[charlus]

Moniker/Name: charlus
 
Answer D.              Total of 781 components

 

[teamrushpntball]

Moniker/Name:    teamrushpntball
 
Answer D.           There are 781 components

 

[iFi audio]

Would the Retro's DAC and HP amp section be different from the Pro iDSD? What would be the differences, if any?

 
Hi,
 
They are very different.
 
The Retro is a traditional push-pull tube amp that was derived from classic tube designs of the "Golden Age of Audio". Like classic amplifiers, the Tube Power Amp drives either the Speakers or the Headphones via an output transformer from the tube power stage (using EL84 tubes).
 
In the Retro Stereo 50, the classic Tube design has been modernised where approriate; while retaining the quintessence of classic Tube design, rather than producing a more or less poor man's copy of classic designs as found so often in modern tube gear (but not always we hasten to add!).
 
However the use of tube technology does impose limits, especially in terms of distortion and noise. The Retro has much better performance than classic amplifiers in areas where modern technology can help without diminishing the sound quality tubes deliver. For example it has a much better Signal-to-Noise ratio and a flatter frequency response and much wider bandwidth than many similar "Golden Age designs".
 
Stereophile measured the quite legendary EICO HF-81 Amplifier from 1959 (yes 55 years ago, they have been discontinued for the better part of five decades and yes, it uses EL84 in push-pull) as having 70dB(A) SNR (at 1 Watt out).
 

 
By comparison, the Retro Stereo 50 offers better than 90dB (A) SNR, that is 20dB or ten times less noisy. Equally, where the 1959 original EICO HF-81 cannot deliver a flat frequency response and is 3dB down at 20kHz, the Retro Stereo 50's tube amp has a flat frequency response to 20kHz and a -3dB point well past 60kHz.
 

 
A fully regulated power supply allows more output power than comparable unregulated designs that must leave headroom for mains overvoltage and will have the power supply collapsing as the power is turned up. Yet even in modernised form, as a Tube Amp for the 21st Century, some limitations remain.
 
In practical terms these limitations are unlikely to cause any issues in the majority of systems and for most listeners. Care has been taken to match for example the headphone jacks correctly to the amplifier for good practical SNR. Some may consider that the tube style distortion inherent to this type of amplifier subtly enhances listening pleasure. It certainly does not create a negative impact on listening pleasure. On the contrary though, we still do not reliably know what makes "Tube sound good", see also our "why tubes" whitepaper¹.
 
Incidentally, Stereophile's test of the EICO HF-81 is found here:
http://www.stereophile.com/content/eico-hf-81-integrated-amplifier-measurements
 
We will post up AP2 test results for the Retro when time allows, so you can compare for yourself.
 
The DAC implementation in the Retro is not just a simple transplant from existing products either. It does offer excellent sound quality, but was designed to be integrated into the Amplifier design. So only a single DAC Chip is used as the tube amplifier ultimatley limits signal/noise ratios. Before you ask, using multiple DACs would give better SNR in the DAC section, but the Amplifier would still limit the overall system SNR.
 
The DAC has a very simple output stage that drives the 100K ALPS Volume Control in the Retro just fine, but would be hopelessly outmatched driving long cables and/or pro audio loads (600 Ohm), which is what the output stage in the iDSD Pro is designed to do, with its discrete Class A circuitry.
 

 
And where the DAC in the iDSD pro has a balanced output, the signal circuitry in the Retro Stereo 50 is resolutely single-ended, all the way up to the final Tube power stage. Which is "better?" Both as it is a case of horses for courses.
 
In many ways the Retro takes full advantage of the benefit of "integrating" functions into a single box, to optimise the performance of the overall package, by focusing only on what matters.
 
For DAC and Phono Stage things like compatibility with other equipment are safely ignored, as there is simply no other equipment, they only need to handle the internal circuitry of the Retro, no chasing headline specs (be it impressive SNR Numbers of huge numbers of Zero's in the THD figure) is useful, as the tube amplifier's limit's in these areas make any gains moot.
 
The Pro line is literally the opposite in approach, as widest possible equipment compatibility as well as cutting-edge technical performance and a "disintegrated" approach are taken to the logical conclusion (well, short of the extremism of AMR products anyway).
 

 
 

¹For those who have more than a passing interest in valves/tubes.
https://www.facebook.com/notes/ifi-audio/itube-tech-notes-part-1-the-magic-of-tubes/588114591224287
 
Additional reading:
Full EICO Review:
http://www.stereophile.com/integratedamps/606eico/
 
http://www.stereophile.com/content/eico-hf-81-integrated-amplifier-restoring-vintage-hi-fi-equipment
Restoring Old Amps...

 

[diamondears]

Hi,

They are very different.

The Retro is a traditional push-pull tube amp that was derived from classic tube designs of the "Golden Age of Audio". Like classic amplifiers, the Tube Power Amp drives either the Speakers or the Headphones via an output transformer from the tube power stage (using EL84 tubes).

