Any Fi X3 300B amp owners out there?

[grantray]

I just became the proud steward of Don Garber's chassis number X3-08, which I'm over the moon about, but I don't have the accompanying papers, which generally include a schematic and parts list. Chassis 08 has the Elna Cerafine power cap with Hammond 125E output trannies. I'd love to get schematics and parts lists for both the Hammond and Hashimoto versions if anyone's holding, or has access to them.

Also, the hum coming through both of my 846As is noticeable to the point I'm worried either the hum pot isn't getting the job done, or Elna might need to be replaced. Basically, the X3 adjusted to as quiet as possible is about the same as my Asano 2A3 before the adjustment. Is this much hum typical in the X3 amps with the Hammonds?

This afternoon I cleaned the hum pot and all tube sockets with Deoxit D5, then hit the hum pot with another squirt of Faderlube as it was definitely dirty/crackly when I tried to adjust out the hum after powering up. I'm guessing the amp has never been serviced, and typical maintenance also looks to be pretty nonexistent.

All that aside, I've been letting it play for over six hours straight, and it's definitely no slouch. The midrange is coming out like it's on psychotropic steroids.

Thanks!

 

[Palustris]

The Fi amp follows the same basic topology as this schematic from the 1947 publication, Practical Amplifier Diagrams. The original inspiration for this topology is the Loftin White 2A3 amplifier. You will probably have to draw out your own schematic with the correct part values and any deviations from the schematic below, but it will give you a starting point.

 

[soundmotor]

I just became the proud steward of Don Garber's chassis number X3-08, which I'm over the moon about, but I don't have the accompanying papers, which generally include a schematic and parts list. Chassis 08 has the Elna Cerafine power cap with Hammond 125E output trannies. I'd love to get schematics and parts lists for both the Hammond and Hashimoto versions if anyone's holding, or has access to them.

Also, the hum coming through both of my 846As is noticeable to the point I'm worried either the hum pot isn't getting the job done, or Elna might need to be replaced. Basically, the X3 adjusted to as quiet as possible is about the same as my Asano 2A3 before the adjustment. Is this much hum typical in the X3 amps with the Hammonds?

This afternoon I cleaned the hum pot and all tube sockets with Deoxit D5, then hit the hum pot with another squirt of Faderlube as it was definitely dirty/crackly when I tried to adjust out the hum after powering up. I'm guessing the amp has never been serviced, and typical maintenance also looks to be pretty nonexistent.

All that aside, I've been letting it play for over six hours straight, and it's definitely no slouch. The midrange is coming out like it's on psychotropic steroids.

Thanks!

I remember those and wish I could help. fi was in the first wave of cool new tube gear in the early 90s.

Neat piece.

 

[grantray]

The Fi amp follows the same basic topology as this schematic from the 1947 publication, Practical Amplifier Diagrams. The original inspiration for this topology is the Loftin White 2A3 amplifier. You will probably have to draw out your own schematic with the correct part values and any deviations from the schematic below, but it will give you a starting point.

Thanks for pulling up that schematic. I'd read his 300B and 2A3 amps are very similar in layout, and peeking through the mesh gives a fairly decent picture as well. My hope was that there was a secret owner's club/archive that I hadn't heard of so I could learn what Hashimoto transformers he used when he didn't use the Hammonds, and how he modified the schematic to suit them. While the amp is SET, the 125E Hammonds he used are designated for push-pull designs. Crazy, right? That kind of weirdness is what has me searching out other collectors of his pieces in hopes of finding the standard correspondence that included a schematic with the relevant parts list.

 

[Palustris]

It's just my personal opinion, but I think the Magnequest DS-025 output transformers (I think these were the original option) were an excellent choice for the 'X' Series of amps. The DS-025 works better with a 2A3 like the JJ 2A3-40, which would be ideal, rather than the 300B.

You would need to adjust the filament voltage from 5V to 2.5V for the change. If this has the Magnequest 5504 power transformer, there are two 2.5V secondaries in series to get the 5V for the 300B. So simply connect the 2.5V secondaries in parallel to get the 2.5A for the 2A3. I did that with my all Magnequest amps using the 5504, the DS-025 and the JJ 2A3-40.

