Glad you like it!

Feel free to send me a schematic, I'm interested in trying that.

Yes indeed ! They who don't understand amplification are those who spew critisism..... PP amplification ( the mosr common amplification mode )....cancels second harmonics and by doing so they cancel out the harmonic relation between pair and odd harmonics , reinjecting some second harmonics ( and other pair harmonics ) the hamony of harmonic content of music is restored ... To create second harmonic distortion onr brings the tube in an operation point to produce some second harmonic distortion , therefor the potentiometer is shifted to the back of the circuit. One can adjust eventualy the sensitivity ( or overloading ) of the input by a resistive divider ( switch or multiple selector ) ....the bass ( hi pass filter output ) can indeed be adjusted by choosing other values of capacitors or and a higher impedance potentiometer (example ...20K )... Best is to double the output capacitors , 2µF by two 1µF in // , or higher values. The inductance is lowered and the ESR of the capsis half.... I don'targue anymore withthose audiophile discussions , the less they know the stubbern they are , .........believers instead of reel experience and reel facts ...you can't argue with a belief. Have a nice day , and yes Steph is right to build and explore this concept from MATT.

Everyone who has heard it loves it!

Thanks!

Yeah he hand built that for me!

It's funny, the online forums all repeat these are horrible for hifi use...

That may be the first thing Paul has said I agree with lol

@@SkunkieDesignsElectronics Haha. Well said! Guess there is a first for everything. 🤣🤣. Cheers, and keep up the great work!! Just got the caps for my R8 as I move through your series of upgrades. 😍😍

Yeah, people drag it off topic trying to outdo each other. Turns into a _____ measuring contest...

Yeah someone brought that up on the forum and tried to make some huge deal out of it. I'm like "Whatever, I'm sure Matt just overlooked this when he rewrote some notes." I'm more of a build it, adjust till it sounds good and then write down the voltages kind of person anyway :)

That's why I build a small amp with no driver stage to test pre-amps. But I know even that isn't perfect. Mainly I just make sure stuff isn't crazy bad :) I honestly have no idea what a APX 515 is.

@@SkunkieDesignsElectronics Thanks for the reply, I think the audio analyzer suite is a great tool and the only alternative I could find under 10K. The APX 515 is one of Audio Precison's two channel analyzers. I only mentioned it because I kept hitting a wall while trying to test differences between in tubes in a Freya Preamp. I kept getting these harmonics that dominated the distortion numbers and were common between all the tubes I tested. I felt like that couldn't be correct so I finally bit the bullet and got the APX 515 (only because I needed it for another purpose) and confirmed that. To be clear these are like -70db so I don't think it would matter when looking at 1% distortion type things. I was able to finally determine that Electro-harmoix 6SN7 tubes had 10dB less noise and greatly reduced distortion than some triode matched JJ tubes. 0.002% vs 0.1% type differences which is quite crazy. I hope to publish those results soon. I really love your work and hope to build the KT120 SE amp when you do that one. In the mean time I hope to be able to learn more about the performance of new production tubes. I would love to look at old tubes but don't have any and can't really practically do that at this point.

I plan to do a "shootout" with an OG FX audio, that nobsound and this color pre-amp when I am finished.

@@SkunkieDesignsElectronics The shootout idea is perfect for me 😊 ...thanks again!

Nope, you are still driving across a 10K pot unless for some reason you decide to short the output, which would be a bad idea! Also this was never intended to drive a 600R input impedance amp, if such a thing even exists. Most amps have around a 50-100K input impedance. Yes the pot does vary the output load across this 10K pot, but in use, you never go past 1/2 volume. The output cap is large enough to deal with this, unless you are trying to drive a ridiculous load. To drive this theoretical 600 ohm load without impacting the low frequency response, you would need a 130uf cap!

@@SkunkieDesignsElectronics I have never designed anything without having some kind of specification in mind. The last amp that I designed and built had an FX loop output using a standard cathode follower. The input had a level control. The output went into a transformer with a balanced 600 Ohm output (XLR) with a single ended output (1/4") with ground lift. The other pre-amp output was derived from a lead off the speaker output transformer with a level control to a 1/4" jack. 600 Ohms is a typical load value in professional gear. I apologize for accidentally falling into a hobbyist webspace. Keep up the great tutorials. Oh...one little thing about ground strips. Look inside any older Fender amp and you will find a nice brass ground strap under the controls.

Yeah, it's such a shame most of us here are just "hobbyists" using mere consumer, hobby webspace gear, and we aren't using pro spec gear like you. And yes I have a spec in mind for everything I build, you just assumed it was something else.

@@SkunkieDesignsElectronics So much sadness in your postings. I am full of sorrow that I missed the electrical specification for your project. I am sure that I would had different thoughts had I read it first. I also do hobby projects. One on the back burner, although I have most of the parts is for one of those trendy little cutsie mini micro Class-D amps. I have a 2.1, which I will use with a couple of thrift store subs and a pair of Realistic speakers. Remember the little black metal ones? I'll power the kit with some rechargeable Li-On batteries. It's for a sound system on-the-go. Out in the woods kind of thing - jamming with friends. I won't have the full spec until I have squeezed the batteries dry of charge. The math says I'll get well over 150 Watts of sound power out of this for a couple of hours. For normal use, it would be much longer than that. Hey! There's the first part of my spec! "Much Longer". I swear - I should be in marketing!!! FYI - I am a design engineer by trade and have (on the side) built, modified and designed quite a few tube amps. Only one went into production. I cannot say who the most famous customer is, but he is currently on tour with Mr. Vai. Have an amazingly amazing Mothers Day!

Thanks, it will be fun to see what the audio analyzer tests show.

@@SkunkieDesignsElectronics Yeah, if modifying the feedback works out well, perhaps a set of controls could be added to allow someone to set various feedback to get a sound he or she likes 🤩 Just make sure that he or she cannot make an oscillator 😉

I would maybe play with lowing the bias voltage on the input tube to make it easier to overdrive?

We will cover that in a future video.

We will see! I'm not the first person to build this one and the guy who designed it put a lot of design and engineering into this.

Putting the volume pot on the input defeats the whole purpose of preserving the second order harmonics from the input tube being driven hard, which is the SOLE purpose of this device. Installing the pot on the input, the amount of "Color" will vary with the volume setting. I'm really not sure what else I can do to try to explain why this pre-amp isn't wired that way. Myself and the designer totally understand why someone looking for a super clean, low distortion pre-amp would install it on the input, that is not the design goal here. "To preserve the harmonic character of the preamp, the gain stage is followed by the buffer which is then followed by the volume control. This means there is no attenuation of the color provided by the gain stage at any volume setting." www.cascadetubes.com/the-12au7-cathode-follower-color-preamp/

Thanks Matt. I do want to test the frequency response and see if that larger cap is really needed, but I left space inside in case I go that route. And yeah I don't see this as a pre-amp for a tube amp, but more for a SS and especially a class D one. In the final video I discuss possibly adding a voltage divider to elevate the tube heaters to about 45VDC. It's not absolutely needed and I wanna see how quiet it is with grounded center tap heaters first.