In the Retro Stereo 50, the classic Tube design has been modernised where approriate; while retaining the quintessence of classic Tube design, rather than producing a more or less poor man's copy of classic designs as found so often in modern tube gear (but not always we hasten to add!).

However the use of tube technology does impose limits, especially in terms of distortion and noise. The Retro has much better performance than classic amplifiers in areas where modern technology can help without diminishing the sound quality tubes deliver. For example it has a much better Signal-to-Noise ratio and a flatter frequency response and much wider bandwidth than many similar "Golden Age designs".

Stereophile measured the quite legendary EICO HF-81 Amplifier from 1959 (yes 55 years ago, they have been discontinued for the better part of five decades and yes, it uses EL84 in push-pull) as having 70dB(A) SNR (at 1 Watt out).




By comparison, the Retro Stereo 50 offers better than 90dB (A) SNR, that is 20dB or ten times less noisy. Equally, where the 1959 original EICO HF-81 cannot deliver a flat frequency response and is 3dB down at 20kHz, the Retro Stereo 50's tube amp has a flat frequency response to 20kHz and a -3dB point well past 60kHz.




A fully regulated power supply allows more output power than comparable unregulated designs that must leave headroom for mains overvoltage and will have the power supply collapsing as the power is turned up. Yet even in modernised form, as a Tube Amp for the 21st Century, some limitations remain.

In practical terms these limitations are unlikely to cause any issues in the majority of systems and for most listeners. Care has been taken to match for example the headphone jacks correctly to the amplifier for good practical SNR. Some may consider that the tube style distortion inherent to this type of amplifier subtly enhances listening pleasure. It certainly does not create a negative impact on listening pleasure. On the contrary though, we still do not reliably know what makes "Tube sound good", see also our "why tubes" whitepaper¹.

Incidentally, Stereophile's test of the EICO HF-81 is found here:
http://www.stereophile.com/content/eico-hf-81-integrated-amplifier-measurements

We will post up AP2 test results for the Retro when time allows, so you can compare for yourself.

The DAC implementation in the Retro is not just a simple transplant from existing products either. It does offer excellent sound quality, but was designed to be integrated into the Amplifier design. So only a single DAC Chip is used as the tube amplifier ultimatley limits signal/noise ratios. Before you ask, using multiple DACs would give better SNR in the DAC section, but the Amplifier would still limit the overall system SNR.

The DAC has a very simple output stage that drives the 100K ALPS Volume Control in the Retro just fine, but would be hopelessly outmatched driving long cables and/or pro audio loads (600 Ohm), which is what the output stage in the iDSD Pro is designed to do, with its discrete Class A circuitry.




And where the DAC in the iDSD pro has a balanced output, the signal circuitry in the Retro Stereo 50 is resolutely single-ended, all the way up to the final Tube power stage. Which is "better?" Both as it is a case of horses for courses.

In many ways the Retro takes full advantage of the benefit of "integrating" functions into a single box, to optimise the performance of the overall package, by focusing only on what matters.

For DAC and Phono Stage things like compatibility with other equipment are safely ignored, as there is simply no other equipment, they only need to handle the internal circuitry of the Retro, no chasing headline specs (be it impressive SNR Numbers of huge numbers of Zero's in the THD figure) is useful, as the tube amplifier's limit's in these areas make any gains moot.

The Pro line is literally the opposite in approach, as widest possible equipment compatibility as well as cutting-edge technical performance and a "disintegrated" approach are taken to the logical conclusion (well, short of the extremism of AMR products anyway).





¹For those who have more than a passing interest in valves/tubes.
https://www.facebook.com/notes/ifi-audio/itube-tech-notes-part-1-the-magic-of-tubes/588114591224287

Additional reading:
Full EICO Review:
http://www.stereophile.com/integratedamps/606eico/

http://www.stereophile.com/content/eico-hf-81-integrated-amplifier-restoring-vintage-hi-fi-equipment

Restoring Old Amps...

Wow. Thanks for the detailed explanation iFi.

 

[dylanmcbean0819]

Answer D Total of 781 components

 

[cskippy]

Moniker/Name:    cskippy
 
Answer D.           There are 781 components

 

[Brooko]

Moniker/Name:    Brooko
 
Answer D.           There are 781 components
 
(Disclosure : I'm also a part-time reviewer on Head-Fi, non professional)
 
BTW - the Retro is gorgeous.

 

[BillsonChang007]

Moniker/Name:      BillsonChang007
Answer D.              Total of 781 components
 
reviewer on TechnoHeadphone.com 

 

[iFi audio]

How is the Retro different? (part 1 of 3)

Its Beauty is not just skin deep

 
As promised, some insights into the internals with measurements as we know you like'em.
 
 
So, okay, it is clad in grass¹ and alu with striking looks, but is beauty only skin deep?
 
Or is there more to the Retro Stereo 50 than meets the eye?
 