 

[grantray]

It's just my personal opinion, but I think the Magnequest DS-025 output transformers (I think these were the original option) were an excellent choice for the 'X' Series of amps. The DS-025 works better with a 2A3 like the JJ 2A3-40, which would be ideal, rather than the 300B.

I know that output transformer well. I have a pair of them powering two JJ 2A3-40s in my Asano 2A3 amp

The X3 amp will be for the design studio where I work, not the home rig. I adore the the X3 something fierce, but the Asano 2A3 in my home rig downright slays. If I can find out the proper Hashimotos and other requisite components Don used for the upgraded X3 via his schematic and parts list he sent with each direct purchase, I'd be mighty inclined to make that happen. (Of course, I'd keep all the original parts for posterity.) Until then, I'm happy to keep it stock. Truth be told, I'm really digging the X3 with a pair of really nice early 90s Paradigm Compact Monitor speakers that are considerably less efficient than my 846A Valencias, which is where the over-the-top hum made itself known. Of course, maybe that means my Altecs need fresh crossovers, but that's a rabbit hole I'm also trying to steer clear of for reasons of sanity

 

[Orest12]

Greetings, All--Have owned a Fi X 300b, chassis #10, since November 99, having bought it directly from Don Garber after a few phone conversations. Originally tried a 2a3 X but it did not have enough drive for my Proac speakers; it was quickly returned. Don Garber then told me he had a "fully optioned" 300b Demo ready to ship--the MasterCard order slip lists it as a "Demo X with MQ TFA-204 outputs and filter chokes," though I do think the MQ is a DS 025. It also has the copper Edison Price speaker connectors and, supposedly, a higher polished chassis. When I ordered it, I asked Don if it could be upgraded somehow before shipment; he seemed a bit annoyed at the dumb question, mentioned that he could "throw in a Black Gate" if that would make me happy, but it would not sound any better.
In all the years I have not used it very much, having that industrial looking Kit One which sounds much more dynamic, is dead quiet, and have several other amps. Regarding the hum problem, I suspect that is common to the amp. My X hums noticeably on start up and quiets down some in a few seconds but the noise never goes away, the hum pot making little or no difference. Since my unit was quite new, couldn't blame the parts, and Don Garber hinted that I could live with it or return it. I never saw this as a bit annoyance, but then I didn't use Altec horns, and the Proacs hide the hum reasonably well.
As an aside, about a year ago I found an old Garber email address and sent him a note asking if he still makes the matching Y preamp which I would like to have. Surprisingly he answered within an hour--yes, he could make the Y; it would require a $500 deposit and delivery would be in five years. I thanked him very much but mentioned that five years at my age is a lifetime. Later last summer when I read that Don Garber had passed, I hooked up the X for a few weeks in his honor; somehow it sounded better than ever; maybe it's finally broken in, or maybe there is some other reason...

 

[Palustris]

The Magnequest TFA-204 is a 3k ohm primary output transformer that is an early Western Electric design for the 300B. So it is probable that the TFA-204 was the original transformer used on the Fi X 300B not the DS-025. I believe that TFA-204 is slightly smaller than the DS-025 making it a better fit in the X chassis.

As to the Valencia crossover, replacing the stock components using high quality parts (air core chokes and MKP caps) made a HUGE difference in my Valencias. I simply made an external crossover box that connected between the amp and drivers and bypassed the internal crossover. I should add that covering the 811 horns with Dynamat sound deadening material made a very constructive change to reduce ringing. Finally, scrape the bug guard off of the gasket separating the driver and horn for another cheap and easy improvement.

 

[Orest12]

Hi and thanks--so rare to find a fellow Fi X owner and anyone familiar with these amps. Found my old paper work from Don Garber. My earlier reference to the Mag TFA-204 was actually from a receipt for the Fi X 2a3 that I bought and returned; sorry, haven't seen this in years. Have also found a letter from Don confirming that my X3 did come with the DS 025 outputs. Other than the type written letter about the X3 there was no schematic or parts list supplied. Do, however, have a hand drawn schematic for the 2a3 amp if anyone is interested. Can also share the X3 letter if desired.

