How to "Tape Loop" using the BHK Preamp


#1

I have been grooving on my BHK preamp feeding BHK 300 mono’s for over 6 months now, and I just love the musical and detailed view they offer into every recording. Just beautiful stuff, and fun, too!

So, I like to record LP’s into hi rez files with an ADC, and that was pretty straightforward with my previous preamp that sported a tape loop function. Is there a good way to do this with the BHK preamp? (Please don’t tell me that I have to unplug my IC’s from the preamp and feed them directly into my ADC every time I decide to record an LP!)


#2

That’s a great question and I am not sure I have a great answer. We never designed a tape out for BHK.


#3

Hi, Paul. I appreciate your weighing in…so, basically you are saying there is no solution?


#4

My two cents where it doesn’t belong. The lack of a tape loop is the reason I didn’t buy a BHK Pre. I need a fixed volume line level out to drive a separate integrated amp I use for outside speakers.


#5

It always belongs. But, no, unless we redid the back panel of the BHK there’s no way I know of getting a fixed level out.


#6

Assuming the OP’s phono pre uses a set of RCA inputs on the BHK pre, why not just connect cables to the corresponding XLR inputs and run those to the ADC? Or even just use a y-adapter from either the RCA outs on the phono pre or from the RCA input to the BHK? Not quite as elegant as a tape loop, but should be OK, no? (Obviously this won’t work if he wants to route more than one source to the ADC, but it sounds like that’s not the case.)


#7

Do you need to be listening while recording? There are numerous options, including for the guy who passed on the BHK, due to no tape outs, unless you want both inside and outside playing at same time.

Setup one input for HT pass through, or do what I do. I have a separate pair of cables going to my ADC. When I want to digitize a LP, I switch cables at the phono preamp. Depending on your phono preamp, this could be easy, or a hassle. My phono preamp has a separate battery power supply and the phono preamp is about 5" x 7". It sits on the top shelf, below my TT, which sits on a Target wall mounted shelf. So very easy access. Or if you are using the balanced outputs to to your amps, just run a pair of single ended cables to the ADC, just don’t change levels during recordings. I’m pretty sure you can use both outputs at the same time. That way you would not have to switch around cables.

Not knowing your ADC, or phono preamp, there may be other options. I’m assuming if you are using fixed outs, that your ADC has a level control. Mine doesn’t, so I actually run the .5m from phono preamp to a pot, then to the ADC. I use Vinyl Studio, with Q-Up on my TT. Except for editing, when I put the track breaks in, and remove the lead in/outs, which I do on the PCs speakers, or my thirty year old Grado Sr60 headphones. I usually do it while watching TV, with the sound going through the main system. I also tend to do it in batches, record 2 - 7 LPs at a time, then edit them after, I am done recording. I can monitor with the PC or the headphones, but seldom do. Once I have the levels set for the LP, I just keep an eye on the meters, to make sure I am not clipping. It has been years since I used a tape monitor output when recording cassettes, but I do remember having to set levels for each LP.

If you post your other gear, ADC, phono preamp, and what you are recording to, including software, maybe we can come up with some other solutions.


#8

Thanks for these thoughts on work-arounds. I am using an Audio Research Reference 2SE phono stage and a Benchmark ADC 1 for the digital conversion. The ADC only takes XLR inputs (weirdly restrictive, but…), and I am using XLR connection between the pre and power amps. I use a pretty expensive XLR IC set, so doubling that up to make switching easier is unattractive, and the Ref 2SE is positioned in a very difficult place for swapping.

I guess I am likely stuck with pulling the cables off of the BHK preamp’s inputs (easier to get to in my rack) and switching them to the ADC when I want to record, and then getting the analog feed off of the Tascam DV-RA1000HD that I use to record the digital file that the Benchmark creates, thus allowing for monitoring capability. Then, when I want to listen to my phono with the best fidelity, I swap 'em back! Oy. What a joy.

It certainly argues for multi-album campaigns, like Jeffstarr does!


