Hello forum members
finally decided to have ago at the JLH phono pre amp project. Have managed to pull most of the parts together passives and transistors etc. I have the original PCB and a new power supply board.
will upload some pics later when back in the workshop
regards
finally decided to have ago at the JLH phono pre amp project. Have managed to pull most of the parts together passives and transistors etc. I have the original PCB and a new power supply board.
will upload some pics later when back in the workshop
regards
quick picture of the front .. don't worry the counter sunk bolts will be changed later so they match .. plus waiting for the master on/off switch to arrive via mail order (RS) .. plus cats eyes not fitted yet, need to decide colour
Attachments
Last edited:
Hello ... on this project I have decided to make the phono preamp with the original power supply when available as a kit from Hart electronics.
These pcb's are no longer available so have made my own as a exact replica .. purely for retro .. nostalgic reasons 🙄
I like the PCB for central star earthing plus can be used for many other projects if needed .. also I have used 2oZ copper for the PCB tracks
more to follow when completed
These pcb's are no longer available so have made my own as a exact replica .. purely for retro .. nostalgic reasons 🙄
I like the PCB for central star earthing plus can be used for many other projects if needed .. also I have used 2oZ copper for the PCB tracks
more to follow when completed
Attachments
Ok people .. some more in progress pics from tonight
so a rear view .. we have mains in and power indicator at the rear
2 sets of inputs (MM & MC) plus the output phono sockets .. just need to add the MM /MC switch and the PSU earth lift switch .. then some engraving to finish the rear off
regards
so a rear view .. we have mains in and power indicator at the rear
2 sets of inputs (MM & MC) plus the output phono sockets .. just need to add the MM /MC switch and the PSU earth lift switch .. then some engraving to finish the rear off
regards
Attachments
some more pics from inside the enclosure
all main cables double insulated with a added main filter for good measure
all main cables double insulated with a added main filter for good measure
Hello James, (or is that the cat's name)
That's looking very good so far, took me a little while to work out what you meant by cats eyes! Obvoiously your 'trademark'.
ISTR that Hart did kits for ETI magazine projects. Was this one of them ? If so, do you know which ETI issue it was in ?
That schematic you posted is the same as the one on Paul Kemble's site. The specs at the bottom have quite a few typos. Nothing important but I'll post corrections later.
I also noticed on the Kemble page that there may have have some mods, like reducing gain of MC input to mitigate bass roll-off. Did you get any documentation like updated schematic, updates, etc. with your board ?
I'm currently looking at phono-preamps for a new preamp build. I put this one into LTspice and on 1st look it's pretty good - very flat RIAA eq, except for a little bass roll-off from the 13Hz rumble filter. This is a candidate, also it's op-amp based cousin the K1500. I just want to work with the correct upto date circuit, that's all.
Cheers,
Simon
That's looking very good so far, took me a little while to work out what you meant by cats eyes! Obvoiously your 'trademark'.
ISTR that Hart did kits for ETI magazine projects. Was this one of them ? If so, do you know which ETI issue it was in ?
That schematic you posted is the same as the one on Paul Kemble's site. The specs at the bottom have quite a few typos. Nothing important but I'll post corrections later.
I also noticed on the Kemble page that there may have have some mods, like reducing gain of MC input to mitigate bass roll-off. Did you get any documentation like updated schematic, updates, etc. with your board ?
I'm currently looking at phono-preamps for a new preamp build. I put this one into LTspice and on 1st look it's pretty good - very flat RIAA eq, except for a little bass roll-off from the 13Hz rumble filter. This is a candidate, also it's op-amp based cousin the K1500. I just want to work with the correct upto date circuit, that's all.
Cheers,
Simon
I will try and upload a PDF later .. this was the original Hart shunt feedback kit k1450 this has had many favorable reviews from Vinyl enthusiasts .. I built the less complicated op amp version years ago and was very pleased with the results .... plus I am going to purchase a turntable hence this project ...
regards
regards
I have a scan of the original construction manual for this - if anyone would like a copy then pm me. It is scanned as individual page files that add up to more than 11mg.
Yes the sensitivities should read ... 3.7mV (mm), 340uV (mc).
The gain numbers are correct .
I have recently encountered this in the thread started by... Anthony.taylor1967...( Gain resistors on JLH phono ) over in analogue source.
Last edited:
Thanks for all the info.
OK, so they didn't change anything apart some part substitutions.