Bijou

 

Cavalli-Lovell-Futterman Mk.I (The Bijou)

The Cavalli-Locell-Futterman is a high quality DIY (do it yourself or self-made) headphone amplifier. The circuit is based on a Futterman that was further developed by Alex Cavalli and Mark Lovell, two DIY headphone amplifier gurus. I discovered the circuit diagram on http://headwize.com . In the meantime there is also a ready-made layout for circuit boards.

An EZ80 is used as the rectifier tube. One E88CCJJ and one ECC99JJ are used per amplifier channel.

© 2005 Alex Cavalli

The components

The empty case made of stainless steel
Thanks again to Gäffi, Peter and Herbert.

The tension stabilization

The finished device in the typical DIY spaghetti construction.

The amplifier is fed by my DAC I. It drives a Sennheiser HD650. The sound is pleasant and fully met my expectations. Unfortunately, I cannot give a more precise sound description, as I cannot compare it with other headphone amplifiers. What is striking for a tube amplifier, however, is the complete absence of (audible) noise and hum.

Audio Valve RKV HPA with PCL805

Tube headphone amplifier with PCL805 08/15/2007

Source Files download

The picture below shows the max Output voltage before soft clipping in OTL mode under 220 Ohm load per channel,  reaching 43 Vrms for 8.3 wattsper channel.

If you are not sure which tube you need, please look at the circuit board and see what is written there (PCL805), or ECL85 (6F5P).

In mid-2015 it has been changed from PCL805 to ECL85 that affects the models of all RKV, Luminare and Solaris.

Description of some technical details ...

The output impedance of Luminare with negative feedback (physical concept: closed loop) is defined as follows.

The control is based on the principle of negative feedback of the open loop gain ( 133 dB ) of the amplifier. 

However, since there is a closed loop. Dynamically because the amplifier tries to keep active voltage at the output losses in upright because he

continuously compares its actual value (feedback) to the desired value (signal) and continuously re-adjusts addition, through the entire range.  

Example: The OTL mode provides Luminare 1V without load resistance and 0.998 V at 60 ohm load resistor.

From these data it can be calculated easily, that the output impedance of the amplifier for this load resistance 0.12 ohm.

The fact of wanting to determine the output impedance by incorporating the tubes, is simply nonsense.

It's not the tube determines the output impedance, but the overall OTL concept.

This applies to RKV 2 + 3 and Luminare. 

The output transformer is not the part of its gain loop.  

If you are interested in the circuit design, read the patent in 1982 below.

Tube Rolling is simply stupid in the models RKV, Luminare and Solaris. You can convince yourself by knocking on the tubes, and you will not hear any knocking sounds in the headphones.

Inside the power inlet a fuse can be found as a protection against overload.

For the 117 V version the value of the fuse should be 1 Ampere Slow.

For the 235 V version the fuse is 0,63 Ampere Slow.

In the end I found what I was looking for at Jogi's tube booth , where there is a circuit with two PCL805s (per channel) in push-pull operation (see under Amplifier - PCL 805-Headphone-Amp). 

The advantages of this circuit:

Very high output power (mei, as a rocker you just need pressure)
Proven design (originally by Helmut Becker)
No output transformer 
Except for the mains transformer and tubes, only standard components


ATTENTION !!

If you want to build and operate this power amplifier, you should know exactly what you are doing. The mains voltage as well as the anode voltage for the output stage tubes (375V) are freely conducted in the device. Improper handling is life-threatening! Even after switching off, you must wait until the electrolytic capacitors are discharged (check with a multimeter) before continuing to work on the device! I am not responsible for any damage caused by the replica!
First construction - we iron a layout!

The schematic was quickly nailed up in Target3001 and turned into a layout. 

But stupid: Just when it was time to create the circuit board, I noticed that I had overestimated the capacity of my circuit board store: There were no photo-positive coated circuit boards in the right size. Damn! However, I still had copper-coated circuit boards WITHOUT photoresist, and it occurred to me that I had once read about the "toner transfer method". 

