My brother has a Hartke Bass Head (I believe the 2500). He wants to add a balanced line out. He had an issue recently where the sound guy wouldn't hook him into the PA because that was all he would work with, wouldn't take the preamp out (effects send).
Anyway, is there a way to add a balanced line out?
Well, the simple solution is to get one of those line impedance adaptors and plug it into the FX send. THERE is the balanced out the guy demands. If you want to be more official, get a "direct box." Many brands are out there, and they are not expensive. They are made for exactly this purpose. Feed them a line level signal and they produce a balanced low impedance signal for feeding down a snake.
I have to wonder at a sound guy who demands a balanced feed but didn;t think to suggest a direct box. When I was running sound, I carried one with me as part of my tools and adaptors kit.
I don't have a Hartke 2500 schematic, but the 3500 has a balanced line out alreqady as do a number of other Hartke models. I don't know your board, but if the 2500 is a more basic model than the 3500, it may use the same board set, and it may be as simple as loading the balanced out parts onto the empty section. Otherwise the balqanced line driver circuit is simple enough, steal it from the 3500 drawings or look on one of many other amps with a direct out balanced, and steal their circuit.
Like Enzo suspects, it already has one !!!!
(http://www.samsontech.com/site_media/cms/images/product/hartke/amplifiers/ha-series-amplifiers/ha2500/HA2500_back.jpg)
It's the one called Direct Out, and has the added options of "Ground Lift" which sometimes lowers hum (try it both ways) and pre/post EQ.
Personally I prefer Post, so people hears same as me.
Quote from: EnzoI have to wonder at a sound guy who demands a balanced feed but didn;t think to suggest a direct box.
Also known as a DI or Direct Interface.
Surprise surprise, yet another sound "engineer" who doesn't actually know anything, or just can't be bothered. Apart from having DI's as part of my PA rig I have often had to busk something on the spot in unusual situations. A soundie who can't manage
some sort of work-around simply isn't trying and deserves a boot up the ... for being a lazy SOB.
(http://emoticoner.com/files/emoticons/smileys/kicked-out-smiley.gif) (http://emoticoner.com)
"The show's the thing" and you bend heaven and earth to get it happening (even if you have to contrive something with clip leads in a cardboard box - I don't
like it, but if that's what it takes ... ).
{and
JM's pic just make it worse}
I'll have to verify that his amp is indeed the 2500 and not some other model. So "Direct Out" is the same as "balanced out" eh?
Not necessarily , Direct Out may be through an unbalanced jack, the classic "Preamp out", but if you see an XLR connector yes.
Post a picture of your brother's amp.
Quote from: joecool85So "Direct Out" is the same as "balanced out" eh?
The short answer is no.
The long answer is that it can cut both ways. Normally when you see a 1/4"/6.5mm socket marked "Line Out", "Pre Out", or similar we assume that it's unbalanced, and when we see an XLR with such markings we assume that it is balanced,
but sometimes the 1/4" is TRS (Tip, Ring, Sleeve or "stereo") and
is balanced, and sometimes an XLR
isn't.
"DI" and "Balanced" both
imply that the output is isolated from amp ground to prevent earth loops,
but there is no law about this and builders and manufacturers do all sorts of things that may appear more up-market than they really are. If it has a statement, diagramme, or ground lift switch, you can normally trust those. {If I had a quid for every time I've whipped the lid off something to find out what's
really going on ...}
Ok, turns out it is a model 2000. So...how about adding that balanced line out now?
So look inside at the circuit boards. Are there any empty spaces for parts not installed? Does the board say anything on it like 1500/2000/2500 or some such? For example the 3500 and 7000 and 5000 share a board.
The difference between a PV Blazer and a PV rage is the reverb. They both use the same board, so if you had a Rage, you could install the missing parts and have a Blazer.
If this is not the case, you can still look at the 3500 or 2500 schematic and steal the circuit, it is not complex. Samnson will send you the schematics for your amp if you ask them. Give them your serial number just in case.
**********************
I found the 2000 schemo, too big to scan, so call Samson for your copy. The board is not shared by the larger models, but the circuits are very similar.
The DI circuit is one dual op amp and small parts, plus XLR. You can then tap in either after teh tone stage or after the graphic.
Enzo, thanks for the help, that's exactly what I needed to know. My brother is up in the air on whether to modify this one or to purchase a 3500 he found locally for cheap. If he keeps his though, now we know how to add his balanced line out.
**edit**
One question, do you think they will give me the schematic for the 2000 and the 2500 since I will need to see the later to add the XLR to the former?
Ask them for the 2000, that is what you have. The direct out circuit is pretty much the same anywhere.
You can probably find the drawings for the 3500/7000 or the 5000 or the HA1200 or HA3500. All we are doing is tapping off the signal path at a nice level somewhere near the graphic stage.
And if nothing else, call them back in a couple days and ask for the other.