Hey guys. The title outlines my problem and below are the specifics. I hope a builder can either contact me or anyone can recommend someone they've had good dealings with and who might be able to meet my requirements.
I've been looking for a preamp for my main system for more than a year, but recently I got some bad news about the product I was most interested in and it now looks like I'm going to have to go the custom route, unless someone knows of a readily available product that meets my needs.
System outline:
1. 2 DACs, both XLR outputs only.
2. 5 amps, all XLR inputs only.
3. Only listen to stereo, no multichannel.
4. Only ever use 1 DAC + 1 amp at a time.
5. Overview:
- The 2 DACs are just different flavours and basically "spot 2" is for visiting DACs that I'm trying to get a feel for. But only XLR.
- The 5 amps are 4 for headphones and 1 pair of active monitors. Due to my setting, I can't rock the speakers all the time and never in the day time. But I like to listen to them when I can. The 4 amps are just ideal pairings for 4 different headphones. I've got rack space and since the amps and the headphones aren't too big or unwieldy like speakers are, I can handle owning multiple sets geared towards specific musical styles/my mood.
- I want it all connected, all the time. I will power components on or off as needed, but I don't want to deal with plugging or unplugging anything.
**I did find that a pro-audio "mixer" is pretty much what I'm looking for in regards to I/O and I/O isolation/impedance matching. However, they're mostly pretty ugly, don't have a remote, have too many dials, and won't look good on an audio shelf/rack with all my other components.
-> that is, unless someone knows a good one that mostly fits my needs listed below 🙂
Preamp requirements:
1. Needs 2x XLR ins + 5x XLR outs.
2. Everything must be able to be connected at all times and not have any performance difference vs. unplugging anything.
3. Due to impedance loads, the outputs will all need to be isolated and buffered to allow all amps to be connected simultaneously, but not create a parallel impedance situation where the input impedance seen by the preamp is too low.
4. I don't want anything run in parallel, such as input/DAC 1 is "on" and then all outputs are also "on". Only 1 input and 1 output can be active at any time.
5. Must work via remote. Apple remote is a handy one.
*A great reference is this custom LDR preamp built by Mike at Redstone Electronics. Mike doesn't do contract work anymore and there are some differences, but overall it's a great reference and he did a beautiful job. Look how flush the OLED is mounted...
Nice stuff, but not 'needs':
1. Volume memory for each "input+output" combination from last use.
2. Use Tortuga Audio LDR preamp boards.
3. Use Tortuga Audio OLED display and Apple remote receiver.
4. Use a tube buffer for the outputs.
5. Use output transformers after the solid-state/tubes to create a pure balanced XLR signal (akin to Empirical Audio's Final Drive component).
Price range:
$2000-4000 (this is just a ballpark estimate. We can talk specifics later)
*we'll try to mitigate the custom casework costs somehow and put the majority of dollars into the component and workmanship.
I've been looking for a preamp for my main system for more than a year, but recently I got some bad news about the product I was most interested in and it now looks like I'm going to have to go the custom route, unless someone knows of a readily available product that meets my needs.
System outline:
1. 2 DACs, both XLR outputs only.
2. 5 amps, all XLR inputs only.
3. Only listen to stereo, no multichannel.
4. Only ever use 1 DAC + 1 amp at a time.
5. Overview:
- The 2 DACs are just different flavours and basically "spot 2" is for visiting DACs that I'm trying to get a feel for. But only XLR.
- The 5 amps are 4 for headphones and 1 pair of active monitors. Due to my setting, I can't rock the speakers all the time and never in the day time. But I like to listen to them when I can. The 4 amps are just ideal pairings for 4 different headphones. I've got rack space and since the amps and the headphones aren't too big or unwieldy like speakers are, I can handle owning multiple sets geared towards specific musical styles/my mood.
- I want it all connected, all the time. I will power components on or off as needed, but I don't want to deal with plugging or unplugging anything.
**I did find that a pro-audio "mixer" is pretty much what I'm looking for in regards to I/O and I/O isolation/impedance matching. However, they're mostly pretty ugly, don't have a remote, have too many dials, and won't look good on an audio shelf/rack with all my other components.
-> that is, unless someone knows a good one that mostly fits my needs listed below 🙂
Preamp requirements:
1. Needs 2x XLR ins + 5x XLR outs.
2. Everything must be able to be connected at all times and not have any performance difference vs. unplugging anything.
3. Due to impedance loads, the outputs will all need to be isolated and buffered to allow all amps to be connected simultaneously, but not create a parallel impedance situation where the input impedance seen by the preamp is too low.
4. I don't want anything run in parallel, such as input/DAC 1 is "on" and then all outputs are also "on". Only 1 input and 1 output can be active at any time.