The layout is printed out with a laser printer and ironed onto the copper of the circuit board with an iron. Then carefully rub the paper with washing-up liquid and the toner covers the tracks that should remain in place during the etching.


Thomas Pfeifer , for example, has more information on this on his website. What can I say: It worked! Even if the edge sharpness is not the very best and I had to repair one or the other membrane afterwards - it wasn't bad at all for the first time.

Power hungry

The first switch-on - still without the anode voltage connected - went well, the heating of the tubes began to glow, all voltages were within tolerance, so after switching off I activated the anode voltage and switched it on again. Not without an ammeter in between - I probably suspected it: As soon as the tubes come up to temperature, the anode current continues to rise ... So quickly switched off the whole moped again. Then something is probably wrong.

The troubleshooting took a lot of nerves, I kept checking the structure, comparing it with the circuit diagram ... nothing! 

Everything as it should be.

After another week I was on the verge of giving up the project, but as a last, desperate step I looked at the original layout on Jogi's side and reproduced it with the circuit diagram - 

HUPS, there is a capacitor where there is none in the circuit diagram! 

Yes, of course, without it the lower tube is at the wrong working point in terms of DC voltage and is fully open! 

You could have seen that on the circuit diagram, but sometimes you can't see the forest for the trees ...

Here is the original scheme from Jogi's site with my correction:

Lo and behold, as soon as the capacitor was installed, the circuit ran, the anode current remained within its limit. To be on the safe side, one last test, signal generator to the input, 330 ohm load resistor and oscillator to the output, and see what the amp does. 

In principle it looks good, the signal comes out nicely amplified, but there is a clear hum. This is confirmed by the hearing test with MP3 player and headphones - it works, but it buzzes like a bag of bumblebees ...
Growl

So what to do


We wanted a two-sided layout, with a thick ground plane on one side. Because my guess was that it is a pure mass problem. In addition, the heating cables should be completely removed from the circuit board and wired freely in order to avoid voltage drops across the ground. 

The implementation of the layout was not so easy, however: I had to have a two-sided board made, the self-etching was too tricky for me, because the board is quite large and so the congruence of the two layers is difficult. 

Since it was the PCBPool Edition, I could only use Target3001 in conjunction with the PCBPool , and the guys are not cheap ...

So I decided to try KiCAD , a free CAD program for circuit board development published under the GPL license. 

Circuit board size practically unlimited, lots of free libraries from other users, that sounds really good, doesn't it?

KiCAD

To anticipate: it took me some time to get used to the KiCAD version of that time (from 2005) ... First the usual training hurdles until one understood the philosophy of the program, and then there was also the one or other bug that made life difficult for you. 

Fortunately, a lot has happened in the meantime, and today I only use KiCAD in my private life. You have no restrictions with regard to the number of pins, etc., you can generate Gerber files directly and are therefore not tied to a circuit board manufacturer.

Back to the topic - somehow I got the circuit board strapped and after three weeks of waiting it was in my mailbox. I ordered them from LeitOn , which made a good impression and, according to the online calculator , had one of the cheapest prices.

Lo and behold, after "moving" the components from the old circuit board to the new one and running through the commissioning tests again, the first hearing test followed, and the humming was significantly reduced, but unfortunately still not completely gone ...
The breakthrough

The real breakthrough came with a tip from Helmut Weigl , who - independently of me - also shared a replica of the amplifier and also stumbled upon the problem with the missing capacitors. 

I helped him with the capacitors, and in return he gave me tips on how to reduce the hum. If that is no help among hobbyists - Thank you, Helmut!



The grounding at the inputs of the two operational amplifiers is very important. 

There should be a central ground point for each channel, to which the voltage divider from the audio input as well as from the feedback and the headphone output refer. Without further ado I created this grounding by scraping open the grounding lines from the potentiometer and connecting them directly to the OpAmps with wire. 

