|
Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
|
Thread Tools |
14th Oct 2017, 10:41 pm | #1 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Three stage, single ended, Portable Record Players
Very few portable record players made in the 1950s and 1960s used this kind of amplifier configuration. I have a Pye "Playboy" from 1958 using an ECC82 (interesting, as by then, the ECC83 was available) and a EL90 (a 6V6 tetrode look-alike).
This has been fully restored, the only changes being the fitting of a stereo-compatible cartridge and the faulty electrostatic tweeter being replaced with a 2.5" coned unit. I did not attempt to repair the Isophon unit as I prefer the sweeter sound of the coned driver, especially given the rather "forward" sound characteristic of a tetrode. The high-gain circuit uses negative feedback to advantage and sounds superb. An greatly underrated player and seldom mentioned here. The point of this, er, rather nerdish Post is to see if esteemed Members know of any other players using a simlar circuit. I only know of a 1955 EAR which used a ECC83 and an EL84. There was a 1957 Rucogram that used these valves, but only one of the ECC83 triodes was used. Anyone?
__________________
Edward. |
15th Oct 2017, 9:38 am | #2 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
|
Re: Three stage, single ended, Portable Record Players
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
15th Oct 2017, 10:55 am | #3 |
Octode
Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
Posts: 1,377
|
Re: Three stage, single ended, Portable Record Players
Hi Edward,
The Ferguson 396G stereo portable, subject of a thread on this page of the forum, would appear to use 1/2 an ECC83 and an EL84 in each channel. The 658RG circuit I posted uses 2 halves of an ECC83 driving an EL84 in each channel. Both channels drive a common output transformer but it is still stereo! The book describes it as 'phantom push pull' but in essence its a three stage single ended amp as far as I can tell. That was the only circuit using these valves I could find. The UCL83 seemed (at least for Ferguson) a more common choice for their portable players having looked through their circuits. All the best Nick |
15th Oct 2017, 2:07 pm | #4 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
|
Re: Three stage, single ended, Portable Record Players
__________________
Frank |
15th Oct 2017, 2:23 pm | #5 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,787
|
Re: Three stage, single ended, Portable Record Players
I wouldn't have thought there was much point in having a three stage single ended amp in a record player with a crystal or ceramic cartridge. You don't need that much gain, even with full tone controls.
|
15th Oct 2017, 4:58 pm | #6 | |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Re: Three stage, single ended, Portable Record Players
Quote:
Also the "Phantom Push-Pull" model, is not really a single-ended circuit as such. The advantage of a 3 stage single-ended circuit is that it allows for good use of feedback and tone controls given it's higher stage gain.
__________________
Edward. |
|
15th Oct 2017, 5:00 pm | #7 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Re: Three stage, single ended, Portable Record Players
Yes, an obscure French model. Oh la la! A nice litte circuit though. Thanks for sight.
__________________
Edward. |
15th Oct 2017, 6:03 pm | #8 |
Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 899
|
Re: Three stage, single ended, Portable Record Players
Hi Edward
i think i may have the EAR version you refer to .It was an absolute wreck when i got it [from a damp garage] but by replacing some caps and the ECc83 its working heres a couple of photos .I have rebuilt part of the cabinet and recovered it with some leftover rexine from another job .It was blue and grey with the usual cream plastic grill.the valves are EZ80/EL84 and the ECC83 |
15th Oct 2017, 8:15 pm | #9 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Re: Three stage, single ended, Portable Record Players
Yes, that's the one. It's from 1955 and these sound great. You made a really good job of this one, it looks super, and I like that replacement mesh grille!
