Got one of the vintage Threshold pre. It's oldie but sounds very yummy. While I don't use it that much, I think it's the keeper till I kick the bucket.
The question is should I recap the FET1? It sounds good as is but it's probably about time for proper recapping and upgrading. I think it's time for at least two big filter electrolytic caps to get a retirement.
I don't have any manual or schema for it but it's not hard to do recapping. While I do recapping, what parts should be upgraded too?
Thanks,
James
The question is should I recap the FET1? It sounds good as is but it's probably about time for proper recapping and upgrading. I think it's time for at least two big filter electrolytic caps to get a retirement.
I don't have any manual or schema for it but it's not hard to do recapping. While I do recapping, what parts should be upgraded too?
Thanks,
James
Filter caps for sure. I would also replace all those 10uF polyesters with something cheap like Auricaps. Going overboard is probably not worth it - too many pots and old switches to make it truly transparent.
Threshold Fet one series II
I'm also interested in this preamp.
I know the original fet one uses transformers for the MC amplification and the Series II a MC headamp.
Is anybody aware of other differences between the two?
Had this preamp myself 23 years ago but traded it in for a Levinson ML-7A.
Found this Japanes refurbishing link for the "Series I":
Threshold FET1
Greetings
I'm also interested in this preamp.
I know the original fet one uses transformers for the MC amplification and the Series II a MC headamp.
Is anybody aware of other differences between the two?
Had this preamp myself 23 years ago but traded it in for a Levinson ML-7A.
Found this Japanes refurbishing link for the "Series I":
Threshold FET1
Greetings
Well they certainly cherished your products from that era!
I'm only wondering why they removed the grease (green stuff) from the Noble pots. Who did principal designing for these preamps (Fet One & Two) Eric Lauchli or you?
I'm only wondering why they removed the grease (green stuff) from the Noble pots. Who did principal designing for these preamps (Fet One & Two) Eric Lauchli or you?
Okay that's sorted out now. Very generously of you that he could print his name also on the circuit board.
Can you recall why you switched from the Jensen transformers in Series I to the MC headamp in Series II?
Won't bother you any further about this subject.
Can you recall why you switched from the Jensen transformers in Series I to the MC headamp in Series II?
Won't bother you any further about this subject.
Caretaking a FET1
I got one from a friend.
Together with two Mundorf Mcap Evo 10µF Silver-Gold-Oil. I replaced the caps in the linestage. If i had to by them myself i would, they are worth every euro. Also, i used the Tuner-Input and routed it straight to the 4,7k resistor at the JFet-Gate, so there is a diy "Direct-Input". 🙂
This preamp sounds absolutly stunning wonderfull !
I have not figured out what the two MPSA42/92's role are ?
I got one from a friend.
Together with two Mundorf Mcap Evo 10µF Silver-Gold-Oil. I replaced the caps in the linestage. If i had to by them myself i would, they are worth every euro. Also, i used the Tuner-Input and routed it straight to the 4,7k resistor at the JFet-Gate, so there is a diy "Direct-Input". 🙂
This preamp sounds absolutly stunning wonderfull !
I have not figured out what the two MPSA42/92's role are ?
schmatic
schmatic.
hope its correct. Had to clean board, replace the volumepot.
schmatic.
hope its correct. Had to clean board, replace the volumepot.
Attachments
Last edited:
Great that this thread is alive again after 11 years!
I use a FET Eleven/G (G stands for Germany, yes it's basically a FET TEN e Series but in 1990 the German market was powerful enough to demand their own names on the front ;-)) with balanced in- and outputs. The German importer in those days the late Werner Baden from WBS, even got a golden shield with Custom Series on its Threshold PRC1 pre-amp.
Well nice you've got a answer from Zen Mod (he's one of the fastest to react!) about the MPSA42/92's.
I use a FET Eleven/G (G stands for Germany, yes it's basically a FET TEN e Series but in 1990 the German market was powerful enough to demand their own names on the front ;-)) with balanced in- and outputs. The German importer in those days the late Werner Baden from WBS, even got a golden shield with Custom Series on its Threshold PRC1 pre-amp.
Well nice you've got a answer from Zen Mod (he's one of the fastest to react!) about the MPSA42/92's.
I wonder, did these Japanese gentlemen repair or upgrade the Jensen MC transformers?
This is what the said they repaired:
C. Repair status
Semi-fixed VR replacement
VR dismantling cleaning
Electrolytic capacitor replacement
Film capacitor replacement
Wiring repair , reinforcement
Solder correction for each part due to aging
MC transformer fixed
And they state that the lid of the transformers was only glued and now the soldered back together.
I've no idea if they rewired it or not.
C. Repair status
Semi-fixed VR replacement
VR dismantling cleaning
Electrolytic capacitor replacement
Film capacitor replacement
Wiring repair , reinforcement
Solder correction for each part due to aging
MC transformer fixed
And they state that the lid of the transformers was only glued and now the soldered back together.
I've no idea if they rewired it or not.
Last edited:
Is the schematic attached to post #10 correct? I wonder whether the second stage MOSFET "Q3" should be reversed, with source connected to +24V and with drain connected to R5.
As drawn in post #10, the feedback loop appears to deliver positive feedback rather than negative.
As drawn in post #10, the feedback loop appears to deliver positive feedback rather than negative.