Lo and behold, your colleague is no longer grumbling! Bingo!!

Layout, the third ...

In October 2012 I implemented the previous knowledge in a new layout so that you can easily and successfully recreate the amplifier. 

There the grounding has been changed again, it is a two-sided layout WITHOUT a ground plane, so that you can theoretically build the amp on a one-sided circuit board if you then lay the missing connections with wire. 

In addition, I brought in some of Helmut's ideas and changed the power supply again so that the operating voltages are cleaner (without ripple voltages) (with the exception of the 350V, where a small ripple voltage has no influence on the hum at the output). 

Furthermore, a new volume potentiometer from ALPS has been added, which has a better synchronization and hopefully lasts longer - the cheap potentiometer from the old amplifier was already starting to scratch ...

I ordered this board from PCB-Joker , where you can get it for 60 €. The gag with this company is that you don't know what you are getting - it can be a printed circuit board between 0.5mm and 2.0mm thick, with any colored solder mask. While the color is not an issue, I was unlucky with the thickness - I got a 0.5 of all things. For this reason I had to attach an additional fastening in the middle of the board, with a normal 1.5mm board this is not necessary.

The complete documents on the RKV can be downloaded here. 

The archive contains:

KiCAD project

Gerber

BOM

Front panel files for the housing

(can be ordered directly from Schaeffer ).

setup and start-up

After setting up the amplifier and checking the equipment (the tubes are not yet fitted!) 

You should first connect only the 36V winding of the transformer and switch on the amplifier. 

Then you should check the following points:
+ 22V via D20 (22V-Zener-diode)
+ 12V at C44 (output of the 12V regulator)
-8.2V via D19 (8.2V Z-Diode)
-18V via D21 (18V-Z-Diode)

If all voltages are OK, you set a voltage to approx. 3.5V with the potentiometer RV2 via C4, the same with RV3 3.5V via C17.

Now you can switch off the amp again and connect the high voltage from the transformer. 

ATTENTION, from now on it will be dangerous !! After switching on you should measure a voltage of approx. 375V via C36 (this voltage is even higher than later in operation, since no tubes are plugged in yet and therefore no anode current is flowing). 

If this voltage is also fine, you can switch off the amp.

IMPORTANT: wait until the C36 is discharged to a safe voltage and then insert the tubes.

If you turn on the amp now, the tubes should heat up. During the heat-up time, a strong fluctuation in the output voltage can be seen at the headphone output, which should calm down after the end of the heat-up time. 

To properly balance the amp, a function generator (1kHz, sine) is connected to the input, a load resistor (300 to 400 ohms, 5 watts) plus an oscilloscope connected to the output. 

Now the amplitude of the generator is slowly increased (don't forget the volume potentiometer) until the signal at the output begins to distort and the peaks of the sinusoidal signal are cut off. 

The amplifier is then set with the potentiometer of the respective channel so that the distortion is symmetrical, ie positive and negative half-waves of the sine are cut off evenly. The other channel is set in the same way.

If you don't have an oscillator / function generator, you can simply set the potentiometer so that about 150V is applied to the output electrolytic capacitor (C13 / C26). Then you should be roughly in the middle of the dynamic range.

A few more tips ...

Here are some more information and tips on how to recreate it. The ZIP archive contains a parts list that should contain pretty much everything you need for a replica. Sources of supply and current prices are also given there. Do not be put off by the price, it really includes ALL parts including custom-made transformer, circuit board and housing, and some things are only available in larger quantities (screws, etc.). So you can definitely still save here.

When making a replica, you should make sure that the entire audio signal chain, if at all, should only be grounded at one point (connected to the protective conductor). The housing is designed so that this ground point is at the headphone jack; the cinch sockets, on the other hand, are isolated from the housing. 