 

[Palustris]

Thanks for confirming that the DS-025 was available on the X chassis; it looks like they are a tight fit. Having checked my own Magnequest power transformers, I can see now that the power transformer on the X is not a Magnequest 5504. I would love to see a scan of the schematic; there should be no problem with copyright now.

 

[Orest12]

From my old dusty files (Ned Carlson would be proud)--hand scribbled by Don Garber schematic for Fi X 2a3, and typed letter of description. Do have a typed letter that came with my X3 that I can post but no schematic. If these are not readable, I can email them if such contact is possible on this forum.

 

[soundmotor]

The Magnequest TFA-204 is a 3k ohm primary output transformer that is an early Western Electric design for the 300B.

Digging out my own dusty files...

IIRC it is a WE design but made by Altec. The TFA-204 was the service replacement for the WE 171A one still in theater use. It would have come out after the 1947 breakup.

My recollection FWIW. Someone else will weigh in if that's wrong.

 

[grantray]

Greetings, All--Have owned a Fi X 300b, chassis #10, since November 99, having bought it directly from Don Garber after a few phone conversations. Originally tried a 2a3 X but it did not have enough drive for my Proac speakers; it was quickly returned. Don Garber then told me he had a "fully optioned" 300b Demo ready to ship--the MasterCard order slip lists it as a "Demo X with MQ TFA-204 outputs and filter chokes," though I do think the MQ is a DS 025. It also has the copper Edison Price speaker connectors and, supposedly, a higher polished chassis. When I ordered it, I asked Don if it could be upgraded somehow before shipment; he seemed a bit annoyed at the dumb question, mentioned that he could "throw in a Black Gate" if that would make me happy, but it would not sound any better.
In all the years I have not used it very much, having that industrial looking Kit One which sounds much more dynamic, is dead quiet, and have several other amps. Regarding the hum problem, I suspect that is common to the amp. My X hums noticeably on start up and quiets down some in a few seconds but the noise never goes away, the hum pot making little or no difference. Since my unit was quite new, couldn't blame the parts, and Don Garber hinted that I could live with it or return it. I never saw this as a bit annoyance, but then I didn't use Altec horns, and the Proacs hide the hum reasonably well.
As an aside, about a year ago I found an old Garber email address and sent him a note asking if he still makes the matching Y preamp which I would like to have. Surprisingly he answered within an hour--yes, he could make the Y; it would require a $500 deposit and delivery would be in five years. I thanked him very much but mentioned that five years at my age is a lifetime. Later last summer when I read that Don Garber had passed, I hooked up the X for a few weeks in his honor; somehow it sounded better than ever; maybe it's finally broken in, or maybe there is some other reason...

Hi Orest.
Nice to meet a fellow Fi X3 owner, and thanks for all the helpful info! From what you've stated, I'm guessing the hum is here to stay, although I'll still get it checked out just to be sure. I've got hum that comes back around after quieting down, which is what has me a little concerned. I'll keep hunting for a schematic in case the day comes I want/need to swap out the 125E Hammonds. Also, do you have a clean shot of the knob he used for the hum pot? Mine must have gotten lost over the years, so I'd to get something close to what Don would have used. Although the brass knobs on his later two-chassis preamps were gorgeous.

 

[grantray]

The Magnequest TFA-204 is a 3k ohm primary output transformer that is an early Western Electric design for the 300B. So it is probable that the TFA-204 was the original transformer used on the Fi X 300B not the DS-025. I believe that TFA-204 is slightly smaller than the DS-025 making it a better fit in the X chassis.
As to the Valencia crossover, replacing the stock components using high quality parts (air core chokes and MKP caps) made a HUGE difference in my Valencias. I simply made an external crossover box that connected between the amp and drivers and bypassed the internal crossover...

Any chance you can recall the brand of aircore chokes you went with? I've been slowly squirreling parts for a spec rebuild, and the chokes are the last components besides connecting wire that I'd need.

