Fitting a tweeter to a Gondolier

[kirstyd]

Just wondering if anyone has done the above and if so what sort of tweeter did you use ?

[RojDW48]

It's going back a bit but I added a tweeter to another RP (HMV I think) which had a biggish elliptical. IIRC it was a little Sony cone tweeter from a scrap cab and I used something like a 4uF stopper cap - there was a little improvement.

[Edward Huggins]

The 10" x 6" Celestion speaker fitted to the Hacker GP42 had a relatively poor HF plot that falls off rapidly above 7 Khz.
It should have been a twin coned unit - I just don't know why Hacker did not specify this?!
If you are able to mount a 3" coned unit concentric to the main speaker then fine, but I don't think there will be enough clearance for this. Also there is not room on the baffle for another (even tweeter sized) speaker.
I would suggest a 9" x 6", 4 ohm, auto speaker (Halfords) with a built in tweeter. Although not original, it may sound far better. Do let us know how you get on.

[Radio Wrangler]

I laughed when I read the title of the thread. Surely it's better to add a tweeter to a gondola than to a gondolier... there'll be a lot less screaming when you drill the holes

Way back, I added Motorola piezo-tweeters to a number of things and found them successful in a number of cases. Worth trying if you can find them. If you want to add moving coil tweeters, you'll need to arrange better crossovers than just a series capacitors, you'll want to take lthe load of the large speaker off of the amp or elsa at some frequencies it will rob power from your good tweeter.

Most hifi tweeters are not very sensitive, but that's OK when mated with insensitive hifi drivers for the other bands. Old record player speakers are quite sensitive to eke out amplifier power, so finding a sensitive enough tweeter to hold up its end of the deal might be a challenge

David

[BRASSBITS]

HI
having read this thread and being a gondolier owner myself got me thinking
what would be the Consequences of fitting a 4 ohm or a 8 ohm speaker in place of the 15 ohm speaker I know it would affect the volume but would it cause any damage to the amp at all
Mick

['LIVEWIRE?']

IMHO, It's not a good idea to connect a lower impedance speaker than that originally specified as it will, correct me if I'm wrong, increase the current in the o/p transformer secondary, which, in turn, will increase that flowing in the primary. The output transformer fitted was designed to match a 15 ohm load, and it would be best to leave it that way.

[mhennessy]

I've never had an opportunity to listen to (or measure) the speaker used in the Gondolier, so I can't yet confirm or refute reports of poor HF.

What I can say is that the Goodmans unit (T27B/61004/15) used in the Mayflower has pretty impressive HF performance for such a large unit, and wonder if it's worth trying one of those as a substitute?

Also, the Celestion used in the later Grenadier also has a very healthy HF output.

On the strength of those facts, it's always seemed strange to me that Hacker would have fitted a speaker that apparently doesn't go beyond 7kHz to an expensive record player. But anything is possible, I guess... After all, the 5-by-8 Goodmans fitted to many of their radios was seriously lacking in HF - fine for AM, of course.

Naturally, it could be that the cartridge is lacking HF - or perhaps even the amplifier? If you can, it would be interesting to feed in some audio from a CD player or similar, which would give a better idea of what the amplifier and speaker is able to do. Set treble to max and bass to min to get a nearly flat response from the amplifier (3dB lift at HF).

One day I hope to measure one of these (Goodmans T27/31004/15), and will report back in detail as soon as that happens. I will also measure the Mayflower speaker at the same time.

In the meantime, I'd consider trying one of these: https://cpc.farnell.com/eurotec-inte...e-1/dp/LS00486

With a bit of ingenuity, it should be possible to mount this in front of the existing speaker - thus saving having to modify the baffle. I reckon that something like 3mm hardboard or MDF would do the job - start by cutting a piece that is the same basic size as the existing speaker, and mount the tweeter in the middle. Then cut out as much as you can around the tweeter (but within the confines of the original speaker) to allow the sound from the main speaker to get out. That tweeter is tiny, which makes it a good candidate for this kind of work.

The only caveat to the above advice is that I haven't seen a Gondolier baffle, so don't know what obstructions have been left when they cut the openings for the speaker (they usually leave something there to help to keep the grill flat). If you have to move the tweeter off-centre to clear an obstruction, then so be it. If you were really lucky, the obstructions might even work in your favour...

You will need a crossover - which might be as simple as 1 capacitor in series with the tweeter - try 2.2uF as a start. If you that there's too much HF, put a resistor in series with the tweeter. If you do that, you might need to reduce the value of the capacitor. If you put 4.7 to 10 ohms in series with the tweeter, you find that 1uF is adequate. Also, try flipping the polarity of the tweeter - it will sound different each way, so pick the one you like best.

