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How good is Tascam HS-P82 recorder vs sound Devices? Recorders, Players & Tape Machines
Old 1st May 2018
  #121
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Quote:
Originally Posted by sentient View Post
Well it really depends on the external amplifier's gain. In the case of the 744T, for example, internal mic amplifiers on channel 1&2 has 67 dB of gain.

I would never recommend using more than 85-90% of the maximum gain range of any preamplifier. The last 10% usually just brings up a lot of noise. It's better to keep the pots at 90% maximum and apply gain in post-production, the end result is cleaner.


I don’t know where you get your information from in regard to S/N ratio vs. gain setting. It all depends on what kind of circuit topology in question. If the trim pot is in the feedback loop (which happens in about 99% of mic preamp) and turning the gain up translates to reducing amount of feedback in the circuit then the actual S/N ration will improve, you get best S/N ratio when the trim pot is all way up. Of course, you will hear more noise cranking the trim pot all the way up but the amount of noise increase in this case is less than amount of gain increase. Don’t get confused because you hear more noise as you turn the trim pot up.
Old 2nd May 2018
  #122
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rojaros's Avatar
Quote:
Originally Posted by Richard Crowley View Post
There appear to be generally four different schemes for accommodating balanced line-level input:
  1. External user pad - i.e. just make the end-user pad their line-level signal down to mic-level.
  2. Internal dumb pad - provide a switched internal line-to-mic level pad. Signal gets chopped down to mic level and then has to go through the internal mic preamp circuit (with attendant inferior signal-to-noise performance). This is what most portable, "pro-sumer" mixers appear to do.
  3. Internal mic/line circuit design - More sophisticated products still use the differential input circuit of the mic input, but they switch the gain (and perhaps other parts) of the circuit to optimize performance for both mic-level and line-level inputs. I have seen this in higher-end professional-grade camcorders, for example.
  4. Separate line-level input - Simply an additional input point in the audio path AFTER the mic preamp circuit. Presumably this is the design that most larger desks use.

My prejudice suggests that SD likely uses #3 , while Tascam may quite possibly use #2 (which is inferior, IMHO)
According to the block diagram of HS-P82 (and also the Tascam DR-680) it's your #4 which is superior to all other. Or else they have faked their block diagrams, which would be a bold statement...

Also the input impedance specs of both Tascam recorders are 2.4kOhm for mic input and the standard 10kOhm for line inputs, which (again if not faked) strongly speaks for your #4 (as opposed to SD Mixpre-6 that doesn't give a block diagram and states 4kOhm for both, mic input and lin input!)

Of course in any cas, if you use an external mic pre, you have to go through some kind of internal preamp, be it either way. I'd guess that going through a dedicated line input stage is less critical soundwise than passing the whole mic pre stage with downpadded level.

tascam HS-P82 user manual - Google Search

https://www.google.com/search?q=tasc...ient=firefox-b
Old 2nd May 2018
  #123
Gear Nut
 

Quote:
Originally Posted by Earcatcher View Post
Here are some measurements from a test in German Audio Magazin, made with the HS-P82.
Where is this "German Audio Magazin" and how do I get hold of it? (search is about as useful as Googling definitively for WMDs...)
Old 2nd May 2018
  #124
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Quote:
Originally Posted by rojaros View Post
According to the block diagram of HS-P82 (and also the Tascam DR-680) it's your #4 which is superior to all other. Or else they have faked their block diagrams, which would be a bold statement...

Also the input impedance specs of both Tascam recorders are 2.4kOhm for mic input and the standard 10kOhm for line inputs, which (again if not faked) strongly speaks for your #4 (as opposed to SD Mixpre-6 that doesn't give a block diagram and states 4kOhm for both, mic input and lin input!)

Of course in any cas, if you use an external mic pre, you have to go through some kind of internal preamp, be it either way. I'd guess that going through a dedicated line input stage is less critical soundwise than passing the whole mic pre stage with downpadded level.

tascam HS-P82 user manual - Google Search

tascam dr-680 user manual - Google Search
Not sure is it's correct to interpret No. 4 as bypassing the mic preamps.

