Putting together a new horn & flea power system for my daughter and her husband. One approach I am investigating is using an SE 45 amp, driving:
- a horn speaker setup from about 300hz up, which has a conventional speaker level high-pass crossover.
- a plate amp (likely Hypex) for the bass horn below 300hz, using the plate amp’s ’high level input’.
my concern is: will I have issues with the load that the SE 45 amp sees? Potential distortion of lower frequencies not having a conventional load? Or am I overthinking things?
The speaker level input to a Hypex amp and managing the bass with software is an awfully appealing approach, makes things very simple. At least until the tech changes and the outdated hardware/software bricks the amps…
- a horn speaker setup from about 300hz up, which has a conventional speaker level high-pass crossover.
- a plate amp (likely Hypex) for the bass horn below 300hz, using the plate amp’s ’high level input’.
my concern is: will I have issues with the load that the SE 45 amp sees? Potential distortion of lower frequencies not having a conventional load? Or am I overthinking things?
The speaker level input to a Hypex amp and managing the bass with software is an awfully appealing approach, makes things very simple. At least until the tech changes and the outdated hardware/software bricks the amps…
I don’t think it will be a problem with the load as the amp will have a high enough input impedance to not load down the tube amps output tx. What I see as the issue is the weakest part of a SE tube amp is the low bass so you will be using a less than perfect source to drive the plate amp. You are better off using the feed through inputs on the plate amp first then going to the tube amp. Or have the preamp have two outputs driving both amps with the same signal and let the plate amp get a clean source. The best bet is to get an electronic crossover to do the job and any other eq needed. Again the high level inputs feed from a tube amp output is less than ideal.
I also suggest to use filtering (low pass for bass, high pass for #45) before amps.
The main bottleneck of #45 SE amps is the OPT inductance. Usually it's low for -real- bass, and the full spectrum music (mainly the bass components) can cause distortion.
Do you know this solution?
https://www.diyaudio.com/community/threads/diy-biamp-6-24-crossover.357657/
In the diyaudio store available some KIT: 6-24 crossover or LXmini crossover.
https://diyaudiostore.com/collections/all-crossovers?filter.v.availability=1
The main bottleneck of #45 SE amps is the OPT inductance. Usually it's low for -real- bass, and the full spectrum music (mainly the bass components) can cause distortion.
Do you know this solution?
https://www.diyaudio.com/community/threads/diy-biamp-6-24-crossover.357657/
In the diyaudio store available some KIT: 6-24 crossover or LXmini crossover.
https://diyaudiostore.com/collections/all-crossovers?filter.v.availability=1
Thank you for the responses. You are probably right, too easy, no free lunch.
I was thinking I might be ok down to 40hz (the bass horn low) with quality iron (Hashimoto), but I ought to know better; I prefer PP DHTs over SE for full range applications, due to the bass response.
I actually bought a 6-24 board, but not sure it’s the solution here. Per the horn manufacturer, the passive speaker crossover wants to see full output all the way down to 135hz for proper filtering. I could build it to start the high pass roll off at 135, and the bass crossover at 300, but since I likely need DSP on the bass horns to match, I think the 6-24 might be superfluous.
maybe my best approach would be to split the line level out from the pre, and
- build a passive input filter to the 45 at 135hz to keep the bass out of the 45 amp.
- use the Hypex amp filters to configure the bass crossover
Thoughts?
I was thinking I might be ok down to 40hz (the bass horn low) with quality iron (Hashimoto), but I ought to know better; I prefer PP DHTs over SE for full range applications, due to the bass response.
I actually bought a 6-24 board, but not sure it’s the solution here. Per the horn manufacturer, the passive speaker crossover wants to see full output all the way down to 135hz for proper filtering. I could build it to start the high pass roll off at 135, and the bass crossover at 300, but since I likely need DSP on the bass horns to match, I think the 6-24 might be superfluous.
maybe my best approach would be to split the line level out from the pre, and
- build a passive input filter to the 45 at 135hz to keep the bass out of the 45 amp.
- use the Hypex amp filters to configure the bass crossover
Thoughts?
I wouldnt bother with a crossover at all, or DSP, or even buying a class D board and power supply, case, etc...
Horn load a full-range, high efficiency 12 inch paper cone speaker in a box big enough to get to 300hZ, something 98-104 db SPL. Run that speaker full range from the 45 amp. Then just add a commercial subwoofer, adjust the cutoff and level dials to taste. Drive the subwoofer from the 45 amps speaker terminals.
Horn load a full-range, high efficiency 12 inch paper cone speaker in a box big enough to get to 300hZ, something 98-104 db SPL. Run that speaker full range from the 45 amp. Then just add a commercial subwoofer, adjust the cutoff and level dials to taste. Drive the subwoofer from the 45 amps speaker terminals.
This is what I do and have a horn tweeter to cover HF, but limit how low it comes to not step on the 12”.
Match the spl between the sub and 12”.
Match the spl between the sub and 12”.
An attractive option for DIY, if your intended SE 45 amplifier is like the currently popular, no loop feedback, is to simply size the coupling capacitor between driving stage and output stage to give a single pole high pass at 300Hz. This removes some of the strain on the output stage and OPT, and also greatly reduces "hang time" when the output stage is overdriven into clipping. Time to bleed back to normal idle is set by this RC time constant. And let the plate amp provide its own low pass, inputs in parallel with SE 45 amp's inputs.
All good fortune,
Chris
All good fortune,
Chris
Any advantage to use a cap on the input to also take the lows off the driver stage?
My amp is 2A3 SET parafeed
My amp is 2A3 SET parafeed
Sure. Exact frequency corner of rolloff will be slightly effected by source impedance, but speaker crossovers are always far from exact. Interior cap coupling is (usually) already there, and free of interactions with source impedance, but a filter at the input, as you say, has its advantage too.
For the penalty of even more dependence on source impedance, and an unbypassed first stage cathode resistor, a second or even higher order high-pass can be done at the input. DIY gives lots of options not otherwise available.
All good fortune,
Chris
For the penalty of even more dependence on source impedance, and an unbypassed first stage cathode resistor, a second or even higher order high-pass can be done at the input. DIY gives lots of options not otherwise available.
All good fortune,
Chris