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Stunning BHSE Tweak - Page 2

post #16 of 27
Thread Starter 

Edited by rsbrsvp - 5/18/14 at 9:01pm
post #17 of 27

Taken from another topic:

in theory, if you are definitely sure you will always be using a preamp, then the DACT would be a BETTER option!  since you wouldn't be employing the rk50's benefit of precise volume adjustment, the dact would run the signal either with at most 2 resistors in the path, and potentially with nothing at all in the signal path (youd have to check the schematic for the dact).  the rk50, even at 0db attenuation, still runs through a sweeper (although a very very good one)

post #18 of 27
Thread Starter 


Edited by rsbrsvp - 5/18/14 at 9:01pm
post #19 of 27

Isn't the DACT a ladder attenuator?  That means you just switch between stages in the ladder with a number of resistors in the signal path on either side.  Only two resistors would call for a shunt attenuator. 


Originally Posted by rsbrsvp View Post

I have indeed replaced the cheap power source in the MAC with the MOJO Audio power source.  I also have the K-Line filter from Ridge Street Audio to remove computer noise not related to noise from the wall.


No, you just replaced one PSU and the one which is arguably the best of the lot.  There are a lot of PSU's inside the computer delivering the multitude of voltages required to run the chip cores, HDD etc. 


As with other snake oil BS that K-line stuff holds no details of what it actually does.  There are only two filters that actually work, galvanic isolation or optical isolation.  Can't use transformers on this as you still need the ground for the USB handshake to work so the only way is to go optical after the USB receiver.  Ohh and optical does not mean toslink which is just bad all the way. 

post #20 of 27

If I ever replace my RA150 balanced speaker amp with a "much better" one, it will be a Firstwatt or BAT balanced power amp without any volume pots. I believe that most high-end DACs these days have enough digital headroom to avoid any audible distortion with digital attenuation, and my phono stage has a separate class A gain cell as well.


But even if I didn't have separate attenuation available with those components, my preamp has a great stepped attenuator and of course there are options form the computer as well in my case (no preamp/attenuator in the DAC). I don't have any need for attenuation from the power/speaker amplifier/electrostatic energizer end of things.

Edited by grokit - 4/20/13 at 2:04pm
post #21 of 27
Thread Starter 


Edited by rsbrsvp - 5/18/14 at 9:01pm
post #22 of 27

Ehhh,.. how on earth is an autoformer (or rather a multi tapped transformer) or a LDR superior in terms of signal path compared to a single resistive track made with such precision?  I know I'm talking to deaf ears here but this is ludicrous even by your standards.  DACT's are worse since they are a series of resistors so on the 3rd step there are 21 resistors in the signal path.  Go louder and there are less and less resistors in the path.  Stepped transformer is the same idea except with meters upon meters of very fine wire.  The LDR's are far from linear devices and computer based attenuators throw away data.  The only truly great way of dealing with volume is in the Ayre KX preamp but it's complicated and can't be retrofitted into anything.  It's also highly vulnerable to the components used. 


You are also aware of all the resistors inside the amp that are in the signal path? 


Just so people get the context of this, the OP once had the brilliant idea of warming up the BHSE with cheap EL34's and then hotswap in some "good" tubes that had busted cathodes after being used in the Single Power trainwrecks.  This is with the amp running so it wouldn't cool down in the meantime.  He asked Justin, Kevin Gilmore and myself about this and we all said it was truly stupid idea but he did it anyway.  Naturally this blew up the active circuitry driving the cathodes of the EL34's.  It is not like the EL34's form an intergral part of the circuitry or anything like that... 

post #23 of 27
Thread Starter 

Edited by rsbrsvp - 5/18/14 at 9:00pm
post #24 of 27

I'm sure I can find the PM's if I'd bother to look plus Kevin and I have discussed this in the past as an example if we can build amps robust enough to handle such tomfoolery.  Nothing to apologize for on my end. 


Also nothing wrong with tweaks but asking people to throw away a 1k$ volume pot based on some very dubious "expertise" has to come under scrutiny.  If you lift the fet resistors on the front end for some reason you are asking for trouble and since they are right after the volume control somebody might do just that.  Not sure if you remember but I've had some Ridge Street cables in the past and the guy came across as pretty clueless. 


I've probably spent more than most trying out volume pots (ordering up to 100 in one go just to get one sample) so I know perfectly well the impact they can have and that maxed out they are indeed out of the circuit. 

post #25 of 27
Removing the rk50 from the circuit changes the input impedance from
100k to several meg ohms making the cable interaction much more
Reactive. Also makes it way easier to blow up the input fet.
Rk50 at full volume adds less than 50 ohms. Dact at full volume
Adds less than 10 ohms.

Evidently when he removed the RK50 he replaced it with a 50K resistor
which makes everything OK. (well 4 of them)
Edited by kevin gilmore - 4/22/13 at 4:14pm
post #26 of 27
Thread Starter 


post #27 of 27
Originally Posted by spritzer View Post
The only truly great way of dealing with volume is in the Ayre KX preamp but it's complicated and can't be retrofitted into anything.  It's also highly vulnerable to the components used. 


Isn't that similar to the way that the Audio-GD Pre-Amp does volume control as well? Using the resistor ladder after the current gain stage as the IV conversion and the volume control at the same time.

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