If the rest of the audio system is grounded somewhere, you can quickly catch ground loops; then you should look where the ground loop is and break it open.

The metal axis of the potentiometer should also be grounded if possible, otherwise it could crack when you touch the (metal) potentiometer in the headphones.

Don't be surprised if you put on the headphones and turn on the amplifier; at the beginning during the first 10-20 seconds you can hear an illustrious humming concert until the tubes have reached their operating temperature. 

Afterwards, the amplifier should be quiet - at least as far as the hum is concerned ...

************************************************

And now of course the all-important question:
How does it sound now?

I would like to say! Together with my Sennheiser HD570, a really strong duo. Nice sound, well-developed bass, that's how it has to be. And it really is the case that with familiar songs you keep hearing small details that you haven't noticed before. So the construction was definitely worth it for me.
Pictures of the construction

Here are a few more photos of the structure and inner workings of the RKV:



Front view ...



... and from behind.



Interior view of the RKV.

The circuit board in detail. 

In the middle the additional fastening necessary for the 0.5mm board.

Pictures of replicas

************************************
March 2017: 

Uli recreated the amplifier with the original layout of Jogi's tube booth, and came to my site because of the hum problem. Obviously the original is not completely hum-free either, but together we were able to calm the amplifier down a bit. Also a very nice replica!

*********************************

January 2014: 

Stefan cloned the headphone amplifier with his own layout and also added a circuit for volume control via a motor potentiometer, which can be remotely controlled using an infrared remote control. The case is self-built. A really nice piece! 

The complete documentation on this replica can you download here. 

Many thanks to Stefan for providing!






***********************************

March 2013: 

Thomas used the current, the third version of KiCAD layout. 

He made the circuit board himself by simply producing the front and back sides separately on two single-sided circuit boards and then putting them back to back. 

The housing is made of laminated wood with bamboo fittings, the front and back panels are made of 3mm MDF panels painted gray. Became very beautiful!

Note: 

The pictures show a Euro plug without a protective conductor. Due to the metal surfaces that can be touched and the high voltages carried in the device, 

I strongly advise you to use the amplifier WITH a protective contact: 

SAFETY FIRST!

In addition, the cable should be led through a rubber grommet etc. at the housing entrance and provided with a strain relief, otherwise the cable could chafe through and the conductors could come into contact with the housing.










*******************************************************
END OF Mario.de

*******************************************************

Dayton DATS V3 音訊元件測試系統

DATS V3 Computer Based Audio Component Test System

DATS V3 音訊元件測試系統  繁體中文化版本 V1.0.5

下載DATV3主程式 2021/9

Dayton Audio has taken the most complete and easy-to-use audio test system and improved it in almost every way when creating the DATS V3 Computer Based Audio Component Test System. With improvements to the accuracy, capability, and reliability of the DATS V2, the DATS V3 sets a new standard for quick and accurate audio component measurements.

Product Highlights

• Rugged aluminum housing with detachable test leads and built-in precision calibration resistor
• Tighter tolerances on internal components for more precise measurements
• Increased output capability means greater separation from the noise floor, resulting in more accurate measurements
• DATS Linearity Test for comparing parameters and impedance plots at multiple drive levels
• Optional under desk mounting brackets included to save desk space
• Only 1" H x 2-1/2" W x 4-1/8" D for easy portability

GPIB Toolkit by John Miles, KE5FX

原文網址 http://www.ke5fx.com/gpib/readme.htm
Welcome to the GPIB Toolkit!

The GPIB Toolkit is a collection of free Windows utilities that will help you make and record research-quality measurements with GPIB-based electronic test equipment.

This is version 1.988 of the Toolkit, released July 29, 2021.

下載中文化GPIB工具包 (4 MB) V1.988, 2021/7/29

Prologix GPIB設定程式繁體中文下載

For troubleshooting help and additional application notes, check the FAQ.

