Pre-Amp Boost

I built a ST120 back a few years back and have several times run into issue where I am playing music at high levels and my stupid receiver clips out...  It has no load.. its just the convenient means to connect via spotify and stream hifi through the DSP to the AMP.  I have a posting to mini-DSP asking about this.. but ..well not much help.

https://www.minidsp.com/forum/hardware-support/20172-minidsp-flex-vs-minidsp-2x4-hd-pre-amp-signal-boost#60351


Questions:
1) Pre-amp input ranges. How can I read what the receiver is putting out via unbalanced RCA and map to what the ST120 expects.

2) Does anyone have a recommendation of "next step" in audio phil build out where I can bypass the entire receiver in "music mode".

Why not build a preamp?

Looking up the minidsp it seems like you might have it in the wrong part of the signal chain.  It doesn’t look like it’s supposed to follow a preamp output.  Does your receiver have “tape outputs”?  If so try connecting from there to the minidsp.  I also noticed the Minidsp 2x4 only outputs up to 0.9 volts which is below standard.  This could also be what’s clipping.  The HD version does have 2 volt outputs.



I have no experience with minidsp but people I respect say if you want the best sound quality, skip the dsp.   Consider taking the minidsp out of the chain and just going from the receiver preamp outputs directly to the amp.

"....Consider taking the minidsp out of the chain and just going from the receiver preamp outputs directly to the amp....."


The issue is the Tube amp handles Front R/ L tower speakers.

In Music mode.. This is stereo (2 channel straight, no DSP signal change ) out.   This is a binding of the Servo Subs (see diagram) for low end.  Each tower is tuned / tied to each sub R vs L.   The 2 x4 Mini HD only splits out for sub (as a 120Hz crossover).

In Movie Mode (TV / Movies / family listening) then the receiver takes control.  It does 7:2 splitting..  controlling the Front R / L speakers via tube amp as pre-amp R/L unbalanced out, and subs it has direct lines to for Sub split.


I would love a DSP (Mini DSP Flex ?) or other recommendation (hense post here) where I can in movie mode , direct wifi link to pre-amp unit for spotify / airplay  but to avoid recabling each time I power on.. it also has to take inputs (R/L from receiver for Movie Mode).

Diagram:


Summary: I am looking for

1) Pre-Amp that has RCA line level inputs (R/L) , input of wifi (Sonos, Apple Airplay), and four RCA output (two for tube amp with input ranges to drive amp,  two for sub with crossover set ~120hz)

Which Yamaha receiver do you have?

TSR-7850

Good receiver. I purchase this smaller unit as I knew most of its power load would be offloaded (Front R/L) to the tube amp. It is mostly a means to get 7:2 surround when in movie mode.. And.. for now to stream Spotify.

It is a sold receiver, but keeps clipping, even when no load. I contacted Yamaha and they did not have a means to fix this as line level RCA out pre-amp was just not built to provide pre-amp...


The MiniDSP 2x4 HD (HD for higher voltate output ) works ok as pre-amp for most listening, but when I crank it up, it was just not designed for this kind of use case.

Brap wrote:Why not build a preamp?

Thanks for input. I thought about that. I even purchased a kit... but more I looked at quality of parts and POT issues to automate turning signal down to automated baseline level (I need logic that defined return to baseline level on power on as delta between Movie reciever input vs music made for scaring wife/kids when the beast came on)

..... it became a major pain.

Buy vs build. So .. looking for buy options before I reach for kit trolling again to hack parts together.

Check out Parasound Halo P-6. This can integrate with all the stuff you have going on, has a bypass for 2 channel listening only too. I have a older P5 and its a solid unit.