Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Hands, Jul 12, 2019.
sw51+ measurements found in this thread: Shortest Way 51+ technical measurements
Thank you for your excellent work. You have a very good laboratory and an excellent method of measurement.
Thank-you, but my apologies at a non-compliant IMD measurement. Corrections have been made:
Shortest Way 51+ technical measurements
Everyone: please download the corrected analyzer pdf files.
In one and a half weeks production of the second batch of SW51 is possible
I counted my options. In the second batch it is possible to manufacture 34 pieces of amplifiers. Of course 3 of the amplifier will be in reserve. Total possible 31 pieces amplifier.
To start production, it is necessary to start producing at least 20 pieces of amplifiers. 3 pieces have already been ordered.
If there are willing to get this amp, please download the preliminary order and send me an email. The return address is on the pre-order form.
The cost of the amplifier has not changed, but slightly increased shipping rates.
So it has been a while since the last post.
What are the impressions?
There are two themes for this amp. This theme was originally for the experimental SW, impressions of the serial SW51 are published in this theme.
How many orders have you received so far for this second batch?
Yes, you can order. If there are more orders than amps, I will make additional amps.
Thanks for your wonderful job and service to the community. I am being very impressed by how nice this amp sounds at this price range.. -- specific impressions to come later. But it easily joined to my personal top 3 "budget wonder amps" (JLH for integrated speaker amp, Asgard 3 for SS head amp, and SW51+ for SET head amp).
By the way, what is the gain for this SW51+ if the stock 6z51p used? And what's the maximum output power (or voltage)? I've gone through this thread and the original fs thread, and found your description of "The output voltage is 2.2 Vp" for the original version. My experience says that sw51(+) can do more than that.
The SW51+ output voltage can up to 5 volts at H output. The voltage margin probably contributes to accurate sound reproduction.
But the power is small. Headphones are not large power.
gain is dependent on load and operating level.
At 1 KHz, 0 dBu input, volume knob set to maximum, HiZ output and 300R load the gain measures 1.72 3.32
At 1 KHz, 0 dBu input, volume knob set to maximum, LoZ output and 32R load the gain measures 0.76 1.52
Maximum output voltage is dependent on load impedance and distortion level tolerated. A much higher Vpp (Voltage peak to peak) may be achieved if greater than 1% distortion is considered. See discussion in SW51 technical measurements thread: Shortest Way 51+ technical measurements
correction: gain measurements on dScope were off by a factor of 2 - explanation in technical measurements
At 2 Vrms input (8.24dbu) -- since knob set to max, no voltage division happened
In = 2 Vrms
Out = 18.4 Vpp = 6.5 Vrms (= 18.5 dbu)
Gain = 6.5/2 = 3.25 (or 10.2 db)
Of course operating level can matter, but does that affect this much? (1.72 gain at 0 dbu in to 3.25 gain at 8.2 dbu in)
I must be wrong (but don't know where).. please school me.
Two differences are involved.
The first gain from your calculation is for a 440 Hz stimulus and when distortion has risen rapidly, to 7.5 %.
The second gain from my measurement was at 1000 Hz and well within linear operation. A gain of 1.72 3.32 calculates to 4.7 10.4 dB.
So there is approximately 5 dB There will be more less gain when running the amp heavily into nonlinear operation. It will be LOUD, but not necessarily good. See additional data in SW51+ technical measurements section.
This amp certainly has potential. Will report when it's settled properly.
Have some spare tubes I can sell cheaply. Siemens EF85, Tungsram EF184. PM if interested.
Are there still slots open for this batch, and if so what are the current shipping prices? I looked at the order form but didn’t see the shipping rates (maybe I missed them!).
Hopefully 20 got ordered or another 19 after mine
I think someones amp on West coast was $375 express shipped for the SW51+ I don't remember where I seen the post one of the threads for the amp.
I filled in the form when it was announced, but I haven't received any official response. I'm assuming @Zampotech is busy setting up production.
Yes, there is still the possibility of ordering. I'm already making an extra batch.
A little later I will show a table of shipping costs.
I'm sorry I didn't answer. Your order is recorded #2 in the General list.
For everything. If I for some reason did not respond, please repeat your request. I will be grateful.
I filled out the form yesterday and had a response from Zampotech this morning, I read earlier in the thread that he will send a more detailed invoice later in the process. I'm really not ready for another amp yet but this is too cool to pass up.
Dear friends. I wish you all a happy New Year.
At the end of the second decade of December, a complete set of components for amplifiers was assembled.
As a result, it was made party #2 and #2+ (additional party)
I didn't bother anyone with the payment for two reasons. The first reason is the holidays. The second reason is the load of mail just before the holiday.
I hope everything's calmed down now.
I'm starting to send the final order form. it will ask for the type of amplifier, type of shipment, mailing address and special requests.
If you do not receive your order form by Monday, please let me know.
If you decide to cancel your purchase, please let me know.
Translation of text from video
"Let everything work out for you. Your 2020 year."
Separate names with a comma.