__________________
Edward. |
16th Oct 2017, 7:03 pm | #10 |
Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 899
|
Re: Three stage, single ended, Portable Record Players
hi Edward
its not finished yet .Whilst the amp works well when i got it the shielded cable from the arm was disconnected from the amplifier [ .i reconnected it to where i thought it should go and it works but theres lots of distortion and hum also the volume can only be turned up a little before everything distorts .must get it out and have another look at it .Its a nice amp with a great big speaker that just fits into the cabinet and b y the looks of the cutout in the cabinet you may have had the option of an autochanger.[A few more photos of how it used to look here] |
17th Oct 2017, 8:22 am | #11 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Re: Three stage, single ended, Portable Record Players
A super "before and after" story. I think it was only ever made as an automatic version using the Collaro RC54. Yours may be an adaption using Collaro 3 speed single player and this MAY have a very rare, high output, Studio "T" cartridge fitted (gives 1 volt!) causing an overload. The amp will only need a medium output cartridge.
__________________
Edward. |
17th Oct 2017, 6:54 pm | #12 |
Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 899
|
Re: Three stage, single ended, Portable Record Players
hmmm interesting .I will take a closer look at the cartridge and let you know [see] what i find
|
25th Oct 2017, 5:35 am | #13 |
Triode
Join Date: Jun 2014
Location: North Yorkshire, UK
Posts: 20
|
Re: Three stage, single ended, Portable Record Players
Hi Edward.
Amongst my collection of stereo valved amps I'm playing with, I have a french portable wide stereo record player. It's similar to my Ferguson 396G as mentioned in my post, with detachable speakers. This one however has three stage rather than two stage single ended amplification: Two ECC81 pre-amp & two EL84'S output: Two valves per channel with the ECC81's being two stage pre-amps. As with my unusual Ferguson 396G I cannot find a circuit diagram for this. It's made by Gilliard of Paris. No model number anywhere but the date of 1961 is rubber stamped inside the plywood case. It works well with quite a lot of volume over the three valve Ferguson, except this one has issues with tone control, but I think the bass control pots has been wired in reverse because it seems to increase base on one channel whilst reducing on the other! It's had work done before I owned it. Good quality Mullard grid caps. Newer volume pot & probably other caps too. I hear these ECC81 pre-amp valves are an odd choice for single ended or so I'm told? I think the output transformers are replaced as there's severe scorching in the cabinet next to one output transformer but there's no scorching on the transformer itself, which is functional. Is this amp similar to what you have mentioned? I'll post some pictures. Kind regards, Rickim. |
25th Oct 2017, 10:32 am | #14 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Re: Three stage, single ended, Portable Record Players
No this amplifier is diffierent as it's stereo. The transfomers are by Audax, a good make and the whole thing looks a well built unit.
__________________
Edward. |
25th Oct 2017, 9:57 pm | #15 |
Triode
Join Date: Jun 2014
Location: North Yorkshire, UK
Posts: 20
|
Re: Three stage, single ended, Portable Record Players
Ah ok thank you. But still a 3 stage single end amp (per channel) with good bass & treble control though?
Nice to hear it's a good quality amp. I've no idea what gives it such credentials other than a reasonable & compact layout & the output transformers being good quality even though they're likely replacements. Regarding the base control acting more like balance (but definitely isn't as that control is to the right of the volume). is it likely that the last repair done when the caps & output transformers were replaced, that the bass pots have been wired wrong in that one increases whilst the other decreases? There is evidence some of the 4 pots have been removed as the grip washer is missing off the bass & balance. Also the volume / power-on is a plastic-shaft replacement, it's plastic shaft being cut short to correct length crudely by clippers not sawn. They need cleaning or replacing anyway. Should I start a new thread for this amp & see if I can get a diagram or some information on similar amps? I've not finished with the Ferguson 396G yet but my questions of tone-control improvements & input impedance matching have gone rather stale, so I've been reading all sorts of information old & new to try to better understand it all in hope of working it out myself. Thanks again. Rickim |
26th Oct 2017, 9:05 am | #16 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
|
Re: Three stage, single ended, Portable Record Players
I think the reason why the responses from Members may have "gone stale" on the Ferguson 396G is because there may not be much enthusiasm for supporting what you are trying to do with this. It goes outside the normal practice for this type of player.
As to your French amp, the tone control circuitry may have been tampered with. Threre is no way, for example, that a bass control should work like an inter-channel balance control.
__________________
Edward. |