Of course, there is a Killer DAC hidden in there, which you almost never find integrated into any Amplifier, but the actual tube amplifier itself has a fair few special items that set the Retro Stereo 50 apart from both original antique Amplifiers and many modern manufacture tube amps, which are often just copies of classic designs.
 

 
Traditionally there two areas where Tube Amplifiers fall behind their solid-state brethren needlessly. These are usable bandwidth and noise. Even in "Golden Age" some tube amplifiers (like the HK Citation 2) offered very wide bandwidth.
 

 
Some so-called "Laboratory Amplifiers" also included very quiet power supplies, but most Golden Age tube amplifiers (and many modern replicas) struggle to offer a flat response 20Hz -20kHz and noise levels, especially hum, tend to be high by modern standards. Those of a "certain age" may even remember the slight hum that indicated the tube HiFi or Tube Radio was turned on.
 
In the Retro Stereo 50 we had an Output Transformer specially designed which offers a very wide bandwidth in the completed Amplifier (11Hz - 60kHz @ -1dB).
 
Our starting point was some of the best output Transformers of the Golden Age, namely the Dynaco Z-565, the Chicago Standard Transformer Co, Inc. 51-29 and the legendary WE D-164684.
 
The Dynaco Z-565
Nice, very nice but....

 
Western Electric D-164684
This one is rare as rocking horse poop.
 
Who would know this unassuming tin can could be so coveted?

 
It took over a dozen prototypes before we were happy with the output Transformer performance in principle and another four or five minor revisions were made before the output transformer could go into production.
 
It measures so pretty...

 
Source: AMR/iFi. Measured on the Audio Precision 2
 
The output Transformer has a single output tap as multiple taps cause resonances. It is optimised for modern, current hungry speakers and thus offers a much lower output impedance than most tube amplifiers.
 

 
 
 
¹Bamboo is technically speaking a grass, not wood, hence it is very sustainable!
http://en.wikipedia.org/wiki/Bamboo
 
To be continued....Parts Quality, Parts Quality and Parts Quality.

 

[Heartsmart]

Moniker/Name: Heartsmart

Answer A. Total of 311

 

[pfloyd]

Moniker: pfloyd

Answer. There are 584 components

 

[BillsonChang007]

 

How is the Retro different? (part 1 of 3)

Its Beauty is not just skin deep

 
As promised, some insights into the internals with measurements as we know you like'em.
 
 
So, okay, it is clad in grass¹ and alu with striking looks, but is beauty only skin deep?
 
Or is there more to the Retro Stereo 50 than meets the eye?
 
Of course, there is a Killer DAC hidden in there, which you almost never find integrated into any Amplifier, but the actual tube amplifier itself has a fair few special items that set the Retro Stereo 50 apart from both original antique Amplifiers and many modern manufacture tube amps, which are often just copies of classic designs.
 

 
Traditionally there two areas where Tube Amplifiers fall behind their solid-state brethren needlessly. These are usable bandwidth and noise. Even in "Golden Age" some tube amplifiers (like the HK Citation 2) offered very wide bandwidth.
 

 
Some so-called "Laboratory Amplifiers" also included very quiet power supplies, but most Golden Age tube amplifiers (and many modern replicas) struggle to offer a flat response 20Hz -20kHz and noise levels, especially hum, tend to be high by modern standards. Those of a "certain age" may even remember the slight hum that indicated the tube HiFi or Tube Radio was turned on.
 
In the Retro Stereo 50 we had an Output Transformer specially designed which offers a very wide bandwidth in the completed Amplifier (11Hz - 60kHz @ -1dB).
 
Our starting point was some of the best output Transformers of the Golden Age, namely the Dynaco Z-565, the Chicago Standard Transformer Co, Inc. 51-29 and the legendary WE D-164684.
 
The Dynaco Z-565
Nice, very nice but....

 
Western Electric D-164684
This one is rare as rocking horse poop.
 
Who would know this unassuming tin can could be so coveted?

 
It took over a dozen prototypes before we were happy with the output Transformer performance in principle and another four or five minor revisions were made before the output transformer could go into production.
 
It measures so pretty...

 
Source: AMR/iFi. Measured on the Audio Precision 2
 
The output Transformer has a single output tap as multiple taps cause resonances. It is optimised for modern, current hungry speakers and thus offers a much lower output impedance than most tube amplifiers.
 

 
 
 
¹Bamboo is technically speaking a grass, not wood, hence it is very sustainable!
http://en.wikipedia.org/wiki/Bamboo
 
To be continued....Parts Quality, Parts Quality and Parts Quality.

 here we go again 

 

[analogsurviver]

Moniker/name : analogsurviver
 
Answer D.              Total of 781 components

 

[EVOLVIST]

We find out the winners tomorrow, don't we?

I'm never very lucky, but I hope this kit goes to some great homes.

 

[bms44974]

Moniker/name : bms44974
 
Answer D.              Total of 781 components