5. Must work via remote. Apple remote is a handy one.
*A great reference is this custom LDR preamp built by Mike at Redstone Electronics. Mike doesn't do contract work anymore and there are some differences, but overall it's a great reference and he did a beautiful job. Look how flush the OLED is mounted...
Nice stuff, but not 'needs':
1. Volume memory for each "input+output" combination from last use.
2. Use Tortuga Audio LDR preamp boards.
3. Use Tortuga Audio OLED display and Apple remote receiver.
4. Use a tube buffer for the outputs.
5. Use output transformers after the solid-state/tubes to create a pure balanced XLR signal (akin to Empirical Audio's Final Drive component).
Price range:
$2000-4000 (this is just a ballpark estimate. We can talk specifics later)
*we'll try to mitigate the custom casework costs somehow and put the majority of dollars into the component and workmanship.
If the above seems like a wall of text or not the right way to be going about this, does anyone have any other recommendation?
I'm just trying to get the music flowing here and have a comfortable way to kick back. I hope someone can help point me in a good direction for that. I'd be much appreciated.
I'm just trying to get the music flowing here and have a comfortable way to kick back. I hope someone can help point me in a good direction for that. I'd be much appreciated.
With due respect, nobody will work that much for that little money.
Start thinking $20000 to $50000 fees and you might find who is both qualified and interested.
Your budget dos not cover even parts cost by far and even less the Design work involved.
Now if you have a tested design and all parts needed, then somebody be interested in your fee just to assemble and test it.
And if in same City or within 1 hour drive, he might even install and setup it.
Not so sure about that.
Start thinking $20000 to $50000 fees and you might find who is both qualified and interested.
Your budget dos not cover even parts cost by far and even less the Design work involved.
Now if you have a tested design and all parts needed, then somebody be interested in your fee just to assemble and test it.
And if in same City or within 1 hour drive, he might even install and setup it.
Not so sure about that.
I just got a custom preamp from Les Bordelon
( LB audio). It is fantastic, and i supplied a lot of the boards and parts, and it was several times the budget you are aiming for. i think the time and cost required to create something that custom is more than you realize. The over the top parts cost would use the budget up, fully balanced discrete direct coupled jfet gain stage, Kimber RCAs, discrete remote controlled resistor attenuator, Blackgate caps, silver wire, matched Toshiba duals, TX 2575 Vishay resistors, shunt regulators, R core transformers, Jung pre regulators, teflon caps, seperate power supply, soft recovery hexfet bridges, etc......
Don’t know what gain stage and construction and parts quality you want to use.........
( LB audio). It is fantastic, and i supplied a lot of the boards and parts, and it was several times the budget you are aiming for. i think the time and cost required to create something that custom is more than you realize. The over the top parts cost would use the budget up, fully balanced discrete direct coupled jfet gain stage, Kimber RCAs, discrete remote controlled resistor attenuator, Blackgate caps, silver wire, matched Toshiba duals, TX 2575 Vishay resistors, shunt regulators, R core transformers, Jung pre regulators, teflon caps, seperate power supply, soft recovery hexfet bridges, etc......
Don’t know what gain stage and construction and parts quality you want to use.........
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Looks like the Bent Audio love runs strong here. I recognize the internals there, but you/Les have a bit of a personal twist on the implementation. Cool.
But yeah, you're right that I was underestimating it. Thanks for the heads up. I did put a qualifier on the ballpark about that, but I guess it was too low nonetheless and just shuffled anyone interested away.
Thanks for the heads up. I'll see what I can do to progress the design of what I'm looking for and source the parts, then post the updates here.
Yes Bent Audo volume control, Borbely gain stages.
you need to get ALL the parts together and build the the boards FIRST to size the chassis.
The power supply I have was a tight fit for parts and its 19 inches deep, we estimated 15 to 17 initially,, but Les didn’t get the chassis made until all the parts were sourced and measured.
you might get the chassis made at one of the small volume audio shops that some users here use, maybe Les could advise. But in reality it will be a diy project
you need to get ALL the parts together and build the the boards FIRST to size the chassis.
The power supply I have was a tight fit for parts and its 19 inches deep, we estimated 15 to 17 initially,, but Les didn’t get the chassis made until all the parts were sourced and measured.
you might get the chassis made at one of the small volume audio shops that some users here use, maybe Les could advise. But in reality it will be a diy project
Hey guys, thanks a lot for all the discussion in here. I was juggling some crazy projects at work and then spending my spare time actually trying to sniff out the trail I caught wind of, so I didn't end up replying after your guys started posting. Sorry about that, but I'm not MIA, so that's good.
