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I have this amplifier that has both balanced and unbalanced inputs with a toggle switch to select either one. The amp has dual volume controls so I decided to connect my phono stage directly to the amp with balanced cables, my question is:
Can I connect both my CD player and phono preamp and select either one with the switch?
Would this cause any damage to either the speakers or the sources?
to get the 'last nth' of performance from this amp, I'd replace the level pot with either a stepped attenuator or a pair of 1% resistors. Probably next to the lowest wattage I could get.
The pots on the amp are a real bargain part. I leave my level controls all the way 'up' to keep them as much out of the circuit as possible.
I haven't cracked the case. Does anyone think their is ROOM for a stepped attenuator?
Too much is never enough
Yeah, there are a lot of 'bargain parts' in certain Parasound components, but I know that is not necessarily an indictment of their sound. Indeed, a lot of parts in the E.A.R. gear I was talking about earlier would be considered 'bargain parts' too.
As an aside, I swapped out the gain controls on the E.A.R. 861 amp I was talking about for much higher quality pots (stepped attenuators would not fit).
Wow - I'm really surprised at a few of the responses in this thread. A few things that I've found to be true in my experience:
* Dual volume pots are better than one single volume pot (channel imbalances are a lot more common on very expensive hi-fi gear than people think)
* Dual voltage gain controls are better than one single gain control
* You can easily use 'gain controls' as volume controls, but adjusting 'gain controls' will also take into account the capacitance of your cables more than traditional 'volume controls' do with an amplifier that has a fixed gain
Personally, I very much strive to eradicate the volume control from my system and solely focus on the voltage gain of my components playing well with each other. You get a ton of transparency, but it is one of the tweakiest audiophile rat-holes you can ever venture down (aside from hardwiring all of your components together so as to entirely avoid RCA or XLR connections).
A lot of the E.A.R. amps, Parasound amps, old McIntosh amps, and a few others that I cant think of at the moment have dual voltage gain controls at their inputs. I know that some Accuphase amps have a single dial which offers 3 settings for their voltage gain too.
Perhaps some people commenting in this thread shy away from the inconvenience of having to bend down and twist two knobs manually. Perhaps some dont like dual volume pots that leave some doubt (unlike stepped attenuators) on whether their volume is equal in both channels. Finally, perhaps there are some that have cables which dont play so nicely with voltage gain controls, and so they abandon ship when the sound seems a little off somehow.
But it also sounds like there are just some who might as well just throw a graphic equalizer in their system in order to screw up the signal even more. To wit, experimenting with removing components and playing with the versatility of amps that the designers intentionally put there was what I always considered the playground of audiophiles (at least for a little bit).
I commend DanS on his willingness to put on a hairshirt and play around with such an ergonomic puzzle. Around 2010 I did the same thing for a while with an E.A.R 861 amp. I was plugging an Ayre universal player's XLRs outs directly into the E.A.R's XLR inputs. I was plugging an E.A.R 834p phono stage's RCA outputs into the E.A.R. 834p's RCA inputs. I would then use a toggle switch on the amp (similar to the one on your Parasound) to switch between my analog and digital sources, and I would then use the gain controls to modify my volume. The speakers that I was using at the time were either restored PK Quad ESLs (the 57s), or the old Greg Timber designed JBL L300. It was a system that changed a few people's ideas about transparency and hi-fi. Of course it was an ergonomic pain in the neck that only allowed two sources, but nobody ever said that sonic purity was easy to achieve.
Funnily enough, now in 2017, I started playing with this concept again. I'm currently running an E.A.R. 834p directly into the inputs of a vintage McIntosh MC-225 using the gain controls at the inputs of the amp to control my volume. The speakers I'm running are those little HornShoppes with NO crossover. My cartridge (on my Well Tempered table) is a Lyra Helikon SL so it is a super-low gain cartridge. The E.A.R. 834p is on the MM setting so as to reduce the gain on that part of the chain too.
As Nelson Pass says on one of his First Watt product pages (I'm paraphrasing a bit here), "we've got all this gain in our systems today and we just throw it away with our volume controls". I ask myself, yeah - why do we do that? I then think, well....I wonder what would happen if I can play off of low gain components across the signal chain and end up with a special level of transparency which currently remains unheard by the audiophile masses?
Today, my system speaks for itself. All the low level information is there, even at the softest volumes. I love it.
BTW, @Dave789 - with respect, I believe you may be off your rocker a bit with the line "The pair of big separate continuous knobs is a design mistake." Ummm - My understanding is that the A-series of Parasound amps was designed by John Curl. That guy's design "mistakes" dont pop up too often, and when they do, it usually is somebody breathing pretty rare air who discovers them.
Thanks again for your input on this matter.
I contacted Parasound about this issue and was told that I can connect only one source at a time directly to the A23 with no risk at all.
There is an improvement on detail and transparency. I like it that way!
Those input attenuators are for gain matching, not volume control.
Obviously it's possible to use them to control volume, but that would be extremely inconvenient even if you only had one source. And as others mentioned, it won't help you with source switching.
The best use case I can come up with for those input attenuators is to connect a DAC with a digital volume control, and adjust them such that the digital volume control is operating in its optimum range to avoid loss of resolution.
Another case is if you're using the A23 along with other amps or AVR in a combined stereo/HT setup and you need to reduce the gain of the A23 to be in line with the other channels.
Two separate volume knobs for L and R are very inconvenient to use as volume control.
They are for fixed gain adjustment to improve total system S/N (or to have volume knob on pre-amp at the angle range with small channel error), and for fixed L/R balance control.
Once one touches the big volume control knobs during cleaning etc., one needs to re-adjust the L/R balance with test signal and multi-meter. The pair of big separate continuous knobs is a design mistake.
The knobs should be small and recessed if it is continuous adjustment type, or the attenuator should be stepped attenuator. If the designer intended everyday volume control, it should be a single stereo knob on the front panel.
Having separate volume gain/attenuation controls for each channel is potentially superior to the "volume knob/balance control" design, circuit design speaking.
'Course, I don't know shit about circuit design, so...
with my DIY box using DACT stepped attenuators (JC-2 like box in the middle) and didn't find adjusting balance that difficult with them.
The GamuT CD-1 sounded better with them than going through the SP-9MKIII's line stage. :)
I don't know if it matters for most of us in the regular world, but certainly, from a design and fidelity perspective, two separate gain or attenuation controls does make sense.
No! The toggle switch does not disconnect the RCA unbalanced inputs. I'm using the unbalanced inputs and I just flipped the switch to balanced but the music is still playing. I think the toggle switch affects only the inverted signal on Pin 3 of the balanced inputs.
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