The GPIB Toolkit is provided with full C++ source code for public- and private-sector, educational and Amateur Radio / hobbyist use. Comments and feedback are always welcome.

John Miles, KE5FX
john@miles.io

TASCAM UH-7000 PCM4220+1795

 

TASCAM UH-7000

Professional USB Audio Interface / Standalone Mic Preamp

The TASCAM UH-7000 is a very interesting device for creating high quality recordings. At the higher end price bracket, we usually see the emphasis of manufacturers on the number of I / O, flexible configuration options, expandability, and the like. But the most massive user request turns out to be unclaimed: give the highest quality two channels, with preamplifiers of the highest category, for the most demanding recordings or for studio overdubbing. The same goes for on-site recording with a laptop. It is unwise to move a rack ADC and an expensive tube microphone preamplifier, because of the risk of damaging expensive equipment. Cheap interfaces fail either in terms of usability or sound quality. The equipment is too divided into studio and mass production. There are very few average options - in fact, none.

Specifications TASCAM UH-7000

Conversion characteristics
Dynamic ADC range	123 dBA
DAC dynamic range	123 dBA
Frequency response of microphone preamplifiers	20 Hz - 80 kHz + 0.005 / -0.16 dB
Signal-to-Noise Mic Preamps before ADC	117 dBA
Distortion of mic preamps before ADC	0.0009%
A	-128dBu
Inputs
Linear 1/2
Connector	TRS, balanced
Maximum	+26.5dBu
Minimum	--38dBu
Impedance	15 kΩ
Microphone 1/2
Connector	XLR, balanced
Maximum	+2dBu
Minimum	-60dBu
Impedance	2.2 k Ohm
Outputs
Linear 1/2
Connector	XLR, balanced
Maximum	+24dBu
Impedance	100 ohm
Headphone
Connector	1/4" TRS
Power	> 45mW + 45mW (Kg + noise <1% at 32 ohm)
Digital interfaces
AES/EBU
Connector	XLR input, XLR output
Format	S/PDIF, AES/EBU
Frequencies	44.1 / 48 / 88.2 / 96 / 176.4 / 192 kHz
USB
Connector	USB A-type
Protocol	USB 2.0
Nutrition
Mains voltage	100-240V, 50 / 60Hz
Consumption	15W
Dimensions (edit)	214 (W) × 81.2 (H) × 233 (D) mm
The weight	2.2 kg

In the category up to $ 600, the E-MU1616M card was undoubtedly popular among the decent digitizers. But it does not have a USB connection, is inconvenient in operation, and, at the moment, has completely gone out of sales. In a hurry to please our readers, the TASCAM UH-7000 is an absolutely healthy alternative to the E-MU1616M, as well as any other professional interface in this category. Among USB interfaces, MOTU Track16, RME Babyface, Apogee Duet immediately come to mind ... This is at its best! 

But, compared to the TASCAM UH-7000, these are, nevertheless, budget sound cards for a laptop.... Their invariable attributes: power from the USB bus or from a rootless Chinese pulse power supply unit, an obscene input for a guitar, a weak headphone amplifier, and 16-20 more connectors on a pigtail, on a Chinese 40-pin connector. This is done with the best intentions, supposedly suitable for anything, and it costs a lot. However, in practice, professionals are not very interested in such devices, their main audience is amateurs, with claims to ...

The absolutely all-metal TASCAM UH-7000 case, quite heavy, with its internal weighty power supply unit from 220 Volts, with full-fledged balanced Neutrik input and output connectors, contrasts sharply with the products of mass culture. Moreover, line and microphone jacks are separated, no XLR / TRS combo. Microphone Amplifiers - High Definition Instrumentation Architecture. The brand name does not bring clarity, it is much more important that this is the newest development of TASCAM, for recording in high DSD and PCM formats. For stand-alone operation (that is, without a computer at all), the TASCAM UH-7000 is officially recommended by the manufacturer as a Hi-End microphone preamplifier for the TASCAM DA-3000 rack-mount DSD / PCM recorder.

