Bryan Amplifier

[Retrospective]

Thanks,i've ordered some plugs that will hopefully get the (bryan amp) up and running then i'll try the 1500(radio) with that first

[Retrospective]

Amp's up and running and I'm impressed!

Unfortunately the radio doesn't want to play, everything seems OK, just no output.

Back to the amp, what a gem. It's extremely fast and musical yet you can pick out all of the detail. There's a lot more detail than the Sugden. The bass is also better defined and there's an impressive cohesion across the frequency range. Neither treble nor bass dominates,vocals are really impressive.

18 watts? I'm not convinced. It seems a lot more muscular. The volume control is currently on zero and it's still a bit loud in quite a large room !

[Trevor]

I am pleased that you like your bryan amplifier I have about 9-10 of them in various condition
Moving on to the tuner it may have the dreaded af 11* disease can you send us a picture of the insides it should be a simple repair
regards Trev

[Retrospective]

Is af11 disease something you can see ? i'll try and post some pics up thanks for all your help gents

[Retrospective]

i've found some af's 14/15/16 but no 11's i've took some pics so i'll try and get them up asap.

['LIVEWIRE?']

Originally Posted by Trevor

I am pleased that you like your bryan amplifier I have about 9-10 of them in various condition
Moving on to the tuner it may have the dreaded af 11* disease can you send us a picture of the insides it should be a simple repair
regards Trev

This refers to the use by many manufacturers in the 60s of AF114/115/116 &117 Transistors(and the earlier OC170 series)all of which suffer from the
'tin whisker' problem, as a search of this forum will reveal. Personally I
replace any of the above 'on sight' with the later AF124/125/126/127 series
These don't have the 'tin whisker' fault, and, although the pin-outs are
different, can usually be fitted in place of the 117 series without too much
trouble.

[Retrospective]

internal pic of 1500 radio.Are the AF replacements easy to fit ? please bear in mind this is my first attempt to rejuvenate a classic radio

[Retrospective]

Can anyone explain the other functions of this amp,rumble in/out and filter in/out ? excuse my ignorance

[Trevor]

Rumble is a high pass filter this is used to cut out low frequency noise from a turntable normally below about 30 hz in means you are using the filter out is a flat response you can see its operation if you look at the woofer cone of your spk while playing a record
The filter is normally a high cut operating at about 6-9 khz try tuning in the noise between fm stations and using it
If you look up re the AF problem you can sort out your tuner they normally go short between collector and screen you can use a voltmeter to sort it
regards Trev

[valvekits]

I managed to draw out the schematic of the power amp board with silicon transistors fitted. Hope this might be of future use.
I am not sure of the correct bias current ?



Eddie

[Trevor]

Sorry to correct you but your drawing is incorrect !
The base junction of the bottom output transistor should be connected to the collector of the pnp driver transistor which is incidently shown upside down also the 4 uf capacitor connected to the 33 ohm resistor is an error somewhere there is a series resistor to set closed loop gain.
Also the junction of the in4818 diodes should also be connected to the mid rail i.e. the amplifier side of the output capacitor
Please don,t not think of me as awkward just trying to help
Please refer to the picture in post no 14 you will see a photo of the circuit diagram
The bias should be about 25 mA ,this can be measured as 25 mv across the bottom 1 ohm emitter resistor
best regards Trevor

[valvekits]

Thanks for your input Trevor. I had also wondered about this quite a bit as I couldn't find the data on the pnp e line transistor which doesn't have any markings. I had already compared it what your schematic but that was a bit blurry for me. Have a look at what I was working from below.

Cheers

Eddie

[valvekits]

Oh and I also made a top view with light shining from the underside if this helps.

Cheers

Eddie

[valvekits]

Okay here is the revised version, thanks Trevor.


Cheers

Eddie

[Trevor]

Cracking job
you are very brave to take the pc board out but it certainly shows the diagram
best regards trev

[valvekits]

I noticed that I also missed a couple of caps off, these mistakes occurred when I tried to tidy up my original sketch.

