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Author Topic: Running a preamp in front of a recorder that doesn't have a true "line-in"  (Read 10445 times)

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Offline Chanher

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I'm wondering what your guys' opinion on running an external preamp in front of a recorder that doesn't have a true "line-in". Instead it has a "mic-in" but simply adds a pad so that it can accept line level signals.

I'm referring specifically to my Tascam Dr-70d and running an MP-2 in front of it. I do plenty of loud concerts and have come to the conclusion that the Dr-70d preamps are more than acceptable for that.

But I have some classical and un-amplified jazz shows coming up and I'm seriously wondering whether it's worth it to run both of my MP-2's in front, as I find the MP-2 preamps's quieter than the stock Tascam preamps. Knowing that the Dr-70d "line-in" is just a padded mic-in, is passing the signal through 2 sets of preamps redundant, unnecessary, and potentially detrimental?

I think the best way to find out is to go and try both ways at quiet concerts and let my ears decide, and I plan on doing that. Wouldn't mind hearing some of your theoretical and real-world opinions first.

EDIT: I tried searching this and couldn't find anything. TIA
« Last Edit: September 08, 2023, 05:56:46 PM by Chanher »
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Offline voltronic

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #1 on: September 08, 2023, 07:04:54 PM »
I'm someone who exclusively records classical / acoustic, and I owned a 70D and a FP-24 (pretty much the same preamp as yours) for a long time. Your instincts are correct that the 70D preamps are not not great for this kind of gig on their own, which is why I now run a Zoom F6.

I think your idea will work fine as long as:

1) You set the 70D inputs to LOW gain range (not sure if this is even a thing in LINE mode)
2) You might need to use the MP-2 tape out (3.5 mm) with a splitter cable. The actual line out on XLR is pro-gear level +4 dBu and may overload the 70D inputs, even if your gain is set conservatively.
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Offline Chanher

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #2 on: September 09, 2023, 12:25:09 PM »
Yes, I think Mp-2 tape out > 1/4 inputs on the Dr-70d is the most logical way to achieve this.

I am willing to admit I am overthinking this but was just hoping to access some of the knowledge here. I am currently sick (and extremely bored) and I think the old living room test is in order. Thanks
« Last Edit: September 09, 2023, 12:58:51 PM by Chanher »
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Offline unclehoolio

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #3 on: September 24, 2023, 07:08:46 PM »
Glad to find this thread, as I'm in the same boat of wanting to run a preamp in front of a digital recorder.  Does anyone know of a 4- or 6-track recorder that does have true line in capabilities, instead of just engaging a pad on the mic input?

Chanher, have you considered the option of upgrading the preamps on your Tascam?  Doug Oade still performs these upgrades/modifications:
https://www.oade.com/index.php?main_page=product_info&cPath=19&products_id=296

I think that there are also other folks out there (e.g. Busman?) that also offer this.
**Edit to add:  apparently there is a whole thread on 70d mods https://taperssection.com/index.php?topic=174046.150, as well as a good summary here https://taperssection.com/index.php?topic=172795.0
so Chanher, my apologies for recommending this if you are already well aware

In addition to my query above, I'm also considering buying a 70D and having Doug mod it.  I was quite impressed with the tapes of Dead & Co from NOLA that Goodcooker pulled, using a Oade mod Tascam (in that case, a 100mkii--but I believe that the 'concert mod' upgrade is the same for both decks):
https://archive.org/details/deadco2023-05-06.lineaudiocm3.oadedr100, and the thread is here https://taperssection.com/index.php?topic=201948.msg2392452#msg2392452
« Last Edit: September 24, 2023, 07:22:35 PM by unclehoolio »
mics:  AKG c480b (x6) + ck61, ck62, & ck63
pre:  2 x Oade m148
recorder:  Zoom F8n Pro; Tascam HD-P2 (with Oade High Definition mod)

Offline Chanher

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #4 on: September 25, 2023, 12:09:05 PM »
I’ve read those Dr-70d mod threads but I never knew Doug has begun to offer a mod, that’s pretty cool and I’m certainly tempted. I’ll listen to those modded 100mkii shows a little more carefully, at first glance they are nice.

While there are a handful of Busman Dr-70d’s out there, he is no longer in the game.

I do think the single biggest advantage of the Dr-70d is the price. If you are patient you can find one for well under $200. I picked up a used one off ebay and have recorded 50+ shows without a single error [knock on wood]. It’s also quite small for a 4 channel recorder and I’m comfortable taking it to sketchy taping situations with the tiny bag I use and the low investment I’ve made.

