fair enough
sorry - I can't help you with any particular finished product ;
perfect .
Listening to some of my own albums without the LS25. I know the sound very well on these records as I mixed and mastered them as well. The sound without the preamp is much better. It is addicting. I've done some research into quality passive attenuators and this sound just might inspire me to make a passive preamp!
I suppose I need to deal with a bit of the learning curve though. I am sure there are some concerns with impedance and the quality of the attenuator and the source selector. I heard Shallco makes good ones? Also cable length becomes an issue. Plus I know nothing of drilling holes and cutting cases to fit the parts... But it is not rocket science and if I can understand the theory of Schoenberg and Messiaen, I suppose I can learn this as well.I need 6 inputs with a tape loop. It would be nice if I have a choice of RCA or balanced as well on all ins and outs.
so - it's time for new thread
if you choose DIY route , take it as fun , not cheaper way for having a new box ;
look for relay based selector , it's more convenient for placement at back plate where connectors usually are ; you can use ALPS pot for start and later try some more seductive one
same for buffer - you don't need it on tape out if you're using tape rec occasionally ; on/of rec out relay is perfect substitute so you're loading signal route with rec only when you're really recording
if you need that rec out permanently - you must place buffer there
main out - if you're careful enough with cables you don't need buffer
if your fave wires are capacitive , you need buffer - either Jfet based or decent tube one
if you choose DIY route , take it as fun , not cheaper way for having a new box ;
look for relay based selector , it's more convenient for placement at back plate where connectors usually are ; you can use ALPS pot for start and later try some more seductive one
same for buffer - you don't need it on tape out if you're using tape rec occasionally ; on/of rec out relay is perfect substitute so you're loading signal route with rec only when you're really recording
if you need that rec out permanently - you must place buffer there
main out - if you're careful enough with cables you don't need buffer
if your fave wires are capacitive , you need buffer - either Jfet based or decent tube one
Passive Pre
Would this help?
http://www.diyaudio.com/forums/swap...sformer-volume-control-tvc-seiden-switch.html
Looney
Would this help?
http://www.diyaudio.com/forums/swap...sformer-volume-control-tvc-seiden-switch.html
Looney
if they're on par with Dave Slagle's and some DIY autoformers/xformers I had opportunity to play with - that's certainly good route
I do know a bunch of studio people. I say people because I can't think of any that are very tech oriented. It's funny. Most just use commercial gear and not too much into hifi. But I'll ask around.
Not a studio guy but I met a tech today. I learned a whole lot and was very enjoyable to speak to someone who is passionate about audio electronics. I am always inspired by people who do what they love in their lives.
Resolution:
After taking measurements of noise in both SE and differential and consulting with ARC, this LS25 II is indeed within spec. So it comes down to my expectation and the high sensitivity of the Focal speakers. ARC's reference speaker is 88db efficiency.
However, there is a 6db gain reduction mod which a tech I consulted here in NYC tells me is the ticket for me. This preamp being high gain @ +18db on high setting, I think.
It is still interesting to me that a Arcam solid state preamp costing less that the 2 6h30 tubes from ARC is dead quiet in my system. Although, sound wise, there is no comparison... Compromise is part of audio life as well, I guess.
Looking forward to doing the mod.
After taking measurements of noise in both SE and differential and consulting with ARC, this LS25 II is indeed within spec. So it comes down to my expectation and the high sensitivity of the Focal speakers. ARC's reference speaker is 88db efficiency.
However, there is a 6db gain reduction mod which a tech I consulted here in NYC tells me is the ticket for me. This preamp being high gain @ +18db on high setting, I think.
It is still interesting to me that a Arcam solid state preamp costing less that the 2 6h30 tubes from ARC is dead quiet in my system. Although, sound wise, there is no comparison... Compromise is part of audio life as well, I guess.
Looking forward to doing the mod.
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Just want to correct error. After reading the tech notes, this mod reduces gain by 6 db from +24 to +18.
Now to the soldering iron
Let me guess: this involves raising R9 from 1.5k to above 4k or thereabouts, right? It seems the only place you can reduce gain and not make S/N worse.
Unless it involves reducing the 15.4k resistors
Basically it's either attenuating the output or increasing the NFB. If i were doing it it would take a lot of auditions to decide which is the lesser evil.
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Let me guess: this involves raising R9 from 1.5k to above 4k or thereabouts, right? It seems the only place you can reduce gain and not make S/N worse.
Unless it involves reducing the 15.4k resistors
The mod from ARC is to take out R9. First of all, their tech note states 1.82k resistor. It's 1.5k and this did nothing for the noise.
For the LS25 mk II preamp. The mod reduced the gain but the noise was just the same.
I suppose if I lower the gain on the VS60 power amp, it'll lower noise. I think I will accept that the SE output on LS25 is just not that great.
completely logical ;
that will lower noise , and that is a way how I understood you in first place , just because gain lowering in preamp doesn't have anything with noise in amplification chain
ask that tech how to lower gain of amp itself
or give us schmtc and we will tell you
I am considering balanced to unbalanced transformer converter. The thing is the ones you can buy might work in a recording studio for instruments but I believe it will detract from the sound in a Hifi system. Do you know of a good hifi balanced to unbalanced transformer converter? The balanced out on the LS25 is very quiet.
I don't have a schematic for VS60. I'll have to get one.
I don't have a schematic for VS60. I'll have to get one.
even if I really like xformers in my audio chain ( now I'm running ancient repeater coils 600:1200 , connected as 1+4 autoformers ; it's between heavily changed Pioneer PD8500CD player (I/V xformer +buffer) and Papa's Koan F4 ; no volume between ) .......
anyway - even if I really like them - I'm using them in place of something , not as cure for something
are your sources balanced , so you have benefits from running balanced up to preamp output ?
edit :
give us few high res pics of VS from inside , and maybe we can figure out something regarding gain
anyway - even if I really like them - I'm using them in place of something , not as cure for something
are your sources balanced , so you have benefits from running balanced up to preamp output ?
edit :
give us few high res pics of VS from inside , and maybe we can figure out something regarding gain
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