It would mean that the recorder had two different types of amplification,
as opposed to different levels of amplification.

I asked the Sound Devices tech what the difference was on the 744t
in using the two channels which don't have built in "mic preamps" but
he wasn't too sure about it.

I'm interested to find out what the difference is in a recorder between
amplifying to line level, and amplifying to a level of recording with
microphones, and if it's only a difference in the level of amplification.
Old 2nd May 2018
  #125
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rojaros's Avatar
Quote:
Originally Posted by aracu View Post
Not sure is it's correct to interpret No. 4 as bypassing the mic preamps.

It would mean that the recorder had two different types of amplification,
as opposed to different levels of amplification.

I asked the Sound Devices tech what the difference was on the 744t
in using the two channels which don't have built in "mic preamps" but
he wasn't too sure about it.

I'm interested to find out what the difference is in a recorder between
amplifying to line level, and amplifying to a level of recording with
microphones, and if it's only a difference in the level of amplification.
No, that is not how it works. Every higher quality mixing board has a microphone pre-amplification stage that brings the mic inputs up to line level, and then a lin level mic that basically buffers all signals and allows for summing.

If you have an external mic preamp, than you go from there to line level input on the next device in your chain. E.g. classically you went from an analogue mic preamp to an analogue compressor limiter, which already only had a line level input, and then to the line level input of your recorder.
So this is technically the cleanest solution to accommodate the low level mic source, bring it up to line level, and then to accommodate to the output impedance of the mic pre with a higher input impedance of the line level input.

I wonder whether the guy at SD doesn't know for sure or doesn't want to speak about the details.

It's sure that the mic pre input needs another impedance than the line level. With Tascam 2.4 kOhm the input impedance of the mic pre is already higher than on many other mic pres (making it easier to connect ribbons and dynamic mics), and the 10kOhm of the line level input is absolutely classical IMHO.
Old 2nd May 2018
  #126
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Earcatcher's Avatar
Quote:
Originally Posted by SocietyOfMind View Post
Where is this "German Audio Magazin" and how do I get hold of it? (search is about as useful as Googling definitively for WMDs...)
I keep a library of equipment tests and product information of stuff that got my interest at some point over the years. I attach the quoted test below. Hope you can read German.
Attached Files
File Type: pdf pa22732_tascam-hs-p82.pdf (1.55 MB, 78 views)
Old 2nd May 2018
  #127
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Quote:
Originally Posted by rojaros View Post
No, that is not how it works. Every higher quality mixing board has a microphone pre-amplification stage that brings the mic inputs up to line level, and then a lin level mic that basically buffers all signals and allows for summing.

If you have an external mic preamp, than you go from there to line level input on the next device in your chain. E.g. classically you went from an analogue mic preamp to an analogue compressor limiter, which already only had a line level input, and then to the line level input of your recorder.
So this is technically the cleanest solution to accommodate the low level mic source, bring it up to line level, and then to accommodate to the output impedance of the mic pre with a higher input impedance of the line level input.

I wonder whether the guy at SD doesn't know for sure or doesn't want to speak about the details.

It's sure that the mic pre input needs another impedance than the line level. With Tascam 2.4 kOhm the input impedance of the mic pre is already higher than on many other mic pres (making it easier to connect ribbons and dynamic mics), and the 10kOhm of the line level input is absolutely classical IMHO.
This is getting close to what I'd like to understand, so any help is much appreciated.

With excellent units like the Merging Horus/Hapi, and others too including some of the very good portable recorders such as those from SD and others, why route the line input through the mic pre? It seems to me that doing so is an unnecessary compromise, unless it is more important to match very precise input parameters to the ADC and the benefits in doing so outweigh those of a simpler signal path to avoid the micpre stage.

There seems to be sufficent space on these boards and inside the units to accomodate additional short circuitry from the line-in to avoid the mic pre. So maybe my own thinking on this is not correct, and a signal path of a line-in through a pad/mic-pre to the ADC is perfectly fine and better than a more direct route avoiding the micpre.

