What's a Balance Preamplifier Should Be Like?

[Mnyb]

1; A

 

[Tonedef]

Analogue only
Subwoofer output
HT bypass

 

[Times]

First of all, thanks @fosi for giving the community the possibility to participate.

For me, I'd love to see this:

- no output switch on the front (if, then on the back)
- Standby on the front, hard power switch on the back
- input selection via turnable knob like the volume, no button to push repeatedly
- keep DAC / digital inputs
- add USB
- add bluetooth
- WIFI and/or Ethernet (for app control)
- physical remote (maybe optional)
- Sub out
- Room Correction, maybe optional through additional license (Dirac, Audyssey,…EDIT: or maybe just an easy way to map REW results onto an integrated EQ?)
- Color options black and silver

For me, some form of built in room correction is mandatory nowadays, so physical tone control buttons are obsolete. No phono stage either, since imho most people would use a dedicated pre-amp anyway. Tape would be nice though. Size is fine, the smaller, the better.

regards,
Times

 

[Fosi Audio]

subwoofer by splitting the frequencies

Hello friend, would you pls advise which low-frequency bands we shall separate for selection? Thank you in advance.

 

[TonyJZX]

this would be how you would do it if you had no budget

https://imgur.com/fmodaEu

but if you had to compromise would you guys just pick 80hz?

or just full range pre-outs ie. XLR all the time, RCA out all the time and you can just adjust on your active sub???

and then if you had cuttoffs on subs would you not need them on the mains as well???

 

[Talisman]

Hello friend, would you pls advise which low-frequency bands we shall separate for selection? Thank you in advance.

If you have to keep it fixed, I would say that it would be advisable to stay on the 75/80 Hz high pass filter

 

[MCH]

Why fixed? Would it be an analog crossover?
Do at least a few selectable frequencies

 

[TonyJZX]

would come down to price right?

if its done in the digital domain its trivial

but if you're doing it analog?

you have to wonder why no one does trim knobs on the main and sub outs like the high end guys

 

[JohnnyNG]

Hello friend, would you pls advise which low-frequency bands we shall separate for selection? Thank you in advance.

If fixed, an 80Hz LR 24dB/oct high/low pass would cover most needs. Would rather fixed than variable at lesser quality. No DAC.

 

[Roland68]

Hello audio lovers! Thanks for your attention again. Recently we have adjusted some features of this balanced preamp. We've canceled the DAC function. Now we need to discuss with you some more details.

1. Is it a must to make it balanced input to balanced output and single-ended input to single-ended output, or allow it to have the function to transfer balanced/single-ended to single-ended/balanced?

Technically, there is no point in building the preamplifier internally symmetrically.
Often it is simply ignorance of this technology and problems when a completely symmetrical signal routing is desired in a device. In reality, success and benefits are disproportionate to the effort required.

If you build a completely symmetrical circuit for a preamplifier, all differences in layout and length between the two symmetrical line paths, as well as all differences in component quality and especially component tolerance, will ultimately have an effect through cancellation in the music signal.

Even if there are interferences in the music signal, it is not necessarily an advantage. With a cable, due to the spatial proximity of the conductors, one can assume that the interference is irradiated evenly. But in a device where there is necessarily a spatial distance between the two circuits of a channel, both the direct and indirect radiation of interference can be very different. Also not good.

 

[Fosi Audio]

Sub out with crossover, even if it's a fairly limited set of choices (e.g. none, 80, 100, 120) to go with typical bookshelf or modest floor.

Hey friend, do you mean we should provide the options to select between those bands? Like 20-30Hz, 80-300Hz, 100-300Hz, and 120-300Hz?

 

[radix]

Hey friend, do you mean we should provide the options to select between those bands? Like 20-30Hz, 80-300Hz, 100-300Hz, and 120-300Hz?

I was thinking that you would have a matched low-pass (for sub out) and high-pass (for line out) filter. The sub out should be mono sum (if only one jack) or stereo. The crossover frequency should be "none" (i.e. no crossover) or some fixed value (e.g. 80 Hz). The crossover would be a conventional one, e.g. LR 24 dB or 2nd order 12 dB. If you want to make it simple, you could have only fixed frequencies, such as 80 Hz or 100 Hz or 120 Hz. I think 80 Hz is a pretty common one and 120 Hz is used in HT. Those are not ranges, but the -3 dB point of the high pass and low pass filters.

If you are OK having a variable crossover frequency, then something like "none", 80-120 Hz would be OK. I don't see much point going down to something like 40-120 or 60-120, as someone with such large tower speakers would likely have a higher-end preamp. But if it's all the same, sure 60-120. I'm not sure there's much value going all the way up to 300 Hz for a sub crossover unless you want to accomadate small desktop speakers. Anyway, if you are going to have variable, there's only one range and you could make it whatever works for your customer's speakers.

Basically, it's like having the option of setting "no crossover, small speakers, large speakers" if you want to keep the interface simple.

 

[burkm]

I think, that a range of 60-120 Hz or Off, (HP + LP; filter slope min. 12db / Octave Linkwitz/Riley or more) should be OK. Subwoofer Out should be Mono for >= 1 subwoofer. Lower does not make sense for an average subwoofer, and higher would only be needed, if very small speakers will be used but rarely on an average 2.1 set.

 

[RCL162]

Can i put opamps inside?

 

[Mikig]

if possible, it would be nice to have the possibility of having instead of tone controls, something a little more advanced, like EQ or DSP... it would help all those who have no way of adding a correction into the system.

 

[LTig]

if possible, it would be nice to have the possibility of having instead of tone controls, something a little more advanced, like EQ or DSP... it would help all those who have no way of adding a correction into the system.

You need both. Advanced EQ for room EQ, tone controls for correction of badly balanced recordings.

 

[amix]

1. Please do not add a built-in DAC. There are already so many cheap but good DACs on the market... Adding a DAC to the preamplifier only makes it more expensive and people who buy seperates would not need this DAC anyway.
2. High-Pass filtered Sub-Out.
3. Place the XLR/RCA switch on the back. It's really not needed on the front.
4. More analogue inputs.
5. Bigger volume knob, source selection, power on on front.
6. Remote control with volume, mute, standby, source selection.
7. No tone controls but processor loop before the signal split via high pass.
8. Old-skool, 1980's loudness.

 

[burkm]

You need both. Advanced EQ for room EQ, tone controls for correction of badly balanced recordings.

A DSP / Advanced EQ plus tone controls should be onboard, because the room and/or headphone(s) need (usually) both.

 

[Magnum]

Just make it simple.

Built in psu. 4 xlr pairs in , 2 xlr pairs pre out.
4 input selectors in the front, big n silky smooth volume knob. + maybe a mute button. A way to make one or more inputs unity gain.

Clear n big 4-segment lcd/oled/dot matrix display. Displays [input number] [volume]: like this: [1 50]

Remote just need volume and input up/down + mute (but add it to the harmony database with codes for direct input codes too).

Make that for a good price and make it measure well for the weirdos here and you have yourself a winner.

 

[amix]

Two analog inputs is not enough!

Into one goes my DAC. Into the other one my phono pre. And I'm full for any future upgrades? Not good.

And for those of us, who also have a tape deck from the past or a reel tape, a tape loop would be nice. So, four analog in, Minimum, two of them XLR.

I also don't see the need for a built-in DAC. Most, who use separates, have a separate DAC.

I just had to repeat myself ;-) Class-A could be nice . Personally I also wouldn't mind tubes.