It took a lot of digging and asking around, and I will have to do some assembling, but I've really lucked out and mostly covered all my needs.
I found some NIB Bent Audio AVC-1 Slagleformer/autoformer modules and the associated internal PCBs for the front panel/volume, rear I/O, and power input. Then I contacted the Bent Audio owner, John Chapman, and we worked out how to reconfigure the I/O logic to work for me, including the front panel buttons and the remote.
I will have to source a chassis and then assemble the parts, but that shouldn't be too hard where I live now and assembly is easier than "no solution". I know some guys who do CAD work, so I'm just focusing on finding the right chassis and brainstorming on the external looks and optimal internal layout.
Preamp will have:
1. 2x XLR ins + 6x XLR outs.
2. Everything can remain connected at all times.
3. DAC output impedance is 22-ohms and collective input impedance is >5000-ohms, so damping remains well over the 10:1 ratio in the worst case scenario.
4. All inputs and outputs are isolated, so only 1 input and 1 output are "in circuit" at any time.
5. Uses the Bent Audio, 13 button remote.
- This includes input switching, output switching, volume control, L/R balance control, mute, and power on/off.
Nice stuff, but not 'needs':
1. Volume memory for each "input+output" combination: I'm not sure yet, I'll find out soon.
2. Use Tortuga Audio LDR preamp boards: Didn't happen, but uses my other leading candidate, Bent Audio Slagleformers. I feel I really lucked out here, I've had my eye on these 2 implementations for several years.
3. Use Tortuga Audio OLED display and Apple remote receiver: Uses Bent Audio displays and LEDS, and Bent Audio remote.
4. Use a tube buffer for the outputs: No buffer right now, but there is room in the chassis for balanced buffers.
5. Use output transformers after the solid-state/tubes to create a pure balanced XLR signal: The Slagleformers achieve this.
It took a lot of digging and asking around, and I will have to do some assembling, but I've really lucked out and mostly covered all my needs.
I found some NIB Bent Audio AVC-1 Slagleformer/autoformer modules and the associated internal PCBs for the front panel/volume, rear I/O, and power input. Then I contacted the Bent Audio owner, John Chapman, and we worked out how to reconfigure the I/O logic to work for me, including the front panel buttons and the remote.
I will have to source a chassis and then assemble the parts, but that shouldn't be too hard where I live now and assembly is easier than "no solution". I know some guys who do CAD work, so I'm just focusing on finding the right chassis and brainstorming on the external looks and optimal internal layout.
Preamp will have:
1. 2x XLR ins + 6x XLR outs.
2. Everything can remain connected at all times.
3. DAC output impedance is 22-ohms and collective input impedance is >5000-ohms, so damping remains well over the 10:1 ratio in the worst case scenario.
4. All inputs and outputs are isolated, so only 1 input and 1 output are "in circuit" at any time.
5. Uses the Bent Audio, 13 button remote.
- This includes input switching, output switching, volume control, L/R balance control, mute, and power on/off.
Nice stuff, but not 'needs':
1. Volume memory for each "input+output" combination: I'm not sure yet, I'll find out soon.
2. Use Tortuga Audio LDR preamp boards: Didn't happen, but uses my other leading candidate, Bent Audio Slagleformers. I feel I really lucked out here, I've had my eye on these 2 implementations for several years.
3. Use Tortuga Audio OLED display and Apple remote receiver: Uses Bent Audio displays and LEDS, and Bent Audio remote.
4. Use a tube buffer for the outputs: No buffer right now, but there is room in the chassis for balanced buffers.
5. Use output transformers after the solid-state/tubes to create a pure balanced XLR signal: The Slagleformers achieve this.
I will update the thread as I receive the parts and move through with the build. It's going to take some time because I'm going to try to push the quality level, but I hope the final results can be a good reference for anyone else interested in this kind of situation. I hope the head'philes out there catch wind of it and some manufacturers start making these kind of pres...
Prices.
The Bent Audio parts so far cost $2400 USD and I'll spend maybe another $1000 USD on the chassis. I just picked up a pair of NIB Hoyt 2135 3.5" VU meters, which I'm going to have to figure out how to install. I'm going to need a lot of help with that as I've always liked them, but don't know much about them besides that I've bought good ones and "real" ones. Those 2 cost $80 USD.
I expect the assembly wire, XLR sockets, and such to cost maybe another $200 USD as I already have the soldering equipment, silver solder, and nice wire.
The VU meter part is now the only real DIY part, the rest is just semi-DIY/assembly. In total, it looks like I'll put this on my rack for around $3700 USD and almost hitting all of my "NEEDS" and "NICE TO HAVES". It sounds pretty awesome to me.
