Unbalanced xlr-rca IC's for Otari MX5050BII2

[Doug_Olitsky]

I' getting ready to DIY IC's for my otari and parts on on their way from parts connex

I'm using dh labs wire, vampire xlr's, onix locking rca's (wbt knock-offs)

I know how to connect the wire at the xlr end

but should the shield be connected at the rca end as well ?

I'm thinking on connecting the shield on both ends (rca and xlr)

when I make unbalanced IC's with Rca's on each end I uasually only attach the shield on the "source end" of the cable

Ideas anybody?

[ecir40]

Doug, I have been busy as hell cause of Gustav. Before the storm came I was going to mount some rca's above the xlr's to have both world's. This way in the future you or the next owner doesn't have to fool with adapters or special cables. If you remove the back panel with the xlr's you will notice there is plenty of room to make this work. While at it I was going to drill two more holes to the left of the xlr's to install two more rca's and wire them straight to the headstack. Removal of the headstack then the two screws for the socket the headstack plugs into allows easy access to the wires to solder the interconnects for the rca's.

Hopefully soon I will get some time to do this and take some pics along the way.

[Doug_Olitsky]

Well taking care of business after Gustav is MORE important than any of this stuff!

I was actually thinking of removing the xlr's and installing rca's in their place. But decided aginst it. the main reason was that its cheaper to DIY a custom diy xlr-rca cable than a diy rca to rca if you can beleive it.

It ran me $117 (ship included) for all...
dh labs wire (16 feet)
vampire xlr's (2 male 2 female)
onix locking rca's (four)

So, for under $60 per pair of high quality IC's I'm all hooked up and ready to tape.

I will be watching for your pics as your idea for tapping directly off the heads has my interest.

[Doug_Olitsky]

I got my shipment from parts connexion and assembled last night. and even though they need a bit of break in time they look and sound great.

The only issue I had was I left my preamp on tape as my source and the monitor selection was still set for source. That created a nasty feedback loop and my one hell of a noise.

Once I switched it to the Tape position the noise was gone and my was out of my throat.

Now I feel I 'm ready to make some real recordings.

[ferriteman]

Hi Doug...I seem to remember that you are using the Seduction pre-amp off your tape heads, am I correct?

I'm a bit unclear here. Does the Seduction box bypass the Otari's electronics for both playback AND record?

I understand for playback it is quite an improvement --do you still here a nice improvement even with 7 1/2 inch 4-track pre-recorded tapes? I understand with the TP tapes that the Bottlehead improves things...but does it also for 4-track tapes at 7 1/2 I wonder.

I've actually bought a subscription to the TapeProject tapes, over 2 months ago, but haven't received anything yet. I was wondering...how long did it take to get your Bottlehead once you ordered it? I mean I realize that the outfit is a fairly small scale operation so you have to be patient.

Anyway I would really like to hear how your recordings turn out using the Bottlehead as compared to the stock Otari electronics. I have a BIII-P so I would think that a comparison would be very relevant here.

Regarding your XLR-to-RCA IC...I bought fairly inexpensive adaptors from Musicians Friend (an online store). No problems. I have no idea with this hot-wire business if they are connected properly but it sounds good to me!

Incidentally, I have concluded that the headphone-amp section of my BIII-P isn't too great; I get a hard, edgy, almost brittle sound through my Grado 'phones. However, when I run the Otari's output to my Stax headphone amp to my Stax phones, the sound is not edgy at all...reasonably balanced with quite a bit of detail. The Stax, being electrostatic, with pass on any defects for sure...you hear everything with them.

Looking forward to hear how it goes with your recording!

[Doug_Olitsky]

Not me Joel has the seduced B III



I had a set of the rca-xlr converters as well and was using crappy IC's

When it came time to make a nice set of IC's it was just as easy to make them rca-xlr.

[ecir40]

Doug, I have been busy as hell cause of Gustav. Before the storm came I was going to mount some rca's above the xlr's to have both world's. This way in the future you or the next owner doesn't have to fool with adapters or special cables. If you remove the back panel with the xlr's you will notice there is plenty of room to make this work. While at it I was going to drill two more holes to the left of the xlr's to install two more rca's and wire them straight to the headstack. Removal of the headstack then the two screws for the socket the headstack plugs into allows easy access to the wires to solder the interconnects for the rca's.

Hopefully soon I will get some time to do this and take some pics along the way.
Finally got around to doing this, it was more work then I thought it would be but final results I think are good. One thing I had to do that I didn't realize at first was install a switch for xlr or rca operation. This was done by switching the low negative signal (now pin 3) to ground when the rca's are used. While I was at it I made all xlr's pin 2 hot.