Crossover design is something of a black art, so expect to experiment a bit before settling on the values that sound best to you. Croc-clip test leads would be ideal. I will point out that everything in the previous paragraph was total guesswork, as I haven't measured either the Gondolier speaker or the tweeter (although I do have one of those tweeters somewhere still in its box, so could do measurements if needed).

Good luck,

Mark

[Radio Wrangler]

It's also possible to increase the impedance of an 8 Ohm tweeter with a small transformer to make the crossover a bit easier and a bit more efficient. The transformer only has to handle the tweeter bandwidth and the tweeter power.

Tweeters are pretty cheap so it's something worth playing around with, but as Mark says, check you're not trying to overcome a problem which has arisen elsewhere.

David

[BRASSBITS]

after reading marks post
does anyone know the difference between the two goodmans speakers fitted to the mayflower Goodmans unit (T27B/61004/15)
and the one fitted in the gondolier part number T27/31004/15
Mick

[mhennessy]

I've been asking that question for years

https://www.vintage-radio.net/forum/...82784&p=523447

Does anyone here know?

The later examples might have switched to a Celestion speaker - though not the same one as used in a Grenadier, as far as I've seen.

[kirstyd]

i have two of these machines .Whilst the older machine [1969]has the good mans speaker the newer one [1971 has an unbranded speaker.The tweeter pictured is the one i am thinking of using .Its two inch and just fits nicely in front of the main unit .the four fixing holes matching up to the slats on the baffle board.I have already cobbled the thing together using a 4 UF non polarised cap that i found in my box of junk and i have to say the difference in sound is quite remarkable .

[Nickthedentist]

Originally Posted by kirstyd

i have two of these machines .Whilst the older machine [1969]has the good mans speaker the newer one [1971 has an unbranded speaker.

The one you've pictured is a Celestion; it will be stamped on the card terminal panel.

[BRASSBITS]

Originally Posted by mhennessy

I've been asking that question for years

https://www.vintage-radio.net/forum/...82784&p=523447

Does anyone here know?

The later examples might have switched to a Celestion speaker - though not the same one as used in a Grenadier, as far as I've seen.

I have seen four different versions of this speaker
the normal one fitted in the gondolier.
one finished in silver a goodmans not the celestion unit
another one in grey with different apertures in the frame
and one again in grey with a transformer mount
near the wire connections

[mhennessy]

Ah yes - that's the Celestion. Look carefully at the terminal board, where "Celestion" should be stamped on the card. It can be hard to see.

That one has an alnico magnet, whereas the later Grenadier uses a Celestion with a ferrite magnet. There's a good shot of that model here: https://youtu.be/kqCWXPx6XWM?t=612

Looking at it, that tweeter does look quite large - the CPC unit has a much smaller magnet system. I'm worried that putting such a large object in front of the speaker might affect the sound of the main speaker makes in an adverse way, but if you're happy, then that's a result

Just out of interest, I've dug out the CPC tweeter that I mentioned earlier. I don't know why there's hardly any info on it, not even the basic dimensions, so here goes:

Overall, it's 58mm square, and only 20mm deep. The faceplate is 2.7mm thick, and it's designed to fit a circular opening of around 50mm. The magnet diameter is 38.5mm.

The thinness of the unit appeals to me for an application like this. I originally bought the tweeter with the idea of adding it to a Sovereign II, but never got around to investigating it properly.

This tweeter is very reminiscent of the Audax units that were so popular back in the '80s and '90s. It's a bit late to dig out my measurement mic, but I might do that in the future.

If anyone happens to have a spare front panel from one of these record players - complete with the main driver, then I'd be happy to investigate further, and come up with a sensible crossover design. These tweeters are cheap, and - most importantly - readily available. meaning that anyone in future would be able to replicate the design.

Cheers,

Mark

[RojDW48]

Originally Posted by kirstyd

i have two of these machines .Whilst the older machine [1969]has the good mans speaker the newer one [1971 has an unbranded speaker.The tweeter pictured is the one i am thinking of using .Its two inch and just fits nicely in front of the main unit .the four fixing holes matching up to the slats on the baffle board.I have already cobbled the thing together using a 4 UF non polarised cap that i found in my box of junk and i have to say the difference in sound is quite remarkable .

That's very similar to the cone tweeter I used with the HMV RP. As Mark suggests, there could be a smoother transition to be had with a bit of judicious fiddling with the x-over.

[BRASSBITS]

Originally Posted by BRASSBITS

I have seen four different versions of this speaker
the normal one fitted in the gondolier.
one finished in silver a goodmans not the celestion unit
another one in grey with different apertures in the frame
and one again in grey with a transformer mount
near the wire connections

I forgot to mention I have seen the Goodmans fitted to Gondoliers with plain cones and with doped edge cones