#9

Why don’t you use an XLR Y adapter on the output of the Audio Research? One could feed BHK and the other permanently connected to the ADC. Use the BHK to monitor what you’re doing. Does that not work?


#10
jeffstarr said

Do you need to be listening while recording? There are numerous options, including for the guy who passed on the BHK, due to no tape outs, unless you want both inside and outside playing at same time.

Thanks. Yes, inside and outside playing at the same time is a must. The inside and outside systems are separated only by a large window wall. I play both systems simultaneously. Party on the deck, party inside.

It’s not a problem, the Cary SLP-05 I bought instead of the BHK is a great unit and includes a tape loop. I’m mostly commenting because I believe not including a tape loop was a PS Audio Over-site and maybe worth correcting on future models/refinements. There are 5 inputs on the BHK. Seems like a lot. 4 inputs and a fixed volume output would be something to consider. Just one man’s opinion.


#11

I wouldn’t disagree.


#12

Unless you are like me and can easily use five inputs. :slight_smile:

And can also find a use for a fixed out as well.


#13

And thus the conundrum. There’s not much real estate on the back of the BHK especially considering dual single and balanced inputs/outputs. Maybe making input five singled ended and the fixed volume output single ended… Just a thought.


#14

Not a bad solution, but I would hate to lose the true balanced connections the unit provides.


#15

Yes, Paul, a y-connector out of the phono is probably my best solution at this point. I’m not quite sure if the loading of preamp plus the ADC unit are something to worry about, but I’m guessing not, as the phono’s output impedance is 400 ohms in balanced.


#16

Most input impedances are quite high. Ours is 100kΩ and the average is 50KΩ so that is almost no load at all. Not to worry with such a low impedance feeding it.


#17

But when you get in to pro gear, input impedance can be quite low. I don’t know if that carries over to Benchmark’s ADC.

My friend had the Lindemann preamp and power amp. The amps input impedance was so low, he couldn’t really use the amp with anything but the matching preamp.

Unless you decide to have custom Y-adaptors made, either the Audioquest or Pangea are quite reasonably priced.


#18
jeffstarr said But when you get in to pro gear, input impedance can be quite low.
? Pro gear is designed to be versatile. Input impedance is typically high and the equipment easy to drive.
I don't know if that carries over to Benchmark's ADC.
The input impedance of the ADC1 is 200k ohms from 20Hz to 20kHz. That is, very high and, thus, exceedingly easy to drive.

#19

Crown is probably the best known pro amps, well that I am aware of. Most of their current amps are 20k balanced, 10k single ended, while not as low as the Lindemann amp, it is low if matched with a tube preamp, and/or long ICs. They have tons of power, but may roll off the highs if not carefully matched.

The input impedance of the BHK 300 is 50k unbalanced, 100k balanced, and the 250 is double that.

Edit: I seem to remember someone telling me that Lindemann got it’s start in pro audio, apparently I got some bad info. As far as Benchmark goes, they design some very fine equipment, for a fair price, so I am not surprised they would have a high input impedance.


#20

Crown is one of many sound reinforcement amps. Lindemann is not a pro manufacturer.

20K ohms is moderately high input impedance, typical for a solid state amp, and much more than sufficient unless you have an incredibly high output impedance as your source, such as 5k ohms. I have no idea what this might be.

For example, it is common for a mic preamplifier to have an output impedance of 50 to 100 ohms. This makes the input impedance of a Crown amp 200 to 400 times greater, making it exceedingly easy to drive. For reference, the output impedance of the DirectStream is 124 ohms unbalanced, which would happily mate with a Crown amp.

Pro equipment is designed to just work with just about anything. For example, you can drive a 1 ohm load with one channel of a Crown amp, with a 16 ohm on the other, driven by different sources of vastly different impedance. The amp will not care.

But amp impedance is completely irrelevant. I’ll be Bach is driving a pro ADC, the Benchmark ADC1, with an input impedance of 200k ohms(!) from 20Hz to 20kHz. Anything can drive this ADC, even an iPhone.