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VHex+ amplifier modules, kits and boards

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vzaichenko

vzaichenko

R.I.P.
Joined 2010
#1
VHex+ started as a fun project and grew into a mature line of amplifiers.
This is a great sounding amplifier, built and appreciated by many people around the globe. Very inexpensive for the level of sound quality it provides.
It's easy to build and very reliable in the long run.

Key specifications with +/-50V rails (VHex+ Classic):
- Maximum output power: 100W @ 8 ohm; 160W @ 4 ohm
- Voltage gain 29db
- Input impedance 27 Kohm
- THD: 1KHz - 0.005%, 10KHz - 0.008%, 20KHz - 0.01% (measured at 50W @ 8 ohm)
- IMD: 14+15KHz - 0.005% (measured at 50W @ 8 ohm)

For VHex+ Classic we offer (note - the price is for a pair!):
- Assembled modules for a stereo amp (without or with the heatsinks);
- Kit for a stereo amp (PCBs + parts);
- Boards set for a stereo amp (PCBs only).

A recent addition to VHex+ product line:
- TubeHex boards set with the tube-based IPS.

PSU boards and Control / Protection System variants are also available.

We provide a comprehensive building guide and technical support for every build.

We do care about the result.

Cheers,
Valery & Jeff

Virtual Zero Audio Store

P.S. 10% discount for your 1-st order (use "welcomefriends" discount code at checkout), valid till August 31, 2018.
 

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#4
Hallo Valery

A few questions:
What is so special with your solutions?
Why should I buy your VHex+ amps.?
What is the different between the TubeHex and the Classic? Technically and sonic wise ;-)
Why do you think tube at the input stage is a good/ better solution?


greetings
F.S.

 
#5
fred sonnen said:
Hallo Valery

A few questions:
What is so special with your solutions?
Why should I buy your VHex+ amps.?
What is the different between the TubeHex and the Classic? Technically and sonic wise ;-)
Why do you think tube at the input stage is a good/ better solution?


greetings
F.S.

Click to expand...

Hi Fred,

VHex+ is a combination of simplicity and very high performance.

This design has got a number of specialties:
- the front-end, combination of the LTP, Lender arrangement and a current-driven VAS. It's highly linear, low internal noise, immune to external noises.
- OPS is simple, well temperature-compensated, low-enough distortion and rather inexpensive.

Many builders and testers appreciated the natural, uncolored sounding of VHex+.

The tube at the input is a matter of taste. It's a good input device in general. Both options perform very well, although I didn't run any thorough A/B test.
If you dare to compare them - please share your impressions 😉

In addition - we support every build, making sure the amplifier works as expected. We do care about the result.

Cheers,
Valery
 
#7
Hi !

I'm interested in your "Simpelstark PLUS V1.3 kit (2 x PCBs + parts)"

As I fried some time ago (stupid accident) one module/board of my dual-mono power amplifier, I already have a chassis with everything inside:
2 SMPS PSUs +/- 47.5 V unregulated (is this OK with your boards)
speaker protection, heatsinks etc

Is it a class AB setup ? What type of mosfets are you using ?
What's its damping factor ?

Thanks

JMK
 
#8
J.M.K said:
Hi !

I'm interested in your "Simpelstark PLUS V1.3 kit (2 x PCBs + parts)"

As I fried some time ago (stupid accident) one module/board of my dual-mono power amplifier, I already have a chassis with everything inside:
2 SMPS PSUs +/- 47.5 V unregulated (is this OK with your boards)
speaker protection, heatsinks etc

Is it a class AB setup ? What type of mosfets are you using ?
What's its damping factor ?

Thanks

JMK
Click to expand...

Hi JMK,

Simpelstark is a rather special amplifier. The "core" of it is an ultra-linear amplifier with the "standard" 29db voltage gain and no global feedback loop.
On top of that, it's equipped with Only Distortion Negative Feedback (18db loop gain), crystallizing the error signal and injecting it at the input of the OPS, mixing it with the VAS signal at 180 degrees phase shift. That's the point where the error signal is subtracted from the VAS output signal, although it corrects the overall error of the amplifier, as this kind of arrangement is equivalent to the global loop of 18db in principle.

The amplifier provides very natural sound throughout the whole audio frequency range without any coloration or "highlighting" any parts of it. We call it a "Delicate Sound" amplifier. Real hi-end 😉

This is a class AB setup, but the OPS arrangement is sort of non-standard - its a "constant gm" type of OPS with the EF driver stage running at 110mA of quiescent current (class A), and then a couple of pairs of common emitter "supporting" transistors, running at just 20-30mA each.

The output impedance of the amplifier is close to 0.05 ohm, resulting in the damping factor of around 150 with 8 ohm speakers. I deliberately keep it not too high - too much of control over the speaker is not always good. In general, "the more is the better" statement is incorrect with regards to the damping factor.

+/- 47.5 V DC unregulated is ok, although we have never practically tested this amplifier with SMPS power supplies. I don't see any issues though.

We don't use any MOSFETs in this version of the amplifier - the OPS purely consists of the BJT power transistors (one pair of 0281/0302 and two pairs of 3281/1302 in each channel).

IPS requires one pair of 2sk246/j103 jFETs, relatively rare, but still available these days.

The kits are available in our store.

