ODS #183 PCB build.

[jazzbass]

Hi ijedouglas,

thanks for the tip, now it sounds great. I haven't measured the voltages yet but the amplifier has really changed for the better.
I'll check the tensions tomorrow.

Franco

[jazzbass]

Hi everybody and specially ijedouglas

I connected the 220 Volt PT instead of the previous 240 Volt connection as suggested by ijedouglas and measured the new voltages. Here are old and new voltage values:

OLD

B+ 486
B2 486
B3 455
B4 380
B5 374

Bias 2 Valve -47,4

NEW

B+ 452
B2 450
B3 428
B4 355
B5 352

the values are close to what reported on Ampgarage referred to a real # 183 which are:

B+ 465
B2 464
B3 441
B4 324
B5 316

Franco

[martin manning]

This result looks good, but seems to be the opposite of what I would expect. If the line voltage is applied to the 220V primary connections you should see higher secondary voltage than the case where it is applied to the 240V connections.

[neskor]

This result looks good, but seems to be the opposite of what I would expect. If the line voltage is applied to the 220V primary connections you should see higher secondary voltage than the case where it is applied to the 240V connections.

yeah, I was thinking the same
something is wrong there
maybe you mix primary wires for 240V and 220V

[ijedouglas]

This result looks good, but seems to be the opposite of what I would expect. If the line voltage is applied to the 220V primary connections you should see higher secondary voltage than the case where it is applied to the 240V connections.

You are right. I think the primaries may be swapped but the end result is correct

[jazzbass]

This result looks good, but seems to be the opposite of what I would expect. If the line voltage is applied to the 220V primary connections you should see higher secondary voltage than the case where it is applied to the 240V connections.

Hi, Martin, ijedouglas, neskor...

I made the same considerations before inverting the wires but I wanted to try the same with the result of obtaining more or less the correct voltages.

I think I have not made any mistakes because I followed the indications indicated on the label of the transformer that I had built with my specifications taken from the diagrams found on Ampgarage. I am attaching a photo of the label.

The sounds I get from the amp are very nice, a great clean, a great boost, a good OD even if I can't push it like in the demos I listened to on youtube (maybe I made a mistake ?!).

Excluding the JM that I had previously built and which I consider to be the best amplifier ever built, I like the #183.

I built # 183 out of curiosity and because with the JM did not have an OD channel.

Do you think it is possible to build an amp with the wonderful cleans of the JM and the ODs of the # 102?
Thank you all for your generosity and patience.

Franco

[jazzbass]

Hi ijedouglas,

certainly every component changes, for better and for worse, the sound of an amp. For example the choice of speakers, I believe, greatly influences the sound but rightly tubes are also important.
After installing the tubes I had at home, I am tempted to take no chances and mount the 7025, which tubes do you prefer in this amp?

Franco

[ijedouglas]

Hi Franco,

Regarding the PT primaries... looks like you have them correctly configured. If the voltages look good and the amp sounds good...it is good

I currently have GE 12AX7WA in my 183 and really like them. I think that was what was in the original. There are others here with far more experience with tube types and tube rolling but I have found that even tubes of the same make/model will sound different. I have had the most luck when using well balanced tubes. Most of all, let your ears and not your eyes decide

[digi2t]

My experience so far with tubes;

I have a pair of '60's NOS RCA ribbed long black plates in V1 and V2, a JJ ECC803S in the PI, and EHX 6CA7's in the power section. It shines in all configurations.

For the second unit, I have a JJ ECC83 in V1, a JJ EC803 in V2, a Sovtek 12AX7LPS in the PI, and the EHX 6CA7's in the power section. To tell you the truth, both sound amazing, but my brain gives an edge to the RCA's. Not really sure if it's the tubes, or just imaginary mojo bias (likely!), but not the first time I've used old RCA tubes, and they never disappoint.

[jazzbass]

Hi ijedouglas, hi digi2t, hi everyone,

Checking the layout of AA Electronics # 183 I noticed a difference with the layout of Tony Albany owned by TAG, the connections of the Rock / Jazz switch are different, the right contact in the Jazz position in Tony's Layout is connected to the left center of the switch while that of AA Electronics is connected to the left Jazz.
I think the error is in the layout of AA Electronics.
Before turning on the soldering iron, I hope someone will get some answers.

Franco

[telekingdom]

Both have a significant error that makes a big difference/change in the tone on a 183.

[jazzbass]

Hi telekingdon,

yours is shocking news ..... I just finished building my first # 183.
Well if both layouts contain errors where can I find the correct Layout?
My # 183 now sounds good after I changed the bass pot and replaced it with a 500K one (as Nik di Ceriatone did). Certainly you have found and corrected the errors, can you please explain what they are? Thank you

Franco

[talbany]

Hi telekingdon,

yours is shocking news ..... I just finished building my first # 183.
Well if both layouts contain errors where can I find the correct Layout?
My # 183 now sounds good after I changed the bass pot and replaced it with a 500K one (as Nik di Ceriatone did). Certainly you have found and corrected the errors, can you please explain what they are? Thank you

Franco

Well if both layouts contain errors where can I find the correct Layout?

Franco
The wiring of the Rock Jazz switch in the layout I did in the files section was taken directly from ODS ser #183 By Shad Dameron who took possession and blue printed the entire amp.Then it was double checked and triple checked .Also the one in the files section was the first layout of #183 posted on the www.
As far as replicating the clean sound of the JM into a 102 style amp is not possible, mainly due to the addition of the reverb/Mixer section implemented in the JM...Apples and Oranges
BTW. In an ODS design? you change the sound of the clean channel, also changes the sound of the overdrive
Tony

[jazzbass]

Hi Tony,

thanks, your help and your experience are always precious, I was a little scared by the generic claims that the two layouts were wrong.

I checked multiple Rock / Jazz switch schematics and in the end I chose to follow the Ceriatone one.

The amp sounds great especially after I replaced the pot bass from 250K to 500K.

However, I would like to improve the performance of the amp when the switch is in the Jazz position, in this position the overall perceived volume is very low compared to the Rock position.

Franco

[drew]

Both have a significant error that makes a big difference/change in the tone on a 183.

You’re just going to leave this cryptic pronouncement here?