EXCREPTS FROM AUDIOGONE DISCUSSION FORUM
**There are some recordings with the phase inverted.
**I have a invert phase switch on phono pre with a remote so I can switch from my chair, is a change in bass and detail in my system and very noticeable.
**One of the things I like about the Jeff Rowland preamps is the phase switch. I use it all the time & sometimes it makes a pretty big difference.
**Phase reversal of the Sheffield direct-to-disk LP's is more audible than of "normal" recordings, and many of the Sheffield's are themselves in reverse polarity. Sheffield recommended the playback system polarity be reversed when playing their LP's.
**Clark Johnson wrote about polarity in a book titled THE WOOD EFFECT, if I recall it had listed many LPs and what polarity they were recorded in.
**Karen quickly nailed an out of phase recording coming from the Quad ESL 63s. Great preamps from that day forward included switchable phase controls. My experience is that vinyl "showed" the difference more distinctly than my digital playback in later years.
**There are some recordings with the phase inverted.
**I have a invert phase switch on phono pre with a remote so I can switch from my chair, is a change in bass and detail in my system and very noticeable.
**One of the things I like about the Jeff Rowland preamps is the phase switch. I use it all the time & sometimes it makes a pretty big difference.
**Phase reversal of the Sheffield direct-to-disk LP's is more audible than of "normal" recordings, and many of the Sheffield's are themselves in reverse polarity. Sheffield recommended the playback system polarity be reversed when playing their LP's.
**Clark Johnson wrote about polarity in a book titled THE WOOD EFFECT, if I recall it had listed many LPs and what polarity they were recorded in.
**Karen quickly nailed an out of phase recording coming from the Quad ESL 63s. Great preamps from that day forward included switchable phase controls. My experience is that vinyl "showed" the difference more distinctly than my digital playback in later years.
Salas i have a "small" problem,
i have :
S7 ON S11 ON all others OFF
Loading:
S1-S4 all OFF input load is 47k
That with Ortofon 2m Blue.
I think that the left channel is about 10% louder than the right.
What is that i must check and alter?
Thank you in advance.
P.S. Your phono is so special, that my blue cartridge sounds like 1000 euro cartridge!!!
i have :
S7 ON S11 ON all others OFF
Loading:
S1-S4 all OFF input load is 47k
That with Ortofon 2m Blue.
I think that the left channel is about 10% louder than the right.
What is that i must check and alter?
Thank you in advance.
P.S. Your phono is so special, that my blue cartridge sounds like 1000 euro cartridge!!!
Did you used a test record or you have that suspicion hearing your normal records ?
How well your first Jfets are matched within channels ?
Correct me if I'm wrong but won't the 40dB ( S8 ON S12 ON all others OFF ) setting be better for 2M Ortofon's ( being > 5mV MM carts ) ?
There are very few components involved in the circuit but simple mistakes can happen. Did you buy the kit from Teabags ?
Check the resistors values, especially the switch resistors R13-16, 19, 20. Nick could tell you further info but do check that the right components was soldered to the right place.
In order to check output levels I use a signal generator followed by an attenuator to lower the signal to 2mV.
You can then check the output levels after gain stage (C3 cap) and then after RIAA stage (C4 cap) so you have an idea where the problem is located.
Check the resistors values, especially the switch resistors R13-16, 19, 20. Nick could tell you further info but do check that the right components was soldered to the right place.
In order to check output levels I use a signal generator followed by an attenuator to lower the signal to 2mV.
You can then check the output levels after gain stage (C3 cap) and then after RIAA stage (C4 cap) so you have an idea where the problem is located.
Oracle1 hi,
As Savvas wrote, you have to check the channels gain with electronic test means first. If there's a significant mismatch like >>1dB, review all passive components values first. If they are correct, then the gain must differ somewhere between the active parts.
You can influence it in the second stage JFETs and correct the situation. When increasing the source resistor's value, gain goes down. And vice versa.
*Q4, R8
As Savvas wrote, you have to check the channels gain with electronic test means first. If there's a significant mismatch like >>1dB, review all passive components values first. If they are correct, then the gain must differ somewhere between the active parts.
You can influence it in the second stage JFETs and correct the situation. When increasing the source resistor's value, gain goes down. And vice versa.
*Q4, R8
I see different schematics & resistors values som 1K and some 470R also some with 3rd resistor, could you share wich one is the correct, TIA?
Ok, all wired up except the jumpers from shunt to phono board. Reading various posts on grounding and the umbilical, I have a wiring question.
I have the female chassis mount 5 pin XLR grounded to the chassis on the RAW power supply and the female chassis mount XLR not grounded to chassis on the phone preamp side.
The Umbilical, shield is grounded to the male XLR plug on BOTH ends. I think this is in error, and shield should not be soldered to male XLR's ground tab on the phone pre end. Correct? Or....
Russellc
I have the female chassis mount 5 pin XLR grounded to the chassis on the RAW power supply and the female chassis mount XLR not grounded to chassis on the phone preamp side.
The Umbilical, shield is grounded to the male XLR plug on BOTH ends. I think this is in error, and shield should not be soldered to male XLR's ground tab on the phone pre end. Correct? Or....
Russellc
UFSP was very easy to setup. Still using the FSP transformer (36VAC) and having a highish Vinput (48VDC) I probably change it in the future. My plan is to have an A/B comparison between the new and old psu. It would be nice if no altering is required, meaning TP trimming. I will set both psus at exact the same voltage and see if I can get away with that
Other than that, it plays beautifully even in my low-budget setup. The comparison though will be in my main setup with Maggies.
Other than that, it plays beautifully even in my low-budget setup. The comparison though will be in my main setup with Maggies.