idea's for a valve preamp

[fisher x 100 a]

looking for a valve preamp.

I have a Rega with Elys 2, Output: 6.8 - 7.2mV

fisher valve amp -the phono input are - HI : 16mv - low : 3.5mv

any suggestions/ideas great-fully accepted

playing records are just too trebbley and bass is all muddled at moment,

thanks

[kevinkr]

Which model Fisher integrated, and has it been treated to fresh supply and coupling capacitors?

It may also be that you could rebuild the phono stage with a better circuit, something passively equalized with a ECC83 in the front end and a ECC88 in the second stage perhaps..

Or you could build SY's new phono stage design which should provide pretty good performance, although you will need to take steps to minimize interconnect capacitance with MM cartridge..

[fisher x 100 a]

its a fisher X 100 A, the amp has been worked over twice. Really want to keep this original as possible also. In saying that - buying five 12ax7 and 4 el84 nos tubes would be expensive if keeping original. running sovtek el84m and jj 12ax7.

wondering if the resistors etc on the phono stage are not matched to the rega of today era's.

[picowallspeaker]

Neither the x 100 t -transistorized- phono stage was capable of playing frequencies lower than 100 Hz .

[kevinkr]

Originally Posted by picowallspeaker

Neither the x 100 t -transistorized- phono stage was capable of playing frequencies lower than 100 Hz .

I suspect given his moniker that he has a Fisher X-100-A which has all vacuum tube based circuitry - no transistors anywhere.

If you meant the output transformers - these are good for 30Hz or better.

I somehow doubt in the heyday of the LP that any reputable hifi manufacturer built an RIAA phono stage that could not reproduce below 100Hz...

The Fisher X-100-A

[fisher x 100 a]

Originally Posted by picowallspeaker

Neither the x 100 t -transistorized- phono stage was capable of playing frequencies lower than 100 Hz .

hi there - could you please explain this - wont the fisher play a rega or.....

[picowallspeaker]

I have (somewhere) the phono and tone/vol PCBs which I removed from the chassis-the old outputs were blown..probably somebody wise attached it to our mains (220)-it did have two interstage transformers!-and I tried the two circuits separately (12 volt operating)...the phono being a little constipated ...

[kevinkr]

Originally Posted by picowallspeaker

I have (somewhere) the phono and tone/vol PCBs which I removed from the chassis-the old outputs were blown..probably somebody wise attached it to our mains (220)-it did have two interstage transformers!-and I tried the two circuits separately (12 volt operating)...the phono being a little constipated ...

I think you are talking about altogether another amplifier, please reread the original poster's comment about using a Fisher valve amp (amplificatore solemente a valvole, non e transistorizato) - the Fisher X-100-A has no pcbs and NO transistors, and was manufactured in NY around 1961 or so. . I have worked on a number of these amps, the one you refer to is probably the later solid state unit..

[picowallspeaker]

Yes it is tran-sis-tor-ised ! But as I see ,it may have the same flaws
TX-100 Kevin you were right ,late sixties ,115-135V 50/60 Hz .The magic had just begun

[Eli Duttman]

Fisher phono sections are not known for good bass extension, sorry. The simplest change is to replace the phono section tubes with Sovtek 12AX7LPSes. The Russian tube is clean and quiet, along with being well balanced.

IMO, you can't retain the OEM circuitry and improve the sound. If it were my unit, I'd change the phono section to RCA style. The attached schematic shows how.