I think if you stick to medium to loud shows this is a great option. I still think it’s not THAT bad for quieter music but there are better options out there. I’ve ran all 4 channels for a jazz performance and the lead guy was so impressed he’s considering trying a commercial release with me if I can simulate those results, albeit I HEAVILY mastered that recording.

Tbh I would love for you to try an Oade Dr-70d and post your results here haha.
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Offline unclehoolio

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #5 on: September 25, 2023, 12:31:47 PM »
Good to know that Busman is no longer in the game.

I agree on the price being a huge advantage!  I may well go ahead and get one and be the guinea pig!  Stay tuned...
mics:  AKG c480b (x6) + ck61, ck62, & ck63
pre:  2 x Oade m148
recorder:  Zoom F8n Pro; Tascam HD-P2 (with Oade High Definition mod)

Offline goodcooker

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #6 on: September 25, 2023, 03:12:35 PM »
In addition to my query above, I'm also considering buying a 70D and having Doug mod it.  I was quite impressed with the tapes of Dead & Co from NOLA that Goodcooker pulled, using a Oade mod Tascam (in that case, a 100mkii--but I believe that the 'concert mod' upgrade is the same for both decks):
https://archive.org/details/deadco2023-05-06.lineaudiocm3.oadedr100, and the thread is here https://taperssection.com/index.php?topic=201948.msg2392452#msg2392452

I'll add a word of caution here if you are thinking about having Doug mod a deck for you. I've had two instances of interference that ruined recordings using the Oade Concert Mod Tascam DR100mkii. Both times the interference was crippling and unfixable.

The first time was running at Jazzfest in NOLA for the Radiators and Continental Drifters - 10 or 15 feet in front of a repeater stack. There was a power supply for the stack underneath the tower and I was pretty close to it. Recording unusable. At first I thought it was a ground loop from the battery I was using since I had used the deck several times that weekend with no issues but I couldn't repeat the problem using the same gear later. It was the location and by deduction the giant probably unshielded power supply.

The second time was at an indoor club that I record at all the time including having used the Oade mod deck with no problems. That night I recorded with two decks simultaneously from the Portico 5012 - a Korg MR1 and the Oade Mod DR100mkii. The Oade deck had the same interference as the first time I had a problem with it. The Korg MR1 no issues. They were using a second soundboard that night for the opening band and it may have been the source of the issue based on it having a large external power supply.

Just giving a heads up. I've been putting off sending the unit back to Doug to see what's up with it. I've had other modded decks and never had a problem.

This reminds me I need to send Doug an email and see what he has to say about it.
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Offline voltronic

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #7 on: September 26, 2023, 10:16:58 PM »
I'm going to catch flak for this, but I'm speaking from experience as someone who owned a modded 70D for a long time:

It no longer makes sense to mod these older cheap recorders when you can get newer recorders that are superior in every way for about the same price after you factor in the mod cost. Sometimes even for the price of the original deck alone. The mods do likely improve performance a bit, but your money is better spent on a better deck. Get one of the new 32-bit float autoranging multi-DAC recorders and you will never look back.

I sold my modded 70D right after I got my Zoom F6, because the improvement in sound quality and features was huge. Yes, the F6 $750. But you can get similar quality for less money with these:

Zoom F3
Tascam X6
Tascam X8

The only old recorder I would still consider buying is a Sound Devices 788, for the fantastic mic preamps alone.
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Offline IMPigpen

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #8 on: September 27, 2023, 10:10:18 AM »
Just my experience since I run a SD Mixpre with my DR-70.  My typical recording is amplified rock/jamband, etc, so not classical.   I've run the MP XLR outs to DR-70 XLR ins with no overloading issues at all (line in and low gain setting). 
Mics: Neumann KM184s; ADK TLs; Naiant X-R omnis & cards; MM-BSM-7M omnis
Pres/Battery boxes: Sound Devices MixPre; Naiant IPA; Sound Professionals SP-SPSB-6
Recorders: Tascam DR-70mkii; Tascam DR-60Dmkii; Tascam DR-40; Roland R-07
Cassette Transfers:  Nakamichi CR-1A->Tascam DR-60Dmkii
DAT Transfers:  Tascam DA-20mkii->Marantz PMD-670

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Offline Chanher

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #9 on: September 27, 2023, 12:06:43 PM »
I'm going to catch flak for this, but I'm speaking from experience as someone who owned a modded 70D for a long time:

It no longer makes sense to mod these older cheap recorders when you can get newer recorders that are superior in every way for about the same price after you factor in the mod cost. Sometimes even for the price of the original deck alone. The mods do likely improve performance a bit, but your money is better spent on a better deck. Get one of the new 32-bit float autoranging multi-DAC recorders and you will never look back.