Let me know if you will have some more questions 😉

Cheers,
Valery

P.S. BTW, you can see an overall topology in the comments to my post on FB:
Just finished testing and measuring the... - Virtual Zero Audio Store | Facebook
 
Last edited:
#13
Building it

vzaichenko said:
Hi JMK,

Simpelstark is a rather special amplifier. The "core" of it is an ultra-linear amplifier with the "standard" 29db voltage gain and no global feedback loop.
On top of that, it's equipped with Only Distortion Negative Feedback (18db loop gain), crystallizing the error signal and injecting it at the input of the OPS, mixing it with the VAS signal at 180 degrees phase shift. That's the point where the error signal is subtracted from the VAS output signal, although it corrects the overall error of the amplifier, as this kind of arrangement is equivalent to the global loop of 18db in principle.

The amplifier provides very natural sound throughout the whole audio frequency range without any coloration or "highlighting" any parts of it. We call it a "Delicate Sound" amplifier. Real hi-end 😉

This is a class AB setup, but the OPS arrangement is sort of non-standard - its a "constant gm" type of OPS with the EF driver stage running at 110mA of quiescent current (class A), and then a couple of pairs of common emitter "supporting" transistors, running at just 20-30mA each.

The output impedance of the amplifier is close to 0.05 ohm, resulting in the damping factor of around 150 with 8 ohm speakers. I deliberately keep it not too high - too much of control over the speaker is not always good. In general, "the more is the better" statement is incorrect with regards to the damping factor.

+/- 47.5 V DC unregulated is ok, although we have never practically tested this amplifier with SMPS power supplies. I don't see any issues though.

We don't use any MOSFETs in this version of the amplifier - the OPS purely consists of the BJT power transistors (one pair of 0281/0302 and two pairs of 3281/1302 in each channel).

IPS requires one pair of 2sk246/j103 jFETs, relatively rare, but still available these days.

The kits are available in our store.

Let me know if you will have some more questions 😉

Cheers,
Valery

P.S. BTW, you can see an overall topology in the comments to my post on FB:
Just finished testing and measuring the... - Virtual Zero Audio Store | Facebook
Click to expand...

Thanks for this quick and detailed answer.
Is there anything special needed for the building?
All parts provided with the kit (beside heatsinks) ?
Is it possible to have a look at the building manual ?

JMK
 
#14
J.M.K said:
Thanks for this quick and detailed answer.
Is there anything special needed for the building?
All parts provided with the kit (beside heatsinks) ?
Is it possible to have a look at the building manual ?

JMK
Click to expand...

Hi JMK,

All the parts will be provided for building the amplifier modules. PSU and COntrol System modules are the separate kits, but as I understand you've got those things in place already.

Setup procedure will be described in the building manual. This is a relatively new product, so the manual is in the final stage of development now - I will let you know as soon as it's done in a few days.

Cheers,
Valery
 
#16
odie1427 said:
Hi Valery,


I just order a PCB board, but i cannot download the build guide, could you please direct me to the link? or maybe can attached the file here.


thanks,
odie
Click to expand...

Hi Odie,

Thank you for your order. I have opened the downloads area for you.

Please click the "Building Guides" link under the DOWNLOADS title at the bottom of the homepage and download the building guide for VHex+ Classic amplifier.

Let us know if you will have some questions on the build.

Cheers,
Valery
 
#17
Simpelstark PLUS V1.3 Building Guide

Gentlemen,

The building guide for Simpelstark+ V1.3 is ready and available in the DOWNLOADS area of the web-store.
It's available to all the registered customers (please login or create an account).

Cheers,
Valery
 
#19
Very interesting your new amp.

Simpelstark PLUS V1.3 kit (2 x PCBs + parts) – Virtual Zero Audio Store

A specialty of this design is high linearity of every stage and low amount of global negative feedback - only 18db of ODNF error correction. The amp is particularly good for acoustic music - jazz, classics, guitars, vocals, drums, cymbals, etc.

The amplifier is dead silent at idle, which is a big advantage for listening at the low volumes and/or with some high-sensitivity speakers.
Click to expand...
SNR A-weighted at 1 watt and 100 watts?


03_01KHz_c909b5a0-94cd-4317-8104-6a14318c1cf8_2048x2048.jpg

​


Post your Solid State pics here.

710687d1540197450-post-solid-pics-08-jpg
 
Last edited:
#20
pelayostyle said:
Which is the "better" amplifier? The VHex or Simplestark?
Click to expand...

Hi Pelayostyle,

Here is my view on this:

VHex+ is an amplifier with a much higher amount of negative feedback and lower output impedance, resulting in more control over the speaker. It's fast and low-distortion, providing very punchy bass drum hits at any volumes.
Some people use it as a reference amplifier when comparing the speakers, because of its overall "transparency" and neutrality.
Particularly good for extensive rock, electronic, jazz, big band, etc.

Simpelstark+ is more "chamber" kind of amplifier, giving the speakers more freedom. It's got an excellent distortion profile, usually seen at the tube amplifiers, although the absolute distortion level is slightly higher than the one for VHex+.
This one is great for acoustic music with all its micro-nuances at all volumes - the sound is extremely natural, like if the musicians would be playing in your room. The noise level of this amplifier is so low - you can hear any lowest level details when the most of the instruments are close to silence, playing some low-volume music fragment.

Hope this helps 🙂

Cheers,
Valery
 
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