1 finished result
2 rear with swithes installed and wired
3 used rear mounted rca's for the direct headstack outputs
4 headstack plug, green left (channel1) blue right (channel 2) the two inner white wires are hot and the two outer wires are ground.
5 soldered before tie wrapped
6 tie wrapped
7 & 8 inner finished pics

Now I just need a tapehead amp, I think I will wait for the newer Seduction II to come out.

Brad

[ferriteman]

Nicely done! Question...the direct output from playback head doesn't require switching?...therefore you can theoretically run an outboard tape head amp but also at the same time be recording using the Otari's electronics?

i.e. so you can record from a source and while you are doing it listen to it directly off the playback head through an outboard tape head amp?

Also...I didn't know there was an updated version of the Seduction coming out...

[ecir40]

Nicely done! Question...the direct output from playback head doesn't require switching?...therefore you can theoretically run an outboard tape head amp but also at the same time be recording using the Otari's electronics?

i.e. so you can record from a source and while you are doing it listen to it directly off the playback head through an outboard tape head amp?

Thanks, this would probably be possible but I imagine doing the above would create some interferance between the two.
The way I was looking at it was that one or the other could be used the way I have it. When playback through a tape head amp is used I would switch from tape to source which I am pretty sure unloads the reproduce amp electronics.

Also...I didn't know there was an updated version of the Seduction coming out...
This thread has some details.
http://www.audioasylum.com/cgi/t.mpl?f=bottlehead&m=130973

[Doug_Olitsky]

Awesome work on the mod. Total flexability. Was it too cramped in the deck to solder the new wire to the Head card slot? I see you had to remove the head stack.

Did you have to realign / re calibrate when you put it back together?

[ecir40]

It would have been way too cramped if the headstacked wasn't removed. By pulling the headstack the way I did gave more than enough room. Tie wrapping the wire of the card slot to the tape guides as in the pic 5 helped unnessary movement while soldering. Using a beldin type shielded wire instead of the type of cable I used would have been even easier.

The heads are not messed with by removing the headstack. There are just three screws holding the headstack to the three tape guides.

You can't see it but in pic 7 there is a wire holder that holds the wires to the card slot. I had to bend this and tie wrapped the new and existing wires to this to keep the wires and solder conections to the card slot from moving around.

BR

[braxus]

Neat Idea Ecir. I'll keep the RCA idea in mind when I get my deck.

[TheReeler]

Perfect DIY job, congrats.

One dummy question. Why did you finally need to install the switches to select XLR or RCA output?. What was exactly the problem with both at the same time if only one at a time was connected?.

[ecir40]

If the XLR was eliminated the switch would not be needed. See the pic in doug's first post. Notice that to run the rca's unballanced you need a jumper across two of the pins for the low signal and ground. If you did this without a switch the xlr's would not work right. The switch is open (jumper not connected) for xlr operation and closed (jumper connected) for rca operation. Hope this clear things up.

I did open the switch once I had everything hooked up just to see what would happen and the result was a substantial loss of gain.

A light popped in my head when I realized a switch was needed on why some equipment that utilize both xlr ballanced and rca unballanced in the market has a switch on the back.

BR

[Doug_Olitsky]

great insight on the switch thing!!


Now who is going to swap out their op amps w/ the the Burson discrete outputs.

http://www.bursonaudio.com/Burson_HDAM_Module.htm


parts connection has 'em, I bet going this route would give the seduction a run for the money

[TheReeler]

If the XLR was eliminated the switch would not be needed. See the pic in doug's first post. Notice that to run the rca's unballanced you need a jumper across two of the pins for the low signal and ground. If you did this without a switch the xlr's would not work right. The switch is open (jumper not connected) for xlr operation and closed (jumper connected) for rca operation. Hope this clear things up.

Yes, thanks.

[ecir40]

Yes, thanks.
No problem, glad I could help.

Now who is going to swap out their op amps w/ the the Burson discrete outputs.


Doug, from what I can tell the reproduce section has two differant kind of opamps being used.

Here are the numbers.

4560DX
JRC
5007

2043DD
JRC
4035

I don't know much about rolling opamps but am pretty sure they are voltage dependant. JRC is Japan Radio Company which is now NJR Corporation and that's about all I could find on the numbers above. bobschneider sounds like he knows a little about this, maybe he will chime in.

BR

[ecir40]

Hi, I finally got around to using the direct rca's to a seduction tapehead amp. Originally I had left the factory wires in place thinking that I could just use the source tape switch to unload the factory reproduce amp while using an external tapehead amp. This did work but the factory wiring from the heads were picking up noise and had to be removed to use an external tapehead amp without any induced noise. I would think that it may be possible still if you were to replace the factory wires with a better shielded pair but haven't tried it.

Brad

[Doug_Olitsky]

good point about better shielded wire, maybe some silversonic or something similar, belden makes good stuff as well. I cant see putting cardas or some higher zoot wire in there.