I wasn't trying to avoid the DIY aspect initially, I just don't have the time for anything intense and in this case, I'd call this more assembly than DIY as everything is already mostly done and all I'll be doing is fastening things to the future chassis and soldering some connections.
Anyway, I'll update the thread as time goes, ask questions, and hopefully it all turns out as nice as I can see it in my head.
Prices.
The Bent Audio parts so far cost $2400 USD and I'll spend maybe another $1000 USD on the chassis. I just picked up a pair of NIB Hoyt 2135 3.5" VU meters, which I'm going to have to figure out how to install. I'm going to need a lot of help with that as I've always liked them, but don't know much about them besides that I've bought good ones and "real" ones. Those 2 cost $80 USD.
I expect the assembly wire, XLR sockets, and such to cost maybe another $200 USD as I already have the soldering equipment, silver solder, and nice wire.
The VU meter part is now the only real DIY part, the rest is just semi-DIY/assembly. In total, it looks like I'll put this on my rack for around $3700 USD and almost hitting all of my "NEEDS" and "NICE TO HAVES". It sounds pretty awesome to me.
I wasn't trying to avoid the DIY aspect initially, I just don't have the time for anything intense and in this case, I'd call this more assembly than DIY as everything is already mostly done and all I'll be doing is fastening things to the future chassis and soldering some connections.
Anyway, I'll update the thread as time goes, ask questions, and hopefully it all turns out as nice as I can see it in my head.
Questions:
Do you want transformer inputs as well?
Are the Tortuga boards exactly what you want?
On the 5 outputs...are these to all be tube/transformer or a mix of SS/transformer and tube/transformer? Or, each output switchable between tube/transformer and SS/transformer? No transformerless balance outs at all?
Is it necessary to mute outputs, or can they all operate simultaneously if properly buffered?
Favorite tube buffer circuit?
Favorite SS buffer circuit (Pass B1?)
What is the input sensitivity of your 5 amps? Do you need to do output gain tweaks to match them all?
What if you took a more minimalist approach, and did input switching, output switching, output buffering (with/without transformers), and a really good volume control (buffered, of course)? Hits the main goals, might be a little less costly.
What's your favorite industrial design style? Early-20th century, Mid-century modern, early 70s brushed metal, Late 70s brushed black anodized, classic-custom (engraved/filled panels)? Sand-blasted glass or mirror? Something else? Packaging and design will be what you see every day.
VU (or something else) meters?
And the last one...the elephant in the room...What's the real budget?
Do you want transformer inputs as well?
Are the Tortuga boards exactly what you want?
On the 5 outputs...are these to all be tube/transformer or a mix of SS/transformer and tube/transformer? Or, each output switchable between tube/transformer and SS/transformer? No transformerless balance outs at all?
Is it necessary to mute outputs, or can they all operate simultaneously if properly buffered?
Favorite tube buffer circuit?
Favorite SS buffer circuit (Pass B1?)
What is the input sensitivity of your 5 amps? Do you need to do output gain tweaks to match them all?
What if you took a more minimalist approach, and did input switching, output switching, output buffering (with/without transformers), and a really good volume control (buffered, of course)? Hits the main goals, might be a little less costly.
What's your favorite industrial design style? Early-20th century, Mid-century modern, early 70s brushed metal, Late 70s brushed black anodized, classic-custom (engraved/filled panels)? Sand-blasted glass or mirror? Something else? Packaging and design will be what you see every day.
VU (or something else) meters?
And the last one...the elephant in the room...What's the real budget?
What do you expect the VU meters to indicate? There will need to be a meter driver with calibration control....
Transformers? Transformer mounting? Tube-buffer? Tubes? Input and output switching? PSU?
An investment that large would seem to require at least some professional input.
Hi BonkM,
Ran across your thread and wanted to let you know we made/sold the Tortuga Audio gear used in Mike's project. After reading your specs we could probably get you most of what you're asking for within shouting distance of your price range. The part that would blow that budget sky high and make for mega-enclosure or multiple smaller boxes is the dedicated tube buffer for each of the 5x outputs. That requirement adds up to quite a lot of hardware. I would try to talk you out of that. You can hang more than one amp on a buffered preamp output before the combined parallel impedances begin to drag down performance. My customers do this regularly with main + sub amps even with our passive preamps that have no output buffer at all but easier for sure with buffered output.
Another way to reduce cost with only a single output buffer is to add switching to your outputs similar to input switching. But that begs a question, if you only ever listen to 1 source (DAC) plus 1 amp at any given time, why burden your system (and your wallet) with the multiple independent buffered outputs?
Anyway, happy to discuss and help if I can.
Best,
Morten
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