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Post by Deleted on Jul 30, 2006 12:35:09 GMT
In an attempt to listen at low volumes and not be on the cusp of being at the bottom of the Solo's volume tracking, I put a variable resistor in line so that the pot can be used roughly half-way up, giving a low volume to my Senn 600's.
I think that this has changed the sound of the headphone slightly though.
I then pushed the resistance up high and listened with the amp turned further up in order to see whether it got much more different. The Senns become lighter and maybe thinner sounding but the very bottom thwack of bass notes remain but die away quicker. Eventually, the amp clips, of course.
Has anyone else tried this and measured what was coming from the Senns?
Hopefully, this doesn't make the Solo sweat?
If there's a technical answer to this, is it possible to answer in English? I've been searching for two hours and can't cope with difficult words.
Ian
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rickcr42
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Post by rickcr42 on Jul 30, 2006 22:25:11 GMT
a better method would be to make an inline pad for the input or if you have the ability to actually change the gain of the amp for better volume control response with your cans. It is well known that stereo volume control pots track poorly at the bottom end of their rotation with the upper 75-90% best. Pretty much the reason (amongs other things ) I consider all commercial headphone amps a comprimise design.One aimed more to walking the "please everyone/all headphones" path rather than the very poor for business headphone specific target market. It would be pretty much impossible to carry and/or ship to dealers multiple versions of the same amp with minor differences depending on the end use headphones and why a solely internet based headphone amp business that does pretty much a custom build per order using a stock chassis (like singlepower) can.Having ready to build chassis work and loaded parts bins readfy to go IS feasable since all shipments are "one of" and custom builds rather than off the shelf Yup.Read this: www.meier-audio.homepage.t-online.de/tipstricks.htmthis graphic tells the whole story,one far too often overlooked as to the "why" certain amps voice a particular way while also being a clue to the knowing how to change the whole deal to satisfy YOU without costing the farm to implement A simple dual pot in a box connected as a rheostat (variable resistor) and NOT as a potentiometer is in effect a headphone tone control harmless to the amp.your ears will fail before the amp does I beleive the Meier Audio explantion is pretty straight forward but if not you could ask Jan Meier directly for futher illumination.He is VERY accessable and one of the good guys good luck rickster
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rickcr42
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Post by rickcr42 on Jul 30, 2006 23:23:04 GMT
for clarity : On the left is the traditional "potentiometer" hookup.this method uses all 3 terminals to form a voltage divider.The right picture is the "rheostat" type hookup and uses only two of the three terminals to form an inline variable resistor.
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Post by Deleted on Jul 31, 2006 20:02:15 GMT
Thanks Rick. I actually understand!!
Presumabely, noise levels are insignificant if I attenuate the input rather than the output?
Also, the headphone sound won't change if I cut the input. Currently, using the Senn 600 on the Solo, I'm right at the bottom of the volume track, just after where the tracking is skewed.
I can afford to cut it quite a bit if I track at 75-90% That's really high up the scale.
OK, I'll try attenuating the input instead.
Ian
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xerxes
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Post by xerxes on Jul 31, 2006 21:58:48 GMT
There's some information here that you might find useful: www.goldpt.com/pre.htmlThis is actually for stepped attenuators, but adding attenuation prior to a potentiometer will follow the same principal. Also, I imagine using a couple of fixed, precision resistors, say 1% tollerance, would give better results than adding another pot/variable resistor.
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rickcr42
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Post by rickcr42 on Jul 31, 2006 23:59:25 GMT
Correct.You get the thermal noise of the resistor (higher resistance+higher noise levels) but should be as you said,insignificant. Again correct-mostly.Since passive parts DO have their own sonic signature it would be best to use the same type resistor for the input pad as are already used in any signal path point of the amp proper. The absolute worst area of rotation for any volume pot and why so many swear of the potentiometer in favor of the stepper. I personally despise stepped atenuators becaus ethey never "step" exactly where I want them to so I endevour to gain match my amps so I am always somewhere in the middle of the rotation at normal levels while still having some slack for those rare low level recordings."Running out of amp" is as bad as havine too much amp. shoot for mid-scale as a happy medium.How I would do it is to use a dual pot connected as described above and adjust for the best volume/rotation comprimise then remove the pot and measure the value between the end and the wiper (the formerly connected end !).that is the value of the inline resistor you will want. the commercial version,originall meant to pad down a "hot" CD player output but just as applicable here www.rothwellaudioproducts.co.uk/html/attenuators.htmlor make something similiar by using adapters made by the same company.Usually all adapters in a single line will use the same barrel as a cost savings (kind of like using one chassis for all products ) so if you buy say a mini-to-male rca adapter and a mini-to-female rca adapter you can usually unscrew the "mini" part and add the opposite "sex" counterpart to the barrel.. Male RCA-Barrel-Female RCA with the resistor inside the barrel connected in series "hot" to "hot" hope this helps
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FritzS
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Post by FritzS on Aug 1, 2006 7:24:43 GMT
the norm for resistors in series with a headphone (output impedance of the headphone amp) is 120 OHM, but Sennheiser recommend near to zero OHM
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Post by Deleted on Aug 1, 2006 8:01:20 GMT
Thanks Rick. I'll give the in line resistors a try. It is better being able to actually use the Solo's volume pot to finely tune the sound. I don't like to listen on headphones too loud and the Solo is a powerful beast.
