It sounds more like your gain-staging is incorrect. I personally love the sound differentiations when I use the variable input impedances on a device. It does not sound like the impedance is the problem in that you do not have to match them necessarily to get a clean sound.

Man, this is just kicking my butt then. I go mic - LA-610 - DM-4800 line input through one of those mic to line plug type transformers. I watch the input meters on the screen of the DM and I'm letting it peak somewhere between -6 and -12. The funny thing about the LA's meter is that it goes from nothing to pegged really easy, depending on the performance. I had the "Gain" at +5 and the level at about 7, no eq boost and then the compressor at like 5 and set to limit with a decent amount of makeup gain. Of course the numbers on the compressor are arbitrary. Maybe I need to back up the preamp output some more. However, when I do, even though the DM is showing signal and I can hear it, the LA isnt showing anything on the output of the pre when it's low. I feel like a serous idiot about this by the way.

Dave, I'd love to send you an example if I can email one to you. SIncew it's not my material, I dont want to post it publicly.

Well, I've got a friend coming over tonight to out the LA-610 through some more paces. I am going to try to set the input to 2k impedance. The manual says that the impedance of the pre should be 10 times that of the mic. I'm also going to try to engage the 15db pad on the input. Hopefully some combination thereof will render better results. I'll follow up.

sound like your input signal is too large?

The funny thing about the LA's meter is that it goes from nothing to pegged really easy,

A pad might be a good idea.

When you say"mic-to-line transformers", is this a simple cable adapter or is there an impedance transformer involved in this? This shouldn't be in the circuit, and will cause mismatching of levels and distortion. You do NOT take the line level output of a mic pre and feed it through a transformer designed to switch a mic from Lo-Z to Hi-Z. Unless you want mass-distortion artifacts...
I used to have a couple of Tascam DM24's. Doesn't your DM4800 have insert points on the channels? That is where I'd return the LA to the Tascam, through the insert return (if possible). This will prevent you from running the preamplified mic through yet another preamp (in the DM). Running a preamp into what is typically labeled as a line input can be iffy, because many mixers simply attenuate the signal and route it through the mic pre circuitry. Try the insert point as a line input. Capiche?

I go mic - LA-610 - DM-4800 line input through one of those mic to line plug type transformers.

Why aren't you going XLR all the way into the Tascam? It seems pretty silly to me to use some conversion adapter that's unnecessary. Turn down the line level of the LA610 and/or the gain on the compressor. In fact I would start without the compressor all together and see if that isn't a contributing factor. At some stage you are too hot so start at the beginning and work your way through.

Dont the XLR's on the DM-4800 switch between mic/line? If so you shouldnt be anywhere except into this with just a cable and the channel switched to LINE.

Then adjust accordingly.

If there is a separate line input then you dont need a transformer of any kind. Like Moon said. This presents a lot of mismatching impedance-wise and will create exactly what you are describing.

There is a mic input and a line input on each channel. The mic inputs are balanced XLR and the line inputs are Balanced 1/4". They are selectable via a switch per channel. So no, there arent any XLR line inputs. There are unbalanced inserts though. You know, I dont see anything on that XLR to 1/4" that says it's a transformer. I'm sure that's what I asked for when I bought it but now I'm not sure because it has been so long. Any suggestions on what I could try tonight to make some headway. I have a radial passive DI. Couldnt I run through that backwards to get the 1/4" to the right level? It does seem like I'm jumping through hoops a bit here. Thanks for all the help thus far.

If you need to diagnose then run it right into the XLR input, engage the 10db pad and start getting your gain structure set up. I'm pretty sure the TRS Line In of the DM4800 runs through the same preamp anyway-also padded. That's how the Tascam I used back in the 90's worked.

You will be doing lots of monkeying if you try to jack rig an adapter to get into the ring of the Insert. It can be done but should be thought out.

Thanks Jack. To show my stupidity even further, I know that one wouldnt usually go preamp to another preamp but that is what you are saying now. But I'm wondering, if I go line level from the LA to the mic pre input on the Tascam, is it really just a matter of taming the signal down with the pad and trim pot so as to not overdrive the pres on the Tascam?

