What effect does the Jazz switch have on an ODS?

[LooseChange]

What effect does the Jazz switch have on an ODS?
Thanks!

[briane]

less volume, less grind. a bit smoother in some ways. Some like it, but I have gotten to leaving it out as it is not as useful as other options IMO.

[bluesfendermanblues]

less volume, less grind. a bit smoother in some ways. Some like it, but I have gotten to leaving it out as it is not as useful as other options IMO.

I still have on my faceplate, but never use it. Never have.
Maybee its usefull for guys playing big body jazz guitars along with the mid swithch engaged ?

[sidehatch]

I've never used it on any other D clones I've owned. I've thought it takes a bit of tone away.

[Pete]

What effect does the Jazz switch have on an ODS?
Thanks!

My $0.02, in clean mode, it takes out the frequencies that are likely to cause a big body archtop to feed back. This of course, sounds like a drop in volume and fullness and you can get away with turning the amp up with such a guitar.

[marcos]

When you use the ODS in Jazz Position try turning up the Bass pot past 2 o´clock. Below this setting most amps sound thin. Turning ther bass up full will yield more bass than the Rock setting, hence the name "Jazz".
I guess the original intention was to offer both a Fender style eq(Rock)and a shelving eq(Jazz) a la Ampeg or Gibson in one amp.This requires a certain compromise as far as pot values and taper are concerned.In the first fifty or so silverface amps the tone controls are actually easier to dial in in the Jazz mode, IMO, due to the larger pot values, which are better suited fot the shelving type eq

[jelle]

+1

In those silverface amps, many things were different. The Rock setting was quite agressive.

[marcos]

I remember one amp that was sort of a transition model, but I don´t remember the serial no.Probably 50 something, made in 1980, with the accent switch ,but no ratio control. It had a 250 KL Treble pot, but still a 1 Meg Bass pot, and also an eq similar to the Skyliner, i.e. 10n cap with 250K Middle pot, but 100K Slope resistor and 500 pF Treble cap.As far as I can remember it had a lot of bass and low mids, but a fairly aggressive top end when in serious overdrive.Used to belong to a friend of mine.Marcos

[marcos]

Another small detail: The reason there is a 1000 pf cap across the Bass pot is to short highs to ground in Jazz mode, in order to make the Bass control work more effectively.If you build an amp without the Rock/Jazz switch you might just as well leave it out IMO.It does,however, affect tone in Rock mode slightly.I prefer the sound without it

[jelle]

Marcos,

There is also one amp from that era that had a 250K treble pot, and a 350K Bass pot. 10nF mid cap. Also the 220K//500pf network at v1b. Accent switch.

Jelle

[marcos]

Looks like another interesting transition model.Looks like HAD started with 1 Meg pots for Bass and Treble, then lowering the pot of the Treble pot to 500 K, then 250 K, then also lowering the value for the Bass pot, finally arriving at the 250 K Treble, 100K Mid, 250 K Bass values that I believe are referred to as the Classic eq in these pages.BTW I have seen two amps that had a 100K Audio pot for the Middle control, which seems to make more sense than the 100 KL pot I see in most schematics.These pots were probably harder to obtain than the common 100 KL.
One more thing: Don´t try to build an amp based on the Nr 40 Schematic,
you will be disappointed.I understand the schematic was drawn from a photograph, which explains the numerous inaccuracies.IMHO trying to build an amp off of this schematic would be a waste of time

[jelle]

Marcos,

The real 70's dumbles can be fun though. And agreed, the schematic on this forum is wrong.

And yes, the evolution of these tonestacks and other parts of the circuitry is interesting. I tend to like the older stuff a lot too

Have fun!

Jelle

[marcos]

Jelle, I totally agree with you. I´ve owned my silver ODS since 1979, it has a voice all its own.I´ve used it on countless gigs, and I got a lot of compliments for my sound. Especially from the P.A .people and fellow musicians.Keep rockin guys

[bluesfendermanblues]

Looks like another interesting transition model.Looks like HAD started with 1 Meg pots for Bass and Treble, then lowering the pot of the Treble pot to 500 K, then 250 K, then also lowering the value for the Bass pot, finally arriving at the 250 K Treble, 100K Mid, 250 K Bass values that I believe are referred to as the Classic eq in these pages.BTW I have seen two amps that had a 100K Audio pot for the Middle control, which seems to make more sense than the 100 KL pot I see in most schematics.These pots were probably harder to obtain than the common 100 KL.
One more thing: Don´t try to build an amp based on the Nr 40 Schematic,
you will be disappointed.I understand the schematic was drawn from a photograph, which explains the numerous inaccuracies.IMHO trying to build an amp off of this schematic would be a waste of time

Marcos, could you point out where inaccuracies are?

Best regards Claus

[marcos]

Ok here we go:
First : The tonestack. The Treble pot should be 500KL, you can see in the pictures that it is much larger than the CTS pots. The cap is a 510 pF ,at least it is in my amp.The Middle pot is a 250 KA (10 % taper).The caps wired to the Bass pot should be .002 (top to wiper) and .022 (wiper to
10 K resistor.)The Bass pot is a 1 Meg Audio (30% taper).You can see that this is a completely different tone stack.The grid stopper at V 1a is 56K.
I have to speculate about the input section of the Overdrive: I have seen at least three amps with this: First, a 220 K resistor to ground with 500 pF cap across it, then a 1.2 Meg resistor followed by 33 K to ground, then another 56 K grid stopper.A tech who has serviced a number of these amps (# 19 - #45 ) told me most of these amps were very similar.
There´s one thing you can see for yourself in the pictures: The 180K resistor to ground after V2b is connected directly to the .01 coupling cap, so it does not form a voltage divider with the large resistor in series with the cap, as shown in the schematic.I don´t know the value for the big resistor, it has been changed in my amp at some time.
The PI input coupling cap is .005, you can roughly estimate the value of the orange drops by their size in the pictures.
The cap on the Accent switch should be a 1 µF electrolytic, the 100n in the schematic would have very little effect across the 100 R resistor in the feedback circuit.2.2 µF is also possible here.
I hope I haven´t forgotten anything.Well,yes, the grid stoppers on V2a and V2b should also be 56 K.
The amp I mentioned in an ealier post (once belonging to a friend of mine) was very similar, except it had a 250KL Treble pot, and the .022
cap on the Bass pot was missing, making it much bassier sounding.
Hope all this information makes things a little clearer