Or maybe some like me who want to use some of these units for their neutral preamps and ADC, but also want to add other external preamps for their own characteristics, are in the minority and do not merit the minimal costs for accommodation.
Old 2nd May 2018
  #128
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rojaros's Avatar
Quote:
Originally Posted by Swing View Post
This is getting close to what I'd like to understand, so any help is much appreciated.

With excellent units like the Merging Horus/Hapi, and others too including some of the very good portable recorders such as those from SD and others, why route the line input through the mic pre? It seems to me that doing so is an unnecessary compromise, unless it is more important to match very precise input parameters to the ADC and the benefits in doing so outweigh those of a simpler signal path to avoid the micpre stage.

There seems to be sufficent space on these boards and inside the units to accomodate additional short circuitry from the line-in to avoid the mic pre. So maybe my own thinking on this is not correct, and a signal path of a line-in through a pad/mic-pre to the ADC is perfectly fine and better than a more direct route avoiding the micpre.

Or maybe some like me who want to use some of these units for their neutral preamps and ADC, but also want to add other external preamps for their own characteristics, are in the minority and do not merit the minimal costs for accommodation.
This is again a misunderstanding IMHO. The block diagrams clearly show that the output of the mic pre stage goes to the line level stage input, and switching to line input just bypasses the mic pre stage and goes straight to where the mic pre signal arrives. This is absolutely classical signal path if you had all the boxes separately.

If you see that, than it's clear that only the line level stage output hits the converters, independently with what the line level input was fed; be it mic pre output or directly line level signal. No difference here!
Old 2nd May 2018
  #129
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Quote:
Originally Posted by rojaros View Post
This is again a misunderstanding IMHO. The block diagrams clearly show that the output of the mic pre stage goes to the line level stage input, and switching to line input just bypasses the mic pre stage and goes straight to where the mic pre signal arrives. This is absolutely classical signal path if you had all the boxes separately.

If you see that, than it's clear that only the line level stage output hits the converters, independently with what the line level input was fed; be it mic pre output or directly line level signal. No difference here!
Which unit are you speaking about?
Old 2nd May 2018
  #130
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rojaros's Avatar
Quote:
Originally Posted by Swing View Post
Which unit are you speaking about?
Still about Tascam HS-P82 and/or DR-680, which both have the same block diagrams and specs of the input stages...
Old 2nd May 2018
  #131
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Quote:
Originally Posted by rojaros View Post
Every higher quality mixing board has a microphone pre-amplification stage that brings the mic inputs up to line level, and then a line level mic that basically buffers all signals and allows for summing.

If you have an external mic preamp, than you go from there to line level input on the next device in your chain.

So this is technically the cleanest solution to accommodate the low level mic source, bring it up to line level, and then to accommodate to the output impedance of the mic pre with a higher input impedance of the line level input.
I think what you are saying is that a mixing board amplifies the signal to line level, then you plug your preamp into it. So in this situation you are going through two different amplifiers.

With a recorder with "built in mic preamps", why go through two amplifiers if it can be narrowed down to one amplifier?
Old 2nd May 2018
  #132
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Quote:
Originally Posted by rojaros View Post
Still about Tascam HS-P82 and/or DR-680, which both have the same block diagrams and specs of the input stages...
I have seen the block diagram for the P82 and it does seem you are correct with the Tascam units. I am looking for a base with more than 8 channels and so was speaking of other units which appear to run the line-in through the mic-pre. Sorry to muddle this thread a bit, but it is of some relevance for those who would like to have some nice external mic pres running through some 'portable' units.
Old 2nd May 2018
  #133
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Quote:
Originally Posted by Swing View Post
other units which appear to run the line-in through the mic-pre
Does the unit have one amplifier or two amplifiers ?
Old 2nd May 2018
  #134
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Quote:
Originally Posted by aracu View Post
Does the unit have one amplifier or two amplifiers ?
For example, the Merging cards appear to run both mic input and line input through the same one amp (page 12 of the Horus manual, and the card specific pages which follow are consistent): http://www.merging.com/uploads/asset...nual_Rev35.pdf
Old 2nd May 2018
  #135
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rojaros's Avatar
Quote:
Originally Posted by Swing View Post
I have seen the block diagram for the P82 and it does seem you are correct with the Tascam units. I am looking for a base with more than 8 channels and so was speaking of other units which appear to run the line-in through the mic-pre. Sorry to muddle this thread a bit, but it is of some relevance for those who would like to have some nice external mic pres running through some 'portable' units.
No problem.