This is essentially it. If your converter is a simple XLR male to TRS converter you could just go straight into the
after you verify the signal path is ok via pure XLR routing. Ideal is for a perfect world.

Remember that the best trouble shooters start at the beginning and make the chain as simple as possible. Verify. Change 1 thing and verify again. It is all just wire regardless of the labels and boils down to gozintas and gozoutas.

The problems arise when you mismatch connections or gain stages. To prevent problems, I used to make my own cables in pairs and had all kinds of conversions-xlr to trs; xlr to ts; xlr to rca; trs to ts; tt to whatever. You get the idea.

If you want maddening I'll relate a story of a live gig at San Diego bay where some kid stuck a pin in the snake going out to FOH (a beautiful Crest board pre-Peavey). During the gig. We found the problem but I was sweating pretty good.

The line ins will not be part of the mic pres. Use that. If you already are and there is nothing else in the path.....(where did you say something about a transformer???) then its all about your gain-staging.

Just FYI -
I just looked over the block diagram for the DM4800. The line inputs do indeed go through the same preamplifier stage as the mic pre, regardless of the switch setting. Therefore, it shouldn't make any difference whether you're coming in via XLR or TRS.

That being said, the only way to bypass this is to come in unbalanced through the insert. John's right - dorking around with this can be a pain (but it's done all the time).

The problem definitely sounds like a gain staging issue to me. Is there any chance you have a spare headphone amp lying around? If so, take the output directly from the pre into the HP amp and listen for that distortion. If you don't have the HP amp, but have a cheap ol' mackie or similar mixer, feed it into one of the line (only line, not mic/line) inputs and listen there too.

If you're not hearing the distortion, then there's your answer.

The other thing - your settings on the 610 sound a little odd.

It sounds like you're driving the input of the compressor pretty hard then squashing it and then trying to make the gain back up again. For both voice and guitar, gentle compression should be all that's needed.

Try backing the compression off, get rid of the limiter switch (I would very rarely consider using a opto limiter for guitar and only a little more commonly for voice). In fact, try bypassing it all together and then bringing it back in gently. If it works while bypassed but occassionally clips, work the gain until there's no more clipping. Then, and only then, re-engage the compressor at more moderate settings.

With my limited experience with the 610, I've found that vocals work fine with the pre gain at 0 and the level knob in the upper portion of the range (or gain at +5 with the level further down) and compression (Peak reduction) between 2 and 4 and the gain to where the signal sits right in the mix.

For guitar (acoustic) - for an average, larger body instrument, the settings aren't too off from the voice with maybe a hint more compression.

Keep us posted...but for now...after a 3 hour rehearsal of the Planets...I'm tired and going to bed.

Cheers-
J.

Now why the hell would they do that? What part of the difference between MIC and LINE do they not get?????

So as I understand it, theres no way around the mic pres except the inserts???

That would suck in my world.

Ok guys. Thanks so much for all your help thus far. I brought in another singer ( a friend) just to try to help me with this problem. I set the impedance to 2k and removed the line out of the LA to the insert and also trimmed back my levels a bit. It sounded really detailed and sweet. I think I got it. My only problem is that this singer is not as hot as the other but I still think I have it now. Maybe it was overdriving the mic pre even through the line input. Cant wait to try it with the singer I was having problems with. Thanks again.

Eric

I used to have to use a couple of Tascam "studio" boards back in the day and they were all like that.

Lots of times if I had something critical to record I would rent a board or use my Crest monitor board. I sort of developed a distaste for Tascam that lingers. I was quite pleased when the studio went digital and went PT.....three months before I got out of the Corps.

Good. sounds like you are on the right track.

On the question of your "transformer" (I'm thinking the better word is "adapter.") If it is just XLRF to TRSM my guess is that it is simply an adapter. If it's in good working order, plugging and XLR cord into it simple converts the type of balanced connector. This should not have contributed to to the problem.

There are some plugs that are designed to match impedance - basically a DI box. These are typically XLRF (balanced) to TS(M) (unbalanced). And the ones I've seen have the input/output impedance marked on the side. If this is what you have it could have been a problem. Again, go into the XLR input.

