“Tested these new NexGen Caps in a old super trem. Compared the original mustards, new sozo and the mallory in the same amp. Reamped the same signal through all and recorded it. I would call these dead nuts on to the sound of the mustards. Maybe just a touch brighter but these were fresh and not broken in. Really great caps.”

Davud Friedman

Rack Systems / Tone Merchants / Friedman Ampliciation

“I just installed SOZO’s in my ’76 Marshall SL 100, an amp that I’ve fully converted to 67 era Plexi spec’s. I had previously swapped out the original green caps with Mallory’s which made an improvement, but still didn’t take it to “Mustard” territory. But now that the SOZO’s are in, that smoothness and clarity is all there with much more pronounced harmonics. Low end is much more focused. I’d dare to say that John has one-upped the Mustards!”

Peter Stroud

Guitarist – Sheryl Crow

“I put a set of your Standard Mustard clones in my Valvetech Hayseed 30. The amp sounded okay to begin with but had some really bad ghost-note issues. After I replaced all the signal caps with Sozos, ALL the ghost-noting disappeared.
Well done!”


“I just installed sozo cap’s in my Line6 Spider Valve and what an amazing difference. These caps really open up the tone of the amp. The treble used to be harsh and the bass a little muddy. Now the bottom end is super tight and the treble is smooth. This upgrade was worth every penny and then some.
Thank’s Sozo”


“I bought 2 – .022 caps for my Tweed Champ just to check the product out.
WOW! What a difference!
I just ordered some more to do a cap job on my Bassman!
I’m convinced! Thanks!”


” I was given a batch of Sozo caps to install in an amplifier. I had
some actual mustard caps laying around. I recently got a SCI Teague LCR meter. I also have a cheaper LCR that measures a couple of other parameters that the SCI does not. I used the SCI to measure a selection of 5 Sozo .047 uF, and 5 Mustard cap .047 uF capacitors. The Mullard mustard caps had increased slightly in capacitance, but were still well within 5% of their value. I then ran the Sozos on a polarizing capacitor conditioner for about three days. I measured both types, and the measurements were so close in the D, Q, ESR, and capacitance that they could have been from the same lot. I can use frequencies ranging from 20 Hz to 120 KHz in 3800 steps. This is where thing get interesting. The Sozos actually outperform the mustard caps in the lower frequencies. An orange drop will look better at 1000Hz., but at 100Hz it suffers an increase in leakage, and loss of Q. This is why the lows when orange drops are used seem a little spongey, and less defined. For the money Sozo can not be beat. That is my professional opinion. The ears are the measuring instrument that counts the most. I put a Marshall Lead 100 with KT66s, and another Marshall Lead 100 clone with Sozos, and used the same tubes, and cabinets. The difference was beyond noticable. It was astounding. Now I need to find some good filter caps. The LCR I used is an older model, but refurbished, and calibrated ones with certification sell for $4950.oo USD. Mine was totally gone through, and cleaned, all components checked, and all ranges calibrated. I absolutely love the LCR meter. The conditioner is made by me, and runs signals of varying frequencies through the caps that will be in the signal path, and either 60, or 120 Hz. for filter caps.”


“Just wanted to let you know I recieved the capacitors put them in the intire signal chain of my crate v328 capacitors total and wow what a difference!! they took the boomy fizzy buzzy sound out of this amp still cant believe the differene they also took the harshness out by atleast 90% ! the only value changed was the .01 phase inverter cap to a .022. these capacitors made a huge differerence the bottom end is all there n punchy and crisp without harshness the highend is way more harmonically rich no harshness unless I cause it way more musical!!thanks for your hard work and effort it makes playing guitar fun again and inspiring!”


“Well, I have built 2 identical Metro 100 watt clones except one with SOZO caps and one that has NOS mustards that I paid a ridiculous amount of money for. The results? With my Les Paul 1959R, I can’t tell the difference between the two amps. They sound identical! Well, at least the one with the mustards look cool. ”



100W Plexi

50W Plexi

Marshall 20 Watt

“John; Put some of them in an old Brown Deluxe that I put an RS clone Mercury Magnetics o/p tranny and M.O.Valve KT-66’s. Sounds really great. I didn’t think that amp could sound any better but it does. It had the old blue “Molded” caps in there that came stock along with some .022 Astrons. I have an old Alnico Celestion in that amp as well. The amp has a B+ of 440v and puts out a clean 32 watts at clipping. I’m going to be doing a reissue 100 watter later this week and I’ll try them in there as well. Thanks again.”

Don Butler


“Got the Caps yesterday!!!! they sound wonderful! They have made the amp much more alive…richer. The coolest thing though is something I was not expecting, the amp now FEELS alive, amazing. I am completely thrilled!! Thanks!”

Valued Customer

“Woooowwwww, she sounds amazing. It’s like a new amp. It stays clean and it’s as loud as you can stand it. Lot’s of punch and it has that Fender thang. I will let Dom Butler know about this also. I had written him about this amp.”


“I agree that the SoZo’s sound really good…I had a set in my amp for a few months until I picked up a set of NOS mustards….I put the mustards in and I “thought” the highs were slightly smoother… and I mean really slightly…could be from variances in the actual values between the mustards and the SoZo’s…i dunno…either way…the next day I couldn’t tell the difference at all…now i just keep em in there for the psychological tone improvement hahaha”

“If I had to say how close the the SoZo’s sound to the mustards…Id have to say they are 99.9% exact…and to me … I cant tell the .1% difference…and they were about $200 cheaper ”

Forum post

“Who would have thought that changing the type of cap would make such a difference. The more I play it the better it sounds. It now has the perfect amount of chime, solid bass, and the glassiness is gone. The most subtle nuances come right through and you heard a little of how it responds to being pushed with a HB. This is rapidly becoming my favorite amp. Just blows the Soldano away.”

Valued customer

“Just installed the blues in my 5e3 type amp, WOW!these caps are awesome..Not brokein yet but already sound superb. The amp had a problem with fizzy sound, now it just sounds fantastic .I can’t believe that by just changing the signal and coupling caps could make such a dramatic improvement. You have really hit a home run with these babies. Thank you, and expect to be getting quite a few more orders from me. Once people hear the difference you’ll be swamped”


“I love the sound of the blue molded caps. Here’s another order.”


Who Is Using SoZo?:

PRS Guitars Bogner Amplification Metropolous Amps 65 Amps Logo Germino Amps Clark Amplification Fargen Tube Amplifiers