High Quality Tape Recorder - UK Vintage Radio Repair and Restoration Discussion Forum

DMcMahon · 21st Apr 2020, 1:41 pm

Interesting article from Wireless World 1970.

llama · 21st Apr 2020, 3:06 pm

This has always been highly regarded. I have a stereo pair of the replay amps myself. Mine is based on the RCA chips specified; sadly these have been obsolete for a long while. However, the articles cover a discrete components version of the circuit which Stuart describes as having equivalent performance.
Graham

Boulevardier · 21st Apr 2020, 4:03 pm

Many years ago, I built the discrete component version, and can confirm that it gives same performance as the original CA3048/CA3052 version. I had a lot of problems with the quad op-amp version, since they share chip power pins in pairs, and don't seem to have sufficient internal decoupling to handle cascaded individual op-amps on the same chip. I found that the discrete-component version with a separate voltage regulator for each individual op-amp gave much more flexibility of configuration.
I agree, justifiably well-regarded circuits - IMHO well up to semi-pro standards.

Mike

Radio Wrangler · 21st Apr 2020, 5:14 pm

I think there was a Hart kit for this.

David

Boulevardier · 21st Apr 2020, 5:24 pm

Yes, Hart made a kit for each section of the circuit. I bought their kit for for construction of the erase/bias oscillator, and it worked perfectly first time. I'm sure Hart are long gone now.

One snag is that Stuart designed these for Bogen heads (oh no!). He gives head parameters, etc to allow adjustment for other heads, but not with any circuit or component detail.

Mike

wd40addict · 21st Apr 2020, 8:16 pm

Bob Stuart later went on to found Meridian with the late Alan Boothroyd. Obviously his interest in HiFi as a hobby must've helped with this change of direction.

Nickthedentist · 21st Apr 2020, 8:18 pm

https://www.vintage-radio.net/forum/...ad.php?t=83982

Paulus.d · 27th Apr 2020, 2:43 pm

Some people built this project? did anyone complete the layout drawings so it can be built again using modern components>

Boulevardier · 27th Apr 2020, 3:11 pm

"Some people built this project? did anyone complete the layout drawings so it can be built again using modern components?"

If it's the Stuart tape circuits you're talking about, yes, I built them. Stuart used boards called "Lektrokit". I don't know what these are/were, but I just used standard Veroboard. Hart produced custom PCBs for their kits - the only kit I bought from them was for the HF oscillator section (because it got me all the ferrite components in one go). Veroboard is obviously much more fiddly, but worked fine for all the other sections. The original ICs are now unobtainable, but modern low-noise op amps or discrete components can be substituted. They are very simple, but very effective, semi-professional standard circuits (IMHO!)

Mike

21st Apr 2020, 3:06 pm	#2
llama Octode Join Date: Jun 2006 Location: St Osyth, Nr Clacton, Essex, UK. Posts: 1,482	Re: High Quality Tape Recorder This has always been highly regarded. I have a stereo pair of the replay amps myself. Mine is based on the RCA chips specified; sadly these have been obsolete for a long while. However, the articles cover a discrete components version of the circuit which Stuart describes as having equivalent performance. Graham __________________ Half my stuff is junk - trouble is, I don't know which half!

21st Apr 2020, 4:03 pm	#3
Boulevardier Octode Join Date: Sep 2017 Location: Bristol, UK. Posts: 1,654	Re: High Quality Tape Recorder Many years ago, I built the discrete component version, and can confirm that it gives same performance as the original CA3048/CA3052 version. I had a lot of problems with the quad op-amp version, since they share chip power pins in pairs, and don't seem to have sufficient internal decoupling to handle cascaded individual op-amps on the same chip. I found that the discrete-component version with a separate voltage regulator for each individual op-amp gave much more flexibility of configuration. I agree, justifiably well-regarded circuits - IMHO well up to semi-pro standards. Mike

21st Apr 2020, 5:14 pm	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,867	Re: High Quality Tape Recorder I think there was a Hart kit for this. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

21st Apr 2020, 5:24 pm	#5
Boulevardier Octode Join Date: Sep 2017 Location: Bristol, UK. Posts: 1,654	Re: High Quality Tape Recorder Yes, Hart made a kit for each section of the circuit. I bought their kit for for construction of the erase/bias oscillator, and it worked perfectly first time. I'm sure Hart are long gone now. One snag is that Stuart designed these for Bogen heads (oh no!). He gives head parameters, etc to allow adjustment for other heads, but not with any circuit or component detail. Mike

21st Apr 2020, 8:16 pm	#6
wd40addict Octode Join Date: May 2009 Location: Stevenage, Herts. UK. Posts: 1,518	Re: High Quality Tape Recorder Bob Stuart later went on to found Meridian with the late Alan Boothroyd. Obviously his interest in HiFi as a hobby must've helped with this change of direction.

21st Apr 2020, 8:18 pm	#7
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,843	Re: High Quality Tape Recorder https://www.vintage-radio.net/forum/...ad.php?t=83982

27th Apr 2020, 2:43 pm	#8
Paulus.d Hexode Join Date: Mar 2008 Location: Margate, Kent, UK. Posts: 355	Re: High Quality Tape Recorder Some people built this project? did anyone complete the layout drawings so it can be built again using modern components>

27th Apr 2020, 3:11 pm	#9
Boulevardier Octode Join Date: Sep 2017 Location: Bristol, UK. Posts: 1,654	Re: High Quality Tape Recorder "Some people built this project? did anyone complete the layout drawings so it can be built again using modern components?" If it's the Stuart tape circuits you're talking about, yes, I built them. Stuart used boards called "Lektrokit". I don't know what these are/were, but I just used standard Veroboard. Hart produced custom PCBs for their kits - the only kit I bought from them was for the HF oscillator section (because it got me all the ferrite components in one go). Veroboard is obviously much more fiddly, but worked fine for all the other sections. The original ICs are now unobtainable, but modern low-noise op amps or discrete components can be substituted. They are very simple, but very effective, semi-professional standard circuits (IMHO!) Mike