Inside The Threshold Fet-10e Phono Preamp – Pics

DaveSpectral · Apr 5, 2013

I found a great deal on this unit from EBay. Notice it is the, “e” version with the balanced outs. I could not find any internal pics of it on the internet at all, so I thought that I would post these two that I took. Feel free to share them wherever you want. The view of the pics is with the front of the unit facing us. All I did to modify them was crop, and I set the sharpness up to full, so people can hopefully read the values on the components. As you can see, it has a circuit board that would make Auric Goldfinger very happy. It is gold plated. My guess is 100 years from now, the board at least will still be in excellent condition.

Sonically, I find this unit to be AMAZING. The Moving Magnet setting is as quiet as it could be. The presentation with an Audio-Technica OC9-3 was nothing less than ASTONISHING. Unfortunately with the gains, there are only TWO settings of 40 and 60 DB.

It is a class-A design throughout. When measured with my Kill A Watt meter, it draws 7.5 watts from a 120 volt wall.

Enjoy the gold!

GaryB · Apr 6, 2013

DaveSpectral said:
I found a great deal on this unit from EBay. Notice it is the, “e” version with the balanced outs. I could not find any internal pics of it on the internet at all, so I thought that I would post these two that I took . . .

Sonically, I find this unit to be AMAZING. The Moving Magnet setting is as quiet as it could be. The presentation with an Audio-Technica OC9-3 was nothing less than ASTONISHING. Unfortunately with the gains, there are only TWO settings of 40 and 60 DB.

Dave,
Congratulations on the nice find. It looks like you got a good deal. How do you compare the sound to your Spectral gear?

A couple of years ago, I bought the same model phono stage and matching 10e line stage and I think that they sound great. Like any gear that is around 20 years old, one can make them even better by restoring them slightly. Old electrolytic capacitors benefit from being replaced in the preamp and the power supply. There are some other changes you can make as well that I documented in a few places. If you're handy with a soldering iron, you can do it yourself or find a friend or good tech to do it for you. Here are a few links for your reading pleasure.

http://www.thresholdlovers.com/forum/viewtopic.php?f=7&t=473
http://www.diyaudio.com/forums/pass-labs/193194-restoring-threshold-fet-10e-few-questions.html

---Gary

flez007 · Apr 6, 2013

Great preamp and finding! Looks very clean and as you are surely aware of, this phono stage is a classic now. i am too listening a fully-restored Melos SHA-Gold, it is a fantastic preamp as well.

DaveSpectral · Apr 6, 2013

GaryB said:
Dave,
Congratulations on the nice find. It looks like you got a good deal. How do you compare the sound to your Spectral gear?

A couple of years ago, I bought the same model phono stage and matching 10e line stage and I think that they sound great. Like any gear that is around 20 years old, one can make them even better by restoring them slightly. Old electrolytic capacitors benefit from being replaced in the preamp and the power supply. There are some other changes you can make as well that I documented in a few places. If you're handy with a soldering iron, you can do it yourself or find a friend or good tech to do it for you. Here are a few links for your reading pleasure.

http://www.thresholdlovers.com/forum/viewtopic.php?f=7&t=473
http://www.diyaudio.com/forums/pass-labs/193194-restoring-threshold-fet-10e-few-questions.html

---Gary

Oh that's YOU! LOL I saw those posts, but didn't notice the phono pre. I am o.k. with soldering, but like I told Jon Soderberg, I am afraid of messing up that beautiful board. He said he would replace all the caps with Solens for about $300 for the four, and about $400 for all.

Here is something that I'm dying to ask you: With mine, when I read a copy of the instructions, and when you look down at the 4 gain switches, it seems like something is explained BACKWARDS. Here is the paragraph that I took out of this thread. Do your gains operate according to the manual? – Mine don’t! LOL

---Now......about the gains, AND THIS IS DOWNRIGHT FLAKEY. First off, I had all of the other settings correct for a low output MC. I must have a later unit here. It came with a copied manual (and it was an, “e” manual.) which was from somebody on EBay who does that as a side-show. In the manual it states that the gains should be set a certain way. Now when you look at the 4 red, individual gain switches that are between the 4 circuit boards, on pic # 2, (below the two upper boards, and above the two lower boards) they seem to be made to set TOWARD the desired type of cartridge. By that I mean to set them for moving magnet, you would move the switches over toward the MM label. This coincides with what it says in the manual about the exposed dots on them. So, that is what I did for the low output OC9-3. THAT IS SIMPLY NOT CORRECT. When I had it all done, I played a record, and I had a distinct lack of gain. It is plugged in to a Marantz 7005 surround sound processor, and it is set for, “Pure Direct” which shuts off unnecessary circuitry, and bypasses everything for audiophile, 2 channel sound. I wound up setting that single Marantz high level input for an extra 10 DB of gain. The noise was still very low, I had enough gain, and I was in HEAVEN. So I told myself that I have to settle this: I went back inside the Fet, selected the right channel gain by pushing the R gains toward MOVING MAGNET, and there it was: The HUGE gain increase that we expect from MC circuitry, on the right channel. This must be a newer unit, (or an older unit?) because when compared to what it says is correct in the manual, the manual has the description BACKWARDS. This is NOT a belated April Fools joke. It could be, that they changed something in between the E manual that I have, and the unit at a later time.---

DaveSpectral · Apr 6, 2013

flez007 said:
Great preamp and finding! Looks very clean and as you are surely aware of, this phono stage is a classic now. i am too listening a fully-restored Melos SHA-Gold, it is a fantastic preamp as well.