I have tons of adapters of all kinds from years of running live sound, but in the studio I try to buy or make the correct cables and keep them out of the signal path. Just one more thing to go wrong.

Don't get hung up on the impedance - 500 ohms will work fine -actually it should work quite well.

Davedog wrote: Now why the hell would they do that? What part of the difference between MIC and LINE do they not get?????

So as I understand it, theres no way around the mic pres except the inserts???

That would suck in my world.

Yeah, it does. I've run across a lotta boards that had this wonderful feature. A&H has done this for YEARS. Mackie and Tascam, too. Pretty much anything that didn't offer inline monitoring. It's a cost-cutting move. It's easier to wire in a few resistors to pad the signal down and use the mic amp as a load buffer than it is to provide a seperate buffer amp for the line input...Bean counters like to wield their power.

Well, the insert really did seem to work well, even with the adaptor thing which is a balanced TRS going into the unbalanced insert. But if that was my problem, then why didnt it show input clipping on the input monitor on the Tascam before and why couldnt I just trim it down to where it would work? Just wondering. THanks again everyone.

Eric

Good question. IF there is a transformer in that "adapter" thingy, that THAT would be the culprit causing the distortion. And because the transformer would create a -20 dB attenuation of signal strength, the resulting signal hitting the mic pre wouldn' be strong enough to show up on the meter. This would also explain why you could turn the trim down and the distortion would not disappear...It was happening IN the transformer, ahead of the mixer input. If there isn't a tranny inside the adapter, I have no idea as to why that would occur. That's why I think you have a transformer in that adapter...

Are you going into the TRS
jack or the TRS jack? A normal plain jane xlr-trs converter isn't gong to handle this (insert) properly as all of the return signal needs to go to the ring portion of the TRS.

At any rate, the problem really was the gain staging and I'm glad you got that fixed. I guess I'm still unclear about your adapter thingee though. Does it actually say transformer on it?

No, it doesnt say anything about being a transformer and it's made by Proel. I am using it into the insert now, I was using in the line in before. The insert seems to work fine. The line in is where I was experiencing all the distortion.

http://www.proelgroup.com/proel/en/diehard/product.jsp?id_prod=11099535551040&id_scat=11103895625210&id_cat=11103895626590

If it looks like this, then you have a plain jane adapter and you are only transmitting half the signal into the insert-and the inverted signal at that. I'll leave it to others to discuss the merits or demerits of the issue.

Also, if you didn't adjust your gain staging inre Jeremy's recommendations then the root problem likely isn't fixed yet. At any rate, the bottom line is if it works. Only then does it matter if it works optimally.

Yup, that's the one. So now what?

The adaptor will route the -ve output of the LA-610 to the insert return and short the +ve output to the output of the DM-4800 pre-amp. Not a good idea, although it should not result in damage to either piece of gear.

It seems strange to me that we have got through nearly two pages of posts about this topic and no-one has yet quoted the figures on levels.

From the DM-4800 specs:
XLR inputs (bal): –60dBu to –4dBu (no pad), –40dBu to +16dBu (–20dB pad)
TRS inputs (bal):–44dBu to +12dBu
Insert returns (unbal): Nominal -2dBu, headroom 16dB (i.e. 14dBuFS)

From the LA-610 specs:
Output level +23dBu (corresponding to +17dBu unbal)

What hits you about these? Could it be that the LA-610 can overdrive the TRS inputs by 11dB (nearly a factor of 4 times in amplitude), but running unbalanced into the insert returns is only a 3dB overdrive? If the OP wants to maintain expected operating levels at the LA-610, it is no wonder that he gets distortion when connecting up via the obvious connections.

As has been pointed out, both the XLR and TRS inputs to the DM-4800 route through the internal pre-amps. If this is not a sonic concern, then use a 12dB in-line balanced attenuator into the TRS input and all will be well. The alternative of going in via the XLR padded can still be overdriven by the 610, but additionally runs the risk of phantom power being accidentally applied to the 610 outputs, which I know can cause damage to a 610.