Now anyone following this thread, could be forgiven for wondering if there was a "Golden Age" of germanium transistors. By that, I mean designers must have spent years struggling with germanium transistors; what with thermal runaway problems and the like. But at some point they must have finally got it nailed and then along came silicon transistors and suddenly it was all over.Having acquired a Bryan 9000 I can now fully appreciate Trevor's interest in the germanium - silicon changeover period which must have been very short in relative terms.
I do remember working on some amps in the early 70's that had the AD family output transistors and they weren't that bad sounding.
It has left me wondering how the Bryan 9000 compares with germanium vs silicon output transistors.


Cheers

Eddie

[Trevor]

I have obtained yet another of these wonderful amplifiers $0 years old all original components and working really well
This 1 is an all silicon unit and once again it shows the superb product that this was
Can anyone give me any further details on these amplifiers
regards trev

[pentasuser]

Hi
Reading this thread reminded me that I had a Bryan 900 sn 2653 stored in a cupboard since 1983 (how time flies), and I'm encouraged to see if it still works. It was in working order when it was put away but in view of the amount of time that's passed I wonder if there are any checks I should make before plugging in. I'm a bit concerned about the condition of the transformer which appears to be insulated with paper which has now gone a bit brittle.
I inherited this amp from an uncle many years ago and didn't realise they were so well thought of.

Does anybody know how the 900 relates to the 9000, was it the budget version or the preceding model?

Also does anybody know the approximate age of this model and what it might be worth.

Regards Pete

[Trevor]

The 9000 has a high and low filter as well as mains outlets which are illegal to use anyway. That's all that is different! Power and distortion etc are the same.

I would make up a lamp limiter with a 60 watt filament lamp and power it up with the lamp limiter. If the amplifier was working when put away I would be suprised if it did not work. These are very long living beasts.

Best of luck with it a really nice amplifier.

Regards

Trevor

[Synchrodyne]

Originally Posted by valvekits

Now anyone following this thread, could be forgiven for wondering if there was a "Golden Age" of germanium transistors. By that, I mean designers must have spent years struggling with germanium transistors; what with thermal runaway problems and the like. But at some point they must have finally got it nailed and then along came silicon transistors and suddenly it was all over. Having acquired a Bryan 9000 I can now fully appreciate Trevor's interest in the germanium - silicon changeover period which must have been very short in relative terms.
I do remember working on some amps in the early 70's that had the AD family output transistors and they weren't that bad sounding.
It has left me wondering how the Bryan 9000 compares with germanium vs silicon output transistors.

The “’Golden Age’ of germanium” is an interesting proposition. It would seem that the much better thermal stability of silicon transistors very quickly won the day, and overwhelmed any performance differences that may have been in favour of germanium. Some amplifier manufacturers were evidently enough concerned about the germanium thermal stability drawback that they waited until silicon transistors were available at reasonable prices before making the transition to solid state. I suppose that one might date the silicon transition as starting en masse around 1967-68, although there were scattered earlier examples, e.g. Goodmans. Those manufacturers who had started early with germanium often made the change to silicon fairly quickly, Leak being an example. Of the UK manufacturers, I think that Armstrong might have been a late adopter of silicon (with its 600 series, circa 1973?).

Memory is not always reliable, but in the recesses I have a recollection of reading somewhere that germanium transistors were actually easier to deal with in the Lin quasi-complementary circuit, because there was less asymmetry (different asymptotic slopes) between the Darlington and conjugate pairs as well as gentler curving in towards the cutoff points. But I have not been able to find verification. It would seem that the symmetry issue was not overtly addressed until the silicon age, so that is some empirical support for the idea that it was not a problem until then. Or maybe it was, and the solution was simply much negative feedback, as was used by some in the silicon age (for example Leak, I think.) Some of the other silicon age solutions (or bypasses) were output triples (e.g. Quad), transformer drive (e.g. Rogers), Class A (e.g. Sugden), fully complementary (e.g. Bailey/Radford) and a diode in the conjugate pair (Shaw, Baxandall), which might then have become the norm for quasi-complementary outputs. Presumably the Baxandall diode could be used in a germanium quasi-complementary circuit if indeed such were beneficial.

Cheers,