Do you know of any truely portable unit with more than eight input channels at the same time?
One could stack up several tascams but that ends up being as bulky as any HD-24 or 48 channel recorder. Maybe several mix-pre 10s? But they seem to put any signal through their mic pre stage.
Old 2nd May 2018
  #136
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Quote:
Originally Posted by rojaros View Post
No problem.

Do you know of any truely portable unit with more than eight input channels at the same time?
One could stack up several tascams but that ends up being as bulky as any HD-24 or 48 channel recorder. Maybe several mix-pre 10s? But they seem to put any signal through their mic pre stage.
Together two small Sonosax boxes, the AD8+ and the R4+, but I have not checked the block diagrams. These are truly portable.

edit: Forgot to mention the zaxcom units. Of course, the sonosax and zaxcom are at higher price points . . .

Last edited by Swing; 2nd May 2018 at 10:18 PM.. Reason: add info
Old 2nd May 2018
  #137
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rojaros's Avatar
Quote:
Originally Posted by Swing View Post
Together two small Sonosax boxes, the AD8+ and the R4+, but I have not checked the block diagrams. These are truly portable.

edit: Forgot to mention the zaxcom units. Of course, the sonosax and zaxcom are at higher price points . . .
Sonosax looks a bit convoluted to me as a system.

Zaxcom Deva 24 looks great, but ... 12k$...
Old 2nd May 2018
  #138
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This debate and anxiety about mic and line input gain design has gone beyond what seems to be sensible. Leave the design of these things to the experts. Horus/Hapi are supreme sounding devices, I continue to be astonished every time I use them. It is obviously not detrimental to performance.

Much more important for these small recorders is if their power supply blows up or their switches break or the display stops working or half works in the dark or if it starts producing pixel lines across the screen etc, These are the real deal breakers for these machines, not how their preamp is designed.
Old 3rd May 2018
  #139
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Quote:
Originally Posted by David Spearritt View Post
It is obviously not detrimental to performance.
I think you are right. It's the word "mic preamp" which is confusing. On a single unit with both line input and "mic preamp", it makes sense to have the same amplifier for different levels of amplification.
Old 3rd May 2018
  #140
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Quote:
Originally Posted by David Spearritt View Post
This debate and anxiety about mic and line input gain design has gone beyond what seems to be sensible. Leave the design of these things to the experts. Horus/Hapi are supreme sounding devices, I continue to be astonished every time I use them. It is obviously not detrimental to performance.

Much more important for these small recorders is if their power supply blows up or their switches break or the display stops working or half works in the dark or if it starts producing pixel lines across the screen etc, These are the real deal breakers for these machines, not how their preamp is designed.
I have no problem with this when I record chamber music or solo classical piano and the very nice and clean mic pres in the units are fine. I've been doing this for years with the Nagra VI, and running extra micpres through lines 5 and 6 when needed.

But I am now expanding the number of channels I use because I have more jazz sessions. And on these sessions I am looking for a different sound. So when I use different mic pres for a reason I want to understand what is happening and, if the signal is going through another mic pre then why. Or if for some reason I want to use a different clean mic pre then same thing, I want to understand what is happening and if the signal is going through another mic pre then why.

It is perfectly valid to want to understand what is being done with the design. This is GS after all and many thousands of posts discuss very minor differences between mic pres.
Old 3rd May 2018
  #141
Gear Nut
 

Quote:
Originally Posted by Earcatcher View Post
I keep a library of equipment tests and product information of stuff that got my interest at some point over the years. I attach the quoted test below. Hope you can read German.
Thanks so much - that's indeed very helpful!