And that's why. Let's tell you right away that the sound on the recording is different from the usual inexpensive mic preamps. Something of its own is present in the sound, a certain signature handwriting. The Neumann TLM sounded even more noble in the midrange than before. And this is without any processing. According to the passport, the microphone preamplifier has a distortion of less than 0.0009%. Therefore, this effect is definitely not caused by saturation or something else, but the correct transmission of the timbre and dynamics of the sound. There was a feeling that the voice on the recording became more beautiful. Explosive consonants and sibilants, even at high amplitudes, do not overload the analogue tract and therefore are then removed by processing without artifacts. The recording is very natural and natural, does not require additional creative searches with a huge chain of intricate plugins.

The large front panel level controls and meters are input only. After the tiny twists of inexpensive audio devices, working with such controls is the height of delight. In addition to more precise adjustment with a large knob, it is worth noting a well-thought-out logarithmic adjustment scale and a significant gain margin. LED multi-segment picmeters in this price category are not found at all.

The voltage margin of the inputs and outputs is very high, which without any problems gives the pairing with studio rack ADC / DAC, where +20 dBu is the norm.

In all aspects, the overall impression is very positive. The TASCAM UH-7000 is a device you can't help but want to have in your arsenal. We especially note the high-quality headphone output and the overall high quality of the converters. A good DAC is immediately audible in headphones and monitors. According to the passport, 123 dBA is declared. This is not as important as really good sound when the difference is heard. The numbers are just numbers.

Here we noted the thermostabilized oscillators with a stability of +/− 1ppm. 

ADC Burr-Brown PCM4220. 

DAC Burr-Brown PCM1795. 

Proprietary microphone preamps are assembled on the TI OPA 1612A, with the highest characteristics: noise 1.1 nV / √Hz, distortion 0.000015%, slew rate 27 V / μs, bandwidth 40 MHz. 

TI NE5532A is used for line inputs and outputs. The choice of these op amps is unusual, unless we remember their ability to operate with supply voltages up to 30 V and at the same time be resistant to short circuits at the output.

If you are more interested solely in listening, the inputs are not needed, but the capacitors must certainly be Nichicon Gold, it makes sense to look towards DSD DACs such as TEAC UD-501, of the same manufacturer. There will be MUSES op-amps, audiophile gold-plated RCA connectors, and a more powerful headphone amplifier.

The major distortion is caused by the LINE input, where is the weakest circuitry of the device. In addition, the line input is dependent, it is regulated in level from the front panel within wide limits.

RightMark Audio Analyzer Test Report

Device under test	[ASIO] UH-7000
Working hours	24-bit, 44 kHz
Sound interface	ASIO
Signal route	External loopback (line-out - line-in)
RMAA version	6.4.1 PRO
Filter 20 Hz - 20 kHz	YES
Signal normalization	YES
Level change	-1.1 dB / -1.2 dB
MONO mode	NO
Calibration signal frequency, Hz	1000
Polarity	correct / correct

Overall results

Frequency response (in the range 40 Hz - 15 kHz), dB	+0.01, -0.16	Very good
Noise level, dB (A)	-115.8	Fine
Dynamic range, dB (A)	115.6	Fine
Harmonic distortion,%	0.0023	Fine
Harmonic distortion + noise, dB (A)	-90.2	Very good
Intermodulation distortion + noise,%	0.0027	Fine
Interpenetration of channels, dB	-115.1	Fine
Intermodulation at 10 kHz,%	0.0056	Fine
Overall score		Fine

Frequency response

	Left	Right
20 Hz to 20 kHz, dB	-0.48, +0.02	-0.50, +0.01
40 Hz to 15 kHz, dB	-0.14, +0.02	-0.16, +0.01