Edit: A neighbour of mine has some attennuators and I just tried it. The very ones that you put on this site Rick. They work well and I can use much more of the pot with them in.
I'm also detecting (I think) a very slight change in the sound. If anything, an improvement. The sound seems a little more open but I have to really concentrate and it has to be something recorded well to hear it. It doesn't alter the sound the same way with the resistance at the other end. (ie adding impedance to the headphone)
... and of course, as someone has pointed out above, the Senns need 0 ohms on the output so I should leave that end well alone, if you'll pardon the expression!
Anyway, I'm going to go for the Rothwells. They look good to me and my amp is easier to fine tune as far as the volume goes. Quite amazing on a headphone that is supposed to be difficult to drive!!!
Even with 10db attenuation on (Rothwells) the headphones are still powerful. I'm using the amp now at maximum 10.30 am!! The Solo really does chuck out a lot of welly!! At least I'm not on the cusp of the poor tracking now though.
Ian
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Post by Deleted on Aug 2, 2006 12:55:38 GMT
After a day with 10db attenuators, I'm happy with the sound as well as being able to 'more finely' adjust the volume. I'm not sure if it's my imagination, but it sounds slightly 'cleaner'.
The attenuators I'm using are the Rothwells. Very good quality. Are there any others with even more attenuation available commercially? I did a search and haven't come up with any. (Except expensive stepped attenuators or passive pre-amps)
Bad idea to add another 10db to the feed? I put the attenuation onto the lead directly into the Solo - how about putting another on the back of the CD player?
Ian
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rickcr42
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Post by rickcr42 on Aug 2, 2006 13:34:02 GMT
not that I am aware of other than in pro audio gear but those are mostly either balanced,can not be had in RCA connectors or are for microphone impedances.
likely actually IS cleaner since you are using a totally different area of the pot rotation.You may also have had input overload issues before that are now corrected though just a guess
The 'bad idea" part mostly that it is best to put attenuators on inputs (is part of a voltage divider formed by the amp input resistor and the inline attenuating resistor) and the additional inline connections. CDP output RCA jack to attenuator RCA plug to attenuator RCA out jack to interconnect RCA plug to interconnect to interconnect RCA plug to attenuator in to attenuator out to amp in RCA
Adds up to 8 connections !
The ultimate would be a single fixed resistor attenuator built right into your interconnects with second best being say a box with switched resistors
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rickcr42
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Post by rickcr42 on Aug 2, 2006 14:00:43 GMT
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Post by Deleted on Aug 2, 2006 14:02:15 GMT
Thanks Rick.
I just phoned the guy at Rothwell in Lancashire and he's offered to make me a bigger attenuator so that I can use the volume pot nearer to 11 or 12 o'clock, since I'm still down at 9 o' clock.
I'll keep the 10 db ones too. Really nice looking attenuators. Actually, they're not that bad and I can just about reach 11 or 12 o'clock but it's still ear splitting there.
I'm sure there is a spark more clarity. I never thought that maybe there was too much going in from the cd player, but turning up now brings me into/closer to the music rather than just get loud and blary!! (That's the best way I can describe what I'm hearing)
It would be nice if there was a gain switch on the amp since it is such a loud monster. (Fantastic sound though!!)
Thanks for your advice Rick,
Edit: Just in case anyone wants to put an attenuator in, (especially before the pre-amp) I used 20db in the end. That allows me to use most of the volume knob's tracking on the Solo. Most of the time, it's roughly halfway up. Classical - 2 o'clock, rock - 11 o'clock. If you like the music loud, maybe 15db would be a good compromise. It's worth doing.
Ian
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