A sonically cleaner route is via the insert returns using a correctly-wired connection. Since special unbalanced wiring is called for here, I would wire a jack plug with a 6dB attenuator connecting to the ring and sleeve only. This route will avoid the DM-4800 pre-amps and should give the headroom needed for good-quality recordings.

Thanks Boswell. This is good specific information. Can I buy what you are talking about because I am NOT good with building any of this stuff. Also, I just realized that I have an "Archer 274-016" XLR balanced to 1/4" TS unbalanced adaptor and it shows like a transformer on the side of it on a tiny diagram. The diagram also shows pin 3 (female) connected to the sleeve and pins 1 and 2 making the windings of the transformer. Can I do anything with this. Sorry I have such a major defecit in the basic building blocks of this stuff. I am learning as I go. Thanks.

The transformer adaptor is not suitable as that one is specifically for matching low-impedance microphones to high-impedance unbalanced inputs. It would saturate if presented with the output of the LA-610.

Whirlwind makes a series of XLR in-line attenuators, but unfortunately only in multiples of 10dB. [[url=http://[/URL]="http://www.sweetwat…"]This[/]="http://www.sweetwat…"]This[/] is the link to the 10dB pad at Sweetwater.

The Audio-Technica AT8202 is similar but switchable 10/20/30dB and is available at Guitar Center and other outlets.

I would be inclined to get the AT device and experiment with the 10dB and 20dB settings between the LA-610 output and the mixer's TRS line input. You presumably already have an XLR to TRS jack cable.

If you wanted to by-pass the mixer pre-amps, these balanced attenuators are not really suitable for feeding the mixer's insert returns. It would be better to get someone who is handy with a soldering iron to help you make your own insert return cable with 6dB unbalanced attenuator.

You need an XLR female connector, a TRS 1/4" phone jack plug, a length of coax cable (balanced or unbalanced) and a pair of 1KOhm 5% resistors. Wire the cable screen to pin 1 of the XLR and the other end to the sleeve of the TRS plug. Wire a 1K resistor between the inner conductor of the cable and pin 2 of the XLR. Wire the other 1K resistor between the TRS ring contact and the sleeve. Wire the TRS end of the cable inner conductor also to the TRS ring. Leave the XLR pin 3 and the TRS tip not connected. Take care that the inner conductor does not short to the connector shell when it is re-fitted. Splitting the resistors between the two ends like this avoids having to cram two extra components in one plug housing. If you have used balanced cable that has an inner pair, you could either wire the two inner conductors in parallel or leave one colour unconnected and chop it back at each end. Good luck.

The down and dirty immediate solution would be to purchase an XLRM-XLRF phase reverse adapter.

Also, if you really can't solder you should learn. It is hard to go very far in the audio business without that skill.

From your LA 610, YOU SHOULD ABSOLUTELY NOT GO THROUGH A TRANSFORMER AT ALL. Your microphone to line transformer is where you're having the problem as those usually have a 1: 10 winding ratio amplifying the line output an additional 10 DB. What you may want to do is running backwards with proper adapters. That way would have a 10 DB loss and it would not overload the inputs on your digital console. Take it from me, I know what I'm talking about. Of course, that is provided you are using a transformer and not an active microphone to line impedance converter. Transformers or bisexual active boxes are strictly straight.

There really shouldn't be any problem taking your line output from the LA 610, whether balanced or unbalanced into your DM4800. I don't care if it goes to the same preamp as the microphone as it is also a viable line input. I'm sure when it is in line input mode some type of hardwire resistive pad network is inserted. It should easily be able to accept a 24 DBm line level output source.

All microphones want to see a minimum of a 1500 ohm load. Sometimes higher but never lower than that. Variable impedance may be cool for folks who know how to utilize that. But most don't. And I really don't think it's very necessary with quality preamps. I've never bothered and I have no interest in bothering with that kind of nonsense. Sure you get a different sound depending on the loading of the microphone. The loading of the microphone is almost not a factor with condenser microphones anyhow. It's a huge factor with any passive output microphone as the loading will affect response.