 

[Palustris]

I believe that I simply used Madisound air core inductors. The brand isn't critical as they are simply turns of high quality copper wire on a plastic former. With an amplifier of only a few watts, there is no need for a large wire guage either; so 16 AWG is fine, although 19AWG is probably good enough. I used an assortment of various caps when I first built the crossovers, but then rebuilt them entirely with Russian KBG-MN capacitors when they became available on epay. They might be harder to find in the correct values now, but there are many popular "boutique" caps you could use. Try to find some composed of copper foil as opposed to "aluminumized" plastic.

 

[grantray]

I believe that I simply used Madisound air core inductors. The brand isn't critical as they are simply turns of high quality copper wire on a plastic former. With an amplifier of only a few watts, there is no need for a large wire guage either; so 16 AWG is fine, although 19AWG is probably good enough. I used an assortment of various caps when I first built the crossovers, but then rebuilt them entirely with Russian KBG-MN capacitors when they became available on epay. They might be harder to find in the correct values now, but there are many popular "boutique" caps you could use. Try to find some composed of copper foil as opposed to "aluminumized" plastic.

Thanks! I've had the Madisounds on the radar for a bit, so it's nice to get positive feedback from someone who's using them in a nearly identical setup.
As for caps, the KBG-MNs just so happen to be what I have squirreled in the basement

 

[grantray]

The Fi amp follows the same basic topology as this schematic from the 1947 publication, Practical Amplifier Diagrams. The original inspiration for this topology is the Loftin White 2A3 amplifier. You will probably have to draw out your own schematic with the correct part values and any deviations from the schematic below, but it will give you a starting point.

While that's certainly true for the Fi 2A3 topologies, I'm not so sure for the same can be said for the X3. The photos I've been able to scour up show the chassis layouts for the X 2A3 and the X3 are distinctly different. You can see click here for several shots of a X 2A3 amp. Besides a little rearranging to allow for those beefy transformers, the biggest difference for me is the lack of the large Cerafinne cap Garber used for the X3. Of course, he could have replaced that single large twin capacitor guy with a series/parallel of smaller fellas strung together inside the walls of the X chassis, but something** tells me not take the amp apart before understanding the logic of Garber's decisions.

**I can neither confirm nor deny I've learned a possibly similar lesson of this logical variety the hard way.

 

[Orest12]

Greetings--as mentioned before, the X3 will hum noticeably on startup, and then become very quiet after just a few seconds. On my Proac 1.5 or Tablette this is no problem; since on Gantray's amp the hum returns that would need to be checked. Regarding the hum pot knob, my X3 did not have one when I bought it; the knob shown is an old brass Dynaco knob I had and put on just for show.
Now a question for all the tube experts here (I only pretend)--in addition to the output transformers, the main power trans, and the filter
chokes, the X3 has three others. On the Cerafine panel is a filament transformer, a Magnetek F5 120 (power transformer?), and another large transformer. The filament thing is obvious, but the others??

 

[grantray]

[Regarding the hum pot knob, my X3 did not have one when I bought it; the knob shown is an old brass Dynaco knob I had and put on just for show.

Well that settles why this X3 didn't come with the knob. Garber never put on one in the first place. What's the rectifier tube you're running, btw? Is that the Sovtek 5AR4/GZ34?

As for the component identification, the way he's using transformers compared to the more simple 2A3 topology is one of the biggest reasons why I'm looking for a schematic.

 

[Orest12]

The amp was shipped in 99 with period EH 300b, average quality, two JAN Phillips 6sn7, and a Sovtek rectifier, which arced in a week. I replaced it with an old Dynaco branded Mullard harvested from a ST70, still testing and sounding as new nearly 60 years later. 300b using: 90’s Svetlana (sounds great), Sovtek (like the EH), Audio Note branded Shuguang black plate (sounds great). Also used briefly Western Electric reissue but the tube manual advises to use this tube vertically if possible. For the driver tubes I recently tried a pair of Psvane Treasure II, the big gray bottles. These are very microphonic in a Cary preamp, but are quiet and play well in the X—no idea why.