Aiyima T20 Fully Balanced Tube Preamp, AKA Why do I do this to myself?

A few years ago I had fun with the very inexpensive FX tube preamps ( not buffers ). When I replaced the stock wall wort with a $35 Pyramid PS-3KX linear regulated power supply I noticed a significant improvement in SQ. The positive and negative power wires I ran through the holes in the Pyramid and exited out the back using a barrel connector adaptor to the FX.

Poultrygeist · « **Reply #28 on:** 5 Sep 2025, 10:26 am »

These barrel adaptors make an easy job of connecting external power supply wires. These are the male version but they are available as female.

Jon L · « **Reply #29 on:** 6 Sep 2025, 11:17 pm »

OPA828 opamp is a highly-regarded JFET-input opamp that usually comes in SOIC configuration, and two are needed per adapter for dual opamp duty.

Its sound is different from most all monolithic opamps in that it really sounds like water, no real flavor to speak of. This can be a very good or not so good thing depending on what one is trying to accomplish in the overall system sound. Usually, modern, high-speed opamps tend to impress first but become somewhat tiring with prolonged listen, which OPA828 seems to avoid.

Comparing OPA828 to OPA2604, which was felt to synergize well with Aiyima T20, was an illuminating experience. If one assigns OPA828 sound as neutral, OPA2604 seems to synergize well with certain components due to its seeming effect of moving a tiny bit of upper-midrange to low-treble energy to high treble, which results in very airy sound with a degree of forgiveness in the hot-recorded upper midrange. This can be very pleasing with many digital sources and class-D amps. OPA828 fights back with more information and neutrality in that upper-midrange to low-treble, minus extra airiness, making music more solid and textured in that area.

Definitely worth checking out both OPA2604 and OPA828 in a given circuit, as one is likely to be more synergistic than the other

viggen · « **Reply #30 on:** 7 Sep 2025, 12:44 am »

I have the OPA134PA I bought by mistake. You got me tempted to get an adapter to fit two of these into the T20.

Jon L · « **Reply #31 on:** 7 Sep 2025, 01:31 am »

Quote from: viggen on 7 Sep 2025, 12:44 am

I have the OPA134PA I bought by mistake. You got me tempted to get an adapter to fit two of these into the T20.

I ordered single-to-dual DIP8 adapters to try OPA627x2 in the dual slot.

viggen · « **Reply #32 on:** 7 Sep 2025, 02:33 am »

I ordered this one
https://www.amazon.com/dp/B0DWMNTCDK?ref=ppx_yo2ov_dt_b_fed_asin_title

Jon L · « **Reply #33 on:** 7 Sep 2025, 02:24 pm »

Same one I ordered. Let's hope it's sturdy.

viggen · « **Reply #34 on:** 7 Sep 2025, 11:45 pm »

it really does sound like water. i think i prefer it over muses02 atm. it's not as soft sounding as muses02 yet more easy to listen to. very clean and very balanced. and your opa828 is supposed to be better than my opa134pa according to google ai:

Quote

The OPA828 is a higher-performance, lower-noise, faster, and wider-bandwidth op-amp compared to the OPA134, which is a legacy op-amp known for its excellent audio quality and ultra-low distortion.

edit: just ordered this on ebay

Quote

[AudioJade] TOP Grade OPA828 V5 Mono to Dual Operational Amplifier HiFi Audio

Jon L · « **Reply #35 on:** **Yesterday** at 03:35 pm »

LOL, received the dreaded "Delayed, not yet shipped" message from Amazon. Who knows when it will show up.

As a consolation, I now have the Opamp decoupling adapters with capacitors.

viggen · « **Reply #36 on:** **Yesterday** at 05:09 pm »

when does the madness end? is that a sparkos brand? i don't see it on their site.

i can only find this one
https://www.creationaudiolabs.com/rock-it-socket?srsltid=AfmBOopHlUIIYCzFRsfJ-4ty1Lzm6wovBsJzMbzMXt4T1G0V31V4oN2Z

Jon L · « **Reply #37 on:** **Yesterday** at 10:16 pm »

Quote from: viggen on Yesterday at 05:09 pm

when does the madness end? is that a sparkos brand? i don't see it on their site.

i can only find this one
https://www.creationaudiolabs.com/rock-it-socket?srsltid=AfmBOopHlUIIYCzFRsfJ-4ty1Lzm6wovBsJzMbzMXt4T1G0V31V4oN2Z

These are not just adapters. Their purpose is to add additional capacitors to decouple the opamp power pins further, with reported benefits. Unfortunately, they are rather expensive.

https://www.aliexpress.us/item/3256808610142833.html?spm=a2g0o.order_list.order_list_main.11.2fc71802I3w90H&gatewayAdapt=glo2usa#nav-description

viggen · « **Reply #38 on:** **Yesterday** at 10:35 pm »

might be cheaper to get one of these then you only need one decoupler for the t20
https://www.ebay.com/itm/355616376599

the rockit socket is also a decoupler with capacitor and only $5 tho the one you have is probably better because it has bigger capacitors haha

let us know if you here a positive diff with the decoupler.

Jon L · « **Reply #39 on:** **Yesterday** at 11:03 pm »

Quote from: viggen on Yesterday at 10:35 pm

the rockit socket is also a decoupler with capacitor and only $5 tho the one you have is probably better because it has bigger capacitors haha

I wish. Looks like one has to buy and solder the SMD capacitor himself, but moreover, rockit only allows one single-channel opamp for the capacitor to work