Oh yes. I think the best deal going in audio is vintage high end. Threshold, Spectral, Krell. They go for 1/3 to 1/2 of what they did then. Think of it this way: How much would the Fet-10e phono be worth if it was made today? LOL Maybe 12 Grand? I've always heard great things about Melos also. The 10e phono, OR the line stage were $3,250 back in THAT day. I think they had a big discount if you bought both.

FWIW, I asked about the difference between the non-e Fet-10 HL and the Fet-9. A good source, (I forgot who) said the Fet-10 has twice as many transistors as the Fet-9.

Edited to add: BTW, the total delivered price was bout $700. The 10e's and the 10e phono's especially are rare. I've seen the e-phono's go from $900-$1,100.

DaveSpectral · Apr 6, 2013

BTW, if anybody wants the full size pics, about 4MB, P.M. me, and I can email them to you. I should have used more light because it's STILL hard to read all of the values on the components.

GaryB · Apr 6, 2013

DaveSpectral said:
. . . I am o.k. with soldering, but like I told Jon Soderberg, I am afraid of messing up that beautiful board. He said he would replace all the caps with Solens for about $300 for the four, and about $400 for all.

Here is something that I'm dying to ask you: With mine, when I read a copy of the instructions, and when you look down at the 4 gain switches, it seems like something is explained BACKWARDS. Here is the paragraph that I took out of this thread. Do your gains operate according to the manual? – Mine don’t! LOL

I think you may be misreading the manual or you have a copy of the wrong manual. I took a couple of photos of the page in the manual describing things and it describes setting the gain exactly the way you did. But it's binary so it's not too hard to figure out. One way has higher gain than the other, so use whatever works.
---Gary

DaveSpectral · Jun 9, 2013

GaryB said:
I think you may be misreading the manual or you have a copy of the wrong manual. I took a couple of photos of the page in the manual describing things and it describes setting the gain exactly the way you did. But it's binary so it's not too hard to figure out. One way has higher gain than the other, so use whatever works.
---Gary

View attachment 9093 View attachment 9094

Oh! Thank you Gary. I never saw this response!

Unfortunately, I have a second problem, which is the value of the switches in the two 8 switch blocks. Could you do me another big favor? The owners manual that the guy sent me stops at the end of page 9. The last thing it says is, “Switches 1-4 select the cartridges capacitive loading in picoFarads.” My partial manual checks out with what you posted.
I think there is at least one more page after that, because I do not know the VALUE of the eight switches. I have my suspicions, but to mention it here will only add to confusion.

Can you either post that page, (P 10) or list the eight switch values with number 1 being the closest to the front of the pre, with the front facing you?
I hate to bother you with this, but I can not find a complete, “e” manual anywhere on the net. I found somebody’s post on the DIY forum, but his was the non-e, and does not add up with what I have here. My manual is labeled, “Fet 10e Cartridge Gain Preamplifier.” – If I just had page 10!

See, before I didn't need this info because I was using a high output moving coil, and I just left all eight of them off. I should have asked you then.
Thanks again!

GaryB · Jun 9, 2013

Dave,
I'm on the road right - visiting Japan on business. I'll see what I can find when I get back. In general, LOMC cartridges don't need capacitance loading. So only resistive loading matters. You should be able to measure the resistor loading with a multimeter at the MC inputs (with the cartridge disconnected). Or wait for me to look it up.

---Gary

DaveSpectral · Jun 11, 2013

GaryB said:
Dave,
I'm on the road right - visiting Japan on business. I'll see what I can find when I get back. In general, LOMC cartridges don't need capacitance loading. So only resistive loading matters. You should be able to measure the resistor loading with a multimeter at the MC inputs (with the cartridge disconnected). Or wait for me to look it up.
---Gary

Thanks again Gary.
I contacted the new Threshold, and they had a copy, and the emailed it to me. I had reason to think they did not have info on their older gear.
Turns out, I had it set right. I have an Audio Technica OC9-3 and I just bought a Rothwell MCL MC Step up transformer. They state it should go in to 47K which I had right, and a capacitance of 150 uF which I had right from my lucky guess at how Threshold laid the switches out.
I hope you can enjoy Japan a little, while on business!

For anyone else, Threshold can be contacted here,
http://www.threshold-audio.com/
and their Tech email is:
support@thresholdaudio.com

Dual · Feb 3, 2019

I'm attaching some photos I took of my preamp a few years back.

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Inside The Threshold Fet-10e Phono Preamp – Pics

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