be quite noisy and the noise doesn't always go up and down with the volume. It stays constant so there is a balancing act to get the output as loud as possible while avoiding compression at the tablet end and then allowing the first amp to boost it to the necessary level that enables the second amp to drive at normal levels.
In the bad old days, it could be done from synths (Cheap ones) and tapes with samples on (No samplers then) which could be very noisy, in order to cut the noise without using a noise gate. Turn synth up loud in order to gain as much sound above the noise of the synth itself and then use an amp (or resistor circuit) as a buffer to reduce the volume so that the sound (and the noise goes down to an acceptable level for power amps to turn up for speakers.
Early noise gates were a bit nasty. Phil Collins snare drum being a horrid example of a nasty noise gate, adjusted badly on purpose to give the effect of a quick shut off!! The sad thing is that it became a trademark of his drumming that everyone seemed to like a lot!!! (The drum entry in 'In the Air')
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Deleted
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Post by Deleted on Jan 6, 2014 22:17:19 GMT
Couple of things I might add. As Frans says, there is nothing inherently wrong with putting one amp in front of another. IIRC, didn't MF bring out a range of amps called 'Superchargers' which were just kick-ass power-amps which took a feed off your weedy power-amp\integrated. This was when MF were going through their "Power is Everything" phase. Second point. I am embarrassed to say that I am that sad individual that really quite liked the gated drum sound that old Phil adopted in the eighties. Loved that kind of long drawn out "attack" to each drum-strike, then a super-quick "decay", as if there was no decay at all. Still think it sounds cool Been listening to Visual Audio Sensory Theater for a few weeks now, and really like them. Listening to April at the moment. Some of the vocals remind me of early Thom Yorke and some of the rhythms, especially of the later albums have a definite U2 flavour to them, maybe something to do with the drumming? Anyway, great band.
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Rabbit
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Post by Rabbit on Jan 6, 2014 22:32:45 GMT
Second point. I am embarrassed to say that I am that sad individual that really quite liked the gated drum sound that old Phil adopted in the eighties. Massive use of the noise gate and a ton of compression so that the snare hits are as loud as possible. A loudness war on a drum!!! It became the drum sound of the time along with the Roland drum machine that he used. (and I did too ) Funnily enough, that drum sound has been sampled so many times by other artists and used on their albums too. Phil playing, but he was never there!! Sad ...... Well, he developed hearing problems himself. Had neck problems. Hand problems. Now fighting depression. There is also 'talk' about reviving Genesis with Peter Gabriel. That's also a bit worrying since it has the potential to be a bit of a let down imo. The guys aren't the same any more. However, poor Phil. Had a bad time of it in recent years.
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