Noise level

	Left	Right
RMS power, dB	-114.6	-114.7
RMS power, dB (A)	-115.7	-115.9
Peak level, dB	-99.8	-91.9
DC offset,%	+0.0	+0.0

Dynamic range

	Left	Right
Dynamic range, dB	+114.4	+114.5
Dynamic range, dB (A)	+115.5	+115.7
DC offset,%	+0.00	+0.00

Harmonic distortion + noise (-3dB)

	Left	Right
Harmonic distortion,%	+0.0022	+0.0024
Harmonic distortion + noise,%	+0.0023	+0.0025
Harmonic distortion + noise (A-weighted),%	+0.0030	+0.0032

Intermodulation distortion

	Left	Right
Intermodulation distortion + noise,%	+0.0025	+0.0028
Intermodulation distortion + noise (A-weighted),%	+0.0018	+0.0020

Interpenetration of stereo channels

	Left	Right
Penetration at 100 Hz, dB	-113	-110
Penetration at 1000 Hz, dB	-114	-114
Penetration at 10,000 Hz, dB	-113	-112

Intermodulation Distortion (Variable Frequency)

	Left	Right
Intermodulation distortion + noise at 5000 Hz,	0.0042	0.0046
Intermodulation distortion + noise at 10,000 Hz,	0.0049	0.0053
Intermodulation distortion + noise at 15000 Hz,	0.0071	0.0076

Measurements of the TASCAM line-out to the Lynx Aurora 8 line-in in 24-bit 44 kHz mode are on a separate page. 

In summary, the THD of both devices do not exceed 0.0005%.

The measurements were performed on a desktop computer without any optimizations. As we can see, there are ABSOLUTELY no problems with noise and interference. Generally, it is their own PSU that makes the differences.

ASIO diagnostics

Device: UH-7000

Features:
Input channels: 4
Output channels: 4
Input latency: 524
Output latency: 710
Min buffer size: 256
Max buffer size: 256
Preferred buffer size: 256
Granularity: 0
ASIOOutputReady - not supported
Sample rate:
8000 Hz - not supported
11025 Hz - not supported
16000 Hz - not supported
22050 Hz - not supported
32000 Hz - not supported
44100 Hz - supported
48000 Hz - supported
88200 Hz - supported
96000 Hz - supported
176400 Hz - supported
192000 Hz - supported
352800 Hz - not supported
384000 Hz - not supported
Input channels:
channel: 0 (Analog 1) - Int32LSB
channel: 1 (Analog 2) - Int32LSB
channel: 2 (Digital 1) - Int32LSB
channel: 3 (Digital 2) - Int32LSB
Output channels:
channel: 0 (Computer 1) - Int32LSB
channel: 1 (Computer 2) - Int32LSB
channel: 2 (Computer 3) - Int32LSB
channel: 3 (Computer 4) - Int32LSB

4 channels of the device allow flexible use of digital I / O as additional I / O or for connecting external processing.

The signal processing, is based on hardware or say, DSP, can be configured by control panel. 

It is clear that now there is little sense in a hardware DSP for studio purposes. One of the applicable options - you can monitor the processed signal in headphones while recording, and select to listen unprocessed sound. 

Or, for example, you can equalize your headphones by increasing gain of high or low frequencies. Useful applications can be found.

We found out that TASCAM UH-7000 is not a sound card, it is not a digitization interface. First of all, it is a high quality microphone preamplifier for well-known brands of high category microphones. 

Further, it is a very high-end DAC and a good headphone output. The TRS line input and hardware DSP are made more "for show", but since no one forces you to use them, this does not spoil the impression. 

We have found the following application for the line input - if you apply an output signal to it, then the output signal will be effectively displayed on the picmeter in front of the device, which is impossible to reach by standard means. At the same time, the sound can be monitored from the headphone output.

The sound quality of the TASCAM UH-7000 impressed us. The genius of TASCAM engineers was revealed here in all its glory. Potentially a hit. More devices of such a high level would be produced!