Getting loaded
Ms. Remy Ann David

Strictly straight in a bisexual way
Ms. Remy Ann David

Everyone here is really just too kind to me. Thank you all for dealing with this. As more and more info comes in, I realize that I feel more and more confused. Especially with making custom cords and stuff. Let me ask this specifically; Will the XLR phase reverse thing like this one - link removed - be sufficient to get me going. I assume that you mean for me to go from line out of LA into this phase reverse thingy and then into the XLR to 1/4" TRS adaptor and then into the unbalanced insert of the console? Sorry but this is crazy. I'm just thinking wow. This LA-610 not be cheap, Tascam not be cheap, why not they be nice to each other, get along, be friends, ugh ugh. Seriously, what a PITA.

The other obvious thing about all of this is that I need to do some studying about all these signals and why they work or dont work the way they do. Thanks again.

E

Also, I do have a radial passive DI. Could I run that backwards and then into the insert with a regular unbalanced instrument cable? Like LA line out into the low-z out and then out of the Radial DI at the instrument input and then into the insert on the Tascam. I think I read in the Radial manual that you can use them in reverse.

Stupid question #27 today. There is a polarity switch for the line out. I have been running it with pin 2 hot. If I switch it, then pin 3 will be hot. Will this help me?

If you are using the
jack then you don't need that switch. If you are using the jack then it is unaffected by your switch as the insert is after that switch in the signal path.

The block diagram on page 137 of the manual would be a good thing to learn to decipher. I don't say that to belittle merely as it will help you design your signal flow better by having that skill.

That said, the phase reverse switch is indicated at the top of page 136 and it is pre-insert as usual.

Just now read the earlier post.

Your simplest thing would be to just go into the
jack of the Tascam and use a -10db XLR pad like one of these:
http://www.sweetwater.com/store/detail/MAX10/

I think at your stage of the game this signal path will be plenty clean enough.

Don't use the Radial DI backwards. You will seriously overload the DM-4800.

Equally, the XLR phase reverser does not solve anything. It would mean that the +ve out of the 610 drives the insert return and the -ve out gets shorted to the mixer's pre-amp output.

I think the phase reverse switch referred to is the one on the 610 that determines whether the output XLR pin 2 or pin 3 is hot. Same function as the XLR phase reverser.

I've just found another source of specifications for the DM-4800 which give a different interpretation of the input sensitivities from the one I was working from previously. I quoted the clip levels from the first sheet, but the second one implies those input levels are r.m.s. and gives no clip level.

Both sources give the same standard -2dBu nominal with 16dB headroom for the unbalanced insert return. If we take the same headroom figures for the pre-amp as for the insert, it would mean both the XLR input with pad engaged and the TRS line input should be able to handle the LA-610 output. However, Eric W's experience is that it does not handle these levels, so the original specification sheet may be correct.

I think Eric W's experience shows he was driving the line level and compressor make up gain too hot on the 610. Lots of folks make that mistake when they start playing with compressors.

There isn't any real reason he shouldn't just go straight into the line level jack of the Tascam. The Tascam boards I've used will handle normal levels just fine.

Well I will try this again with the XLR line output of the LA-610 straight into the Tascam's XLR mic input with the 20db pad engaged. Before I was going line in through the adaptor and thinking that I was bypassing the pre. Maybe, for some magical reason, it will work better without the adaptor. I dont know and I have to get a singer back over here to try it out. I have three that I am trying to get with right now to solve this problem. Thanks so much for the help. I will also see about getting that XLR to unbalanced cable made for the insert. Thanks guys.

TheJackAttack wrote: I think Eric W's experience shows he was driving the line level and compressor make up gain too hot on the 610. Lots of folks make that mistake when they start playing with compressors.

There isn't any real reason he shouldn't just go straight into the line level jack of the Tascam. The Tascam boards I've used will handle normal levels just fine.

This is entirely possible too. I was going by the output meter for the compressor and I didnt think it was peaking that hot according to the meter. Perhaps I should have been wrong though. I also thought that the Tascam would show me a clip in the on screen input meter but I was showing between -6 and -12. Is there something between that LCD meter and the actual input that can get overdriven without any indication on the Tascam?