No, gain doesn’t change heat at outputs as that is controlled by bias current set by R131/132 and rail voltages.
One thing it does affect a little is the offset. Note that the feedback is DC coupled to common so that whatever mismatch there is is amplified by the feedback ratio.
Yes, R107 is intended to do that. My experience is that it still moves around a bit as device temperatures stabilize.
In my experience with the original Wayne's boards the trimmer has a very wide range as well. VERY sensitive to adjustment and it is pretty difficult to get to absolute zero. I'll also confirm there is some fluctuation with temperature change. I let my boards heat up for a good 30 minutes before final adjustment.
The schematic we have had modified the sensitivity of that pot somewhat - hopefully putting some finer resolution on the setting.
That part of the circuit for this daughtercard has been modified a bit with a resistor in series with the pot and a lower pot value so it should be a bit less sensitive to adjustment. Hopefully it's a small improvement to Wayne's fine work.
Dear XRK971, you often illustrate a spectrum analysis of equipment in decibels relative to full scale (dBFS), what is this full scale?
Hi Nico,
All of my audio input interfaces (except new Behringer UC2) are Focusrite products Solo, 2i2, or 2i4 2nd gen and their rated maximum full scale input is 22dBu. That converts to 27.6Vpp or 9.75Vrms. I always like to stay at no more than -10dB FS to prevent clipping o saturation.
Scarlett Solo | Focusrite
Look under detailed specs.
The front end on the Focusrites have a 50dB gain knob and have 52k input impedance.
They are quite robust little units considering sometimes they get lit red meaning clipped input. There is an LED light ring that tells you if you clip.
All of my audio input interfaces (except new Behringer UC2) are Focusrite products Solo, 2i2, or 2i4 2nd gen and their rated maximum full scale input is 22dBu. That converts to 27.6Vpp or 9.75Vrms. I always like to stay at no more than -10dB FS to prevent clipping o saturation.
Scarlett Solo | Focusrite
Look under detailed specs.
The front end on the Focusrites have a 50dB gain knob and have 52k input impedance.
They are quite robust little units considering sometimes they get lit red meaning clipped input. There is an LED light ring that tells you if you clip.
Hi Folks,
I think we have enough interest to start another GB for the Yarra board set. The logistics of doing a GB via the PayPal invoice system was just too much for me and I am going to try something different. I have posted the Yarra as a listing on my Etsy shop as a pre-order. When I receive enough orders to proceed with the GB, I will place the order for the boards. Note that the price is slightly higher to cover the higher overhead on Etsy and to cover the bonus input selector board that has pads for either Lorlin or C&K rotary switches.
Yarra is here:
Yarra Class A modular preamplifier PCB | Etsy
If you choose to get Melbourne or WBA18 daughter boards at the same time, choose the options that include them limited to one pair of each type or 1 pair of both DBs on this order.
If you just want to order WBA18 daughterboards, the listing is here:
WBA18 Class A preamplifier daughterboards | Etsy
Melbourne’s are here:
Melbourne Class A preamplifier daughterboards | Etsy
I think we have enough interest to start another GB for the Yarra board set. The logistics of doing a GB via the PayPal invoice system was just too much for me and I am going to try something different. I have posted the Yarra as a listing on my Etsy shop as a pre-order. When I receive enough orders to proceed with the GB, I will place the order for the boards. Note that the price is slightly higher to cover the higher overhead on Etsy and to cover the bonus input selector board that has pads for either Lorlin or C&K rotary switches.
Yarra is here:
Yarra Class A modular preamplifier PCB | Etsy
If you choose to get Melbourne or WBA18 daughter boards at the same time, choose the options that include them limited to one pair of each type or 1 pair of both DBs on this order.
If you just want to order WBA18 daughterboards, the listing is here:
WBA18 Class A preamplifier daughterboards | Etsy
Melbourne’s are here:
Melbourne Class A preamplifier daughterboards | Etsy
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Hi JP,
That’s a really nice rear panel. Very professional looking. It’s taking shape finally. I am looking forward to getting my ampninsoxe the case!
Thanks for arranging this for us.
X
That’s a really nice rear panel. Very professional looking. It’s taking shape finally. I am looking forward to getting my ampninsoxe the case!
Thanks for arranging this for us.
X
So, can we pre order now? and does this override any interest shown in the thread. Just to clear things up for people and avoid doubling up on orders.
(I think I'll be after 2 sets of the WBA18).
Yes, if the item is available for preorder it will appear in the shop. The list on the thread is to gauge interest - and unofficial. The ultimate list is the Etsy shop order list. Please note that Etsy requires me to ship to exactly the address you have listed. If it doesn’t work you need to edit it until it is accepted by the USPS website as a valid address. India and HK are where I have the most problems as they often have relative address as the standard (“3rd door of 5th house house after the butcher shop on intersection of street X and Y.,” etc) 🙂
Hi X, any idea at this stage as to when the BA18 daughter boards will be ready via your etsy shop. I know you are still verifying the build at the moment.
JPS, thanks for posting the photo of the Yarra chassis rear panel - all looking very nice.
Do you have any news from HIFI2000 as to expected shipping date ex Italy for all the orders?
Do you have any news from HIFI2000 as to expected shipping date ex Italy for all the orders?