I sold my modded 70D right after I got my Zoom F6, because the improvement in sound quality and features was huge. Yes, the F6 $750. But you can get similar quality for less money with these:

Zoom F3
Tascam X6
Tascam X8

The only old recorder I would still consider buying is a Sound Devices 788, for the fantastic mic preamps alone.
No I think this is good advice. In the last few years alone the quality of recorders have only gone up IMO and you simply can't go wrong getting the latest gear. I got my Zoom F3 used for $275 and I'm officially a 32FP advocate now. It's simply a game-changer for me as I'm often taping in non-traditional taping scenarios. Being able to start the recorder an hour (or sometimes more) before the show starts, stow the bag out of harms way, and not return until the show is over is like a veil has been lifted.

If you're primarily a "taperssection" or "controlled-environment" style taper where you have clear and easy access to your bag, nothing wrong with sticking with 24-bit and it's older recorders. Any recorder/preamp from the last 10 years is still relevant IMO and will result in HQ recordings if you know what you're doing.  I only keep my mod'd UA-5 from 20 years ago for nostalgia purposes; the last time I used it I noticed the (albeit subtle) drop in quality.

The ability to set levels correctly is an acquired skill (and even an art form) and I sometimes wonder if the next generation of tapers will not even have to learn it if 32FP technology continues at it's current rate haha.

We'll try to avoid the modification-debate, but I'll be the first to admit they are subtle, and certainly not necessary. They can add "flavor", and at best those "flavors" have allowed me to produce recordings that don't require any post-processing. In fact, I'll go ahead and advise to forget mods, forget the latest recorders, put your money in your mics! :)


Just my experience since I run a SD Mixpre with my DR-70.  My typical recording is amplified rock/jamband, etc, so not classical.   I've run the MP XLR outs to DR-70 XLR ins with no overloading issues at all (line in and low gain setting). 
This goes against all my experiences with my MP-2 but hey, real world results are real world results.


I'll add a word of caution here if you are thinking about having Doug mod a deck for you. I've had two instances of interference that ruined recordings using the Oade Concert Mod Tascam DR100mkii. Both times the interference was crippling and unfixable
That's definitely a bummer, it sounds like it could be isolated to the mod, or perhaps a defect in the recorder. Good to know though. There's hundreds of Doug's mods out there without this problem so hopefully this is an isolated incident with a quick fix.
« Last Edit: September 27, 2023, 12:18:06 PM by Chanher »
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Offline goodcooker

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #10 on: September 27, 2023, 02:13:08 PM »

Once you get past the bottom price range of the prosumer level decks that many of the folks who frequent this board tend to use you get results that are similar to what once required the use of outboard preamplifiers, AD converters and/or custom modified recorders.

New product lines like the Zoom F series, the Sound Devices Mixpre recorders and a few others have bridged the gap in sound quality that used to be so vast.

I still use preamps since I like to change it up sometimes. I used the Portico in the field once since I got it just to make sure it works as expected. I'm not likely to take it back out into the field if it's not mounted in a rack and only for something paid or very mission specific. The Oade Wmod UA5 and the Aerco are always going to be in rotation though. I love the way they sound. I miss the days when I could listen to different sources of the same show with a PSP2, Oade 148, Sonosax SXM2, etc in the mix.
Line Audio CM3/OM1 || MBHO KA500 hyper>PFA|| ADK A51 type IV || AKG C522XY
Oade Warm Mod and Presence+ Mod UA5s || Aerco MP2(needs help) || Neve Portico 5012 || Apogee MMP
SD Mixpre6 || Oade Concert Mod DR100mkii

pocket sized - CA11 cards > SP SB10 > Sony PCM A10

http://www.archive.org/bookmarks/goodcooker

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Offline DSatz

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #11 on: September 27, 2023, 02:35:36 PM »
I don't think that there's a way to know which approach is best without measuring the noise with and without an external preamp, and with various combinations of gain settings.

Where did you get the information that the input is resistively padded for the "line in" setting? It may be true or not. It may be (either instead or in addition) that the feedback to the op amps is increased for the lower gain setting. I see nothing in the reference manual or elsewhere that says directly, but maybe you've seen a detailed schematic.

