- 1,818 Posts. Joined 12/2010
- Location: Castleford, West Yorkshire, England.
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AudioValve RKV-II (OTL amp) (2014 version) + AudioValve Box adapter"VERTO" for Stax Headphone (and for low impedance orthodynamic/eletrodynamic headphone) - Page 2
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To reassure you (... or not ).
My next post (in this thread) will be held in the second half of August, once received the Verto box.
It is bound to be a bit long because it will split into three distinct sections: photographs of the new system; one or more report of listening of the RKV-Verto combo (with my source high-end Audiomat) ; new measures of the RKV-Verto combo, made to the voltmeter and the microphone, under the same conditions as those made last year with the combo RKV- Wee, to cut short all new technical criticisms that would put in doubt the qualities of this amplification 'made by Audiovalve', especially for his answer supposedly disastrous above 6 KHz; well, I have the firm intention to prove otherwise.
Edited by eric65 - 8/9/14 at 12:08am
Could I by chance get a discount Eric if I talk about this piece in the GS-X mk 2 thread, Show me your Schiit thread, Stax thread, BHSE thread, I hate pineapples!!! thread, Beats appreciation thread? And ANY others I missed. Just say go!
The scary bit is that, as of today, Eric hasn't actually listened to a verto box, it's all been speculation based on previous experience with wee type transformer box. Mind you, Eric is getting his box sometime this week so you're bound to hear from him very soon! The comparisons against Electra (heard once) and Stax amps (owned in the past) will be based of memory but I can guess the ranking already .
Imminent receipt of Verto box.
I plan to make a direct comparison with the Wee Box modified (1:50 transformers disabled) on the RKV-II amp.
I have (in addition to my memory) of comparison reports:
Combo RKV-Wee (modified) versus combo RKV-Wee (unmodified) (subjective report)
Combo RKV-Wee (unmodified) versus SRM-727 / SRM 007t2 / Electra (subjective report and objective (blind test) report).
I should be able to give soon elements of direct and indirect comparison for all these amps without too solicit my auditory memory.
Besides measures (objective), of course.
- 41 Posts. Joined 1/2011
- Location: france
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Your position is understandable.
I am a French reseller in direct contact with Mr Helmut Becker, designer of AudioValve products
I can say that Eric gets from me or Mr Becker no advantage to promote the Verto box.
Ho yes, a little advantage ! Eric has got from me a 50€ discount….and paid 640€ for his Verto.
You can believe me. But of course you are not required.
Thank you, Pierre.
Objective response : in Volt and relative gain in dB / frequency, from amplifier RKV-II, combo RKV-Wee and RKV-Verto
Combo RKV-Wee (unmodified)
Output RKV = Input Wee = 0.20 Volt (at 1 kHz)
Output Wee = 0.20 Volt x 50 = 10 Volt (at 1 kHz) (with 1:50 Wee transformers)
My results are as follows: for 6 distinct frequencies (250 Hz 500 Hz 1 kHz; 2 kHz; 5 kHz; 10 kHz). Voltage measured, depending on the frequency, in input of the Wee (and therefore in output of the RKV) with the Wee transformers 1:50 connected, and with for load an electrostatic headphones Stax SR-009 145000 Ohm of impedance.
Signal sinus 250 Hz : 0.205 V (relative gain : 0 dB)
Signal sinus 500 Hz : 0.203 V (relative gain : 0 dB)
Signal sinus 1 kHz : 0.201 V (relative gain : 0 dB)
Signal sinus 2 kHz : 0.193 V (relative gain : - 0.3 dB) (to compare to the +2 dB of Kevin Gilmore graph)
Signal sinus 5 kHz : 0.160 V (relative gain : - 1.9 dB) (to compare to the -4 dB of Kevin Gilmore graph)
Signal sinus 10 kHz : 0.115 V (relative gain : - 4.8 dB) (to compare to the -17 dB of Kevin Gilmore graph)
Output RKV = Input Verto = 1.69 Volt (at 1 kHz)
Output Verto = 1.69 Volt x 5.9 = 10 Volt (at 1 kHz) (with 1:5.9 Verto transformers)
Signal sinus 250 Hz : 1.692 V (relative gain : 0 dB)
Signal sinus 500 Hz : 1.681 V (relative gain : 0 dB)
Signal sinus 1 kHz : 1.666 V (relative gain : 0 dB)
Signal sinus 2 kHz : 1.614 V (relative gain : - 0.3 dB) (to compare to the +2 dB of Kevin Gilmore graph)
Signal sinus 5 kHz : 1.354 V (relative gain : - 1.8 dB) (to compare to the -4 dB of Kevin Gilmore graph)
Signal sinus 10 kHz : 0.965 V (relative gain : - 4.7 dB) (to compare to the -17 dB of Kevin Gilmore graph)
Combo RKV-Wee (modified) (1:50 Wee transformers disabled)
Output RKV = Input Wee = Output Wee = 10 Volt (at 1 kHz) (without 1:50 Wee transformers)
Signal sinus 250 Hz : 9.980 V (relative gain : 0 dB)
Signal sinus 500 Hz : 10.00 V (relative gain : 0 dB)
Signal sinus 1 kHz : 10.00 V (relative gain : 0 dB)
Signal sinus 2 kHz : 10.01 V (relative gain : 0dB)
Signal sinus 5 kHz : 10.01 V (relative gain : 0 dB)
Signal sinus 10 kHz : 10.21 V (relative gain : + 0.2 dB)
And more comments : here : http://www.homecinema-fr.com/forum/post178219963.html#p178219963
- 2,513 Posts. Joined 6/2001
- Location: Wheeling, IL USA
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all my measurements were at 100 vrms output.
The standard for measurements.
10v of output shows but a small fraction of the issues.
Not the least of which is the decrease of damping
factor of the amplifier at higher voltage swings.
measured your way, my numbers are about -5db at 10khz
lets see some real pictures showing square waves at
100 vpp output
using only a voltmeter you have no idea what the real
voltage is, whether there are any peaks in the signal etc...
Edited by kevin gilmore - 8/21/14 at 6:56am
As promised, here are the links (*) to reports of listening to the combo AudioValve RKV-Verto versus RKV + Wee modified (Wee transformers 1:50 bypassed) with the Stax SR-009 headphone.
Two different listening, for two different audiences: one ported to the ultra transparency, and very high presence and resolution ; the other ported to the captivating beauty of tone (timbre).
A nearly flawless box. It would only take a small additional technical improvement of the Verto box to obtain a hypothetical Verto mk2 box with no fault : the possibility of disconnect / reconnect the excellent 1:5.9 transformers of the Verto box, to have, then, the box with the perfect versatility and which would respond so perfectly at the slogan (that I have just created for AudioValve brand) :
" A single box; two listens; two audiences " : in any case you will be happy!
(*) use your favorite translator
Edited by eric65 - 8/23/14 at 12:43am
A box (Verto mk2) with switchable Transformers would be a more appropriate term.