I can make out about 70% of written German... for the rest there's Google translate. Conversational German is another matter! (aber ich habe ein paar gute deutsche Freunde, die versuchen mein Deutsch zu verbessern)

I don't suppose the DR-680 mk II was tested?
Old 3rd May 2018
  #142
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Plush's Avatar
Manufacturers goof us over by not publishing block diagrams and schematics. This used to always be included in the owner's manual / documentation.

When a line input goes through a mic amp, the mic amp is called a head amp.
So it is neither a great mic amp nor a great line input.
Old 3rd May 2018
  #143
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Agreed. I am not even close to the exotic efforts made by a lot of the people on GS, but if I have $2k to $6k invested in each of several external mic and mic pre channels it is only rational to try and understand what is happening with the signal path before buying a new unit. This is not to detract from the quality of the portable recorders and similar units as they stand but to learn how they are designed and best used. I'll probably create another thread re my search and hope to have some help, as my intent was not to stray too much from the main topic here.
Old 3rd May 2018
  #144
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rojaros's Avatar
I think the different viewpoints come from different applications. For those of us who use the recorders more or less exclusively for multitracking live music it's different form all the diverse ENG and filming applications.
The issues of using an external mic pre of a trusted sound signature without the sound being messed with too much is a valid point of view. The other practical points of view are valid, too.
Old 4th May 2018
  #145
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Quote:
Originally Posted by Plush View Post
Manufacturers goof us over by not publishing block diagrams and schematics. This used to always be included in the owner's manual / documentation.

When a line input goes through a mic amp, the mic amp is called a head amp.
So it is neither a great mic amp nor a great line input.
Well really only the line input is compromised if at all, with a front end pad. The mic path is certainly not compromised.
Old 4th May 2018
  #146
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The term "head amp" is vague and usually refers to either headphone amplifiers or amplifiers for loud music amplification bought
separately from the speaker cabinets.

Nagra, Merging and Sound Devices use a more unified design than the traditional technology in which a separate amplifier is plugged into a mixing board amplifier. The advantage is that the signal is going through one amplifier instead of two.
Old 4th May 2018
  #147
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loujudson's Avatar
Quote:
Originally Posted by David Spearritt View Post
Evidence direct from SD given above. 40dB pad in the mic/line switch.
I will concede that this may be true, BUT the 4xx and 5xx series are very different beasts than the 7xx series.
Old 4th May 2018
  #148
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Plush's Avatar
A “head amp” refers specifically to a front end microphone preamp that uses a pad to accommodate a line input. In other words the head amp does double duty. It is the only “amp.”

Has nothing to do with a gtr. amplifier or Marshall head.
Old 4th May 2018
  #149
Gear Maniac
 

Quote:
Originally Posted by Plush View Post
A “head amp” refers specifically to a front end microphone preamp that uses a pad to accommodate a line input.
It is a fairly obscure term (at least these days) and one I've encountered most commonly when applied to the first preamp (gain/trim) on Yamaha mixers. Of course, not altogether surprisingly, these are switchable between mic and line-level inputs, but I note that Yamaha appear to use the term often simply as an alternative to preamp (e.g. 7.2 Head amps | 7) Level issues | Audio Quality in Networked Systems | Self Training | Training & Support |
Yamaha
)

I echo David's point that line-level capability doesn't inherently compromise the mic preamp.

Cheers,

Roland
Old 20th May 2018
  #150
Quote:
Originally Posted by cinstance View Post
There is one important difference between Tascam recorders and Sound Devices recorders that is not known to many people. The line level inputs on the Tascam actually can bypass the mic preamp, while on the Sound Devices they cannot. For those intend to use external preamp with the recorder, it will make a big difference. I tested my lowly Tascam DR 680MKii against my Sound Devices 702T, both use line input fed by a pair of Grace Design M101s recording a grand piano. The difference is staggering to my ear. The sound comes out from the Tascam is noticeably more clear and better defined.
Fascinating! Thanks for sharing that point :-) I should try out my DR680mk1 vs 552
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