In any case I really think that actual noise measurements would need to be made in order to know the answer. It can't be determined from mere intuition or "general principles". Agreed, the noise spec of this recorder's preamps is not the very greatest, but an awful lot depends on the gain settings that you would use in an actual recording situation, with or without an outboard preamp in front of the recorder's inputs.
music > microphones > a recorder of some sort

Offline voltronic

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #12 on: September 27, 2023, 07:31:32 PM »
Where did you get the information that the input is resistively padded for the "line in" setting? It may be true or not. It may be (either instead or in addition) that the feedback to the op amps is increased for the lower gain setting. I see nothing in the reference manual or elsewhere that says directly, but maybe you've seen a detailed schematic.

I think you are probably spot on with the op amp feedback changing to create the three gain level settings. That would explain why I found the HIGH gain range of the 70D incredibly noisy, and only when you got to the bottom of the MID gain range were the preamps useable for acoustic concert recording.

It's worth noting that this behavior did not improve even slightly after I had my 70D modded with better-quality opamps spec'd by Jim Williams. The improvements I heard from the mod were greater treble extension and clarity, but the preamp noise was unchanged. In retrospect, I wish I hadn't spent the money to mod my unit but at that time there weren't any recorders with 4+ preamps I could afford, other than the Zoom H6 which is a mess of preamp noise in its own right.
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Offline Chanher

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #13 on: September 28, 2023, 09:32:00 AM »
I still use preamps since I like to change it up sometimes.  The Oade Wmod UA5 and the Aerco are always going to be in rotation though. I love the way they sound. I miss the days when I could listen to different sources of the same show with a PSP2, Oade 148, Sonosax SXM2, etc in the mix.
Keep us updated on your Tascam. I'm curious to the source of the problem but I'd also like to hear more of it in the field.

I don't think that there's a way to know which approach is best without measuring the noise with and without an external preamp, and with various combinations of gain settings.

Where did you get the information that the input is resistively padded for the "line in" setting? It may be true or not. It may be (either instead or in addition) that the feedback to the op amps is increased for the lower gain setting. I see nothing in the reference manual or elsewhere that says directly, but maybe you've seen a detailed schematic.

In any case I really think that actual noise measurements would need to be made in order to know the answer. It can't be determined from mere intuition or "general principles". Agreed, the noise spec of this recorder's preamps is not the very greatest, but an awful lot depends on the gain settings that you would use in an actual recording situation, with or without an outboard preamp in front of the recorder's inputs.

Yes I'm guilty of simply reading on this forum that the "line in" is padded and taking it for fact. I do recall that it might have been one of the modders, Jim Williams or even Doug, who stated this and then it was relayed by a TS member.  Either way you're right, an accurate answer requires actual noise measurements, using gain settings in actual recording situations. I wish I knew how to do this, and would be willing to do the work sometime in the winter when things slow down.

I can't help agreeing with the general consensus that if you have the money, don't hesitate to skip this level of recorder and at least look into the possibility of the newer Sound Devices and Zoom F series. You can always throw a preamp in front! If you don't have the money, I can happily report I've made all kinds of recordings with a DR-70d that I enjoy.

In the meantime, I'll do my best to try different scenarios in the field and provide listening samples. I now have 2 pairs of at853Rx's, although these aren't my preferred mics for quieter music, especially classical.
« Last Edit: September 28, 2023, 09:36:31 AM by Chanher »
Line Audio CM4 / AT853Rx (c,h,o) / Studio Projects C4 MKII (c,h,o)
Sound Devices MP-2 / bm2p+ Edirol UA-5
Zoom F3 / F6 / Marantz Oade Warm Mod PMD661 / Tascam DR-70D

Offline unclehoolio

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Re: Running a preamp in front of a recorder that doesn't have a true "line-in"
« Reply #14 on: September 28, 2023, 01:07:01 PM »
While I don't yet have a my preferred preamp (m148, still in acquisition mode) to run in front of a recorder, for purposes of comparative listening exercises, I do have the opportunity over the next couple of weeks to record some amplified shows (Billy Strings, JRAD) and generate some A/B comparisons.  I have 2 pair of AKG480/ck61 that just came back from being serviced by Harman Pro, which I need to run anyway to verify performance before the 90d warranty window closes.  For sure can do SD-MP6ii vs Zoom F8n.  If anyone is interested in loaning me an Oade mod tascam, etc. to put into the mix, then please drop me a PM.
mics:  AKG c480b (x6) + ck61, ck62, & ck63
pre:  2 x Oade m148
recorder:  Zoom F8n Pro; Tascam HD-P2 (with Oade High Definition mod)

 

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