The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Lets talk about pot values for the SP-9

    Share

    spin

    Posts : 11
    Join date : 2015-01-11
    Age : 35
    Location : Delaware

    Lets talk about pot values for the SP-9

    Post by spin on Fri Jan 30, 2015 8:42 pm

    Hi everyone, my name is Tommy. I'm new around here, but have been trolling for a couple weeks now. I have recently decided to get back to my 'roots', so to speak, and build a hi-fi system. After a bit of research and some recommendations, I came across tubes4hifi. Roy was beyond helpful and super accommodating with my order. I ordered an SP-9 (I'm afraid to give up tone control, baby steps, I'll build more), a PH-14 phono preamp, and a pair of mk3's. My order came in two shipments and Roy mistakenly sent me two parts kits for the SP-9. The parts kits were identical other than the fact I received a 100ka in one and a 250ka volume pot in the other. Before I send one of these bags back, I was wondering which would best suit my application. Most of the information I was able to gather points to using the 100k, but I wanted to be sure. I would like to use the 250k just for the fact that the PCB has extra ground pads that fit the shielded wire I plan to use perfectly. My main source is going to be the PH-14, and will be my only source for the time being.

    Thanks in advance for any help you can offer. I'll have quite a few more questions along the course of this build I am sure. I hope you will forgive my lack of Hi-Fi knowledge, we've all got to start somewhere. I can, however, solder pretty darn well, and I've built quite a few devices, almost all pertaining to guitar. I'm looking forward to this project and future projects in hi-fi audio.

    Here is a 100w 2 channel optically switched high gain guitar amp I built based on the schematic of the Soldano SLO 100.





    Facebook of my small DIY pedal company


    Last edited by spin on Fri Feb 06, 2015 10:51 am; edited 1 time in total

    DynakitParts
    Admin

    Posts : 181
    Join date : 2008-11-30

    Re: Lets talk about pot values for the SP-9

    Post by DynakitParts on Fri Jan 30, 2015 10:20 pm

    Tommy,
    Nice workmanship....What output tubes are you using with your guitar amp....6L6's ?

    By the way...Welcome to our Forum.

    Kevin


    spin

    Posts : 11
    Join date : 2015-01-11
    Age : 35
    Location : Delaware

    Re: Lets talk about pot values for the SP-9

    Post by spin on Thu Feb 05, 2015 8:25 pm

    Thanks! Yeah, I am using JJ 6l6 tubes in that amp.

    I opted to go with 100k volume pot for the SP-9 build. I ordered a 'make before break' rotary switch and the resistors to build a ladder attenuator.

    My next question is about the balance control. I have enough parts to build a stepped attenuator for this as well. A balance pot is completely new to me since I pretty much deal only in mono devices. Am I correct in assuming that the balance pot is two 'W' taper pots wired inversely?

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: Lets talk about pot values for the SP-9

    Post by MontanaWay on Thu Feb 05, 2015 10:37 pm

    spin wrote:Hi everyone, my name is Tommy. I'm new around here, but have been trolling for a couple weeks now. I have recently decided to get back to my 'roots', so to speak, and build a hi-fi system. After a bit of research and some recommendations, I came across tubes4hifi. Roy was beyond helpful and super accommodating with my order. I ordered an SP-9 (I'm afraid to give up tone control, baby steps, I'll build more), a PH-14 phono preamp, and a pair of mk3's. My order came in two shipments and Roy mistakenly sent me two parts kits for the SP-9. The parts kits were identical other than the fact I received a 100ka in one and a 250ka volume pot in the other. Before I send one of these bags back, I was wondering which would best suit my application. Most of the information I was able to gather points to using the 100k, but I wanted to be sure. I would like to use the 250k just for the fact that the PCB has extra ground pads that fit the shielded wire I plan to use perfectly. My main source is going to be the PH-14, and will be my only source for the time being.

    Thanks in advance for any help you can offer. I'll have quite a few more questions along the course of this build I am sure. I hope you will forgive my lack of Hi-Fi knowledge, we've all got to start somewhere. I can, however, solder pretty darn well, and I've built quite a few devices, almost all pertaining to guitar. I'm looking forward to this project and future projects in hi-fi audio.

    Here is a 100w 2 channel optically switched high gain guitar amp I built based on the schematic of the Soldano SLO 100.





    Facebook of my small DIY pedal company

    WOW!...that is AMAZINGLY clean and neat wiring!!! WELL DONE!!!!!!

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: Lets talk about pot values for the SP-9

    Post by TMadden on Fri Feb 06, 2015 9:48 am

    spin wrote:Thanks! Yeah, I am using JJ 6l6 tubes in that amp.

    I opted to go with 100k volume pot for the SP-9 build. I ordered a 'make before break' rotary switch and the resistors to build a ladder attenuator.

    My next question is about the balance control. I have enough parts to build a stepped attenuator for this as well. A balance pot is completely new to me since I pretty much deal only in mono devices. Am I correct in assuming that the balance pot is two 'W' taper pots wired inversely?


    Fantastic work on the guitar amp! The ALPS balance control normally used in the SP9 has a MN taper. http://www.alps.com/prod/info/E/PDF/Potentiometer/TAPER.PDF

    spin

    Posts : 11
    Join date : 2015-01-11
    Age : 35
    Location : Delaware

    Re: Lets talk about pot values for the SP-9

    Post by spin on Fri Feb 06, 2015 10:47 am

    So at center detent, both channels are at max. And it looks like linear taper to ground with a little knee. That's how I first pictured it in my mind. I did find this image when looking into it the other day:



    This is where I got the idea of two 'W' pots wired inverse to each other. At center detent it is passing 90% of each channel. My logic thinks that the 100% at center would be the better way to go. But something is telling me that the 'W' taper configuration would 'feel' better. Has anyone explored this before?

    Sponsored content

    Re: Lets talk about pot values for the SP-9

    Post by Sponsored content Today at 4:48 pm


      Current date/time is Sun Sep 25, 2016 4:48 pm